Malaria

Infectious Agent

Malaria in humans is caused by protozoan parasites of the genus Plasmodium : Plasmodium falciparum, P. vivax, P. ovale , or P. malariae . In addition, P. knowlesi , a parasite of Old World (Eastern Hemisphere) monkeys, has been documented as a cause of human infections and some deaths in Southeast Asia.

Transmission

Plasmodium species are transmitted by the bite of an infective female Anopheles mosquito. Occasionally, transmission occurs by blood transfusion, organ transplantation, needle sharing, nosocomially, or from mother to fetus.

Epidemiology

Malaria is a major international public health problem; 91 countries reported an estimated 216 million infections and 445,000 deaths in 2016, according to the World Health Organization (WHO) World Malaria Report 2017. Travelers going to malaria-endemic countries are at risk for contracting the disease, and almost all of the approximately 1,700 cases per year of malaria in the United States are imported.

Information about malaria transmission in specific countries is derived from various sources, including WHO (see Chapter 2, Yellow Fever Vaccine & Malaria Prophylaxis Information, by Country). The information presented here was accurate at the time of publication; however, the risk of malaria can change rapidly and from year to year (because of changes in local weather conditions, mosquito vector density, and prevalence of infection). Updated information can be found on the CDC website at www.cdc.gov/malaria.

Malaria transmission occurs in large areas of Africa, Latin America, parts of the Caribbean, Asia (including South Asia, Southeast Asia, and the Middle East), Eastern Europe, and the South Pacific (Maps 4-8 and 4-9).

Map 4-8.Malaria-endemic countries in the Western Hemisphere
Map 4-8.Malaria-endemic countries in the Western Hemisphere

In this map, countries with areas endemic for malaria are shaded completely even if transmission occurs only in a small part of the country. For more specific within-country malaria transmission information, see Chapter 2, Yellow Fever Vaccine & Malaria Prophylaxis Information, by Country.

Map 4-9.Malaria-endemic countries in the Eastern Hemisphere
Map 4-9.Malaria-endemic countries in the Eastern Hemisphere

In this map, countries with areas endemic for malaria are shaded completely even if transmission occurs only in a small part of the country. For more specific within-country malaria transmission information, see Chapter 2, Yellow Fever Vaccine & Malaria Prophylaxis Information, by Country.

The risk for acquiring malaria differs substantially from traveler to traveler and from region to region, even within a single country. This variability is a function of the intensity of transmission within the various regions and the itinerary, duration, season, and type of travel. Risk also varies by travelers’ adherence to mosquito precautions and prophylaxis recommendations. In 2015, 1,513 cases of malaria (including 11 deaths) were diagnosed in the United States and its territories and were reported to CDC. Of these cases for which country of acquisition was known, 85% were acquired in Africa, 9% in Asia, 5% in the Caribbean and the Americas, and 1% in Oceania or the Middle East.

Clinical Presentation

Malaria is characterized by fever and influenzalike symptoms, including chills, headache, myalgias, and malaise; these symptoms can occur intermittently. In severe disease, seizures, mental confusion, kidney failure, acute respiratory distress syndrome, coma, and death may occur. Malaria symptoms can develop as early as 7 days after being bitten by an infectious mosquito in a malaria-endemic area and as late as several months or more after exposure. Suspected or confirmed malaria, especially P. falciparum , is a medical emergency requiring urgent intervention, as clinical deterioration can occur rapidly and unpredictably. See Box 4-3 for frequently asked clinical questions.

Box 4-3. Clinician frequently asked questions

How do I address concerns about side effects from prophylaxis?

  • Prophylaxis can be started earlier if there are concerns about tolerating a particular medication. For example, mefloquine can be started 3–4 weeks in advance to allow potential adverse events to occur before travel. If unacceptable side effects develop, there would be time to change the medication before the traveler’s departure.
  • The drugs used for antimalarial prophylaxis are generally well tolerated. However, side effects can occur. Minor side effects usually do not require stopping the drug. Clinicians should determine if symptoms are related to the medicine and make a medication change if needed.

What should be done if a dose of prophylaxis is missed?

  • In comparison with drugs with short half-lives, which are taken daily, drugs with longer half-lives, which are taken weekly, offer the advantage of a wider margin of error if the traveler is late with a dose.
  • For a weekly drug, prophylactic blood levels can remain adequate if they are only 1–2 days late. If this is the case, the traveler can take a dose as soon as possible, then resume weekly doses on the originally scheduled day. If the traveler is >2 days late, blood levels may not be adequate. The traveler should take a dose as soon as possible. The weekly doses should resume at this new day of the week (the next dose is 1 week later, then weekly thereafter).
  • For a daily drug, if the traveler is 1–2 days late, protective blood levels are less likely to be maintained. They should take a dose as soon as possible and resume the daily schedule at the new time of day.

What happens if too high a dose of prophylaxis is taken?

  • Overdose of antimalarials, particularly chloroquine, can be fatal. Medications should be stored in childproof containers out of reach of infants and children.

Isn’t malaria a treatable disease? Why not carry a treatment dose of antimalarials instead of taking malaria prophylaxis?

  • Malaria could be fatal even when treated, which is why it is always preferable to prevent malaria cases rather than rely on treating infections after they occur.

What should be done if fever develops while traveling in a malaria-endemic area?

  • Malaria could be fatal if treatment is delayed. Medical help should be sought promptly if malaria is suspected. Travelers should continue to take malaria prophylaxis while in the malaria-endemic area.

What should be done if a traveler who took malaria prophylaxis develops fever after returning from their trip?

  • Malaria prophylaxis, while highly effective, is not 100% effective. Travelers should be advised that they should seek medical care immediately if fever develops, report their travel history, get tested for malaria, and get treated promptly if infection is confirmed.
  • Malaria smear results or a rapid diagnostic test must be done immediately (within a few hours). These tests should not be sent out to reference laboratories with results available only days to weeks later. Empiric treatment with antimalarials is not recommended as the malaria smear provides critical information for appropriate treatment. If a patient has an illness suggestive of severe malaria, a compatible travel history in an area where malaria transmission occurs, and malaria testing is not immediately available, it is advisable to start treatment as soon as possible, even before the diagnosis is established. CDC recommendations for malaria treatment can be found at www.cdc.gov/malaria/diagnosis_treatment/index.html.

Diagnosis

Travelers who have symptoms of malaria should seek medical evaluation as soon as possible. Consider malaria in any patient with a febrile illness who has recently returned from a malaria-endemic country.

Blood smear microscopy remains the most important method for malaria diagnosis. Microscopy can provide immediate information about the presence of parasites, allow quantification of the density of the infection, and allow determination of the species of the malaria parasite—all of which are necessary for providing the most appropriate treatment. Microscopy results should ideally be available within a few hours. These tests should be performed immediately when ordered by a health care provider. They should not be saved for the most qualified staff to perform or batched for convenience. In addition, these tests should not be sent out to reference laboratories with results available only days to weeks later. Assistance with speciation of malaria on smears is available from CDC (www.cdc.gov/dpdx).

Rapid diagnostic tests (RDTs) for malaria detect antigens derived from malaria parasites. Malaria RDTs are immunochromatographic tests that most often use a dipstick or cassette format and provide results in 2–15 minutes. RDTs offer a useful alternative to microscopy in situations where reliable microscopic diagnosis is not immediately available. Although RDTs can detect malaria antigens within minutes, they have several limitations. RDTs cannot distinguish between all of the Plasmodium species that affect humans, they may be less sensitive than expert microscopy or PCR for diagnosis, they cannot quantify parasitemia, and an RDT-positive test result may persist for days or weeks after an infection has been treated and cleared. Thus, RDTs are not useful for assessing response to therapy.

Both positive and negative RDT results must always be confirmed by microscopy. Microscopy confirmation of the RDT result should occur as soon as possible because the information on the presence, density, and parasite species is critical for optimal management of malaria. The Food and Drug Administration (FDA) has approved an RDT (the BinaxNOW Malaria test) for hospital and commercial laboratory use; the test is not approved for use by individual clinicians or patients. Laboratories that do not provide in-house, on-the-spot microscopy services should maintain a stock of malaria RDTs so that they will be able to perform immediate malaria diagnostic testing when needed.

PCR tests are also available to detect malaria parasites. Although these tests are more sensitive than routine microscopy, results are not usually available as quickly as microscopy results, thus limiting the utility of this test for acute diagnosis and initial clinical management. Use of PCR testing is encouraged to confirm the species of malaria parasite and detect mixed infections. As noted above, the CDC malaria laboratory can assist in speciating malaria by microscopy. It also provides PCR-based species confirmation. And, the CDC laboratory can assess malaria parasites for mutations that confer resistance to medications (www.cdc.gov/dpdx).

In resource-limited settings, and particularly in sub-Saharan Africa, overdiagnosis and the rate of false-positive microscopy for malaria may be high. Warn travelers that a local diagnosis of malaria may be incorrect. In such cases, acutely ill travelers should seek the best available medical services, and continue their prophylaxis regimen until they have a definitive diagnosis.

In the United States, reporting malaria disease is mandatory. Health care providers must report laboratory-diagnosed cases of malaria occurring in the United States and its territories to local or state health departments. More information on reporting malaria can be found at www.cdc.gov/malaria/report.html.

Treatment

Malaria can be treated effectively early in the course of the disease, but delay of therapy can have serious or even fatal consequences. Specific treatment options depend on the species of malaria, the severity of infection, the likelihood of drug resistance (based on where the infection was acquired), and the patient’s age and pregnancy status.

Detailed CDC recommendations for malaria treatment can be found at www.cdc.gov/malaria/diagnosis_treatment/treatment.html. Clinicians who require assistance with the diagnosis or treatment of malaria should call the CDC Malaria Hotline (770-488-7788 or toll-free at 855-856-4713) from 9 am to 5 pm Eastern Time. After hours or on weekends and holidays, clinicians requiring assistance should call the CDC Emergency Operations Center at 770-488-7100 and ask the operator to page the subject matter expert on call for the Malaria Branch. In addition, it is advisable to consult with a clinician who has specialized travel or tropical medicine expertise or with an infectious disease physician.

Travelers who reject the advice to take prophylaxis, who choose a suboptimal drug regimen (such as chloroquine in an area with chloroquine-resistant P. falciparum ), or who require a less-than-optimal drug regimen for medical reasons, are at increased risk for acquiring malaria and then needing prompt treatment while overseas.

In addition, some travelers who are taking effective prophylaxis but who will be in remote areas may decide, in consultation with their travel health provider, to take along a reliable supply of a full course of an approved malaria treatment regimen (see Box 4-4 for the definition of reliable supply). In the event that a traveler carrying a reliable supply is diagnosed with malaria, he or she will have immediate access to treatment. CDC recommends that the reliable supply be acquired in the United States to allow the traveler’s doctor to consider the traveler’s other medical conditions or medications when selecting an antimalarial, to avoid the possibility of obtaining counterfeit drugs in the local pharmacy or market, and to avoid depleting local resources. In rare instances when access to medical care is not available and the traveler develops a febrile illness consistent with malaria, the reliable supply medication can be self-administered presumptively. Advise travelers that this self-treatment of a possible malarial infection is only a temporary measure and that prompt medical evaluation is imperative.

Two malaria treatment regimens available in the United States can be prescribed as a reliable supply: atovaquone-proguanil and artemether-lumefantrine. The use of the same or related drugs that have been taken for prophylaxis is not recommended to treat malaria. For example, atovaquone-proguanil may be used as a reliable supply medication by travelers not taking atovaquone-proguanil for prophylaxis. See Table 4-8 for the dosing recommendation.

Table 4-8. Reliable supply regimens for malaria treatment

Drug 1

Adult Dose

Pediatric Dose

Comments

ATOVAQUONE-PROGUANIL

The adult tablet contains 250 mg atovaquone and 100 mg proguanil. The pediatric tablet contains 62.5 mg atovaquone and 25 mg proguanil.

4 adult tablets, orally as a single daily dose for 3 consecutive days

Daily dose to be taken for 3 consecutive days:

5–8 kg: 2 pediatric tablets

9–10 kg: 3 pediatric tablets

11–20 kg: 1 adult tablet

21–30 kg: 2 adult tablets

31–40 kg: 3 adult tablets

>41 kg: 4 adult tablets

Contraindicated in people with severe renal impairment (creatinine clearance <30 mL/min). Not recommended for people on atovaquone-proguanil prophylaxis. Not recommended for children weighing <5 kg, pregnant women, and women breastfeeding infants weighing <5 kg.

ARTEMETHER-LUMEFANTRINE

One tablet contains 20 mg artemether and 120 mg lumefantrine.

A 3-day treatment schedule with a total of 6 oral doses is recommended for both adult and pediatric patients based on weight. The patient should receive the initial dose, followed by the second dose 8 hours later, then 1 dose twice per day for the following 2 days.

5 to <15 kg: 1 tablet per dose

15 to <25 kg: 2 tablets per dose

25 to <35 kg: 3 tablets per dose

≥35 kg: 4 tablets per dose

Not for people on mefloquine prophylaxis. Not recommended for children weighing <5 kg, and women breastfeeding infants weighing <5 kg.

1 If used for presumptive self-treatment, medical care should be sought as soon as possible.

Medications that are not used in the United States to treat malaria, such as halofantrine or sulfadoxine-pyrimethamine, are widely available overseas. CDC does not recommend halofantrine for treatment because of documented adverse cardiac events, including deaths. These adverse events have occurred in people with and without preexisting cardiac problems and both in the presence and absence of other antimalarial drugs. Sulfadoxine-pyrimethamine is not recommended because of widespread resistance to this drug.

Box 4-4. What is a reliable supply?

A reliable supply is a complete course of an approved malaria treatment regimen obtained in the United States before travel.

A reliable supply:

  • Is not counterfeit or substandard
  • Will not interact adversely with the patient’s other medicines, including prophylaxis
  • Will not deplete local resources in the destination country

Prevention

Malaria prevention consists of a combination of mosquito avoidance measures and chemoprophylaxis. Prevention measures must address all malaria species in the area of travel and apply to both short-term and long-term travelers. Although highly efficacious, the recommended interventions are not 100% effective.

Preventing malaria involves striking a balance between effectiveness and safety: ensuring that all people at risk for infection use the recommended prevention measures and preventing rare occurrences of adverse effects. An individual risk assessment should be conducted for every traveler, taking into account not only the destination country but also the detailed itinerary, including specific cities, types of accommodation, season, and style of travel. Traveler characteristics (such as pregnancy or underlying health conditions) and malaria characteristics at the destination (such as intensity of transmission and local parasite resistance to drugs) may modify the risk assessment. Depending on the level of risk, it may be appropriate to recommend no specific interventions, mosquito avoidance measures only, or mosquito avoidance measures plus prophylaxis.

Several factors increase a traveler’s risk for malaria. Travel—even for short periods of time— to areas with intense malaria transmission can result in infection. Malaria transmission is not distributed homogeneously throughout a country, so it will be important to review the exact itinerary to determine if travel will occur in highly endemic areas. In countries where malaria is seasonal, travel during peak transmission season also increases risk. Travelers going to rural areas or staying in accommodations without screens or air conditioning will also be at higher risk. The highest risk for malaria is associated with first- and second-generation immigrants living in nonendemic countries who return to their countries of origin to visit friends and relatives (VFRs). VFR travelers often perceive themselves to be at no risk because they grew up in a malarious country and consider themselves immune. However, acquired immunity is lost quickly, and VFRs should be considered to have the same risk as other nonimmune travelers (see Chapter 9, Visiting Friends & Relatives: VFR Travel). Travelers should also be reminded that even if a person has had malaria before, he or she can get it again, and preventive measures are still necessary.

Mosquito Avoidance Measures

Because of the nocturnal feeding habits of Anopheles mosquitoes, malaria transmission occurs primarily between dusk and dawn. Contact with mosquitoes can be reduced by remaining in well-screened areas, sleeping under mosquito nets (preferably insecticide-treated nets), using an effective insecticide spray in living and sleeping areas during evening and nighttime hours, and wearing clothes that cover most of the body.

All travelers should use an effective mosquito repellent, such as those that contain DEET (see Chapter 3, Mosquitoes, Ticks & Other Arthropods). Repellents should be applied to exposed parts of the skin when mosquitoes are likely to be present. If travelers are also wearing sunscreen, sunscreen should be applied first and insect repellent second. In addition to using a topical insect repellent, a permethrin-containing product may be applied to bed nets and clothing for additional protection against mosquitoes.

Chemoprophylaxis

All recommended primary prophylaxis regimens involve taking a medicine before, during, and after travel to an area with malaria. Beginning the drug before travel allows the antimalarial agent to be in the blood before the traveler is exposed to malaria parasites. In choosing a prophylaxis regimen before travel, the traveler and the travel health provider should consider several factors. These include the presence of antimalarial drug resistance in the area of travel (see Chapter 2, Yellow Fever Vaccine & Malaria Prophylaxis Information, by Country), length of travel, the patient’s other medical conditions, allergy history, medications being taken (to assess potential drug interactions), and potential side effects. Long-term travelers, defined as people who travel for ≥6 months, have additional considerations, listed in Box 4-5. Table 4-9 lists some of the benefits and limitations of medicines used for malaria prophylaxis; additional information about choosing a malaria prophylaxis regimen can be found at www.cdc.gov/malaria/travelers/drugs.html.

Table 4-9. Considerations when choosing a drug for malaria prophylaxis

Drug

Reasons to Consider use of this Drug

Reasons to Consider Avoiding use of this Drug

Atovaquone-proguanil

  • Good for last-minute travelers because the drug is started 1–2 days before travel.

  • Some people prefer to take a daily medicine.

  • Good choice for shorter trips because the traveler takes the medicine for only 7 days after traveling rather than 4 weeks.

  • Well tolerated—side effects uncommon.

  • Pediatric tablets are available and may be more convenient.

  • Cannot be used by women who are pregnant or breastfeeding a child that weighs <5 kg.

  • Cannot be taken by people with severe renal impairment.

  • Tends to be more expensive than some of the other options (especially for long trips).

  • Some people (including children) would rather not take a medicine every day.

Chloroquine

  • Some people would rather take medicine weekly.

  • Good choice for long trips because it is taken only weekly.

  • Some people are already taking hydroxychloroquine chronically for rheumatologic conditions; in those instances, they may not have to take an additional medicine.

  • Can be used in all trimesters of pregnancy.

  • Cannot be used in areas with chloroquine or mefloquine resistance.

  • May exacerbate psoriasis.

  • Some people would rather not take a weekly medication.

  • For short trips, some people would rather not take medication for 4 weeks after travel.

  • Not a good choice for last-minute travelers, because drug needs to be started 1–2 weeks before travel.

Doxycycline

  • Some people prefer to take a daily medicine.

  • Good for last-minute travelers because the drug is started 1–2 days before travel.

  • Tends to be the least expensive antimalarial.

  • People already taking doxycycline chronically to prevent acne do not have to take an additional medicine.

  • Doxycycline also can prevent some additional infections (such as rickettsial infections and leptospirosis), so it may be preferred by people planning to hike, camp, and swim in fresh water.

  • Cannot be used by pregnant women and children aged <8 years.

  • Some people would rather not take a medicine every day.

  • For short trips, some people would rather not take medication for 4 weeks after travel.

  • Women prone to getting vaginal yeast infections when taking antibiotics may prefer taking a different medicine.

  • People may want to avoid the increased risk of sun sensitivity.

  • Some people are concerned about the potential of getting an upset stomach from doxycycline.

Mefloquine

  • Some people would rather take medicine weekly.

  • Good choice for long trips because it is taken only weekly.

  • Can be used in all trimesters of pregnancy.

  • Cannot be used in areas with mefloquine resistance.

  • Cannot be used in patients with certain psychiatric conditions.

  • Cannot be used in patients with a seizure disorder.

  • Not recommended for people with cardiac conduction abnormalities.

  • Not a good choice for last-minute travelers because drug needs to be started ≥2 weeks before travel.

  • Some people would rather not take a weekly medication.

  • For short trips, some people would rather not take medication for 4 weeks after travel.

Primaquine

  • One of the most effective drugs for prevention of P. vivax , so it is a good choice for travel to places with >90% P. vivax .

  • Good choice for shorter trips because the traveler takes the medicine for 7 days after traveling rather than 4 weeks.

  • Good for last-minute travelers because the drug is started 1–2 days before travel.

  • Some people prefer to take a daily medicine.

  • Cannot be used in patients with G6PD deficiency.

  • Cannot be used in patients who have not been tested for G6PD deficiency.

  • There are costs and delays associated with getting a G6PD test; however, it only has to be done once. Once a normal G6PD level is verified and documented, the test does not have to be repeated the next time primaquine or tafenoquine is considered.

  • Cannot be used by pregnant women.

  • Cannot be used by women who are breastfeeding, unless the infant has also been tested for G6PD deficiency.

  • Some people (including children) would rather not take a medicine every day.

  • Some people are concerned about the potential of getting an upset stomach from primaquine.

Tafenoquine

  • One of the most effective drugs for prevention of P. vivax malaria but also prevents P. falciparum .

  • Good choice for shorter trips because the traveler takes the medicine once, 1 week after traveling rather than 4 weeks.

  • Good for last-minute travelers because the drug is started 3 days before travel.

  • Cannot be used in people with G6PD deficiency.

  • Cannot be used in patients who have not been tested for G6PD deficiency.

  • There are costs and delays associated with getting a G6PD test; however, it only has to be done once. Once a normal G6PD level is verified and documented, the test does not have to be repeated the next time tafenoquine or primaquine is considered.

  • Cannot be used by children

  • Cannot be used by pregnant women.

  • Cannot be used by women who are breastfeeding.

  • Not recommended in those with psychotic disorders

In addition to primary prophylaxis, presumptive antirelapse therapy (also known as terminal prophylaxis) uses a medication toward the end of the exposure period (or immediately thereafter) to prevent relapses or delayed-onset clinical presentations of malaria caused by hypnozoites (dormant liver stages) of P. vivax or P. ovale . Because most malarious areas of the world (except the Caribbean) have at least 1 species of relapsing malaria, travelers to these areas have some risk for acquiring either P. vivax or P. ovale , although the actual risk for an individual traveler is difficult to define. Presumptive antirelapse therapy is generally indicated only for people who have had prolonged exposure in malaria-endemic areas (for example, missionaries, military personnel, or Peace Corps volunteers).

Box 4-5. Malaria considerations for the long-term traveler (travel >6 months)

Considerations

  • Malaria preventive measures are the same for both short- and long-term travelers
  • Increased risk of acquiring malaria—longer stay means increased duration of exposure
  • Laxity in attention to mosquito avoidance over time
  • Poor adherence to a lengthy course of malaria prophylaxis due to forgetfulness, fear of side effects, and the possible waning of a sense of risk and need
  • Travel between highly endemic or low-endemic areas within a country or region
  • Decreased sense of risk and concern about malaria after engaging in local conversations and lore (particularly regarding malaria immunity over time)
  • Becoming ill with malaria in countries with limited access and quality of health care

Additional advice for long-term travelers

  • Emphasize continued adherence to and safety of malaria prophylaxis drugs
  • Develop a plan for seeking immediate care when ill with fever, including where to get promptly tested and treated for malaria
  • Advise traveler to purchase travel insurance, including contingencies for medical evacuation
  • Consider having a reliable supply of a treatment dose of antimalarials available in case malaria is diagnosed

Obtaining Medications Overseas

The medications recommended for prophylaxis of malaria may be available at overseas destinations. However, combinations of these medications and additional drugs that are not recommended may be commonly prescribed and used in other countries. Travelers should be strongly discouraged from obtaining prophylaxis medications while abroad. The quality of these products is not known; they may have been produced by substandard manufacturing practices, may be counterfeit, may contain contaminants, may not be protective, and could be dangerous. Additional information on this topic can be found in Chapter 6, Perspectives : Avoiding Poorly Regulated Medicines and Medical Products during Travel, and on the FDA website (www.fda.gov/Drugs/ResourcesForYou/Consumers/BuyingUsingMedicineSafely/BuyingMedicinefromOutsidetheUnitedStates/default.htm).

Medications used for Prophylaxis

Atovaquone-Proguanil

Atovaquone-proguanil (Malarone) is a fixed combination of the drugs atovaquone and proguanil. Prophylaxis should begin 1–2 days before travel to malarious areas and should be taken daily, at the same time each day, while in the malarious areas, and daily for 7 days after leaving the areas (see Table 4-10 for recommended dosages). Atovaquone-proguanil is well tolerated, and side effects are rare. The most common adverse effects reported in people using atovaquone-proguanil for prophylaxis or treatment are abdominal pain, nausea, vomiting, and headache. Atovaquone-proguanil is not recommended for prophylaxis in children weighing <5 kg (11 lb), pregnant women, or patients with severe renal impairment (creatinine clearance <30 mL/min). Proguanil may increase the effect of warfarin, so international normalized ratio monitoring or adjustment of warfarin dosage may be needed. However, there are no data regarding the clinical impact of the administration of atovaquone-proguanil and warfarin at the same time.

Table 4-10. Drugs used in the prophylaxis of malaria

Drug

Usage

Adult Dose

Pediatric Dose

Comments

Atovaquone-proguanil

Prophylaxis in all areas

Adult tablets contain 250 mg atovaquone and 100 mg proguanil hydrochloride. 1 adult tablet orally, daily

Pediatric tablets contain 62.5 mg atovaquone and 25 mg proguanil hydrochloride.

  • 5–8 kg: 1/2 pediatric tablet daily

  • 8–10 kg: 3/4 pediatric tablet daily

  • 10–20 kg: 1 pediatric tablet daily

  • 20–30 kg: 2 pediatric tablets daily

  • 30–40 kg: 3 pediatric tablets daily

  • >40 kg: 1 adult tablet daily

Begin 1–2 days before travel to malarious areas. Take daily at the same time each day while in the malarious area and for 7 days after leaving such areas. Contraindicated in people with severe renal impairment (creatinine clearance <30 mL/min). Atovaquone-proguanil should be taken with food or a milky drink. Not recommended for prophylaxis for children weighing <5 kg, pregnant women, and women breastfeeding infants weighing <5 kg. Partial tablet doses may need to be prepared by a pharmacist and dispensed in individual capsules, as described in the text.

Chloroquine

Prophylaxis only in areas with chloroquine-sensitive malaria

300 mg base (500 mg salt) orally, once/ week

5 mg/kg base (8.3 mg/kg salt) orally, once/week, up to a maximum adult dose of 300 mg base

Begin 1–2 weeks before travel to malarious areas. Take weekly on the same day of the week while in the malarious area and for 4 weeks after leaving such areas. May exacerbate psoriasis.

Doxycycline

Prophylaxis in all areas

100 mg orally, daily

≥8 years of age: 2.2 mg/kg up to adult dose of 100 mg/day

Begin 1–2 days before travel to malarious areas. Take daily at the same time each day while in the malarious area and for 4 weeks after leaving such areas. Contraindicated in children aged <8 years and pregnant women.

Hydroxychloroquine

An alternative to chloroquine for prophylaxis only in areas with chloroquine-sensitive malaria

310 mg base (400 mg salt) orally, once/week

5 mg/kg base (6.5 mg/kg salt) orally, once/week, up to a maximum adult dose of 310 mg base

Begin 1–2 weeks before travel to malarious areas. Take weekly on the same day of the week while in the malarious area and for 4 weeks after leaving such areas.

Mefloquine

Prophylaxis in areas with mefloquine-sensitive malaria

228 mg base (250 mg salt) orally, once/ week

≤9 kg: 4.6 mg/kg base (5 mg/kg salt) orally, once/week

>9–19 kg: 1/4 tablet once/week

>19–30 kg: 1/2 tablet once/week

>30–45 kg: 3/4 tablet once/week

>45 kg: 1 tablet once/week

Begin ≥2 weeks before travel to malarious areas. Take weekly on the same day of the week while in the malarious area and for 4 weeks after leaving such areas. Contraindicated in people allergic to mefloquine or related compounds (quinine, quinidine) and in people with active depression, a recent history of depression, generalized anxiety disorder, psychosis, schizophrenia, other major psychiatric disorders, or seizures. Use with caution in people with psychiatric disturbances or a previous history of depression. Not recommended for people with cardiac conduction abnormalities.

Primaquine 1

Prophylaxis for short-duration travel to areas with principally P. vivax

Presumptive antirelapse therapy (PART or terminal prophylaxis) to decrease the risk for relapses of P. vivax and P. ovale

30 mg base (52.6 mg salt) orally, daily

30 mg base (52.6 mg salt) orally, daily

0.5 mg/kg base (0.8 mg/kg salt)

up to adult dose orally, daily

0.5 mg/kg base (0.8 mg/kg salt)

up to adult dose orally, daily

Begin 1–2 days before travel to malarious areas. Take daily at the same time each day while in the malarious area and for 7 days after leaving such areas.

PART indicated for people with prolonged exposure to P. vivax, P. ovale , or both: daily for 14 days after departure from the malarious area.

Contraindicated in people with G6PD deficiency. Also contraindicated during pregnancy and lactation, unless the infant being breastfed has a documented normal G6PD level.

Tafenoquine 1

Prophylaxis in all areas

Presumptive antirelapse therapy (PART or terminal prophylaxis) to decrease the risk for relapses of P. vivax and P. ovale

200 mg orally

300mg orally

Not indicated in

children <16 years old

300 mg orally

Begin taking daily for 3 days prior to travel to malarious areas. Then, take weekly while at the malarious area, and for 1 week after leaving the malarious area.

PART indicated for people who had prolonged exposure to P. vivax, P. ovale or both: Administered as a single dose.

Contraindicated in people with G6PD deficiency. Also contraindicated during pregnancy and lactation unless the infant being breastfed has a documented normal G6PD level

Abbreviation: PART, presumptive antirelapse therapy.

1 All people who take primaquine or tafenoquine should have a documented normal G6PD level before starting the medication.

Chloroquine and Hydroxychloroquine

Chloroquine phosphate or hydroxychloroquine sulfate (Plaquenil) can be used for prevention of malaria only in destinations where chloroquine resistance is not present (see Chapter 2, Yellow Fever Vaccine & Malaria Prophylaxis Information, by Country). Prophylaxis should begin 1–2 weeks before travel to malarious areas. It should be continued by taking the drug once a week, on the same day of the week, during travel in malarious areas and for 4 weeks after a traveler leaves these areas (see Table 4-10 for recommended dosages).

Reported side effects include gastrointestinal disturbance, headache, dizziness, blurred vision, insomnia, and pruritus, but generally, these effects do not require that the drug be discontinued. High doses of chloroquine, such as those used to treat rheumatoid arthritis, have been associated with retinopathy; this serious side effect appears to be extremely unlikely when chloroquine is used for routine weekly malaria prophylaxis. Chloroquine and related compounds have been reported to exacerbate psoriasis. People who experience uncomfortable side effects after taking chloroquine may tolerate the drug better by taking it with meals. As an alternative, the related compound hydroxychloroquine sulfate may be better tolerated.

Doxycycline

Doxycycline prophylaxis should begin 1–2 days before travel to malarious areas. It should be continued once a day, at the same time each day, during travel in malarious areas and daily for 4 weeks after the traveler leaves such areas. Insufficient data exist on the antimalarial prophylactic efficacy of related compounds such as minocycline (commonly prescribed for the treatment of acne). People on a long-term regimen of minocycline who need malaria prophylaxis should stop taking minocycline 1–2 days before travel and start doxycycline instead. Minocycline can be restarted after the full course of doxycycline is completed (see Table 4-10 for recommended dosages).

Doxycycline can cause photosensitivity, usually manifested as an exaggerated sunburn reaction. The risk for such a reaction can be minimized by avoiding prolonged, direct exposure to the sun and by using sunscreen. In addition, doxycycline use is associated with an increased frequency of vaginal yeast infections. Gastrointestinal side effects (nausea or vomiting) may be minimized by taking the drug with a meal or by specifically prescribing doxycycline monohydrate or the enteric-coated doxycycline hyclate, rather than the generic doxycycline hyclate, which is often less expensive. To reduce the risk for esophagitis, travelers should be advised to swallow the medicine with sufficient fluids and not to take doxycycline shortly before going to bed. Doxycycline is contraindicated in people with an allergy to tetracyclines, during pregnancy, and in infants and children aged <8 years. Vaccination with the oral typhoid vaccine Ty21a should be delayed for ≥24 hours after taking a dose of doxycycline.

Mefloquine

Mefloquine prophylaxis should begin ≥2 weeks before travel to malarious areas. It should be continued once a week, on the same day of the week, during travel in malarious areas and for 4 weeks after a traveler leaves such areas (see Table 4-10 for recommended dosages).

Mefloquine has been associated with rare but serious adverse reactions (such as psychoses or seizures) at prophylactic doses; these reactions are more frequent with the higher doses used for treatment. Other side effects that have occurred in prophylaxis studies include gastrointestinal disturbance, headache, insomnia, abnormal dreams, visual disturbances, depression, anxiety disorder, and dizziness. Other more severe neuropsychiatric disorders have been occasionally reported and include sensory and motor neuropathies (such as paresthesia, tremor, and ataxia), agitation or restlessness, mood changes, panic attacks, forgetfulness, confusion, hallucinations, aggression, paranoia, and encephalopathy. On occasion, psychiatric symptoms have been reported to continue long after mefloquine has been stopped.

FDA also includes a boxed warning about rare reports of persistent dizziness after mefloquine use. Mefloquine is contraindicated for use by travelers with a known hypersensitivity to mefloquine or related compounds (such as quinine or quinidine) and in people with active depression, a recent history of depression, generalized anxiety disorder, psychosis, schizophrenia, other major psychiatric disorders, or seizures. Mefloquine should be avoided in people with psychiatric disturbances or a history of depression.

A review of available data suggests that mefloquine may be used safely in people concurrently on β-blockers, if they have no underlying arrhythmia. However, mefloquine is not recommended for people with cardiac conduction abnormalities. Any traveler receiving a prescription for mefloquine must also receive a copy of the FDA medication guide, which can be found at www.accessdata.fda.gov/drugsatfda_docs/label/2008/019591s023lbl.pdf.

Primaquine

Primaquine phosphate has 2 distinct uses for malaria prevention in people with normal G6PD levels (see cautionary note below): primary prophylaxis in areas with primarily P. vivax and presumptive antirelapse therapy (terminal prophylaxis). When taken for primary prophylaxis, primaquine should be taken 1–2 days before travel to malarious areas, daily, at the same time each day, while in the malarious area, and daily for 7 days after leaving the area (see Table 4-10 for recommended dosages).

When used for presumptive antirelapse therapy, primaquine is administered for 14 days after the traveler has left a malarious area. When chloroquine, doxycycline, or mefloquine is used for primary prophylaxis, primaquine is usually taken during the last 2 weeks of postexposure prophylaxis. When atovaquone-proguanil is used for prophylaxis, primaquine may be taken during the final 7 days of atovaquone-proguanil, and then for an additional 7 days. Primaquine should be given concurrently with the primary prophylaxis medication. However, if that is not feasible, the primaquine course should still be administered after the primary prophylaxis medication has been completed. Primary prophylaxis with primaquine or tafenoquine (see below) obviates the need for presumptive antirelapse therapy.

The most common adverse event in people with normal G6PD levels is gastrointestinal upset if primaquine is taken on an empty stomach. This problem is minimized or eliminated if primaquine is taken with food.

In G6PD-deficient people, primaquine can cause fatal hemolysis. Before primaquine is used, G6PD deficiency MUST be ruled out by laboratory testing.

Tafenoquine

Tafenoquine (Arakoda 100-mg tablets, Krintafel 150-mg tablets) can be used to prevent malaria in adults and as presumptive antirelapse therapy for people >16 years of age (see Table 4-10 for recommended dosages).

When used for prophylaxis, a loading dose of tafenoquine is taken daily for 3 days before leaving for a malaria-endemic area. Maintenance doses are taken weekly while in the malarious area (start 7 days after loading dose is complete) and a final dose in the week after leaving the area. Doses should be taken on the same day each week.

For presumptive antirelapse therapy, one 300-mg dose of tafenoquine is administered after leaving the malarious area. Ideally, this single dose should overlap with the last dose of the antimalarial used for prophylaxis, but if that approach is not feasible, tafenoquine can be taken after primary prophylaxis has been completed. As with primaquine, presumptive antirelapse therapy is not needed if tafenoquine is taken for primary prophylaxis.

Like primaquine, tafenoquine can cause fatal hemolysis in people with G6PD deficiency. Before tafenoquine is used, G6PD deficiency MUST be ruled out by laboratory testing. Tafenoquine is also contraindicated in pregnancy and during breastfeeding. Rare psychiatric adverse events have been observed in people with a history of psychotic disorder using tafenoquine at higher doses. Therefore, tafenoquine should not be used as prophylaxis in people with a history of psychotic disorder, but can be administered for presumptive antirelapse therapy, which is likely to be associated with a very small risk of psychiatric adverse reactions. The most common adverse events reported with use of tafenoquine are gastrointestinal disturbances, dizziness, headache, and clinically nonsignificant decreases in hemoglobin. Tafenoquine should be taken with food.

Travel to Areas with Limited Malaria Transmission

For destinations where malaria cases occur sporadically and risk for infection to travelers is assessed as being low, CDC recommends that travelers use mosquito avoidance measures only, and no prophylaxis should be prescribed (see Chapter 2, Yellow Fever Vaccine & Malaria Prophylaxis Information, by Country).

Travel to Areas with Chloroquine-Sensitive Malaria

Areas with chloroquine-sensitive malaria include many Latin American countries where there is predominantly P. vivax malaria. Chloroquine-sensitive P. falciparum is present in the Caribbean and Central American countries west of the Panama Canal. For destinations where chloroquine-sensitive malaria is present, in addition to mosquito avoidance measures, the many effective prophylaxis options include chloroquine, atovaquone-proguanil, doxycycline, mefloquine, and tafenoquine. In countries where there is predominantly P. vivax , primaquine is an additional option.

Travel to Areas with Chloroquine-Resistant Malaria

Chloroquine-resistant P. falciparum is found in all parts of the world except the Caribbean and countries west of the Panama Canal. Although chloroquine-resistant P. falciparum predominates in Africa, it is found in combination with chloroquine-sensitive P. vivax malaria in South America and Asia. Resistance of P. vivax to chloroquine has been confirmed only in Papua New Guinea and Indonesia. For destinations where any chloroquine-resistant malaria is present, in addition to mosquito avoidance measures, prophylaxis options are atovaquone-proguanil, doxycycline, mefloquine, and tafenoquine.

Travel to Areas with Mefloquine-Resistant Malaria

Mefloquine-resistant P. falciparum has been confirmed in Southeast Asia on the borders of Thailand with Burma (Myanmar) and Cambodia, in the western provinces of Cambodia, in the eastern states of Burma on the border between Burma and China, along the borders of Laos and Burma, the adjacent parts of the Thailand-Cambodia border, and in southern Vietnam. For destinations where mefloquine-resistant malaria is present, in addition to mosquito avoidance measures, prophylaxis options are atovaquone-proguanil, doxycycline, and tafenoquine.

Prophylaxis for Infants, Children, and Adolescents

All children traveling to malaria-endemic areas should use recommended prevention measures, which often include taking an antimalarial drug. In the United States, antimalarial drugs are available only in oral formulations and may taste bitter. Pediatric doses should be calculated carefully according to body weight but should never exceed the adult dose. Pharmacists can pulverize tablets and prepare gelatin capsules for each measured dose. If the child is unable to swallow the capsules or tablets, parents should prepare the child’s dose of medication by breaking open the gelatin capsule or crushing the pill and mixing the drug with a small amount of something sweet, such as applesauce, chocolate syrup, or jelly, to ensure the entire dose is delivered to the child. Giving the dose on a full stomach may minimize stomach upset and vomiting.

Chloroquine and mefloquine are options for infants and children of all ages and weights, depending on drug resistance at their destination. Primaquine can be used for children who are not G6PD deficient traveling to areas with principally P. vivax . Doxycycline may be used for children aged ≥8 years. Atovaquone-proguanil may be used as prophylaxis for infants and children weighing ≥5 kg (11 lb). Prophylactic dosing for children weighing <11 kg (24 lb) constitutes off-label use in the United States. Pediatric dosing regimens are included in Table 4-10.

Prophylaxis During Pregnancy and Breastfeeding

Malaria infection in pregnant women can be more severe than in nonpregnant women. Malaria increases the risk for adverse pregnancy outcomes, including prematurity, spontaneous abortion, and stillbirth. For these reasons, and because no prophylaxis regimen is completely effective, women who are pregnant or likely to become pregnant should be advised to avoid travel to areas with malaria transmission if possible (see Chapter 7, Pregnant Travelers). If travel to a malarious area cannot be deferred, use of an effective prophylaxis regimen is essential (along with mosquito avoidance measures).

Pregnant women traveling to areas where chloroquine-resistant P. falciparum has not been reported may take chloroquine prophylaxis. Chloroquine has not been found to have harmful effects on the fetus when used in the recommended doses for malaria prophylaxis; therefore, pregnancy is not a contraindication for malaria prophylaxis with chloroquine or hydroxychloroquine.

For travel to areas where chloroquine resistance is present, mefloquine is the only medication recommended for malaria prophylaxis during pregnancy. Studies of mefloquine use during pregnancy have found no indication of adverse effects on the fetus.

Experts are evaluating the safety of atovaquone-proguanil use during pregnancy. Proguanil has been used for decades in pregnant women; however, until such time as these data are fully evaluated, atovaquone-proguanil is not recommended for use during pregnancy. Doxycycline is contraindicated for malaria prophylaxis during pregnancy because of the risk for adverse effects seen with tetracycline, a related drug, on the fetus. These adverse effects include discoloration and dysplasia of the teeth and inhibition of bone growth. Primaquine and tafenoquine should not be used during pregnancy because the drug may be passed transplacentally to a G6PD-deficient fetus and cause hemolytic anemia in utero.

Women planning to become pregnant may use the same medications that are recommended for use during pregnancy. CDC does not make recommendations about delaying pregnancy after the use of malaria prophylaxis medicines. However, if women or their health care providers wish to decrease the amount of antimalarial drug in the body before conception, Table 4-11 provides information on the half-lives of the recommended malaria prophylaxis medicines. After 2, 4, and 6 half-lives, approximately 25%, 6%, and 2%, respectively, of the drug remains in the body.

Table 4-11. Half-lives of malaria prophylaxis drugs

Drug

Half-Life

Atovaquone

2–3 days

Chloroquine

1–2 months

Doxycycline

15–24 hours

Hydroxychloroquine

1–2 months

Mefloquine

2–4 weeks

Primaquine

4–7 hours

Proguanil

12–25 hours

Tafenoquine

14–28 days

Very small amounts of antimalarial drugs are excreted in the breast milk of lactating women. Because the quantity of antimalarial drugs transferred in breast milk is insufficient to provide adequate protection against malaria, infants who require prophylaxis must receive the recommended dosages of antimalarial drugs listed in Table 4-10. Because chloroquine and mefloquine may be prescribed safely to infants, it is also safe for infants to be exposed to the small amounts excreted in breast milk. Data about the use of doxycycline in lactating women are very limited; most experts, however, consider the theoretical possibility of adverse events to the infant to be remote.

Although no information is available on the amount of primaquine that enters human breast milk, both the mother and infant should be tested for G6PD deficiency before primaquine is given to a woman who is breastfeeding. Because data are not yet available on the safety of atovaquone-proguanil prophylaxis in infants weighing <5 kg (11 lb), CDC does not recommend this drug to prevent malaria in women breastfeeding infants weighing <5 kg. However, it can be used to treat women who are breastfeeding infants of any weight when the potential benefit outweighs the potential risk to the infant (such as treating a breastfeeding woman who has acquired P. falciparum malaria in an area of multidrug-resistant strains and who cannot tolerate other treatment options). No data are available on the safety of tafenoquine in infants, so tafenoquine is not recommended in women who are breastfeeding.

Choosing a Drug to Prevent Malaria

Recommendations for drugs to prevent malaria differ by country of travel and can be found in Chapter 2, Yellow Fever Vaccine & Malaria Prophylaxis Information, by Country. Recommended drugs for each country are listed in alphabetical order and have comparable efficacy in that country. No antimalarial drug is 100% protective; therefore, prophylaxis must be combined with mosquito avoidance and personal protective measures (such as insect repellent, long sleeves, long pants, sleeping in a mosquito-free setting or using an insecticide-treated bed net). When several different drugs are recommended for an area, Table 4-9 may help in the decision-making process.

Changing Medications as a Result of Side Effects During Prophylaxis

Medications recommended for prophylaxis against malaria have different modes of action that affect the parasites at different stages of the life cycle. Thus, if the medication needs to be changed because of side effects before a full course has been completed, there are some special considerations (see Table 4-12).

Table 4-12. Changing medications as a result of side effects during malaria chemoprophylaxis

Drug Being Stopped

Drug Being Started

Comments

Mefloquine

Doxycycline

Begin doxycycline, continue daily while in malaria-endemic area, and continue for 4 weeks after leaving malaria-endemic area.

Atovaquone-proguanil

If the switch occurs ≥3 weeks before departure from the endemic area, atovaquone-proguanil should be taken daily for the rest of the stay in the endemic area and for 1 week thereafter.

If the switch occurs <3 weeks before departure from the endemic area, atovaquone-proguanil should be taken daily for 4 weeks after the switch.

If the switch occurs after departure from the endemic area, atovaquone-proguanil should be taken daily until 4 weeks after the date of departure.

Chloroquine

Not recommended.

Primaquine

Tafenoquine

This switch would be unlikely as primaquine is recommended only for primary prophylaxis in areas with mainly P. vivax for people with normal G6PD activity. Should that be the case, begin primaquine, continue daily while in malaria-endemic area, and continue for 7 days after leaving malaria-endemic area.

For people with normal G6PD activity, begin tafenoquine as soon as possible after the last dose of mefloquine while in the malarious area. Take daily for 3 days, weekly while in the malarious area and a final dose in the week after leaving the malarious area.

Doxycycline

Mefloquine

Not recommended.

Atovaquone-proguanil

If the switch occurs ≥3 weeks before departure from the endemic area, atovaquone-proguanil should be taken daily for the rest of the stay in the endemic area and for 1 week thereafter.

If the switch occurs <3 weeks before departure from the endemic area, atovaquone-proguanil should be taken daily for 4 weeks after the switch.

If the switch occurs after departure from the endemic area, atovaquone-proguanil should be taken daily until 4 weeks after the date of departure.

Chloroquine

Not recommended.

Primaquine

Tafenoquine

This switch would be unlikely as primaquine is recommended only for primary prophylaxis in areas with mainly P. vivax for people with normal G6PD activity. Should that be the case, begin primaquine, continue daily while in malaria-endemic area, and continue for 7 days after leaving malaria-endemic area.

Not recommended.

Atovaquone-proguanil

Doxycycline

Begin doxycycline, continue daily while in malaria-endemic area, and continue for 4 weeks after leaving malaria-endemic area.

Mefloquine

Not recommended.

Chloroquine

Not recommended.

Primaquine

Tafenoquine

This switch would be unlikely as primaquine is recommended only for primary prophylaxis in areas with mainly P. vivax for people with normal G6PD activity. Should that be the case, begin primaquine, continue daily while in malaria-endemic area, and continue for 7 days after leaving malaria-endemic area.

Not recommended.

Chloroquine

Doxycycline

Begin doxycycline, continue daily while in malaria-endemic area, and continue for 4 weeks after leaving malaria-endemic area.

Atovaquone-proguanil

If the switch occurs ≥3 weeks before departure from the endemic area, atovaquone-proguanil should be taken daily for the rest of the stay in the endemic area and for 1 week thereafter.

If the switch occurs <3 weeks before departure from the endemic area, atovaquone-proguanil should be taken daily for 4 weeks after the switch.

If the switch occurs following departure from the endemic area, atovaquone-proguanil should be taken daily until 4 weeks after the date of departure.

Mefloquine

Not recommended.

Primaquine

Tafenoquine

Primaquine is recommended only for primary prophylaxis in areas with mainly P. vivax for people with normal G6PD activity. Should that be the case, begin primaquine, continue daily while in malaria-endemic area, and continue for 7 days after leaving malaria-endemic area.

For people with normal G6PD activity, begin tafenoquine as soon as possible after the last dose of chloroquine while in the malarious area. Take daily for 3 days, weekly while in the malarious area, and a final dose in the week after leaving the malarious area.

Primaquine

Doxycycline

Begin doxycycline, continue daily while in malaria-endemic area, and continue for 4 weeks after leaving malaria-endemic area.

Atovaquone-proguanil

Begin atovaquone-proguanil, continue daily while in malaria-endemic area, and continue for 7 days after leaving malaria- endemic area.

Chloroquine

Not recommended.

Mefloquine

Tafenoquine

Not recommended.

Not recommended.

Blood Donation After Travel to Malarious Areas

People who have been in an area where malaria transmission occurs should defer donating blood for a period of time after returning from the malarious area to prevent transmission of malaria through blood transfusion (Table 4-13).

Table 4-13. Food and Drug Administration recommendations for deferring blood donation in people returning from malarious areas

Group

Blood Donation Deferral

Travelers to malaria-endemic areas

May not donate blood for 1 year after travel.

Former residents of malaria-endemic areas

May not donate blood for 3 years after departing. If they return to a malaria-endemic area within that 3-year period, they are deferred for an additional 3 years.

People diagnosed with malaria

May not donate for 3 years after treatment.

Risk assessments may differ between travel health providers and blood banks. A travel health provider advising a traveler going to a country with relatively low malaria transmission for a short period of time and engaging in low-risk behaviors may choose insect avoidance only and no prophylaxis for the traveler. However, upon the traveler’s return, a blood bank may still choose to defer that traveler for 1 year because of the travel to an area where transmission occurs.

CDC website: www.cdc.gov/malaria

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Authors

Kathrine R. Tan, Paul M. Arguin