HIV Infection

Infectious Agent

HIV, an enveloped positive-strand RNA virus in the Retroviridae family.


HIV can be transmitted through sexual contact, needle- or syringe-sharing, unsafe medical injection or blood transfusion, and organ or tissue transplantation. It can also be transmitted from mother to child during pregnancy, at birth, and postpartum through breastfeeding. HIV may be transmitted occupationally to health care workers who are exposed to blood and other potentially infectious bodily fluids via percutaneous injury or splash exposures to mucous membranes or nonintact skin (see Chapter 8, Health Care Workers).


HIV infection occurs worldwide. As of the end of 2014, an estimated 37 million people were living with HIV infection. Although sub-Saharan Africa has experienced a substantial decline in the number of new infections annually, from 2.3 million in 2000 to 1.4 million in 2014 (a 41% decline), it remains the most affected part of the world (25.8 million cases or 70% of all people living with HIV infection). Although the reported adult HIV prevalence in many regions of the world is low, certain populations are disproportionately affected, such as sex workers, people who inject drugs, men who have sex with men, transgender people, and prisoners. Sex workers are particularly vulnerable; the prevalence among sex workers is 12 times as high as in the general population.

The risk of HIV infection for international travelers is generally low, although the risk is determined less by geographic destination and more by behaviors such as injection drug use and unprotected sex. Travelers who might undergo medical procedures in low-income countries, whether scheduled or in an emergency, should be aware that the blood supply (and organs and tissues used for transplantation) might not be adequately screened, increasing the risk of HIV transmission, and that HIV can be transmitted by unsafe medical injection practices (reusing needles, syringes, or single-dose medication vials).

Clinical Presentation

HIV infection is a chronic disease characterized by ongoing viral replication and a gradual exhaustion and destruction of CD4 T lymphocytes. As the CD4 cell count declines, an HIV-infected person’s susceptibility to opportunistic infections and infection-related malignancies increases. An estimated 40%–90% of people experience symptoms during acute HIV infection, which often presents as an infectious mononucleosislike or influenzalike syndrome, but the clinical features can be highly variable. Symptoms typically begin a median of 10 days after HIV infection and can include fever, maculopapular rash, arthralgia, myalgia, malaise, lymphadenopathy, oral ulcers, pharyngitis, and weight loss. The presence of fever and rash has the best positive predictive value. Unfortunately, acute symptomatic HIV infection is rarely diagnosed by health care providers, as its symptoms are often attributed to other viral infections or secondary syphilis.


Any traveler who reports risk behaviors for HIV infection, suspects that she or he may have been exposed to HIV, or has symptoms that could be consistent with HIV infection should be tested. HIV can be diagnosed with laboratory-based or point-of-care assays that detect anti-HIV antibodies, HIV p24 antigen, or HIV-1 RNA. In the United States, the recommended laboratory-based screening test for HIV is a combination antigen/antibody assay that detects antibodies against HIV as well as p24 antigen. The combination antigen/antibody assay becomes reactive approximately 2–3 weeks after HIV infection. It is estimated that 99% of people will develop a reactive combination antigen/antibody result within 6 weeks of infection, but in rare cases, it can take up to 6 months to develop a reactive test result. Point-of-care HIV antibody tests performed on oral fluid (instead of blood) have been associated with a lower sensitivity during early HIV infection. The earliest time after exposure that HIV infection can be diagnosed is approximately 9 days, when HIV-1 RNA becomes detectable in blood. Any person with unknown HIV status who is diagnosed with an AIDS-defining illness, such as Pneumocystis pneumonia, should be tested for HIV. For further information on HIV testing, travelers should talk to their health care provider, or identify an HIV testing site near them by visiting the National HIV Testing Resources website at or call CDC-INFO toll-free at 800-CDC-INFO (800-232-4636) or 888-232-6348 (TTY). Both of these resources are confidential.


Prompt medical care and effective treatment with antiretrovirals can partially reverse HIV-induced damage to the immune system and prolong life. Effective treatment also substantially reduces the risk of HIV transmission to others. US guidelines recommend that all people diagnosed with HIV infection be offered treatment for their own health and to prevent transmission to others. Detailed information on specific treatments is available from the Department of Health and Human Services AIDSinfo ( Travelers may contact AIDSinfo toll-free at 800-448-0440 (English or Spanish) or 888-480-3739 (TTY).


Although no vaccine can prevent HIV infection, travel medicine clinicians have several HIV prevention options available.


Travelers should be advised that they are at risk if they:

  • Have sexual contact (heterosexual or homosexual) with an infected person or a person whose HIV infection status is unknown.
  • Use or allow the use of contaminated, unsterilized syringes or needles for any injections or other procedures that pierce the skin, including acupuncture, use of illicit drugs, steroid or vitamin injections, medical or dental procedures, ear or body piercing, or tattooing.
  • Receive infected blood, blood components, or clotting factor concentrates. HIV infection by this route is rare in facilities where donated blood and plasma are screened for HIV.
  • Work in a health care setting. Typically, exposures occur as a result of percutaneous exposure to contaminated sharps, including needles, lancets, scalpels, and broken glass (from capillary or test tubes). See Chapter 8, Health Care Workers.

Risk Reduction

To reduce their risk of acquiring HIV, travelers should:

  • Avoid sexual encounters with people who are infected with HIV, whose HIV infection status is unknown, or who are at high risk for HIV infection, such as people who inject drugs, sex workers (both male and female), and other people with multiple sexual partners.
  • Use condoms consistently and correctly, especially if engaging in vaginal, anal, or oral sex with a person who is HIV infected or whose HIV status is unknown.
  • Avoid injecting drugs.
  • Avoid sharing needles or other devices that can puncture skin.
  • Avoid, if possible, blood transfusions or use of clotting factor concentrates and exposure to nonsterile injections and other invasive medical equipment.
  • Ensure that if traveling for purposes of medical treatment (see Chapter 2, Medical Tourism), the blood and blood products used in the facility where the traveler will be treated are screened for HIV, and that such facilities exercise proper infection control practices.


People who are sensitive to latex should use condoms made of polyurethane or other synthetic materials (not lambskin) and should carry their own supply of male or female condoms. If no condom is available, travelers should abstain from sex with people who are HIV-infected or whose HIV status is unknown. Barrier methods other than condoms do not prevent HIV transmission. Spermicides alone are also not effective. The widely used spermicide nonoxynol-9 can increase the risk of HIV transmission and should not be used.

Preexposure Prophylaxis

Preexposure prophylaxis (or PrEP) is highly effective in preventing HIV infection. PrEP consists of 2 oral antiretroviral medications (tenofovir and emtricitabine), coformulated as a single pill (Truvada) that is taken once daily. Daily PrEP can lower the risk of HIV infection from sex by as much as 90% or injection drug use by as much as 70% and is indicated for people at substantial risk for HIV infection. Detailed information is available from CDC ( Travelers who may have sex with people who are infected with HIV or who are at high risk for HIV infection and travelers who may inject drugs should discuss PrEP with their primary care and travel medicine providers. Travelers taking PrEP should carry proper documentation and be aware that some countries (see below for further information) may deny entry to people with evidence of HIV infection, which PrEP medications might mistakenly indicate to customs officials.

Sterile Syringes and Needles

Syringes and needles used to draw blood or administer injections should be sterile, single use, disposable, and prepackaged in a sealed container. If possible, travelers should avoid receiving medications from multidose vials, which may have become contaminated by used needles. Travelers with diabetes, hemophilia, or other conditions that necessitate routine or frequent injections should be advised to carry a supply of medication, syringes and needles, and disinfectant swabs sufficient to last their entire stay abroad. These travelers should request documentation of the medical necessity for traveling with these items (a letter from a licensed health care provider) to avoid having them confiscated, such as by inspection personnel at ports of entry (see Chapter 2, Travel Health Kits for more information about traveling with medications).

Postexposure Prophylaxis

Travelers who will be working in a medical setting (such as a nurse volunteer drawing blood or medical missionary performing surgeries) may have contact with HIV-infected or potentially infected biological materials. Detailed advice regarding management of postexposure prophylaxis in the occupational setting is found in Chapter 8, Health Care Workers. General recommendations on postexposure prophylaxis include the following:

  • People who have been exposed to HIV in a nonoccupational setting (through sex or needle sharing) should seek immediate medical consultation to consider postexposure prophylaxis.
  • Postexposure prophylaxis for potential exposure to HIV as a result of mass-casualty events is generally not warranted, except in special circumstances (for example, a blast injury in a facility that contained a large archive of HIV-infected blood specimens).
  • Clinicians seeking advice on postexposure prophylaxis can call the US National HIV/AIDS Clinicians’ Consultation Center PEPline toll-free at 888-448-4911 (

HIV Testing Requirements for US Travelers Entering Foreign Countries

International travelers should be advised that some countries screen incoming travelers for HIV infection and may deny entry to people with AIDS or evidence of HIV infection. These countries usually screen only people planning extended visits, such as for work or study. People intending to visit a country for an extended stay should review that country’s policies and requirements. This information is usually available from the consular officials of the individual nations. Information about entry and exit requirements compiled by the Department of State can be found by country at

CDC website:


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  2. CDC. Preexposure prophylaxis for the prevention of HIV in the United States: clinical providers’ supplement. Atlanta2014 [cited 2016 Sep. 23]. Available from:
  3. Joint United Nations Programme on HIV/AIDS (UNAIDS). Global report: UNAIDS report on the global AIDS epidemic 2013. Geneva: UNAIDS; 2013 [cited 2016 Sep. 23]. Available from:
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  6. Smith DK, Grohskopf LA, Black RJ, Auerbach JD, Veronese F, Struble KA, et al. Antiretroviral postexposure prophylaxis after sexual, injection-drug use, or other nonoccupational exposure to HIV in the United States: recommendations from the US Department of Health and Human Services. MMWR Recomm Rep. 2005 Jan 21;54(RR-2):1–20.


Philip J. Peters, John T. Brooks