HIV Infection

Infectious Agent

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


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 infection occurs worldwide. As of June 2017, an estimated 36.7 million people were living with HIV infection. Sub-Saharan Africa is the most affected part of the world (25.5 million cases or 69% of all people living with HIV infection), and the Eastern Europe and central Asia region has experienced the largest increases in new HIV infections (60% increase from 2010 to 2016). 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. Travelers’ risk of HIV exposure and infection is determined less by geographic destination and more by the behaviors in which they engage while traveling, such as unprotected sex and injection drug use. Travelers who might undergo scheduled or emergency medical procedures should be aware that HIV can be transmitted by unsafe nonsterile medical injection practices (reusing needles, syringes, or single-dose medication vials). This problem may be greater in low-income countries where the blood supply as well as organs and tissues used for transplantation may not be screened properly for HIV.

Clinical Presentation

As many as 90% of people will recall experiencing symptoms during the acute phase of HIV infection. Acute HIV infection can present as an infectious mononucleosis-like or influenzalike syndrome, but the clinical features are highly variable. Symptoms typically begin a median of 10 days after infection and can include fever, maculopapular rash, arthralgia, myalgia, malaise, lymphadenopathy, oral ulcers, pharyngitis, and weight loss. The presence of fever and rash have the best positive predictive value.


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. Travelers can find detailed information on HIV testing locations at


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. 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) for more information.


Travelers can reduce their risk of HIV infection in multiple ways. They can avoid sexual encounters with people whose HIV status is unknown, and use condoms consistently and correctly with all partners who are HIV infected or whose HIV status is unknown. They should also not inject drugs or share needles, and avoid exposure to blood or blood products and nonsterile invasive medical equipment. Travelers who do inject drugs should only use sterile, single-use syringes and needles that are safely disposed after every injection.

Preexposure Prophylaxis

Preexposure prophylaxis (or PrEP) with tenofovir-emtricitabine is highly effective in preventing HIV infection and is recommended as a prevention option for adults at substantial risk of HIV acquisition (see 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. Free, expert PrEP advice is available to health care professionals on the Clinician Consultation Center’s PrEPline (855-448-7737; 11 am–6 pm EST).

Postexposure Prophylaxis

Postexposure prophylaxis (or PEP) with antiretroviral medications is another method to prevent HIV infection (see PEP is recommended as a prevention option after a single high-risk exposure to HIV during sex, through sharing needles or syringes, or from a sexual assault. PEP must be started within 72 hours of a possible exposure. 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. In certain settings, clinicians may prescribe PEP medications that a traveler could use in an emergency situation. Free, expert PEP advice is available to health care professionals on the Clinician Consultation Center’s PEPline (888-448-4911; 11 am–8 pm EST). Detailed advice regarding management of postexposure prophylaxis in the occupational setting is found in Chapter 9, Health Care Workers.

HIV Testing Requirements for US Travelers Entering Foreign Countries

International travelers should be advised that some countries screen incoming travelers (usually those with an extended stay) for HIV infection, and may deny entry to people with AIDS or evidence of HIV infection. 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 is found by country at

CDC website:


  1. Brett-Major DM, Scott PT, Crowell TA, Polyak CS, Modjarrad K, Robb ML, et al. Are you PEPped and PrEPped for travel? Risk mitigation of HIV infection for travelers. Trop Dis Travel Med Vaccines. 2016 Nov 28;2:25.  [PMID:28883969]
  2. CDC. Preexposure prophylaxis for the prevention of HIV in the United States: a clinical practice guideline. Atlanta 2014 [cited 2018 Feb 26]. Available from:
  3. CDC. Preexposure prophylaxis for the prevention of HIV in the United States: clinical providers’ supplement. Atlanta 2014 [cited 2018 Feb 26]. Available from:
  4. Joint United Nations Programme on HIV/AIDS (UNAIDS). UNAIDS Data 2017. Geneva: UNAIDS; 2017 [cited 2018 Feb 26]. Available from:
  5. Kuhar DT, Henderson DK, Struble KA, Heneine W, Thomas V, Cheever LW, et al. Updated US Public Health Service guidelines for the management of occupational exposures to human immunodeficiency virus and recommendations for postexposure prophylaxis. Infect Control Hosp Epidemiol. 2013 Sep;34(9):875–92.  [PMID:23917901]


Philip J. Peters, John T. Brooks