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Human immunodeficiency virus primary infection
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Human immunodeficiency virus primary infection

Contributors: Mamello Ntsele MBChB, FCDerm, Neil Mendoza MD, Anisa Mosam MBChB, MMed, FCDerm, PhD, Ncoza C. Dlova MBChB, FCDerm, PhD, Paritosh Prasad MD, Susan Burgin MD
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Primary human immunodeficiency virus infection (PHI) syndrome, also called acute retroviral syndrome and seroconversion disease, is an acute mononucleosis-like illness that develops anywhere from 1-6 weeks following exposure to human immunodeficiency virus (HIV). Acute HIV infection, according to the Fiebig classification, is the period between viral acquisition and the emergence of HIV-specific antibodies. This period is associated with a high viral load. Patients with PHI syndrome may be asymptomatic or they can present with a variety of nonspecific symptoms and signs. A high index of suspicion is needed to make the diagnosis.

PHI syndrome is believed to occur in 50%-66% of newly infected individuals. Symptoms are variable; fever, headache, lymphadenopathy, nausea, diarrhea, rash, and pharyngitis are usually present. Other symptoms include vomiting, arthralgias, and photophobia. Rarely, neurological symptoms and hepatosplenomegaly are seen. Symptoms usually resolve within 15 days.

The rash is characteristically a morbilliform truncal exanthem that may resemble an exanthematous drug eruption or a viral exanthem. The palms and soles are usually spared. An enanthem with erythema and oral ulcers may be seen in more than half of patients with the syndrome. Genital ulcers are seen in around one-third.

PHI is important to recognize from a public health perspective. Patients with PHI are 10 times more likely to transmit HIV compared with patients in the chronic phase of HIV infection. Patients with PHI syndrome are most likely to present to primary care physicians, emergency rooms, urgent care and walk-in centers, or general medicine clinics. Approximately 90% of cases are not diagnosed at the primary encounter.

Related topics: acquired immune deficiency syndrome, HIV/AIDS-related pruritus, HIV-associated lung disease, human immunodeficiency virus disease, papular pruritic eruption of HIV


B20 – Human immunodeficiency virus [HIV] disease

111880001 – Acute HIV infection

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Differential Diagnosis & Pitfalls

  • Other causes of fever and lymphadenopathy (Epstein-Barr virus infection, cytomegalovirus infection, toxoplasmosis) – Testing for these pathogens can be performed.
  • Exanthematous drug eruption if there is a history of preceding medication use.
  • Influenza – Lymphadenopathy is not a typical finding and patients have prominent respiratory symptoms.
  • Measles – Conjunctivitis, coryza, and cough are usually seen with measles. Patients also have rash and fever.
  • Rubella – Rash and lymphadenopathy may be present.
  • Secondary syphilis – Patients typically have rash (involvement of the palms and soles is common) and lymphadenopathy.
  • Brucellosis – There is a spectrum of possible symptoms. Patients with acute infection are usually febrile and may have lymphadenopathy. The patient should be questioned regarding possible animal exposure or the consumption of unpasteurized dairy products.
  • Malaria – Patient should have a consistent travel history.

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Last Reviewed:01/14/2019
Last Updated:01/16/2020
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Patient Information for Human immunodeficiency virus primary infection
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Contributors: Medical staff writer


Primary HIV infection (PHI) syndrome is an acute, flu-like illness that develops anywhere from 1-6 weeks following exposure to HIV (the human immunodeficiency virus). Chronic infection with this virus can cause AIDS (acquired immune deficiency syndrome). The HIV virus destroys the body's ability to fight infections and some cancers by progressively attacking and damaging the cells of the immune system. The most common way of becoming infected is through unprotected sex with an infected partner.

The HIV virus is spread through exposure to the bodily fluids of an infected person through sex (vaginal, anal, or oral), blood exposure (through needle sharing, accidental blood exposure, blood transfusions, unsterilized medical equipment, or transplants), or from mother to child (during pregnancy, delivery, or through breast-feeding). The fluids must enter the body; ordinary skin contact and contact with sweat, tears, saliva, urine, or stool does not cause infection. There is no evidence that insect bites spread the virus.

You might see the first sign of infection within 1-2 months after becoming infected, and signs may disappear within 1-4 weeks. HIV is often mistaken for other types of viral infection, so be sure to consult with your doctor to confirm your diagnosis.

Who’s At Risk

More than 950,000 Americans may be infected with HIV, and one fourth of them may not know they are infected. Anyone can become infected, but in the US, African Americans and Hispanics are affected 7 and 3 times more often, respectively, than whites.

Other risk factors for acquiring HIV infection are:
  • Having unprotected sex with multiple partners
  • Having unprotected sex with someone who is HIV positive or whose infection status is unknown
  • Having another sexually transmitted disease, such as syphilis, gonorrhea, chlamydia, herpes, or bacterial vaginosis
  • Having hemophilia and receiving blood products between 1977 and April 1985
  • Receiving a blood transfusion before 1985
  • Sharing drug needles or syringes
  • Being born to or breast-fed by an untreated, infected woman
Approximately half of individuals newly infected with HIV will have primary HIV infection syndrome, so see your doctor promptly if you suspect you have signs of this condition.

Signs & Symptoms

A temporary (transient) rash of small, pink-to-red spots primarily involves the trunk. People usually notice swollen lymph nodes, fever, headache, nausea, and/or diarrhea, as well as a sore throat. Other symptoms include vomiting, joint pain (arthralgias), and sensitivity to light (photophobia). Men may notice open sores (ulcers) in the mouth or on the penis.

Self-Care Guidelines

Even without symptoms, you can pass (transmit) the virus to others. People with primary HIV infection syndrome are 10 times more likely to transmit HIV than will those who are in the chronic phase of HIV infection. If you think you might have been exposed to someone with HIV, or if you have any of the known risk factors yourself (see the list under "Who Gets It"), avoid sexual activity, stop using needles to inject street drugs, and seek medical care and testing.

If you are infected:
  • Find a competent doctor who understands HIV.
  • Eat healthy foods.
  • Keep up with immunizations.
  • Avoid smoking and illegal drug use.
  • Get enough exercise and rest.
  • Avoid other infections your immune system might have trouble fighting by washing your hands thoroughly and often, learning how to deal with pets and other animals, avoiding unpasteurized or raw foods, and drinking pure water.
If you choose to use any over-the-counter medicine or supplements, or alternative medicine practices such as acupuncture, be sure to let your doctor know about them.

When to Seek Medical Care

Anyone with flu-like symptoms and/or risk factors for HIV (see the list under "Who Gets It") should avoid sexual activity, stop any non-medical needle use, and seek medical care and testing.


Your doctor will base the diagnosis on your symptoms and signs as well as the likelihood that you may be in a high-risk group, such as people who are sexually promiscuous, use illicit intravenous drugs, or engage in unprotected or unsafe sex, especially men who have sex with men.

Primary HIV infection occurs before an individual develops sufficient HIV antibodies needed to test positive on a blood test. These antibodies can take 2-4 months to develop. Therefore, repeated HIV-antibody blood tests over time are recommended when an individual is very likely to be infected.

Any person with primary HIV infection should notify sexual partner(s) immediately. In most states, doctors are required by law to report HIV infections to the public health department.

A number of drugs have been developed to treat HIV and infections. Although a cure is not possible, people with HIV infection live longer now and enjoy a much better quality of life than those in the early years of HIV awareness. Treatment is tailored for each person to make it as simple, effective, and with as few side effects as possible, and this often involves taking a mixture of medications, carefully overseen by your doctor.


Bolognia, Jean L., ed. Dermatology, pp.1199-1214. New York: Mosby, 2003.

Freedberg, Irwin M., ed. Fitzpatrick's Dermatology in General Medicine. 6th ed, pp.1238-2148. New York: McGraw-Hill, 2003.
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Human immunodeficiency virus primary infection
A medical illustration showing key findings of Human immunodeficiency virus primary infection : Diarrhea, Fatigue, Fever, Headache, Nausea, Vomiting, Rash, Lymphadenopathy, Widespread distribution, Myalgia, Pharyngitis
Clinical image of Human immunodeficiency virus primary infection - imageId=2583139. Click to open in gallery.  caption: 'Widespread erythematous papules and plaques on the back.'
Widespread erythematous papules and plaques on the back.
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