HIV / AIDS
Human Immunodeficiency Virus (HIV) is a retrovirus that infects approximately 40,000-50,000 people in the US annually. It is the causative agent in the Acquired Immune Deficiency Syndrome (AIDS). Transmission methods for infection are limited to exposure to body fluids, and include sexual activity, IV drug use, blood transfusion or other administration of blood products (particularly before 1990), and maternal-fetal transmission.

 

Pathophysiology

At the time of infection with the virus, most patients are asymptomatic. An "HIV seroconversion syndrome" typically occurs from 1 to 6 weeks after infection, when the virus actively replicates. At this point, HIV serology will remain negative (it typically takes 6 months to react), but a viral load study will be positive.

Symptoms of this syndrome are often described as "mono-like," and can include fever, headache, lymphadenopathy, fatigue, pharyngitis, rash, and GI upset. Aseptic meningitis is an uncommon but serious finding, and the diagnosis of aseptic meningitis in an otherwise healthy individual should prompt investigation into possible HIV infection. The non-specific nature of the typical seroconversion syndrome often leads to a missed opportunity to diagnose the disease early in its course.

Over the course of a typical infection with HIV, patients can expect their CD4 count to drop from a normal value of ~1,000 cells/mm3. Average progression is a decline by approximately 75 cells/mm3 per year, although there is extremely wide individual variation.

Generally, diagnosis can be made definitively by 6 months after infection. Most patients progress to AIDS within 13 years of infection. Once CD4 counts drop below 400, a well-described series of stages occur, each of which is typically accompanied by particular symptoms and opportunistic infections.

Diagnosis

There are currently three widely-used tests for the diagnosis of HIV infection.

Note that confirmed HIV infection is not the same as AIDS.

AIDS is defined by the presence of one of the following three conditions in an HIV positive patient:

There are a variety of presentations that should raise your suspicion that HIV may be present. They include penumonia or zoster in a young person, recurrent yeast vaginitis, aseptic meningitis, any STD, kaposi's, thrush, or the presence of rash in a mono-like presentation (+/- posterior nodes).

Treatment

All HIV+ patients should receive the following vaccinations:

Disease progression is usually described in terms of four stages. These stages are not discrete, but are useful for predicting the typical course of disease progression. CD4 count and viral load are measured routinely in all HIV+ patients. Be aware that this field is rapidly changing, and the recommendations listed below are listed merely so that you have something to say if anyone asks.

Stage I (Early):   (CD4 >400) As described above. Conventions vary widely between providers, but antiretroviral therapies are often started when CD4<500. Combination therapies are widely accepted as preferable to monotherapy. The three major classes of antiretrovirals are:

Stage II (Middle):   (CD4 <400 but >200) Many patients remain asymptomatic, although fatigue &/or fever may be present.
Pathogen / SxProphylaxisTreatment
Bacterial infectionsN/ATypical antibiotics. See bugs & drugs page for details.
Hairy LeukoplakiaN/A(cannot be scraped off oral surfaces - thrush can)
Kaposi'sN/AMany - observation, cryotherapy, radiation, excision, alpha-interferon
Peripheral NeuropathyN/AB12, B6
Skin infectionsN/AAs in non-infected patients
Thrush (Candidiasis)Fluconazole (CD4<50)Troches for oral/esophageal, flu-, keto-, itraconazole (can be scraped off oral surfaces, while hairy leukoplakia cannot)
TBN/AIsoniazid, Rifampin
VZVN/AAcyclovir

Stage III (Advanced):   (CD4 <200 but >50) Presentation varies widely between patients, and often within the same patient at various times.
Pathogen / SxProphylaxisTreatment
PCP (Pneumocystis carinii pneumonia)Trimeth-Sulfa (Bactrim)Dapsone, pentamidine, others

Stage IV (Late):   (CD4 <50)
Pathogen / SxProphylaxisTreatment
CMVAcyclovir (CD4<50)Ganciclovir, Foscarnet
CMV RetinitisAcyclovir (CD4<50)Ganciclovir, Foscarnet
CNS LymphomaN/AOften fatal, no Tx available
Cryptococcal MeningitisN/AAmphotericin
MACRifabutin or Azithro (CD4<75)Clarithromycin, Azithro
ToxoplasmaTrimeth-Sulfa (Bactrim)Sulfa, Clindamycin