The authors would like to acknowledge David A. Miller for his contributions that remain unchanged from the first edition.
HIV infection, 042.
HIV INFECTION
I. Etiology/incidence
A. HIV infection and AIDS are common; approximately 38 million adults and 2.3 million children are infected worldwide.
B. The incidence of HIV infection varies among groups.
1. Heterosexually acquired HIV infection is frequent in Africa and Asia, and the incidence of heterosexually acquired HIV infection is rising rapidly in Western societies as well.
2. In Western nations, men who have sex with men, illicit use of injected drugs, and congenital spread have been responsible for most HIV infections to date.
II. Course of infection and important pathophysiologic markers
A. Retroviral infection by one of the strains of the human immunodeficiency virus
C. HIV infection is chronic and progressive.
1. Initially, a rapid increase occurs in the number of viral particles in the blood.
2. During a period of clinical latency, which can be prolonged, the number of viral particles in each milliliter of blood (the viral load) is low.
3. During the development of symptomatic HIV disease and AIDS, the viral load increases and the number of CD4+ lymphocytes measurable in the blood decreases.
D. Therapy against HIV infection may alter the rate of progression to advanced immunodeficiency.
1. Recent data suggest that persons with HIV disease and AIDS live longer than in the past, and that medications and appropriate management have clearly reduced mortality from HIV disease and AIDS.
DOCUMENTING HIV DISEASE
I. The medical history
A. Review of significant risk factors
1. Documented risk factors for viral transmission
a. Men who have sex with men
b. Men and women who have unprotected sex with multiple partners
c. Men and women who exchange sex for money or drugs, or who have sex partners who do
d. Sexual partners of HIV-infected individuals. Note that sexual transmission through rectal, vaginal, and oral sex has been documented.
e. Persons who are being treated for sexually transmitted infections (STIs)
f. Persons who share equipment used to inject drugs
g. Receipt of a blood transfusion in the early or mid 1980s, prior to screening of the blood supply
h. Placental transmission from an infected mother to her unborn child
i. Transmission at the time of delivery
j. Transmission during breast feeding, both to the infant from an infected mother and to the mother from an infected infant
k. Transmission via blood in health care settings, including
i. Accidental needlestick
ii. Splashing of blood onto wounds
iii. During dental procedures
B. Current symptoms
1. Acute retroviral syndrome
a. Flulike illness
i. Fever
ii. Chills
iii. Fatigue
iv. Diffuse erythematous rash
b. Serologic tests for HIV may be indeterminate, negative, or positive, depending on the length of time that has passed since the infection.
c. HIV viral load measures are clearly elevated, and the CD4+ T-lymphocyte count is within normal limits or is slightly reduced.
d. Often missed clinically because of rapid resolution without the need for acute medical care
e. When documented, clearly dates the onset of infection
2. Latent HIV infection—the “asymptomatic phase”
a. Few or no symptoms or signs of HIV-related illness; patient may have persistent generalized lymphadenopathy
b. Positive enzyme-linked immunosorbent assay (ELISA) and Western blot for HIV infection
c. Variable HIV viral load and CD4+ T-lymphocyte count
3. Symptomatic HIV disease (formerly AIDS-related complex)
a. Fever, chills, diarrhea, unintended weight loss
b. Appearance of non–AIDS-defining infections that are normally kept quiescent by an intact immune system, including
i. Shingles (herpes zoster)
ii. Thrush (candidiasis)
(a) Oral
(b) Mucocutaneous
(c) Vaginal
iii. Frequent bacterial infections
c. Laboratory evidence of declining CD4+ T-lymphocyte count or increasing HIV viral load
4. AIDS
a. Measurable immunodeficiency, with the appearance of one of many AIDS indicator illnesses or opportunistic infections (see later section, Prophylaxis Against Opportunistic Infections); common opportunistic organisms include, among others,
i. Pneumocystis jiroveci (formerly P. carinii)
ii. Cryptosporidium parvum
iii. Candida albicans
b. The CD4+ T-lymphocyte count is typically below 500/mcl.
c. AIDS is diagnosed in the absence of opportunistic disease if the CD4+ T-lymphocyte count is below 200/mcl.
CLINICAL EVALUATION OF THE PATIENT AT RISK FOR HIV INFECTION
I. Serologic testing
A. Screening tests
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1. ELISA for HIV
a. Initial test to screen for antibodies to HIV
b. Requires seroconversion (process in which patient’s HIV status changes from HIV negative to HIV positive), which occurs approximately 3 weeks to 6 months after exposure to the virus. Thus, enough time must have elapsed since exposure for antibodies to be detected on the ELISA so an accurate result can be obtained.
2. Rapid screening tests are also available that determine results in less than 30 minutes.
a. In general, these tests are not as reliable as ELISA because they have a higher rate of false-positive results.
b. However, they are most useful in urgent care situations.
i. Hospital emergency rooms
ii. After HIV exposure in health care settings
iii. When the patient is not likely to return for screening results
iv. Other settings such as clinics, small blood banks, etc.
c. These tests include
i. Saliva test (OraQuick—also available as a serum/blood test)
ii. Urine test (Calypte HIV Urine Enzyme Immunoassay [EIA])
iii. Blood tests
(a) OraQuick Advance Rapid HIV-½ Antibody Test
(b) Reveal Rapid HIV-1 Antibody Test
(c) Uni-Gold Recombigen HIV Test
(d) Multispot HIV-1/HIV-2 Rapid Test
d. These tests have not replaced the ELISA in screening for HIV infection, although all are reasonably sensitive and specific.
3. One kit is FDA approved and is available for patients to use at home.
a. Home Access Express Test
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