Page 2539 - Hematology_ Basic Principles and Practice ( PDFDrive )

C H A P T E R 157

HEMATOLOGIC MANIFESTATIONS OF HIV/AIDS

Howard A. Liebman and Anil Tulpule

Human immunodeficiency virus type 1 (HIV-1) is the pathogenic provide protection against HIV-1 infection and coinfection is fre-
infectious agent responsible for the development of the acquired quent in sex workers in West Africa.
immunodeficiency syndrome (AIDS). Chronic HIV infection leads
to progressive immunodeficiency and immune dysregulation result-
ing in an increased risk for opportunistic infections, increased inci- TRANSMISSION OF HIV-1
dence of certain malignancies, autoimmune disorders, and varied
organ system dysfunction. Although nearly every organ system can HIV-1 may be transmitted by sexual contact with an infected indi-
be affected by HIV infection, hematologic manifestations involving vidual, by use of contaminated needle in parenteral drug use, exposure
the bone marrow and peripheral blood occur in all patients in the to infected blood products, or by prenatal transmission from infected
course of the disease. This chapter will provide a general overview of mother to her infant.
the epidemiology of AIDS, HIV virology, and immunopathogenesis, HIV-1 has been recovered from both semen of HIV-infected men
and more comprehensive review of the hematologic manifestations and from cervical and vaginal secretions of HIV-infected women. The
of HIV infection. virus can be detected in seminal fluid during the first 4 weeks of
infection. Several factors are associated with increased viral content
of seminal fluid including advanced symptomatic HIV infection,
DEFINITION AND EPIDEMIOLOGY OF HIV INFECTION higher plasma viral loads, CD4 lymphocyte counts less than 0.2 ×
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10 /L, the presence of leukocytes in the seminal fluid, and HAART.
Although the original definition of AIDS was based upon clinical Factors that influence the levels of HIV-1 in female vaginal secretions
symptoms and signs alone, knowledge of the viral pathogenesis has include advanced HIV stage of HIV infection, menstruation, con-
led to a series of revised case definitions by the US Public Health comitant vaginal infection, ulcerative and nonulcerative sexually
Service (USPHS) and Centers for Disease Control and Prevention transmitted diseases, and a high HIV-1 viral plasma load. Prevention
(CDC). The present case definition for HIV-1 infection divides the and treatment of sexually transmitted disease has been associated with
+
disease into three stages as defined by CD4 lymphocyte counts and a decrease in HIV-1 transmission.
the presence of AIDS-defining conditions (Tables 157.1 and 157.2). The risk of HIV infection with transfusion of a single unit of
A diagnosis of AIDS can be made by recognition of well-characterized infected blood is estimated at greater than 90%. The use of coagula-
clinical symptoms and signs (see Table 157.2) with evidence of HIV tion factor concentrate prepared before routine screening of blood
infection (clinical AIDS). HIV infection in an individual with a products for HIV-1 in the United States resulted in a sadly high
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blood CD4 lymphocyte count of less than 0.2 × 10 /L classifies the incidence of HIV infection in patients with congenital bleeding
patient as having “immunologic AIDS.” With the advent of routine disorders. With active blood product screening and inactivation
testing for HIV infection in developed countries, a significant propor- protocols used in the preparation of coagulation factor concentrate,
tion of individuals with HIV infection who are receiving highly active HIV transmission has been essentially eliminated. With screening of
antiretroviral therapy (HAART) have little or no clinical manifesta- all blood units in the United States, receipt of a unit of screened blood
tions of viral infections and can maintain near normal immunologic is associated with an estimated risk of transmission of approximately
function. However, many of the same individuals suffer from 1 in 500,000.
HAART-related toxicities. The World Health Organization (WHO) HIV-1 may be transmitted to a fetus or infant from the mother
originally used an alternative case definition because of the limited in utero, at the time of delivery, or postpartum through breastfeeding.
availability of resources for serologic, virologic and immunologic The risk is greatest when the mother has advanced HIV disease,
testing of patients in poor countries, but after 2007 required serologic higher HIV viral load in the plasma, and active injection drug use.
confirmation of HIV-1 infection. Therefore the early estimates of At time of delivery, active chorioamnionitis, premature rupture of
HIV-related disease worldwide were limited by this more clinically amniotic membranes (>4 hours) and vaginal delivery, as opposed to
based definition. elective cesarean section, have been associated with an increased risk
The CDC estimates the 2013 prevalence of HIV infection in the of maternal-infant transmission. Prematurity, low gestational age, and
United States at 1,201,039 Americans age greater than 13 years with breastfeeding have been reported as risk factors for HIV transmission.
a 2013 estimated incidence of 50,000 new infections. The WHO has The use of antiretroviral agents in pregnancy, delivery, and during
estimated that there were 2.7 million new HIV infections in 2013 the first 6 weeks of life has resulted in a significant reduction in
with an estimated prevalence worldwide of 33 to 37 million people transmission from an estimated 25% to 8% with zidovudine alone
infected by HIV, with 2.1 million new infections and 1.5 million and ever greater benefit with the use of HAART. To date, except for
HIV-related deaths. Sub-Saharan Africa accounts for 71% of all HIV the use of efavirenz, there is no evidence to suggest an increased risk
infections. Vertical transmission from mother to infant continues in of congenital birth defects with the use of antiretroviral agents for
Africa and areas in Asia because of a lack of antiviral medications. this indication. The use of antiretroviral therapy during pregnancy
A second, but molecular distinct virus, HIV-2, is endemic to has resulted in a nearly 50% reduction in the number of children
regions of West Africa. HIV-2 and the simian immunodeficiency with perinatal acquired HIV infection. The WHO reported that in
virus of sooty mangabeys are essentially identical, confirming its 2013, 67% of pregnant women living with HIV infection in low- and
simian origin that subsequently crossed over into man. Less is known middle-income countries are receiving some form of effective HIV
about the epidemiology of HIV-2, but infection appears to result in prophylaxis.
a less virulent clinical course than HIV-1 infection. Despite being Transmission can also occur by the sharing of needles and sy-
structurally closely related to HIV-1, infection with HIV-2 does not ringes between injection drug user. The use of cocaine and other

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