Aggregate population models and dynamics

Perinatal HIV Transmission

Aggregate Population

One of the more tragic consequences of the HIV / AIDS pandemic is the prevalence of infected children. An estimated 4 million children have been diagnosed with the disease worldwide since HIV was first described in 1981 and greater than 90% of these infections occurred perinatally (Lundy and Janes, 2009, p. 468). Children's immune systems are especially vulnerable to HIV and they typically progress to developing AIDs quickly; rarely to they survive to adulthood and are often are faced with losing one or more parents to the disease.

Causes of Perinatal HIV Transmission

In more developed countries almost all HIV infections in newborns are acquired from HIV-infected mothers perinatally (Lundy and Janes, 2009, p. 468). In the United States these infections are more likely to occur because the mothers had little or no access to quality prenatal care. Access to prenatal care in the United States is divided along racial lines, with African-American and Hispanic children representing 63% and 21.6% of all HIV-infected infants being born. The effectiveness of treating pregnant mothers with highly active antiretroviral therapy (HAART) was revealed when the perinatal HIV transmission rate was reduced from 25-30% to less than 2% with HAART treatment.

Worldwide there were 430,000 children born with HIV in 2009, out of a total of 2.7 million new infections overall (Wang and Ho, 2011, p. 973). Close to one third of these infections were incubated within the intravenous drug user community, and together with other forms of substance abuse, represents the biggest factor driving HIV infection rates in the U.S. And other countries. The reason HIV is so prevalent among this population is in part due to the negative effects substance abuse has on immune health, which in turn creates conditions favorable for increased viral pathogenicity and maternal viral load (Wang and Ho, 2011, p. 976). The helps explain why HIV-infected pregnant women are more likely to transmit HIV to their newborns if they abuse drugs or alcohol during the pregnancy.

Maternal drug and alcohol abuse also has a negative impact on neonatal immune health (Wang and Ho, 2011, p. 976). Neonatal macrophages were found to be more susceptible to HIV infection than maternal macrophages, and this susceptibility is enhanced when the cells were exposed to opiates. Fetal immunity has also been shown to be compromised when the pregnant mother abuses alcohol.

The mode of maternal-fetal transmission is not well understood, but in light of the evidence showing maternal viral load has a dosage effect on transmission susceptibility, the placenta probably plays a major role (Wang and Ho, 2011, p. 976). Studies examining the impact of maternal alcohol consumption on placenta function have shown a number of negative effects, including a smaller placenta size, impaired blood flow, reduced nutrient transport, altered endocrine activity, low birth weight, and an increased chance for miscarriage. Cocaine and heroin use have also been shown to increase the porosity of the maternal/fetal barrier in the placenta, and placental transport systems appear to be directly or indirectly affected by commonly abused drugs.