HIV

Causative agents

HIV is a lentivirus (i.e. reverse transcriptase transcribes its RNA genome into DNA to be inserted into the host’s DNA).  There are two types, HIV-1 and HIV-2.  Within type 1 (the most common and the most virulent) there are four groups, M, N, O, and P.  Group M is the most prevalent, and within it there are at least 16 different subtypes, which are further compounded in their classification due to continuous mutation.[1]

Statistics

HIV is now a pandemic (global outbreak) affecting over 150 countries on 6 continents.[1]  In 2007, there were an estimated 33.2 million people living with HIV and 2.1 million deaths, 330,000 of which were of children under 15.[2] Half of all children born with HIV will die from HIV related complications before their second birthday.[3]  However, up to 75% of those deaths are preventable through diagnosis and beginning treatment within the first 12 weeks after birth.[3]

Modes of Transmission

Contact with infected body fluids, including blood, semen, breast milk, etc can result in the transmission of HIV.[4] Common modes of transmission are through contaminated needles, sexual contact, and from HIV positive mother to child transmission in utero, at birth or through breast feeding.[4] A single dose prior to delivery can reduce the chance of transmission by up to 43%.[5]

Methods of diagnosis

HIV infections have been diagnosed and monitored by CD4 T cell enumeration, antibody detection, antigen detection, and testing for viral nucleic acid. [6] Since infants may possess their mother’s antibodies for up to 18 months, antibody detection is ineffective in diagnosing infants. HIV RNA real-time PCR not only can detect HIV in infants, but also reduces the average window period (time until detection) between 11 and 31 days depending on the generation of antibody test used.[7]

Annotated Bibliography 

1. McCutchan, F.E., Global epidemiology of HIV. J Med Virol, 2006. 78 Suppl 1: p. S7-S12.

2. Anonymous, 2007 AIDS epidemic update. 2007, UNAIDS: Geneva.

3. Anonymous, Early HIV diagnosis and treatment saves lives of newborn babies. 2008, UN.

4. Anonymous, BVGH Global Health Primer. 2007, Bio Ventures for Global Health: Washington DC.

5.  Suksomboon, N., N. Poolsup, and S. Ket-Aim, Systematic review of the efficacy of antiretroviral therapies for reducing the risk of mother-to-child transmission of HIV infection. J Clin Pharm Ther, 2007. 32(3): p. 293-311.

6. Stevens, C.D., Clinical Immunology and Serology: A laboratory perspective. 2nd Edition, 2003, F.A. Davis Company: Philadelphia.

7. Busch, M.P., et al., Time course of detection of viral and serologic markers preceding human immunodeficiency virus type 1 seroconversion: implications for screening of blood and tissue donors. Transfusion, 1995. 35(2): p. 91-7.