March 31, 2013

Q&A: Modes of Transmission of the HIV Virus

Although the incidence of HIV has dropped considerably since the height of the epidemic, millions of new HIV infections occur globally each year. An understanding of the risk factors for HIV infection lies at the foundation of successful preventive strategies, which should combine both behavioral and biomedical interventions to reduce HIV infection risk.

This article is for Medical Students & Professionals
This is a Question & Answer revision article designed for medical students and professionals preparing for the PLAB, MRCP or USMLE examinations. They are based on actual questions from these examinations. You may find the HIV Disease article more useful, or one of our many articles on Diseases & Conditions, Medical Syndromes, Health & Wellness or Home Remedies.
In this article:
Risk factors for HIV infection
MCQ exam: clinical scenario
MCQ exam: answer
MCQ exam: explanation

Risk factors for HIV infection

Risk of HIV infection varies by type of sexual or parenteral exposure. However, estimates of risk are mostly based on observational studies and are difficult to quantify since transmission risk also depends on other cofactors that greatly enhance (and occasionally reduce) the probability of infection. As an example, risk factors for HIV transmission include high viral load in the source patient, and risk factors for HIV acquisition after exposure include sexually transmitted infections (STIs), and lack of circumcision, as well as certain host and genetic factors.

MCQ exam: clinical scenario

Which is not considered a common method of transmission for HIV?

a). Coitus
b). Sharing of sharps
c). Breastfeeding
d). Urine
e). Blood transfusion

MCQ questions & answers on

MCQ exam: answer

The correct answer is D.

MCQ exam: explanation

There is little evidence to show that HIV can be transmitted through urine. The most common ways in which HIV is spread throughout the world include sexual contact, sharing needles, and by transmission from infected mothers to their new-borns during pregnancy, labor (the delivery process), or breastfeeding. Risk factors for HIV transmission include high viral load, certain sexual behaviors, presence of ulcerative sexually transmitted infections, lack of circumcision, as well as certain other host and genetic factors.

1). UpToDate: HIV infection: Risk factors and prevention strategies. Available online:

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