AFRO-NETS> HIV infection chance from one sex act

[Brian Pazvakavambwa <bpazva@sdnp.org.mw>]

HIV infection chance from one sex act
-------------------------------------
From: Gail Snetro <gsnetro@iafrica.com>

AP US & World Thursday, February 08, 2001

By DANIEL Q. HANEY
AP Medical Editor

CHICAGO (AP) -- A study of heterosexual couples in Africa concludes 
that the chance of catching the AIDS virus from a single sexual en-
counter with an infected person is one in 588. This risk is calcu-
lated for people who do not use condoms and who have sex regularly 
with one infected partner. Earlier estimates from North America and 
Europe vary but have generally placed the risk at about one in 1,000 
for heterosexuals. In this study, researchers followed 174 sexually 
monogamous couples in Rakai, Uganda, in which one partner had HIV and 
the other did not. They were given condoms but usually did not use 
them. Typically the couples had sex nine or 10 times a month, and 
over time, 38 people became infected. Earlier data from the same re-
search team showed that the risk of people transmitting HIV is slight 
if the amount of virus in their bloodstream is low. Those findings 
have encouraged the belief that the wide use of AIDS drug combina-
tions, which make virus levels fall dramatically, will slow the 
spread of the disease. The latest figures were presented by Dr. 
Ronald H. Gray of Johns Hopkins University at the Eighth Annual Ret-
rovirus Conference in Chicago, which concluded Thursday. 

Among the findings:

* Infected teen-agers are three times more likely than people over 40 
  to spread HIV to others during each sexual encounter. This difference 
  cannot be explained by the fact that young people are more sexually 
  active.

* The risk that an HIV-infected woman will transmit the virus to an 
  uninfected man is one in 454. For an infected man to an uninfected 
  woman, it is one in 769. This difference is not large enough to be 
  statistically meaningful, and many have assumed that HIV spreads more 
  readily from men to women than vice versa.

* The risk of spread depends greatly on how much virus people carry. 
  In those whose level of virus is less than 1,700 copies per millili-
  tre of blood, the risk is one in 10,000. When levels are over 38,500, 
  risk is one in 294.

* The risk of transmission appears to be the same for different sub-
  types of virus. Some have speculated that AIDS is much more prevalent 
  in Africa because a different variety of the virus dominates there.

* None of the circumcised men in the study caught HIV. Some experts 
  have raised the possibility of promoting circumcision as a way to 
  control the epidemic.

Whether the transmission risk is the same among couples outside Af-
rica is unclear, especially since virus levels may be higher in Af-
rica, where so few infected people get treated. However, Dr. Helene 
Gayle, AIDS chief at the U.S. Centers for Disease Control and Preven-
tion, said the latest data at least offer a general estimate of this 
risk.

Copyright 2001 The Associated Press. All rights reserved.

--
Dr. Brian Pazvakavambwa
Malawi
mailto:bpazva@sdnp.org.mw

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