EDITOR – According to Peter Lamptey1 "In Africa slightly more than 80% of infections are acquired heterosexually". The high levels of
heterosexual infection in Africa have been "generated by actuarial models and antenatal data"2. These high levels are not supported by data
originating from prospective epidemiological studies.
In 1997 Padian published a paper entitled "Heterosexual Transmission of Human Immunodeficiency Virus (HIV) in Northern California: Results
from a Ten-Year Study" 3. The data were divided in two parts, cross-sectional and prospective. From the cross-sectional study they estimated
that: "infectivity for male-to-female transmission is low, approximately 0.0009 per contact" and "approximately eight-times more efficient than
female-to-male transmission". Using their estimate of male-to-female transmission, it would take 770 or 3333 sexual contacts respectively to
reach a 50% or 95% probability of becoming infected. If sexual contact were to take place repeatedly every three days this would require a
period of 6.3 and 27.4 years respectively. Based on Padian’s estimate of female-to-male transmission it would require 6200 and 27000
contacts and a period of 51 and 222 years respectively (see Table).
In 2001, a community based study4 was reported from Uganda, where "174 monogamous couples, in which one partner was HIV-1 positive,
were retrospectively identified from a population cohort" involving 15,127 individuals. The probability of transmission per sexual contact was
0.0009 for male-to-female and 0.0013 for female-to-male respectively (see Table). The authors concluded that "The probability of HIV
transmission per sex act in Uganda is comparable to that in other populations, suggesting that infectivity of HIV subtypes cannot explain the
explosive epidemic in Africa"5. In other words, there is no more heterosexual transmission of HIV in Africa than anywhere else, including Britain,
USA, Australia and Europe.
Table. Number of years to attain 50% and 95% probabilities transmission of HIV assuming sexual contact once every three days
Table. Number of years to attain
50% and 95% probabilities transmission of HIV assuming sexual contact once every
three days
STUDY
DIRECTION OF TRANSMISSION
per contact PROBABILTY
Years for 50% PROBABILTY
Years for 95% PROBABILTY
USA
M to F
0.0009
6.3
27.4
F to M
0.0001125
51
222
Uganda
M to F
0.0009
6.3
27.4
F to M
0.0013
4.4
19.5
Eleni Papadopulos-Eleopulos Biophysicist, Department of Medical Physics, Royal Perth Hospital, Perth, Western Australia
Valendar F. Turner Consultant Emergency Physician, Department of Emergency Medicine, Royal Perth Hospital, Perth, Western Australia
John M Papadimitriou Professor of Pathology, University of Western Australia, Perth, Western Australia
Helman Alfonso Department of Research, Universidad Metropolitana Barranquilla, Colombia
Barry A. P. Page Physicist, Department of Medical Physics, Royal Perth Hospital, Perth, Western Australia
David Causer Physicist, Department of Medical Physics, Royal Perth Hospital, Perth, Western Australia
Sam Mhlongo Head & Chief Family Practitioner, Family Medicine & Primary Health Care, Medical University of South Africa, Johannesberg, South Africa
Todd Miller Assistant Scientist, Department of Molecular and Cellular Pharmacology, University of Miami School of Medicine, Florida, United States of America
Christian Fiala Gynaecologist, Department of Obstetrics and Gynaecology, General Public Hospital, Korneuburg, Austria
References
1. Peter R Lamptey Regular review: Reducing heterosexual transmission of HIV in poor countries. BMJ 2002; 324: 207-211.
2. Stuart W Dwyer President Mbeki might have a case on rethinking AIDS. BMJ 2002; 324: 237
3. Padian NS, Shiboski SC, Glass SO, Vittinghoff E. Heterosexual transmission of human immunodeficiency virus (HIV) in northern California: results from a
ten-year study. American Journal of Epidemiology 1997;146:350-357.
4. Gray RH, Wawer MJ, Brookmeyer R, et al. (2001). Probability of HIV-1 transmission per coital act in monogamous heterosexual, HIV-1 discordant couples in
Rakai, Uganda. Lancet 357:1149-1153.
5. Gray RH, Brookmeyer R, Wawer MJ, et al. The Probability of HIV-1 Transmission Per Coital Act in Monogamous HIV-Discordant Couples, Rakai, Uganda.
8th Conference on Retroviruses and Opportunistic Infections 2001, Chicago.
Competing interests:
No competing interests
12 February 2002
Eleni Papadopulos-Eleopulos
Biophysicist
V Turner, J Papadimitriou, H Alfonso, B Page, D Causer, S Mhlongo
Department of Medical Physics, Royal Perth Hospital
Rapid Response:
Heterosexual Transmission of HIV in Africa
EDITOR – According to Peter Lamptey1 "In Africa slightly more than 80% of infections are acquired heterosexually". The high levels of
heterosexual infection in Africa have been "generated by actuarial models and antenatal data"2. These high levels are not supported by data
originating from prospective epidemiological studies.
In 1997 Padian published a paper entitled "Heterosexual Transmission of Human Immunodeficiency Virus (HIV) in Northern California: Results
from a Ten-Year Study" 3. The data were divided in two parts, cross-sectional and prospective. From the cross-sectional study they estimated
that: "infectivity for male-to-female transmission is low, approximately 0.0009 per contact" and "approximately eight-times more efficient than
female-to-male transmission". Using their estimate of male-to-female transmission, it would take 770 or 3333 sexual contacts respectively to
reach a 50% or 95% probability of becoming infected. If sexual contact were to take place repeatedly every three days this would require a
period of 6.3 and 27.4 years respectively. Based on Padian’s estimate of female-to-male transmission it would require 6200 and 27000
contacts and a period of 51 and 222 years respectively (see Table).
In 2001, a community based study4 was reported from Uganda, where "174 monogamous couples, in which one partner was HIV-1 positive,
were retrospectively identified from a population cohort" involving 15,127 individuals. The probability of transmission per sexual contact was
0.0009 for male-to-female and 0.0013 for female-to-male respectively (see Table). The authors concluded that "The probability of HIV
transmission per sex act in Uganda is comparable to that in other populations, suggesting that infectivity of HIV subtypes cannot explain the
explosive epidemic in Africa"5. In other words, there is no more heterosexual transmission of HIV in Africa than anywhere else, including Britain,
USA, Australia and Europe.
Table. Number of years to attain 50% and 95% probabilities transmission of HIV assuming sexual contact once every three days
Table. Number of years to attain
50% and 95% probabilities transmission of HIV assuming sexual contact once every
three days
STUDY
DIRECTION OF TRANSMISSION
per contact PROBABILTY
Years for 50% PROBABILTY
Years for 95% PROBABILTY
USA
M to F
0.0009
6.3
27.4
F to M
0.0001125
51
222
Uganda
M to F
0.0009
6.3
27.4
F to M
0.0013
4.4
19.5
Eleni Papadopulos-Eleopulos Biophysicist, Department of Medical Physics, Royal Perth Hospital, Perth, Western Australia
Valendar F. Turner Consultant Emergency Physician, Department of Emergency Medicine, Royal Perth Hospital, Perth, Western Australia
John M Papadimitriou Professor of Pathology, University of Western Australia, Perth, Western Australia
Helman Alfonso Department of Research, Universidad Metropolitana Barranquilla, Colombia
Barry A. P. Page Physicist, Department of Medical Physics, Royal Perth Hospital, Perth, Western Australia
David Causer Physicist, Department of Medical Physics, Royal Perth Hospital, Perth, Western Australia
Sam Mhlongo Head & Chief Family Practitioner, Family Medicine & Primary Health Care, Medical University of South Africa, Johannesberg, South Africa
Todd Miller Assistant Scientist, Department of Molecular and Cellular Pharmacology, University of Miami School of Medicine, Florida, United States of America
Christian Fiala Gynaecologist, Department of Obstetrics and Gynaecology, General Public Hospital, Korneuburg, Austria
References
1. Peter R Lamptey Regular review: Reducing heterosexual transmission of HIV in poor countries. BMJ 2002; 324: 207-211.
2. Stuart W Dwyer President Mbeki might have a case on rethinking AIDS. BMJ 2002; 324: 237
3. Padian NS, Shiboski SC, Glass SO, Vittinghoff E. Heterosexual transmission of human immunodeficiency virus (HIV) in northern California: results from a
ten-year study. American Journal of Epidemiology 1997;146:350-357.
4. Gray RH, Wawer MJ, Brookmeyer R, et al. (2001). Probability of HIV-1 transmission per coital act in monogamous heterosexual, HIV-1 discordant couples in
Rakai, Uganda. Lancet 357:1149-1153.
5. Gray RH, Brookmeyer R, Wawer MJ, et al. The Probability of HIV-1 Transmission Per Coital Act in Monogamous HIV-Discordant Couples, Rakai, Uganda.
8th Conference on Retroviruses and Opportunistic Infections 2001, Chicago.
Competing interests: No competing interests