HIV Pearls

• That’s very interesting that during the chronic phase of HIV infection genital transmission risk is relatively low. Why would that be?
  
  
• I know solid evidence exists that male circumcision (MC) markedly reduces men’s risk of contracting HIV, but does it reduce the risk of other STIs?
  
  
• I can see that in Zambia the percentage of people reporting multiple partners has declined. But what about concurrent sexual partners (overlapping in time)? I understand they may be especially risky for HIV infection.
  
  
• In addition to Swaziland, are there other recent examples of countries with generalized HIV epidemics where number of sexual partners has declined?
  
  
• I realize multiple sexual partners is a major driver of HIV transmission, especially in the generalized epidemics of Eastern and Southern Africa. Are there recent examples where people have reduced sexual partners?
  
  
• Preventing unintended pregnancy in HIV+ women and preventing HIV infection among women are important to prevent mother-to-child transmission (MTCT). But how important are they?
  

• USAID is beginning an effort to prevent mother-to-child transmission of HIV by providing the antiretroviral drug Nevirapine to HIV+ women late in pregnancy, and to the infants in the early neonatal period. But it seems sensible to also try to prevent additional infant HIV infections by providing postpartum contraception to women who don’t want to conceive. Does that make sense?
  

That’s very interesting that during the chronic phase of HIV infection genital transmission risk is relatively low. Why would that be?

At least 4 possible reasons may well explain the relatively low transmission rate during the chronic phase of infection, such as observed in discordant couple studies.

1. Immune response producing low viral load in the infected person. After the phase of acute infection, the body’s immune system kicks in and reduces viral loads and genital secretion of virus to very low levels. This is widely accepted as the key reason for reduced transmission. (These low levels tend to remain until the final advanced phase when the immune system starts to fail, though some events like STI’s may induce spikes in viral load and genital shedding.)
   
   
2. Some immunity in the exposed but uninfected person. There is evidence that some people develop some immunity that is associated with decreased risk of acquisition (e.g. a type of immunity called mucosal immunity, generating neutralizing antibodies.)
   
   
3. Selection over time for reduced propensity for infection. There is some natural variation both in the infectiousness of certain infected people and in the susceptibility of others to becoming infected. Over time, partnerships with the most propensity for transmission tend to produce infections, leaving those with less propensity for transmission to become a higher proportion of the exposed population. Similarly there are behavioral factors such as sexual practice and frequency, such that those at highest risk are infected first. As a consequence, couples with lower infectivity/susceptibility may be overrepresented in observational studies.
   
   
4. Changes in the virus in the host over time. It is quite clear that the “founding” virus that causes initial infection changes in the host markedly over time. Through high rates of replication and mutation, differential survival in response to strong immune response leads to a family of variant virus forms. Only certain virus variants appear likely to be founder viruses. It appears plausible that some of that change for survival in the host might make the virus less transmissible from one person to the next. For example speculatively, it appears the virus develops something of a different/thicker outside envelop coating to evade the immune system, which might make it more difficult to travel through transmitting and receiving genital mucosa/environment to cause a new infection. (However, it is also known that the body retains smaller reservoirs of earlier virus forms that could later be released.)

I know solid evidence exists that male circumcision (MC) markedly reduces men’s risk of contracting HIV, but does it reduce the risk of other STIs?

Yes, not only for men but for their female partners. Evidence from a recent randomized trial found that MC reduced men's risk of genital herpes (HSV-2) and human papillomavirus (HPV), the virus largely responsible for cervical and penile cancers.

The same study also found that female partners had a decreased risk of genital ulceration, trichomonas, and bacterial vaginosis, in addition to a reduced exposure to HPV.

Thus, men and their female partners both experience important reproductive health benefits.

I can see that in Zambia the percentage of people reporting multiple partners has declined. But what about concurrent sexual partners (overlapping in time)? I understand they may be especially risky for HIV infection.

A recent study from Zambia also found a decline in concurrent sex partnerships, at least among men. The authors used data from the Zambia Sexual Behavior Surveys from 1998, 2000, and 2003. Men reporting more than one concurrent partner:

Year	Rural Men (%)	Urban Men (%)
1998	13	8
2003	8	6

The percentage of women reporting more than one partner was extremely low. It is harder to measure concurrent partnerships and people have only recently focused on it. The methodology in the three surveys differed somewhat, but were to a large extent overlapping and estimates of concurrency declined “according to all measures derived from the three surveys…”

In addition to Swaziland, are there other recent examples of countries with generalized HIV epidemics where number of sexual partners has declined?

Yes, Zambia. The most recent (2008) UNAIDS Report on the global AIDS epidemic provides levels from the Zambia 2007 DHS which show continuation of decline in proportions of men and women reporting more than one partner in the last 12 months.

DHS Year	Men (%)	Women (%)
1996	27	4
2002	21	2
2007	14	1

As with Swaziland, there is concern about underreporting of numbers of partners, especially from women, but the consistent decline over three surveys with similar methodology provides some confidence some considerable decline is real.

I realize multiple sexual partners is a major driver of HIV transmission, especially in the generalized epidemics of Eastern and Southern Africa. Are there recent examples where people have reduced sexual partners?

Yes, Swaziland appears to be one. Soul City supported national-level population-based surveys in 2002 and 2007 using the same survey organization (CIETAfrica) and methodology. The percent reporting more than one partner in the last 12 months declined markedly (56 percnet to 24 percent for men and 19 percent to 5 percent for women.)

What caused this apparent decline? Probably a variety of behavior change program activities in the country promoting partner limitation, as well as spontaneous behavior change that people seem to make, simply related to fear of AIDS. However, another possibility is that people may increasingly understate numbers of partners in surveys because it is considered more “socially desirable.” But it seems unlikely this could fully account for such a major reported decline. And the 2007 results track pretty well with the 2007 DHS results for people reporting more than one partner in the last 12 months – 22.9 percent for men and 2.3 percent for women.

Preventing unintended pregnancy in HIV+ women and preventing HIV infection among women are important to prevent mother-to-child transmission (MTCT). But how important are they?

Quite important in order to reach the UNGASS (United Nations General Assembly Special Session) goals to reduce the proportion of infants infected with HIV by 20% by 2005 and 50% by 2020. In fact it is fair to say the UNGASS goals cannot be met without these two other elements.

For example, in a recent analysis of 8 key African countries, experts from Johns Hopkins University and WHO conclude that short course ARV prophylaxis for HIV-infected pregnant women (and their infants) by itself would likely reduce MTCT an average of 4%. On the other hand, a comprehensive strategy that adds 1) a reduction in primary HIV infection by 5% and 2) a reduction in pregnancies among HIV-infected women by 10%, comes fairly close to the 2005 UNGASS goal in all 8 countries.

Reference: Sweat M et al. Linkages between family planning and HIV PMTCT programs: Opportunities and challenges. Presentation at Montreux, Switzerland. May 2004.

USAID is beginning an effort to prevent mother-to-child transmission of HIV by providing the antiretroviral drug Nevirapine to HIV+ women late in pregnancy, and to the infants in the early neonatal period. But it seems sensible to also try to prevent additional infant HIV infections by providing postpartum contraception to women who don’t want to conceive. Does that make sense?

Definitely. In fact WHO and various partners have outlined a comprehensive approach that includes 4 elements:

1. Primary prevention of HIV infection;

2. Preventing unintended pregnancies among HIV-infected women;

3. Preventing HIV transmission from HIV-infected women to their children; and

4. Providing care for HIV-infected mothers and their infants.

The concept of providing contraception for HIV+ women after they deliver falls squarely in element 2. It is also an example of good reproductive health care that should be offered to all women postpartum and thus in element 4 as well.

Reference: WHO. Strategic approaches to the prevention of HIV infection in infants. Report of a WHO meeting. Morges, Switzerland, 20-22 March 2002.

Related Pearls

New Pearls 

Family Planning Pearls 

Birth Spacing Pearls