The Body Covers: The 47th Interscience Conference on Antimicrobial Agents and Chemotherapy
ICAAC 2007 Study Summaries: Michael Silverman, M.D.
September 19, 2007
My name is Dr. Michael Silverman, and I'm from the University of Toronto, in Canada, and also a volunteer who works in Zimbabwe with Ve'ahavta, which is a Canadian humanitarian organization that gives free medical care in the developing world. We have been working in Zimbabwe doing mother-to-child transmission studies, trying to prevent mother-to-child transmission of HIV. Since August of 1999, we have been keeping track of what percentage, and what total number women who are pregnant have HIV in the area. We don't keep names, it's non-nominal data -- we just keep the numbers.
What has been dramatic has been a steady fall in the percentage of women who have HIV in this area. The fall has gone from 26.6 percent down to 15.6 percent. That's a 41 percent fall in the prevalence of HIV in the pregnant women. It's strongly statistically significant.
How do you track them, by the way? What are your methods?
What we do is: All women who agree to have an HIV test done in pregnancy have our pretest counseling. If they consent to testing, then they're tested. We don't keep track of their names, but we do keep track of just how many were positive and how many were negative, and the total of how many were checked. The total number checked per month has not changed.
It's been very high total numbers -- we have checked over fifteen and a half thousand women, and the steady drop in the number [of pregnant women who are HIV infected] has been very dramatic. This is despite the fact that the economy has been collapsing.
Initially, we would like to say that it's because more and more people are using condoms, and because educational programs are working. We've been working really hard trying to keep educational programs going in the face of a collapsing economy. We have been doing puppet shows and AIDS clubs, and we're doing condom distribution and, as I said, voluntary counseling and testing for everyone who would like it in the community. We give free Septra and other opportunistic infection prevention medications to all those who are HIV positive and we have a HAART program for treating people with HIV.
Naturally, we are not treating as many people as we'd like because of resource shortages, but we have 888 people who are on HAART.
We'd like to think that those things are what are driving down the outbreak. However, when we look at the number of people who are known to be HIV positive and using condoms, there does not seem to be any trend towards an increased use of condoms.
This is different than what's been seen by other groups in Eastern Zimbabwe, who looked and felt that there was an increased use of condoms, and that was why the HIV prevalence was falling there, as well.
The prevalence seems to be falling throughout the country. Now, this is the largest study done in pregnant women [in Zimbabwe], but there have been other studies done with house-to-house screening, where everyone in the house is asked to come out and ask for permission to do an HIV test. In those programs, also, there's been a decrease in prevalence.
But in our area, we seem to be finding a decrease in prevalence, despite a lack of improvement in condom use. What we think is happening is that the collapse in the economy is actually leading to an improvement in HIV-positive rates. That is, a lot of the things that normally would drive the epidemic, such as lorry [truck] drivers driving up and down the roads and then having brief sexual encounters, have been stopped because of the collapsing economy. The lorry drivers are nowhere near driving as often because the companies have been closing, and they are running out of petrol [gasoline].
Could you describe a little bit -- for those who don't know what's going on in Zimbabwe -- what is the climate there right now?
Unfortunately, it's been extremely difficult. Many people are still surviving, but based on resorting to subsistence farming. A lot of the urbanization and a lot of the developments, in terms of modernization are being reversed by the collapse in the currency. Because of that, Zimbabwe right now is the fastest shrinking economy in the world. They are felt to have over 7,000% inflation. There are currency controls that prevent trading the currency at anything but official rates, which makes it almost impossible to do business, and therefore, many businesses have closed. Things like bars are no longer able to stay open because they can't import alcohol. People have no currency to buy alcohol with.
The buses have stopped running because, again, there's no money for petrol, and the people can't really pay for bus fare. So it's hard to get to a bar. A lot of the men are no longer staying in the city, working and then coming home to visit their wives only occasionally, because there are no jobs in the city, with over 80% unemployment.
I guess this means the men can no longer frequent sex workers.
You can't pay the sex worker if you have no currency.
I guess this means that another risk factor for HIV -- concurrent relationships -- has also become more rare.
It's hard to have a concurrent relationship when you can't get out of earshot of your spouse, because you can't travel. So, people, because of the economic collapse, are being forced to stay home, and the country is sort of becoming like it's being quarantined.
It's not an intervention that we're recommending for HIV control elsewhere. But it's an interesting observation, in terms of what drives an epidemic. This is sort of the opposite of what's happening in Eastern Europe, where there's a boom in the economy, which can help drive HIV rates.
Normally we think of poverty as leading to HIV -- but relative poverty leads to HIV. If someone has money, and is near someone else who doesn't have money, they can force the person who doesn't have money to make inappropriate choices, and dangerous choices, such as prostitution.
However, if nobody's got any money then it takes away any of the leverage that would come with having some money. If everyone is in poverty then some of the pressure towards sex work and all these other things is taken away.
Wow. So, bad a political situation and poverty leads to less prevalence of HIV.
Again, not something we're advocating. It's an unfortunate social experiment, natural experiment, that's been happening in the country, based on what's happening within a severe collapsing economy and a rapidly deteriorating situation. It's been going on for some time, but it's been accelerating. As it accelerates, the pattern seems to be continuing, and seems to be continuing to push down HIV prevalence rates.
This is the largest survey of pregnant women ever done in Zimbabwe? Are you continuing the survey?
We're continuing to follow the patients and we're continuing to follow -- well, rather than follow the patients, we're continuing to follow all new people who are pregnant, all new women who are pregnant. But follow-up of individuals is very difficult in this situation. There are no telephones. It's difficult to maintain computer records when there's no electricity, and it's difficult to contact people when you can't go out and find them and they can't get to you.
We do -- through keeping paper records and logbooks -- continue to monitor what percentage of the women are HIV positive. We continue to try, in a very difficult situation, to do educational programs and condom distribution as much as we can, hoping that they will at least be part of it and help. But it's not clear how much of the effect is from that. I think a lot of the effect is from the collapsing economy.
Let's go over some of the data on the poster-- it says HIV prevalence is decreasing among pregnant women, by 1.4% per month.
That's right. If you take, let's say, January's numbers, and you get a percentage, February's on average will be 1.4% of January's numbers lower. That is: it's not falling by 1.4% every month -- otherwise it would be zero -- but by 1.4% of the previous numbers, is how much it's falling.
That seems to be linear. We tried a number of different models and we tried to break up this by different years, and by different clusters of years. It seems to be consistent throughout. There's a consistent, ongoing fall -- and even up to August 1 of 2007, the fall is continuing.
Thanks Dr. Silverman for taking the time to talk to me.
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