Thursday, March 29, 2012

Some Quick Epi on HIV in Tanzania

Because I had my epidemiology midterm right before my run on Thursday, I had epi on the brain, so bear with me (or skip this entry) while I do some quick calculations.

According to this study by Hallett, et al,, the incidence rate for HIV in Tanzania (from 2004 to 2008) was 3.37 cases per 1000 person-years. The calculation for this is a bit complicated, but for simplicity's sake, we'll just say that over the course of a year, 3-4 people out of a thousand in Tanzania will contract HIV. This does not take into account those that already are HIV+ (which was about 7% of the population, according to this study). According to this study by Prejean, et al., the incidence rate in the US in 2008 was 0.19 per 1000 person-years.

So looking at the rate ratio (3.37/0.19), people in Tanzania have 17.7 times the rate of contracting HIV than those in the US.
And with the rate difference (3.37-0.19), there were 3.18 excess new cases per 1000 person-years. (The word "excess" does not mean that the 0.19 is an acceptable amount, it's just the terminology used in the field.)

This means that if you follow 100,000 people in the US and 100,000 people in Tanzania for a year, there will be 337 new cases of HIV in Tanzania, 19 more in the US, for a difference (excess) of 318. And these numbers, remember, do not include anyone already living with HIV.

I am not downplaying the issue of HIV/AIDS in the US. I'd like to prevent those 19 new US cases just as much. In the summer of 2007, I volunteered at Don Miller Homes in Baltimore, and saw first-hand the effects of HIV/AIDS and realized while major progress has been made in the US, we still have a long way to go to battle this disease. I'm just trying to demonstrate the magnitude of the problem in Tanzania. We're going to be up against a lot in this fight, and hopefully our efforts, and the efforts of the community, will start driving down these numbers.

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