Q&A: an epidemic of confusing numbers

There is a lot of confusion and conflicting information regarding the rates of HIV infection in Swaziland, so I’ll try to clarify some things and give you the most up-to-date numbers we have. We work closely with groups that gather the authoritative figures on this stuff, including NERCHA and the in-country Baylor Clinic doctors, so I’m pretty confident about the accuracy of this info. Actually, I’m far more confident than pretty… but that’s for me and my therapist to work out. On to the Q&A.

Question: What percentage of the population in Swaziland is infected with HIV?

You’d think this would be a pretty straight-forward question and answer, but there are actually a few different ways to measure the epidemic’s scope within a given population and that’s why you sometimes see conflicting numbers. Let me define a few terms first.
First of all, there is the rate of HIV “incidents,” which counts only the number of new HIV cases, and there’s the rate of “prevalence,” which counts all existing HIV cases. We use the prevalence numbers, as they give a more complete picture of the epidemic. So all the numbers I’ll be quoting will be prevalence rates.
There are really 3 main rates measuring HIV prevalence in Swaziland’s population: the overall rate, which includes babies and grandpas and everyone in between; the 15-49 rate, which is the age group most sexually active in a population—and includes the so-called “productive population” of income-earners and consumers; and then there’s the ANC rate, which stands for “antenatal care” and looks exclusively at the HIV rate among pregnant women using health clinics during their pregnancy.
The overall rate is usually the smallest number because it includes lots of people who aren’t even sexually active—like babies and elderly. The ANC rate is always the highest number because it’s measuring a group of women (who always have higher infection rates than men) who are obviously sexually-active AND have obviously had unprotected sex (thus the pregnancy). That’s why the 15-49 year-olds rate is popular among health educators and practitioners: it includes both men and women, pregnant or not, within the largest demographic segment of sexually-active adults. So you have 3 main HIV rates (there are plenty more, believe me, but these are the big 3), all slightly different and all frequently used without explanation. So without further ado, here are the statistics-- remember these correctly and you’ll be better informed than most health workers in Swaziland.

• The overall rate of HIV prevalence: 19% (that’s the highest national overall rate in the world.)

• The 15-49 rate of HIV prevalence: 26% (that’s the latest from Demographic Health Survey, from May 2008)

• The ANC rate of HIV prevalence: 39% (that’s from the national sero-sentinel surveillance study—remember, just pregnant women in this number).

Question: can you please confuse me even more by throwing more numbers and categories at me?

Sure. Here you go… Swaziland’s ANC rate, at 39%, is actually down from it’s peak of 42.6% in 2004. So nearly half of all pregnant women here were HIV positive 4 years ago—and this recent decrease may well be more of a “leveling off” trend than an actual long-term decline. Currently the mother-to-child transmission rate is 14%, meaning that about 14% of babies born to HIV-positive moms are becoming infected. And that’s much too high—that rate should be below 5% with proper treatment and precautions.
Still reading, huh? Okay, here’s more. A closer look at that 15-49 rate shows that among 30-35 year-olds in Swaziland the HIV infection rate is currently a staggering 43%. This reveals an important feature of the HIV epidemic here: it’s killing off an entire generation. My generation, in fact. If I was a 33-year old Swazi man instead of a 33-year old American man, I could rightly assume that close to half of my peers—certainly half of my female friends-- were infected with HIV, and that many of them would not know their status, would not seek treatment and would die within a decade.
It’s also interesting to note that female infection rates are always higher than male ones. It’s basic anatomy: they’re just more susceptible to the HIV virus. In Swaziland’s 15-49 age group, the female HIV prevalence rate is currently 31%, whereas the male rate is 20%-- a very significant difference. Among Swaziland’s overall rate, 22% of the women and 15% of the men are HIV positive.

Question: I heard that tuberculosis (TB) is a bigger killer in Swaziland than HIV/AIDS… is that true?

It is true that TB kills more people than full-blown AIDS in Swaziland. But there is an important connection between HIV infection and TB infection: they often go hand-in-hand. So in many cases it’s hard to say that a person died from either one or the other. The sad thing is, TB is curable.
That brings us to the HIV-TB co-infection rate, of which Swaziland has the highest in the world: 81%. This rate tells us the number of TB patients who are infected with the HIV virus. In Swaziland most of the people infected with HIV do not actually die of AIDS; it takes a while to develop full-blown AIDS (the CD4 count needs to drop below a certain threshold before you even officially have AIDS), and other “secondary opportunistic” diseases often kill them first. Of all these secondary opportunistic diseases to which HIV-positive people are susceptible, TB is by far the biggest killer. TB is really, really common here. So for these reasons and more, the HIV-TB co-infection rate is important.
That 81% number is the prevalence of HIV infection among newly-diagnosed TB patients. What it means to us as PCVs is, when we come across someone with TB, we can be relatively sure that they’re HIV positive and therefore need treatment immediately, or else they’ll die quite rapidly-- their immune system doesn’t stand a chance against full-blown TB. But in rural areas, that’s much easier said than done. In fact, one need not be HIV-positive to die of TB here, just weak and isolated from proper treatment.
One recent case is that of Gogo (grandma) Nkambule. We first met her on a homestead visit back in the middle of November. She walked up to us, talked with us in English for a while about her situation (70 years old and trying to care for 5 or 6 little kids with no income after their father dropped them at her house 5 years’ prior). She was complaining of a nighttime cough and occasional pain in the side of her chest. We both immediately suspected TB, of course, but she said that it wasn’t TB, that she was negative for TB, and we simply had no means of getting her to a hospital. We did not know her HIV status, but at 70 and facing food scarcity problems she was clearly vulnerable to infectious diseases, with or without HIV.
Then after one month we visited her homestead again, delivering 15kg of rice from the Red Cross, and this time she was bed-ridden, blankets and a pillow on the dirt floor of her hut, with an older daughter tending to her. She’d severely deteriorated—ankles swollen, unable to walk, coughing persistently, barely able to talk with us. She’d been to a hospital and we looked at the medications they gave her, which revealed that she’d been diagnosed with TB (for some reason, she still did not think she had it). Jamie gave her some tips to reduce the swelling in her ankles and encouraged her to take the meds faithfully. We left after about 15 minutes. Today I learned that last night, 8 days after that visit, they buried her. She probably died a few days prior to that (so, around Christmas day)—just over a month after being able to walk and talk and care for her grandkids.
So death by TB can happen quickly for those already weakened, whether by age or malnourishment or HIV. And of course our fear is that the little kids she was caring for have contracted TB (patients with full-blown TB spread it to an average of 10-15 people). They’ll now be moved to another relative’s nearby homestead, where it’s possible that TB will continue its spread through that family. This is how a TB epidemic spreads so rapidly—and add to that the over-crowded public busses and khumbis, often the only means of getting to a hospital.

Question: I heard that the life expectancy in Swaziland is like 21 years old or something… is that true?

No, thankfully it’s not that bad. But Swaziland’s life expectancy rate is indeed among the lowest (if not THE lowest—I’m not sure) in the world. Again, you have some competing numbers to contend with, so I’ll tell you what I know.
Apparently there are 2 basic measurements of life expectancy used by the World Health Organization (WHO): the basic life expectancy rate and the healthy life expectancy rate. I suppose the latter rate is looking at how long the average person lives in relatively good health—so maybe terminally ill people are not factored into this number… I don’t know. Look it up and let me know—it’s a new term to me. Anyway, these numbers are estimating the average age that a person born this year can expect to reach. So here they are, as currently reported by WHO:

• Average "healthy" life expectancy in Swaziland: 33 years old for men, 35 for women.
• Average life expectancy (which must include the sick and dying, right?): 41 years for men, 43 for women.
  

Question: how can a baby born to an HIV-positive mother be HIV-negative?

In fact it’s quite common that HIV-positive women give birth to perfectly healthy HIV-negative babies. Most babies of these women are actually born HIV-negative. Apparently, that placenta really does an amazing job at isolating the baby and its fluids from things like infected blood. Don’t ask me how. Fetuses develop their own unique blood supply and it stays separate from mommy’s blood. But where viral transmission can—and does—occur is during the baby’s delivery and during the initial year of feeding.
Here’s the crazy thing: breast milk carries the HIV virus, but it can pass through a newborn’s digestive tract without ever infecting it—especially if mommy’s HIV is being properly managed—and will nourish the baby just as well as HIV-negative breast milk. Where mommy and baby run into trouble seems to be when mommy MIXES formula and HIV-positive breast milk. The way our Baylor Clinic pediatric doctor friends explain it, a newborn’s digestive system is still fragile and forming and can be “scraped” or injured very easily. Breast milk is perfectly designed to be processed by that fragile tract, but formula can actually create tiny little micro-tears and cuts as it passes through their gut—which normally would not bother anything; but when you add HIV-positive breast milk into that damaged little tract, the infection rate jumps up dramatically—the virus gets into the blood stream. So what doctors in the know are currently recommending for HIV-positive mothers (in addition to adhering to their treatment) is that they either breast feed exclusively OR use formula exclusively, but they should never combine the two (“mix feed”). But many Swazi women don’t know this—or do not understand it—and figure that formula feeding is best if they’re HIV-positive. But formula is expensive here, and soon the mom runs out of it and resorts to breast-feeding. That’s part of the reason Swaziland’s mother-to-child infection rate is 14% while it’s just 5% in Botswana, where they’ve managed to spread the good word about exclusivity in newborn feeding practices. Ideally, the HIV-positive mommy would breastfeed exclusively (no formula) for the first 6 months, then after that switch to formula and other baby food (no breast milk!), if possible.