Category Archives: Prevalence

Chagas’ Disease is NOT the new AIDS: Part I

IN SPITE OF WHAT YOU MAY HAVE READ IN MY FAVORITE NEWSPAPER (the NY Times):

It is a great picture of the bug, though. Why do biting arthropods always have their portraits taken while posing on human flesh?

Chagas’ Disease, while being a medical nightmare, is not the new AIDS.

  • The first, and perhaps biggest problem with this article is calling Chagas’ Disease the “new” anything. Chagas’ disease was discovered in 1909 by a brilliant Brazilian scientist, Carlos Chagas. Chagas’ discovery was justly recognized for this great discovery during his own lifetime.
  • Chagas’ disease is like AIDS, in that it targets certain populations, but that is where the similarity stops. Chagas’ disease is spread by a vector (bugs of the family Reduviidae) that is exquisitely evolved to infect the poor, as it is related to low-quality housing. AIDS does target the poor of the world more than the rich, but there are certain groups that AIDS targeted, or continues to target, that have nothing to do with economic standing. AIDS is not transmitted by arthropod vectors (though there was concern in the early years of the pandemic), but by sexual contact and contaminated transfusions and medical equipment. Chagas’ disease can be spread by transfusion, but this risk is decreasing. As of a few years ago,around two decades after the blood supply began being screened for HIV,  the blood supply in the US began being screened for Chagas’ disease.
  • Chagas’ disease is called a Neglected Tropical Disease. These are diseases that have high prevalence in the hotter regions of the globe, affect a large number of people but yet do not get a lot of attention from the press, their governments, NGOs, and even much of the local population. For example, many residents of Lima (where the power is) don’t even know what Chagas’ disease is, even though it afflicts a large number of Peruvians. Why?  It doesn’t occur in Lima, and public education about the disease does not extend to those who won’t get it, even though they may be the ones most able to help.
  • Stigma: Yes, it sucks to get AIDS or Chagas’ or both together. But tell me from your heart of hearts: Which would you rather tell your co-workers and parents–that you’ve contracted HIV or that you’ve contracted Chagas’. I’m betting on Chagas’. 30 years into the epidemic, and HIV/AIDS still carries a burden unmatched by any other disease.
  • Research funding: No comparison. HIV/AIDS has been a research juggernaut over much of the pandemic. As a result, we’ve made brilliant and amazing progress in treatment and prevention of the disease. Chagas’ disease is still treated by the same two lousy drugs that were used over a decade ago. Some research is being done on new treatments, but I you’d be embarrassed to see the shoestring some of those labs run on. Moreover, most of these studies involve using drugs that were already approved for other indications, such as anti-fungals and anti-malarials.(They ain’t much money to make sellin’ drugs to po’ folk in the developin’ world.)

    No mention of Chagas' disease here.

    No mention of Chagas’ disease here.

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My dog has Ehrlichiosis!! Anaplasmosis!! Lyme Disease!!

Or does it?

The American Dog Tick (only infects American dogs)

When I was a practicing vet, I saw how the medicine of fear works to beef up the wallets of practicing vets. As much as I like a meaty wallet, I found that hucksterism just isn’t my cup of suet. Am I being hyperbolic? Using too many high-cholesterol food metaphors? Probably. Also, working now in public health, I find that one of main jobs is to instill the proper amount of fear in the population at large.

What’s an appropriate amount of fear?

Why, what we in public health decide is appropriate!

Anyway, if you have a dog, or if you worry about the above vector-borne diseases, or if you have an interest in how medicine can be practiced when it’s just consumer and provider and no third-party payer, read my article from The Bark.

Updated: What’s Another 2 Million (or 3 or 4 or 5 Million) People Sick?

There is more uncertainty in the total number of Chagas’ cases  than there are total cases of HIV infection in Latin America.

I picked up the just-off-the-(virutal)press issue of the American Journal of Tropical Medicine and Hygiene, the publication of the American Society of Tropical Medicine and Hygiene. There were three new articles on Chagas’ Disease. So in the same issue I read that 18 million or 9.8-11 million  or 9-13 million individuals are infected with Trypanosoma cruzi. One paper–the World Health Organization’s 2002 report, Control of Chagas’ Disease: Second Report of the WHO Expert Committee–claims that Chagas’ Disease is the main cause of death in endemic areas.

So what is the point here? Certainly not to compare one disease to another. Not all of those infected with Trypanosoma cruzi will go on to develop the debilitating and fatal chronic form of the disease, but presumably every case of HIV will infection will progress to AIDS, or require years, if not decades, of  treatment. Interestingly, there are more and better drugs for the treatment of HIV infection than there are for chronic Chagas’ Disease. To complicate matters,  immune suppression, like that caused by HIV infection, is a factor in the activation of chronic Chagas’ Disease, and there are an unknown number of cases of co-infection with Chagas’ Disease and HIV. Chagas’ Disease runs a more severe course in those who  are immune-suppressed.

So what is the point here?

It is that Chagas’ is so widespread that just the level of error in our estimates is even greater than our best estimates for the total prevalence of HIV in the same geographic area.