Category Archives: external parasites

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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What we talk about when we talk about lice: Lice story, Part II

A LITTLE  LOUSE CAN DO LOT OF DAMAGE

So can a big one, if it's a body louse and not a head louse.

There are few very important things to know about lice.

First of all, lice are very species specific. Cattle lice (there are 4 common kinds in the United States) do not infect sheep. Sheep lice do not infect hogs. And what ever Rick Santorum’s current anxieties are, no species of animal lice infects people. I am sure that he will sleep better knowing this.

Secondly, lice are often quite specific to an area of the body. Human head lice (Pediculis capitis humanus) stay on the head. They do not like moving towards the torso. They like to lay their eggs on hair.

Picture from Wikimedia Commons

Body lice–Pediculus humanus humanus, or sometimes Pediculus humanis corporis–are indistinguishable from head lice, yet except in the laboratory, they will not breed with head lice. They prefer to lay eggs in clothing, especially along the seams. (Bad infestations, therefore, can be prevented by avoiding clothing.)

Thirdly, there is an  important distinction between head lice and body lice from an epidemiological point of view. Head lice really don’t cause any serious problems. Kids get sent home from school, squeamish parents lose it and stay up all night itching–even though they are not infested–and the washing machine and vacuum cleaner do overtime. However, other than the chaos and the irrational panic, there is little to worry about.

Body lice, on the other hand, are the vector for some rather serious diseases.

Epidemic typhus

Spread in the feces of lice (like Chagas’ Disease), epidemic typhus is caused by infection with the bacteria Rickettsia prowazekii. Typhus is one of the reasons that, at least until our last couple of wars, more death to soldiers and civilians during conflicts has been caused  by germs and disease than by bullets, cannonballs, spears, arrows, bayonets, bombs…..

Trench Fever

Caused by the bacteria Bartonella quintana, trench fever is described as a “moderately serious” disease, and though rarely lethal, was responsible for yet another of the epidemics that plagued soldiers during the War to End All Wars. It is not to be confused with Trench Mouth or Trench Foot, both of which also plagued soldiers in the First World War.

Louse-Borne Relapsing Fever

Caused by Borrelia recurrentis, relapsing fever occurs epidemically in areas of poverty and deprivation. It is currently prevalent in Sudan. If left untreated, mortality rates can reach 30%-70%

Take home message: Head lice don’t cause disease, and war, poverty, and deprivation are bad for your health.

Keep Smiling!

Pediculosis capitis(head lice): 3rd Time’s a Charm, Part I

I WAS LIVING in South Carolina when I escaped the  first invasion of  head lice. I was working as a relief veterinarian (9th inning, generally, extra if it was all tied up) all over Georgia and the Carolinas, when my then-girlfriend discovered the wages of volunteering to work with minors, which she did regularly (no good deed goes unpunished).  I laughed from wherever it was on the coast I was spaying kitties and giving dogs vaccinations they actually needed, while back in our Appalachian mountain home my dutiful live-in girlfriend and KB, our boarder, shampooed, picked, vacuumed and did the wash. (Was my absence during this period of duress a critical factor in the eventual demise of our relationship? I can only wonder. Note to self: breakups can be achieved by liberally sprinkling pillowcases with lice and nits, then leaving for a week. Avoids uncomfortable talk about not being communicative and leaving toilet seat up.) By the time I came back from yet another marathon session of animal care,  once again brain-softened from the smell of disinfectant and exhausted and grouchy from sleepless nights in motels,  there was nary a nit nor a louse to be found.

We are talking about head lice here, causative agent Pediculus capitis humanus. Over the years I have devised a scale of  the relative disgust caused by various infectious agents. It’s not really very useful for anything medically, except it does have some social utility. For example, you may discuss a Lyme disease infection at the dinner table, but talks of your child’s pinworms, however benign they may seem to you, will cause people to put down their forkfuls of vermicelli, no matter how tasty.

In any case, the general rule of  the Disgust Scale is that infections go in the following order of rising disgust:

1. Viral infections, such as a cold or influenza

2.Bacterial infections, such as Lyme disease or bacterial pneumonia

3.Fungal infections, such as ringworm or athlete’s foot.

4. Parasitic infections, such as Guinea worm or intestinal roundworms.

Obviously, this is just a general rule, and has nothing to do with the alarm provoked by a disease, or by its actual seriousness. A case of flesh-eating bacteria is clearly both more serious and more off-putting than a case of ringworm (which is neither ringed nor a worm, cf. Cavius porcellus, or the Guinea pig). A case of herpes labialis vs. strep throat? You be the judge.

Also obvious is that there is variation within each of these categories, even with the type of parasite. For example, while head lice infestations are disturbing, body lice infestations are downright gross. And crab lice? I haven’t heard these brought up at afternoon tea since I was in college.

TO BE CONTINUED….

ALSO:

On our New Year’s Day post we failed to identify, the lovely Sharmila Tagore, a Bollywood queen of the ’60s, shone here in a picture from her film Evening in Paris,  waterskiing down the Champs-Élysées.