Dr. Peter Hotez generated dramatic headlines with the publication of his most recent article in PLoS Neglected Tropical Diseases when he compared Chagas disease to HIV/AIDS in terms of the many burdens of the disease. The article noted the similarities and differences between Chagas disease and HIV/AIDS but many news outlets seemed to only hone in on the similarities and somewhat sensational title of the article itself. Read the article yourselves and decide! It’s freely available at the link below:
I’m writing because I disagree and I’ve talked to the disease detectives Besser called upon. They are keeping their eyes on it and they are concerned! After doing research on the geographic distribution of Chagas disease vectors in North America myself and attending the Dr. James Steele Diseases in Nature conference in San Antonio this past week and the Research! America forum on Neglected Tropical Diseases two weeks ago in Houston, I heard the evidence firsthand! The pathogen is causing autochthonous infections in Texas.
Even my sister’s late dog, Jake, tested borderline positive for Chagas disease exposure with an antibody titer of 1:80 as did the kissing bugs on her property in south central Texas. She had two different species of the vectors Triatoma gerstaeckeri and Triatoma sanguisuga present. Sadly, she has gone on to lose 3 more of her dogs in the past year to strange and hard to diagnose illnesses. Three of the four dogs had heart problems: arrythmias, enlarged heart, and valve problems. One passed away in 2 weeks with acute Chagas symptoms, however, this dog was never tested for the disease. Only one dog was tested for the disease and tested positive. She asked multiple times along the way to get them tested and was dismissed repeatedly. This is why it is so important to increase education and research of this pathogen. My sister lost four of her pets, her friends, in a year in what proved to be an extremely expensive and heartbreaking mystery.
I also had the opportunity to interview Ed Wozniak who is leading some of the most important epidemiological, ecological, and behavioral research into the vectors and their behavior. Ed also works on rabies and handles venomous snakes. He says he doesn't have a death wish, I think he is just an adrenaline junky. Ed works in region 8 of Texas with the Zoonoses Control division of the Texas Department of State Health Services. He strongly disagrees with those who say Chagas isn't a problem in Texas, but don' take my word for it, read the interview below!
Dr. Bessner has recently said that the triatomine kissing bugs found in Texas do not transmit Chagas disease to humans, what is your response?
That’s not right at all. Really we have a lot of the species here that are also present in Mexico and well known to be vectors of Chagas disease, including Triatoma gerstaeckeri and [Triatoma] lecticularia for instance.
A paper was published in the last few years that stated the reason why Chagas disease is so low here is because we have better housing and the insects don’t defecate while feeding. But you’ve found something different, right?
The housing does probably impede exposure to some extent but it does not prevent it. I’ve gotten hundreds of bugs found in or on houses, mostly Triatoma gerstaeckeri but occasional [Triatoma] lecticularia and [Triatoma] sanguisuga, and Triatoma protracta woodi. Those bugs do find their way into the house. They find their way into the people’s bedrooms and are oftentimes recovered after they’ve fed on the inhabitants. They wake up with a bite wound and they tear into the bedding and they find the bug.
I find the time frame of defecation to be really quite variable. I’ve had Triatoma gerstaeckeri defecate while feeding, right in front of me. And I’ve had other ones that feed and you know, it’s a while after before they defecate. Once they’re full of blood though they tend to be heavy and do not wander far from where they took their blood meal. That’s why people oftentimes find them in their bedding. I’ve got it photographically documented, of them feeding and defecating at the same time.
So what would you say is the prevalence rate of the disease in the triatomines you’ve sampled?
In the bugs it varies between what we’ve tested so far, between 35-75%.
How does that compare to other countries where Chagas disease is endemic and a problem?
It’s actually higher than some of those areas and comparable to some of the others. 50% is pretty high and that’s a good average.
So where in Texas have you sampled, actually?
I’ve sampled mostly across south central Texas, from Edwards county, Val Verde county, Uvalde county, Medina, Bexar, and a couple other counties east of San Antonio.
Would you say the triatomines are ubiquitous in the landscape, spread kind of evenly everywhere?
Nah, different species seem to have somewhat of a difference in preference of habitat. [Triatoma] gerstaeckeri seems to prefer the more arid region although I have seen them east of San Antonio as well. [Triatoma] sanguisuga is definitely further east.
I also know that you have sampled them in other interesting areas, like your house. Where did you find them around your house, so people reading this know where to look for them?
Mostly around where there ‘s lights but I’ve also found them on the dark sides of the house as well. I’ve watched the bugs out in the field, around the house and I’ve seen them come and go out of crevices, really thin crevices, in many cases where you look at it and you really don’t even see an opening and yet they squinch down and squeeze right on in there.
Here’s a question and I get this a lot because I’m looking at how climate change may be affecting the spread of leishmaniasis and I heard even some professors at UT say that Chagas disease didn’t use to be here and it’s here now because of climate change. I feel like I haven’t actually seen any evidence in the literature but is there some truth to that statement that transmission is actually increasing and Chagas disease didn’t used to be here in the past or has it sort of always been here and just…
I think it’s been around for a while. Somebody sent me a really old article dated back to the 1950s of finding Trypanosoma cruzi in bugs in Texas but there may be increased awareness and there may be increased numbers of bugs now. There seems to be a lot more of them, a lot more of them get turned in, that may be an increase in knowledge of the general public. But it also could be that some of these species are adapting to these modern houses.
Are there any other public health statements you’d like to make for the readership of the blog?
It is also quite possible for people to become sensitized and have an allergic reaction to the bite of the bugs, which indicates 2 things. Both that there is repeated exposure and the fact that they’re pumping in salivary fluid that has allergenic proteins in it.
Can you describe what a bite of one of these triatomines looks like again?
It’s been described to me like as a mosquito bite. Oftentimes, in a lot of cases, there is a visible perforation or hole in the center. In some cases you may not see that if it swells. It’s just kind of a red raised lesion on the skin.
I think more work needs to be done on Trypanosoma cruzi strains that are present because that’s another argument the people have made: that the strains we have are not pathogenic. But the pathology that’s been seen in nonhuman primates and dogs certainly suggests against that. I’d like to see more reservoir host surveillance. If Mexican Free Tail Bats, for instance, are really good hosts and can carry that parasite around? They can easily bring different strains, strains from areas known to have major problems with it right here into Texas. They migrate all the way from all Central America up here and bat caves are great ways to look for triatomines, especially the immature stages.
So if someone finds a triatomine in their home, what should they do with it?
If it they think they’ve been exposed to it, probably the best thing to do is get it tested and if it tests positive then I would recommend that they go to their physician and describe what happened and ask that they draw a blood specimen for testing.
Should they send their triatomines to you?
They can send them to me if they like and I will gladly speciate them and send them on to a testing facility.
Follow-up questions, June 22, 2012:
What is your other hypothesis concerning another invasive species impacting Chagas disease in Texas?
I don’t know if it would necessarily impact Chagas disease or be susceptible to T. cruzi per say but the Mediterranean gecko has colonized houses and it lives in the same cracks and crevices as the bugs. During the day the geckos are in their asleep and easy prey for the bugs, especially the immature stages [of the bugs]. I tested to see if the bugs would feed on such a host and found that they went for them with vigor beyond what I expected. Within minutes they were attached to ‘em and feeding and fed to completion and molted off of those blood meals and they’re just fine. I raised up several batches of [Triatoma] gerstaeckeri nymphs that I hatched from eggs all the way to up to third stage nymphs. I shipped those all off to CDC for their colony. To the best of my knowledge they still have those insects. Now they’re up to the last nymphal stage and I think some of them have maybe molted to adults.
So basically, this could be helping the triatomines, especially tg, maybe adapt to modern houses because there is now a continuous food source and might be leading to increases in population size?
Unlike the situation in south America where they live in thatched roofs and they have ready access to peridomestic wildlife or the people or the people’s domestic animals that live inside the huts, our houses are a lot tighter so they don’t have as much access to us but they could very well live within the space between the exterior and interior walls where those lizards are at and those lizards are a readily available blood source.
And if you see the lizards in your house that means that if the lizards can get in then the triatomines can get in?
Yeah, they can slip in when you open the door or whatever just like a lot of other things. There may be other ways they get in too, we find them in our house occasionally and we do find triatomines as well.
Here is Ed's contact info:
2201 east main st room 151
Uvalde, tx, 78801
If you find a triatomine and want to send it in, download the submission form from the TDSHS found here: