I received this question from Asia Kelly the other day:
Dr. Lerner, thank you for the informative post about Chagas disease. I am a biology student at the University of Texas Pan American in the Rio Grande Valley, South Texas. Last night I believe that I saw an “assassin bug” last night outside of my home near my front door. I am a little worried because I frequently sit outside at night on my porch and I get bitten by what I assumed to be ants or mosquitoes. I’m concerned that I may have been bitten by this insect. I’m wondering if the bite from that bug would cause a rash, swelling, or any sign that it has bitten me. I’m actually very concerned. Also, TV personality Dr. Oz said in a recent show that there is no cure or treatment and that most people will die from chagas in about 20 years. I’m interested in your opinion about this and I’d like to know of any information you might know about the prevelance of this disease in my area. I looked for your email on this site, but cannot find it. Thank you so much.
Ms. Kelly:
You would have to be extremely unlucky to get Chagas’ Disease in the United States. Although Trypanosoma cruzi, the parasite responsible for Chagas’ Disease does exist within our borders, there have only been 7 autochthonous cases, meaning cases acquired here. Admittedly, at least three of those cases were in Texas, but all of those cases were infants, which points out another reason why I don’t think that you are going to get Chagas’: Assassin (kissing) bugs are big bugs, around 2 cm in length. If one gets on you or bites you, you are likely to know it. You can get bitten in your sleep, but we have to remember that it is unlikely that the bugs are in your house. Typically, they live in the cracks in the walls of mud houses, between the bricks of unplastered walls, or in the fronds or thatch that are used for roofing. Some species live outside (like the North American species of triatomines), but these species–judging by the lack of autochthonous cases in the US–don’t seem to pose much danger.
Furthermore, remember that the infectious material is not the insect’s saliva, as it is with tick-borne or mosquito-borne diseases (like ehrlichiosis and West Nile Virus). The parasites are found in the feces of the assassin bugs. That means that if the insect doesn’t defecate while it bites you, it can’t infect. Apparently, the triatomines that we have here in the US don’t have that behavior.
So, while history has shown that it is possible to acquire Chagas’ disease in the US, it has also shown that it is extremely unlikely. Perhaps this will change, either to due to global warming, evolution, or the introduction of a competent vector–either inadvertently or intentionally–into the United States.
As far as vector -borne disease in the Rio Grande Valley go, I’d be more worried about those transmitted by mosquitoes. Dengue, for one, has reared its ugly head along this area, and will probably do so again.
