Saturday, November 1, 2014

Chagas in Virginia and Texas; and Using Dogs as Sentinels for Parasite Spread

Chagas disease or American Trypanosomiasis is a disease that makes me cringe. Not only because of the high potential it increases its endemic range in the next 20 years, but because of the vector that trasmits it.

Health officials in Texas are becoming concerned about the rise of a "new to the region" blood sucking insect with a deadly bite known as the "kissing bug". Trust me, they are gross. Also, trust me that you don't want to know how big they are, or why they are called the kissing bug.

Kissing/Triatomid Bug - They come in at night and bite you in the face (kissing). The parasite is spread through their feces, so once they bite you, the rub their abdomen on you and the parasite enters the wound. Gross right?
The kissing bug or triatomid bug carries a potentially deadly parasite that can cause Chagas disease. The bugs originiated in Central and South America as well as Mexico. There are growing numbers of reports about cases being discovered in the United States, especially Virginia and Texas.

Virginia seems like a strange place for Chagas to pop up, but Northern Virginia has a large number of Bolivian immigrants currently living there, and continuing to immigrate there. Texas on the other hand makes perfect sense based on geography, and researchers at Texas A and M have apparently discovered the vector in Dallas, TX.

If you have questions, please use the comments section below!

A person infected with Chagas can live for many years without showing any signs. Similiar to HIV or Hepatitis infections, Chagas can be"latent" for many years. Approximately 30% of patients will suffer from cardiac disorders, and roughly 10% will suffer from digestive tract issues. In later years, the infection can lead to sudden death or heart failure which is caused by progressive destruction of cardiac muscle.

Screening in the blood supply began in 2007 and physicans began paying more attention after the increases in incidence and prevalance in the U.S. It is estimated that Chagas affects 8 million people across Mexico, Central and South America. In the United States infection estimates range from 300,000 to 1 million.

Recently, an interesting dispatch came out in Emerging Infectious Diseases from a group at Texas A and M; "Shelter Dogs as Sentinels for Tyrpanosoma cruzi Transmission across Texas"and it raised some interesting points:

  1. Enzoonotic cycles involving infected wildlife reservoirs and domestic dogs occur in the southern United States. Beyond the vector transmission via bite from the kissing bug, the parasite can also be spread via consumption of infected bugs or contaminated food products, blood transfusions, and "congenitally".
  2. Dogs manifest similar symptoms to humans.
  3. No vaccine avvailable for humans or dogs
  4. Texas is a high-risk state for transmission of T. cruzi to dogs
The study established a network of seven canine shelters across Texas and collected blood samples from roughly 30 dogs at each shelter. Detection of T. cruzi was done by Chagas STAT-PAK (link). A total of 205 blood samples were collected and 18 (8.8%) were seropositive for T. cruzi antibodies. Seroprevelence ranged from 6.7% to 13.8%. The authors went on to explain that based on some testing anomalies, this is most likely a conservative (low) estimation.

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