NEW ORLEANS – Researchers reported high prices on the Trypanosoma cruzi parasite responsible for Chagas disease, in a few studies…
NEW ORLEANS – Researchers reported high prices on the Trypanosoma cruzi parasite responsible for Chagas disease, in a few studies on free running and protection dogs in Texas, suggesting that the pathogen is more widespread
But that There were good news for Texas hunters in another study presented here: although survey data indicate frequent potential exposure to the insect that transmits T. cruzi none of the over 1000 hunters tested had been infected.
Results of the three studies were reported during a poster session at the American Society of Tropical Medicine and Hygiene Annual Meeting.
Dogs and T. cruzi
Chagas disease affects approximately 8 million people worldwide, including about 300,000 in the United States. However, it tends to fly under the radar in the country, perhaps because it is generally considered a tropical disease.
Similarly, although T. cruzi is known to infect dogs and cause serious disease, it is not among the parasitic organisms that American veterinarians routinely screen for.
In order to better manage infections rates in dogs, researchers at Texas A & M University in College Station under Sarah Hamer, DVM, PhD student, conducted two studies: one in guard dogs in seven places across the state, and another in pet dogs from poor semi-rural areas called “colonies” in the lower Rio Grande Valley.
In the Protection Dog Study, presented by Carolyn Hodo, DVM, PhD, the researchers tested 608 dogs for T. cruzi and four other vector-borne pathogens (including Dilofilaria immitis heartworms). Prices of T. cruzi ranged from 5.5% in Fort Worth to 29.5% in San Antonio; The total average was 1
Hodo and colleagues noted that these percentages were comparable to those seen for D. immitis routinely screened in the United States, suggesting that it would be logical to do the same for T. cruzi . In addition, while dog heart worms are not a health impact, Chagas disease is safe. Hodo said that dogs are “useful as sentinals for vector-borne diseases.”
In this case, she told MedPage Today that’s for sure, because the T. cruzi vector – so-called kissing bugs – requires many blood measures and is equally likely to feed people like on dogs. A large number of infected dogs is a signal that T. cruzi is also very prominent in the environment.
Even higher prevalence is seen in the colonia study, presented by Italo Zecca, MPH, where 231 dogs from seven communities were tested. Seroprevalence for T. cruzi ranged from 20.0% to 55.9%, with an overall average of 35.5%. Many of the protection dogs in Hodo’s study came from people’s homes where they would have been mainly indoors, most dogs in colonies live outdoors.
The robbery in both studies should be interpreted carefully, researchers said. In the colony study, PCR molecular tests were positive in only 3.9% of the dogs. Zecca and colleagues indicated that positive PCR results “may signal acute infection or dogs more prone to being infectious to vectors.” But specificity for T. cruzi serological tests is known to fall well below 100%.
This question has also been raised in the Hunters Study, reported by Sarah Gunter, PhD, of Baylor College of Medicine, Houston. Serological testing of 1,093 individuals who identified themselves as hunters gave positive results in 23 – but no one was confirmed with the CDC’s “gold standard” testing for Chagas, Gunter said.
It was “good news,” she said, considering the survey Response from the 1,093 participants indicated frequent exposures to situations and environments where infection could occur. Most respondents knew nothing about Chagas disease and some took measures to reduce the risk.
Participants were asked a number of questions about likely contact with kissing bugs or blood from potentially infected animals.
More than 90% reported deer and 72% contact with wild boar, both of which are known reservoirs for T. cruzi . Only 40% said they had heard of Chaga’s disease.
Gunter told MedPage Today that it should be a public health priority to educate hunters about Chagas disease and what they can do to minimize the risk. She noted that the state’s Parks and Wildlife Department (which facilitates the current study) carries out training programs where such education can easily be included. This training is mandatory for all hunters born after September 2, 1971.
The studies were funded primarily through government grants and internal university funds. Abaxis donated test kit for studies of protection dogs. An author of that study was affiliated with Zoetis, which sells veterinary diagnostics and other products.
2018-10-31T18: 00: 00-0400