Eco-bio-social determinants for house infestation by non-domiciliated Triatoma dimidiata in the Yucatan peninsula, Mexico

Background Chagas disease is a vector-borne disease of major importance in the Americas. Disease prevention is mostly limited to vector control. Integrated interventions targeting ecological, biological and social determinants of vector-borne diseases are increasingly used for improved control. Methodology/principal findings We investigated key factors associated with transient house infestation by T. dimidiata in rural villages in Yucatan, Mexico, using a mixed modeling approach based on initial null-hypothesis testing followed by multimodel inference and averaging on data from 308 houses from three villages. We found that the presence of dogs, chickens and potential refuges, such as rock piles, in the peridomicile as well as the proximity of houses to vegetation at the periphery of the village and to public light sources are major risk factors for infestation. These factors explain most of the intra-village variations in infestation. Conclusions/significance These results underline a process of infestation distinct from that of domiciliated triatomines and may be used for risk stratification of houses for both vector surveillance and control. Combined integrated vector interventions, informed by an Ecohealth perspective, should aim at targeting several of these factors to effectively reduce infestation and provide sustainable vector control

Dialysis-associated peritonitis in children

Peritonitis remains a frequent complication of peritoneal dialysis in children and is the most common reason for technique failure. The microbiology is characterized by a predominance of Gram-positive organisms, with fungi responsible for less than 5% of episodes. Data collected by the International Pediatric Peritonitis Registry have revealed a worldwide variation in the bacterial etiology of peritonitis, as well as in the rate of culture-negative peritonitis. Risk factors for infection include young age, the absence of prophylactic antibiotics at catheter placement, spiking of dialysis bags, and the presence of a catheter exit-site or tunnel infection. Clinical symptoms at presentation are somewhat organism specific and can be objectively assessed with a Disease Severity Score. Whereas recommendations for empiric antibiotic therapy in children have been published by the International Society of Peritoneal Dialysis, epidemiologic data and antibiotic susceptibility data suggest that it may be desirable to take the patient- and center-specific history of microorganisms and their sensitivity patterns into account when prescribing initial therapy. The vast majority of patients are treated successfully and continue peritoneal dialysis, with the poorest outcome noted in patients with peritonitis secondary to Gram-negative organisms or fungi and in those with a relapsing infection

Low seroprevalence of Trypanosoma cruzi infection and chronic chagasic cardiomyopathy in a region with abundance of triatomine vectors in Yucatan Peninsula of Mexico

The Yucatan Peninsula of Mexico is endemic with Chagas disease. The main vector responsible for Trypanosoma cruzi transmission is Triatoma dimidiata which is abundant in domestic, peridomestic and sylvan cycles. The abundance of vectors favours T. cruzi transmission and is a high risk for developing chronic chagasic cardiomyopathy (CCC). In the past 10 years, little information was available on parasite seroprevalence and the prevalence of CCC in the Yucatan Peninsula. In the present work, we studied two Mayan communities with a high abundance of T. dimidiata and a random serial sample of 233 patients with an altered electrocardiogram or cardiac failure admitted to the Regional Hospital. A homemade enzyme-linked immunosorbent assay and indirect immunofluorescence standardized techniques were used to detect anti-T. cruzi IgG. In addition, Mayan volunteers were monitored by electrocardiography. In the Mayan communities, 4.8% (3/63) subjects were positive for T. cruzi antibodies none of them presented electrocardiographic alterations, however in seronegative subjects were detected right or left ventricle hypertrophy in 25% (16/63). A remarkable finding was that 90% of the Mayan population recognized the vector and 65% of them had experienced contact with triatomines bites. At the Regional Hospital 0.42% (1/233) were positive for T. cruzi antibodies showing compatible diagnosis with CCC; the most frequent pathology in this population was hypertension in 65% (151/233) and the less frequent was dilated myocardiopathy 6% (14/233). In conclusion, the prevalence of T. cruzi infection and CCC can be considered low in Yucatan, Mexico

Pre-exposure to faeces or saliva of Triatoma dimidiata decreases parasitemia in mice challenged with Trypanosoma cruzi: a description of the inflammatory reaction at the inoculation site

Under natural conditions, Trypanosoma cruzi infection is transmitted to mammals when faeces contaminated with metacyclic trypomastigotes gain access through skin lesions, mucosa or bite wounds. Natural infection of bugs with T. cruzi can vary greatly from less than 1% up to 70%, depending on triatomine species: in the case of Triatoma dimidiata, the percentage of infection is around 30%. In this work uses biological fluids (saliva and faeces) from Triatoma dimidiata to inoculate experimental animals once or multiple times, before inoculation with faeces contaminated with metacyclic trypomastigotes discrete type unit Ia (TcI). The site of infection was analyzed for histological changes based on hematoxile-eosine technique and toluide blue stain for mast cells. Inoculation with saliva led to the recruitment of eosinophils and mononuclear cells at the inoculation site, whereas inoculation with faeces led to the recruitment of neutrophils. Mice inoculated multiple times exhibited a strong inflammatory reaction from the first hour. Mono- or multi-exposure to T. dimidiata fluids before inoculation with metacyclic trypomastigotes helped to control the level of parasitemia. Previous contact with saliva or faeces of T. dimidiata reduces parasitemia in T. cruzi I -infected mice