Dynamics of transmission of Trypanosoma cruzi in a rural area of Argentina: III. Persistence of T. cruzi parasitemia among canine reservoirs in a two-year follow-up

Abstract

A new cross-sectional survey of household- associated mongrel dogs as well as follow-up of previously parasitemic individuals was carried out in 1984 toy means of xenodiagnosis and serologic techniques to get a deeper insight into the relationship of T. cruzi parasitemia and age among canine hosts in a rural area of Argentina. Persistence of detectable parasitemia was age-independent, or at most, loosely related to age, confirming the pattern observed in 1982. Similarly no significant age-decreasing effect was recorded among seropositive dogs in: a) the probability of detecting parasites in a 2-year follow-up; b) their intensity of infectiousness (=infective force) for T. infestans 3rd-4th instar nymphs, as measured by the percentage of infected bugs observed in each dog xenodiagnosis. Moreover, not only was the infective force of seropositive dogs for bugs approximately constant through lifetime, but it was significantly higher than the one recorded for children in the present survey, and for human people by other researchers. Therefore, and since T. infestans field populations show high feeding frequencies on dogs, the latter are expected to make the greatest contribution to the pool of infected vectors in the rural household of Argentina. This characteristic should be sufficient to involve canine reservoirs definitely as a risk factor for human people residing in the same house. The increased severity of parasitemia observed among dogs in this survey may be related to the acute undernutrition characteristic of canine populations of poor rural areas in our country, which is expected to affect the ability of the host to manage the infection.

Trypanosoma cruzi (Agent of Chagas Disease) in Sympatric Human and Dog Populations in “Colonias” of the Lower Rio Grande Valley of Texas

“…One seropositive dog lived in the same house as the human (BH54) that was positive on only one serologic assay. In bivariable analyses, only the relationship between colonia and seropositivity was associated with a P value below the cutoff (within-colonia seroprevalence ranged from 9.4% to 31.8%, P = 0.130, Fisher's exact test), but all four putative risk factors were retained in the regression model based on previous findings 10,50,51. A logistic regression model did not reveal differences in the odds of canine seropositivity by sex, age, or breed group (Table 3).…”

HumanTrypanosoma cruziInfection and Seropositivity in Dogs, Mexico

“…Several observations support our hypothesis. First, dogs maintain parasitemia long after infection ( 29 ) and are the preferred source of blood meals for Triatoma infestans ( 30 ). Second, the prevalence rate of infective T .…”

Reservoir host competence and the role of domestic and commensal hosts in the transmission of Trypanosoma cruzi

“…The prevalence of xenodiagnosis-positive dogs and their infectiousness either were ageindependent or declined marginally or significantly with age ( Figure 1B) (Enriquez et al, 2014;Gürtler et al, 2007a;Gürtler et al, 1998bGürtler et al, , 1996aGürtler et al, , 1992aGürtler et al, , 1986bLauricella et al, 1989). The potential contribution of pups to bug infection (P a ) was approximately 50% greater than that of the older age groups combined (Gürtler et al, 1996a).…”