Abstract
BackgroundChagas disease is an anthropozoonosis caused by the protozoan parasite Trypanosoma cruzi that represents a major public health problem in Latin America. Although the United States is defined as non-endemic for Chagas disease due to the rarity of human cases, the presence of T. cruzi has now been amply demonstrated as enzootic in different regions of the south of the country from Georgia to California. In southeastern Louisiana, a high T. cruzi infection rate has been demonstrated in Triatoma sanguisuga, the local vector in this area. However, little is known about the role of small mammals in the wild and peridomestic transmission cycles.MethodsThis study focused on the molecular identification and genotyping of T. cruzi in both small rodents and T. sanguisuga from a rural area of New Orleans, Louisiana. DNA extractions were prepared from rodent heart, liver, spleen and skeletal muscle tissues and from cultures established from vector feces. T. cruzi infection was determined by standard PCR using primers specific for the minicircle variable region of the kinetoplastid DNA (kDNA) and the highly repetitive genomic satellite DNA (satDNA). Genotyping of discrete typing units (DTUs) was performed by amplification of mini-exon and 18S and 24Sα rRNA genes and subsequent sequence analysis.ResultsThe DTUs TcI, TcIV and, for the first time, TcII, were identified in tissues of mice and rats naturally infected with T. cruzi captured in an area of New Orleans, close to the house where the first human case of Chagas disease was reported in Louisiana. The T. cruzi infection rate in 59 captured rodents was 76%. The frequencies of the detected DTUs in such mammals were TcI 82%, TcII 22% and TcIV 9%; 13% of all infections contained more than one DTU.ConclusionsOur results indicate a probable presence of a considerably greater diversity in T. cruzi DTUs circulating in the southeastern United States than previously reported. Understanding T. cruzi transmission dynamics in sylvatic and peridomestic cycles in mammals and insect vectors will be crucial to estimating the risk of local, vector-borne transmission of T. cruzi to humans in the United States.
Highlights
Chagas disease is an anthropozoonosis caused by the protozoan parasite Trypanosoma cruzi that represents a major public health problem in Latin America
Chagas disease is an anthropozoonosis caused by the protozoan parasite Trypanosoma cruzi and represents a major public health problem in Latin America with a burden of disease five times higher than malaria as measured by DALYs [1]
Beard et al [9] reported a domestic transmission cycle in southern Texas in which six dogs tested positive for T. cruzi infection and three died of Chagas disease. These findings suggest that the typically sylvatic T. gerstaeckeri may have passed the parasite from a sylvatic, enzootic cycle to a peridomestic cycle in dogs, which in this case may play an important role in supporting peridomestic transmission of T. cruzi [9] and increased risk of exposure for humans
Summary
The United States is defined as non-endemic for Chagas disease due to the rarity of human cases, the presence of T. cruzi has been amply demonstrated as enzootic in different regions of the south of the country from Georgia to California. The United States (US) was initially defined as non-endemic for Chagas disease due to the rarity of human cases [3], T. cruzi has been amply demonstrated as enzootic in different regions of the south of the country from Georgia to California [1,4]. More than 130 triatomine insect species have been described throughout the Americas Eleven of these species have been found naturally infected with the parasite in the US and are considered potential Chagas disease vectors.
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