Genotype diversity of Trypanosoma cruzi in small rodents and Triatoma sanguisuga from a rural area in New Orleans, Louisiana

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.

Congenital Transmission of Trypanosoma cruzi in Argentina, Honduras, and Mexico: An Observational Prospective Study

“…14 The high frequency of non-TcI DTUs in Honduras and Mexico is in agreement with the recent findings of a greater diversity than previously reported in the T. cruzi DTUs circulating in Mexico and the US. 16,[40][41][42] It confirms the high frequency of non-TcI infections in Mexican patients determined by lineage-specific serology. 43 Our genotyping by PCR was limited to discriminating between TcI and non-TcI because of the very short sequence length of the marker used, and differences among non-TcI DTUs should be studied further.…”

Evolutionary ecology of Chagas disease; what do we know and what do we need?

“…For example, it was believed that TcI DTU was largely predominant in Mexico and to some extent in Central America (over 95% of the strains), but recent studies have documented the presence of non‐TcI parasite strains in triatomines from different regions in Mexico and Central America at high frequencies (Ibanez‐Cervantes et al., ; Pennington, Paiz, Grajeda, & Cordon‐Rosales, ; Torres‐Montero, López‐Monteon, Dumonteil, & Ramos‐Ligonio, ), and a high proportion of patients appear to be infected with non‐TcI parasite strains (Risso et al., ). Similarly in the southern United States, initial work reported only TcI and TcIV DTUs (Roelling et al., ), but recent studies also indicate the presence of TcII DTUs in rodents (Herrera, Licon, Nation, Jameson, & Wesson, ), as well as the predominant presence of TcII‐TcV‐TcVI in autochthonous human cases (Garcia et al., ). Together, these observations indicate clearly that T. cruzi genotype distribution in Central and North America is still poorly understood (Brenière, Waleckx, & Barnabe, ).…”

Trypanosomatids in Small Mammals of an Agroecosystem in Central Brazil: Another Piece in the Puzzle of Parasite Transmission in an Anthropogenic Landscape

“…DTU TcII is also a widely distributed genotype and it has been found to infect several mammalian taxa in distinct habitats and biomes [35][36][37]. Although DTUs TcIII and TcIV are widely distributed and may infect a wide variety of mammals, they appear to occur at significantly lower rates, most likely because they are maintained in very low parasitemia in nature, which hampers their detection [23,32].…”