PCR-based identification of Trypanosoma lewisi and Trypanosoma musculi using maxicircle kinetoplast DNA.

Trypanosoma lewisi, transmitted by rat fleas, is a widespread pathogen specific to rats with records of human infection cases. Its closely related species with global distribution, Trypanosoma musculi, is transmitted between mice by ingestion of infected fleas. These trypanosomes are of similar morphology, making it difficult to distinguish them by microscopy. In this study, we have developed a rapid, sensitive and reliable PCR method for the diagnosis of T. lewisi and T. musculi. The T. lewisi-specific amplicons were not produced by other Trypanosoma, such as T. musculi, T. brucei complex or T. cruzi, neither by an outgroup of Leishmania amazonensis. The detection limits of the three pairs of T. lewisi-specific primers were 50ng, 1ng and 10ng of total DNA, respectively. The primers designed for T. musculi primers showed specifically that amplicon strictly in T. musculi and their detection limits were 10ng and 1ng of total DNA. To simplify the detection process, we managed to apply our method directly on tail blood samples without complicated DNA purification. In conclusion, PCR with our primers could be a highly sensitive, specific protocol to detect and distinguish T. lewisi and T. musculi from other trypanosomes.

Fine-scale genetic structure in populations of the Chagas' disease vector Triatoma infestans (Hemiptera, Reduvidae).

Fine scale patterns of genetic structure and dispersal in Triatoma infestans populations from Argentina was analysed. A total of 314 insects from 22 domestic and peridomestic sites from the locality of San Martín (Capayán department, Catamarca province) were typed for 10 polymorphic microsatellite loci. The results confirm subdivision of T. infestans populations with restricted dispersal among sampling sites and suggest inbreeding and/or stratification within the different domestic and peridomestic structures. Spatial correlation analysis showed that the scale of structuring is approximately of 400 m, indicating that active dispersal would occur within this distance range. It was detected difference in scale of structuring among sexes, with females dispersing over greater distances than males. This study suggests that insecticide treatment and surveillance should be extended within a radius of 400 m around the infested area, which would help to reduce the probability of reinfestation by covering an area of active dispersal. The inferences made from fine-scale spatial genetic structure analyses of T. infestans populations has demonstrated to be important for community-wide control programs, providing a complementary approach to help improve vector control strategies.