Suitability of in-vitro xenodiagnosis: development of Trypanosoma cruzi in Triatoma infestans depending on larval stage of bugs and number of trypomastigotes taken during in-vitro blood meal.

A study on artificial xenodiagnosis was carried out for the identification of T. cruzi, the causative organism of the American Trypanosomiasis (Chagas Disease) using the natural vector T. infestans. It was investigated whether one single T. cruzi (strain B) is sufficient for successful infection of T. infestans. Since the infection took place by artificial feeding, the average amount of blood taken by larval stages I-V in one meal was determined. On the basis of these results the feeding solution (defibrinated cattle blood) containing the corresponding T. cruzi-concentration/ml was prepared and twenty-one days after the infection feces were investigated for the presence of T. cruzi. It could be shown that one T. cruzi is sufficient for infection of larval stages I-V, although the rate of infection in larval stages IV and V was much lower than in larval stages I-III. These experiments demonstrate that xenodiagnosis can also be performed in-vitro. The possible negative effects due to biting of bugs for in-vivo xenodiagnosis of patients can be avoided. Using this method, far more bugs can be used than in conventional xenodiagnosis increasing the likelyhood of detecting at least one infected T. infestans. Additional experiments simulating postal dispatch during three days at 4 degrees C and 27 degrees C proved that blood samples from far distant places may be sent to be examined at laboratory.