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Anthroponotic visceral leishmaniasis, transmitted by Phlebotomus argentipes Annandale & Brunetti (Diptera: Psychodidae) sand flies, is regarded as a major problem of public health importance in the Indian subcontinent. Understanding the feeding behavior of the vector can be used to investigate changes in human-vector contact during intervention programs. An enzyme-linked immunosorbent assay (ELISA) was modified to make it suitable to identify the origin of P. argentipes and Phlebotomus papatasi Scopoli (Diptera: Psychodidae) blood meals. The sensitivity and specificity of the precipitin ring test and ELISA were compared, as well as the stability of the tests across different stages of blood meal digestion. The ELISA was more sensitive and specific than the precipitin test for identifying the sources of blood meals. When using the ELISA method with a plate reader, it was possible to obtain 100% sensitivity and specificity. When comparing the techniques across digestion stages, it was found that there was a drop in sensitivity, 48 and 72 h postblood meal for precipitin and visually read ELISA, respectively. However, the sensitivity of the ELISA using a plate reader was not altered by the digestion time. The feeding habits of P. argentipes and P. papatasi from the Terai region of Nepal, determined by the ELISA developed, showed P. papatasi to be highly anthropophilic, and P. argentipes appeared to feed both on humans and animals, in particular bovines.

Observational studies in the Indian subcontinent have shown that untreated nets may be protective against visceral leishmaniasis (VL). In this study, we evaluated the effect of untreated nets on the blood feeding rates of Phlebotomus argentipes as well as the human blood index (HBI) in VL endemic villages in India and Nepal. The study had a 'before and after intervention' design in 58 households in six clusters. The use of untreated nets reduced the blood feeding rate by 85% (95% CI 76.5-91.1%) and the HBI by 42.2% (95% CI 11.1-62.5%). These results provide circumstantial evidence that untreated nets may provide some degree of personal protection against sand fly bites.