Feeding behavior and activity of Phlebotomus pedifer and potential reservoir hosts of Leishmania aethiopica in southwestern Ethiopia

Abstract

20 Background 21 Cutaneous leishmaniasis (CL) is a major public health concern in Ethiopia. However, knowledge 22 about the complex zoonotic transmission cycle is limited, hampering implementation of control 23 strategies. We explored the feeding behavior and activity of the vector (Phlebotomus pedifer) and 24 established the role of livestock in CL transmission.25 Methods 26 Blood meal origins of engorged sand flies were determined by sequencing host DNA. A host choice 27 experiment was performed to assess the feeding preference of P. pedifer when humans and hyraxes 28 are equally accessible. Ear and nose biopsies from goats and bovines were screened for the presence 29 of Leishmania parasites. Sand flies were captured indoor and outdoor with human landing catches 30 (HLC) and CDC light traps to determine at which time and where P. pedifer is mostly active. 31 Principal findings 32 A total of 180 sand flies were found to bite hosts of 12 genera. Humans were the predominant blood 33 meal source (59.4%, p < 0.001) in all habitats, even in caves, where hyraxes are abundant. Only 34 10.6% of the sand flies fed on hyraxes based on the blood meal analysis, but the host choice 35 experiment revealed that sand flies have a significant preference for feeding on hyraxes over 36 humans (p = 0.009) when hosts are equally accessible. Only a single goat nose biopsy from 412 37 animal samples was found with Leishmania RNA. We found that P. pedifer is predominantly 38 endophagic (p = 0.003), but occurs both indoors and outdoors. A substantial amount of sand flies 39 was active in the early evening, which increased over time reaching its maximum around midnight. 40 Conclusion 41 We indicate that Leishmania transmission in southwestern Ethiopia is, in contrast to earlier 42 suggestions, likely mainly anthroponotic and that livestock does not play a role in transmission. 43 Combined indoor and outdoor vector control measures at night are required for efficient vector 44 control.45 Author summary 46 Cutaneous leishmaniasis is a major public health problem in Ethiopia. It is caused by 47 Leishmania aethiopica protozoa that are transmitted when female sand flies take a blood 48 meal. Hyraxes are assigned as the reservoirs of the infection, because many were found 49 infected with Leishmania. There is very limited knowledge about the behavior of sand flies 50 and other potential hosts of the infection. However, this information is a prerequisite for 51 disease control, which is currently hampered. In this study, we found that humans are likely 52 the main source of the infection and that the role of hyraxes in disease transmission needs 53 further investigation to decide whether they should be included in control programs. 54 Livestock appears not play a role in transmission, even though sand flies like to feed on 55 them. We also show that sand flies are active indoors and outdoors, but have a preference 56 for feeding inside human dwellings and that they are mostly active around midnight. 57 Overall, we conclude that disease prevent...