Objective To analyze the Leishmania infection status in some counties of Henan province, assess the risk of local transmission of visceral leishmaniasis and provide evidence for the effective prevention and control of visceral leishmaniasis.

Methods The incidence data of visceral leishmaniasis in Xin'an county, Mengjin district, Linzhou city during 2020−2022 were collected from National Disease Reporting Information System. The sandfly samples were captured in Xin'an county, Mengjin district, Linzhou city, Xiuwu county, and Boai county in 2022. DNA was extracted from sandflies and the kinetoplast target gene of Leishmania spp. were detected by polymerase chain reaction to determine Leishmania infection in sandfly. The data of Leishmania antibody in dogs from 5 counties from 2020 to 2022 were collected and analyzed statistically. The internal transcribed spacer 1 gene was amplified, sequenced, and subjected to phylogenetic analyses, using the DNA from the patients, the positive dogs and the positive sandflies.

Results Linzhou city has been the first to experience local cases since 2016, with a total of 17 local cases from 2020 to 2022. Xin'an county and Mengjin district have had local cases since 2020, with 4 and 1 local cases from 2020 to 2022, respectively. There have been no local cases in Xiuwu county and Boai county. In 2022, a total of 3778 sandflies were captured in Xin'an county, Mengjin district, Linzhou city, Xiuwu county and Boai county, with a minimum infection rate of 0.16% (6/3 778). The minimum infection rates of sandflies in Xin'an county, Mengjin district, and Linzhou city were 0.44% (2/457), 1.46% (2/137), and 1.52% (2/132), respectively. The sandflies in Xiuwu county and Boai county were all negative. There was no statistically difference of the positive rates in sandflies among the three counties ( χ²=2.277, P=0.532). From 2020 to 2022, a total of 1 025 dogs were tested in 5 counties and districts, with an average positive rate of 14.24% (146/1025). Among them, no dogs were tested in Boai county, and all dogs in Xiuwu county were negative. The positive rates of dogs in Xin'an county, Mengjin district, and Linzhou city were 15.50% (40/258), 17.24% (5/29), and 15.17% (101/666), respectively. There was no statistically difference of the positive rates in dogs among the three counties ( χ²=0.102, P=0.950). The phylogenetic analysis indicated that the patients, the positive dogs and the positive sandflies were infected by the same type of Leishmania, which were clustered into one group with Leishmania infantum and Leishmania donovani.

Conclusion There was complete transmission chain of visceral leishmaniasis in some counties in Henan province, and comprehensive measures should be taken to prevent and control visceral leishmaniasis from “Human-animal-media”, in order to block the transmission of visceral leishmaniasis in Henan Province as soon as possible.