Abstract:

Objective To investigate the current endemic status of visceral leishmaniasis in Henan Province and to provide basis for surveillance and scientific control. Methods The visceral leishmaniasis endemicity data and the information from individual cases tracking in Henan Province in 2020 were collected. Based on the reported cases, epidemiological investigations and interventions were carried out in the villages where the local cases were reported. Blood samples were collected from the patients’ family members and neighbours within an area of 100 m radius centered on the patient’s residence, meantime, blood samples were also collected from all domestic and stray dogs in the natural villages where the patients reside. The rk39 immunochromatographic test strip was used to detect serum anti-Leishmania antibody in the samples of villagers and dogs. DNA was extracted from the blood samples of patients (provided by the reporting hospital within 1 week of the case report), villagers and a number of dogs to detect Leishmania kinetoplast target gene by PCR. Then internal transcribed spacer 1 (ITS-1) was amplified and sequenced for those samples with kinetoplast gene positive to identify the species of Leishmania. From May to September, methods of manual capture and light traps were used to collect sandflies in four villages (Yinjiagou, Xiaoguan, Sanzongmiao and Huzhanggou villages) for morphological identificatiobn by dissestion. DNA was extracted from female Phlebotomus chinensis. PCR was performed to detect Leishmania kinetoplast target gene for determining Leishmania infection in the andflies. Results A total of 16 cases of visceral leishmaniasis were reported in Henan Province in 2020. The 16 cases covered the age ranging from 8 months to 68 years old. Thirteen cases had typical clinical symptoms, including fever, pancytopenia, and splenomegaly. The average time and the median time from onset to definitive diagnosis were 45.3 d and 30 d, respectively. Among the 16 cases, 13 were local infections, and 3 were imported cases from other provinces. Among the 13 local cases, 6 cases were children including 4 children less than two years old, who reside in seven countries of Zhengzhou, Luoyang and Anyang. Most infections occurred from October to May of the following year (11/13). A total of 376 blood samples were collected from the residents, the positive rate of rk39 antibody was 0.5% (2/376) and all of the 376 blood samples were negative for PCR test. A total of 721 blood samples were collected from dogs. The positive rate of rk39 antibody was 17.5% (126/721). The positive rates of dogs in Zhengzhou, Luoyang and Anyang were 21.8% (59/271), 15.0% (50/333) and 14.5% (17/117), respectively, with no significant difference among the three cities (χ² = 5.5693, P > 0.05). PCR was performed on 99 dog samples. The positive rate was 36.4% (36/99). Among the 66 seropositive dogs, 36 were positive by PCR with a positive rate of 54.5% (36/66), while 33 seronegative dogs were all negative in the PCR test. The ITS-1 sequences amplified from the patients had 100% homology with the L. infantum sequence (GenBank accession number MG041377). The ITS-1 sequences amplified from the positive dogs had 100% homology with the L. infantum sequence （GenBank accession number MN648767）. A total of 1 115 sandflies were captured and identified as P. chinensis, Sergentomyia khawi and S. squamirostris. Among them, 39 female P. chinensis were negative in PCR detection. Conclusion There exists local transmission of visceral leishmaniasis caused by L. infantum in Henan Province, and the positive rate of canine Leishmania infection in dogs is relatively high. It is necessary to strengthen the management of dogs to prevent further spread of visceral leishmaniasis in Henan Province.

Key words: Visceral leishmaniasis, Leishmania infantum, Epidemiological investigation, Sandfly, Henan Province