Investigation On Hosts And Study On Influencing Factors Of Desert-type Kala-azar In Jiashi County, Xinjiang Uygur Autonomous Region

Desert-type kala-azar caused by Leishmania infantum and transmitted by Phlebotomus major wui primarily infects infants under two years of age. It is distributed in the desert areas of southern Xinjiang Uygur Autonomous Region and western Inner Mongolia Autonomous Region. Since its vertebrate reservoir host is unknown, it is difficult to carry out targeted preventive measures. Desert-type kala-azar is a serious threat for the infants under two years of age in the endemic areas. The objective of the study was to investigate domestic animals as potential hosts of desert-type kala-azar and to understand their role in the epidemiology of kala-azar. It also clarifies the influencing factors of desert-type kala-azar through case-control study, in the hope of providing a scientific basis for the control strategy of desert-type kala-azar.An investigation was conducted to gain an understanding of the prevalence of Leishmania infection in human and domestic animals in a desert-type kala-azar endemic village in Jiashi County. The positive rate of PCR in human was13.4%(25/187) and was not statistically significant in different genders, different ages and different occupations. The positive rate of rK39strip tests in domestic animals was36.1%(194/538). The positive rate of rK39strip tests was statistically significant between sheep and goats with a higher rate in sheep (x2=16.187,.P=0.000). The sheep with lesions had a higher seroprevalence than the sheep without lesions (x2=4.614, P=0.032). No significant difference was observed in seroprevalence among different age groups of sheep. The positive rate of PCR in domestic animals was16.2%(87/537) and was not statistically significant between sheep and goats, in different age groups of sheep or between groups of sheep with and without lesions, rspectively. The difference of positive rate of PCR between human and domestic animals was not statistically significant. A statistical difference was oberved between the methods of rK39-immunochromatographic strip test and PCR assay in detecting Leishmania infection in domestic animals. The results implied that the presence of Leishmania infection in domestic animals and they are potential hosts of desert-type kala-azar.Analysis of family aggregation with binominal distribution were conducted in human and domestic animals of Leishmania infection respectively. The results demostrated that the distribution of human of Leishmania infection corresponded to binominal distribution without family aggregation, while the distribution of domestic animals of Leishmania infection did not corresponded to binominal distribution with family aggregation. The presence of family aggregation in domestic animals with Leishmania infection may suggest that these domestic animals participate in the spread of desert-type kala-azar in study area.A1:3matched case-control study was conducted on21cases of kala-azar and63matched controls. It showed that the number of domestic animals was a proctective factor(P=0.011, OR=0.689). When the distance between bedrooms and enclosures of livestock was short, it increased the risk of kala-azar (P=0.005, OR=1.649). The interaction of the number of domestic animals and the distance between bedrooms and enclosures of livestock was significantly different (P=0.011). The results suggested that the number of domestic animals and the distance between bedrooms and enclosures of livestock are influencing factors of kala-azar in the foci of desert-type kala-azar in study area.