Seasonal Prevalence and Risk Factors of canine Leishmania Infection in Beijing, China

Abstract

Background Leishmaniasis, a severe zoonotic disease where dogs act as the main reservoir for Leishmania infantum (L. infantum), poses a significant public health threat. Despite recent cases in Beijing, China, there is a lack of comprehensive studies on canine leishmaniasis (CanL) in this region. This study aimed to determine the prevalence of CanL in Beijing and identify associated risk factors. Methods Enzyme-linked immunosorbent assay (ELISA) was used to detect anti-L. infantum antibodies, and quantitative real-time PCR (qPCR) was used to identify Leishmania DNA. The study included 737 dogs: 575 were tested with both ELISA using serum samples and qPCR using whole blood samples, while the remaining 162 were tested only with qPCR. Variables related to the dogs were collected and evaluated through univariate analysis (the Chi-square test) and multivariate logistical regression analysis. For dogs that tested positive on ELISA or qPCR and exhibited suspicious clinical symptoms, we collected lymph node punctures and skin scrape material to reconfirm Leishmania infection by qPCR. Results ELISA and qPCR prevalence rates were 4.87% (28/575) and 3.26% (24/737), respectively, with all qPCR-positive samples confirmed as L. infantum by PCR amplification of the internal transcribed spacer (ITS) gene. QPCR and ELISA demonstrated strong consistency (P = 0.00) in detecting Leishmania among the 575 dogs subjected to both tests. Multivariate analysis revealed a higher prevalence of CanL during springtime in Beijing (ELISA: OR = 9.31, 95% CI = 2.75–31.47; qPCR: OR = 7.22, 95% CI = 2.49–20.94), and among younger dogs (0-2Y) (ELISA: OR = 5.49, 95% CI = 1.70–17.80; qPCR: OR = 4.51, 95% CI = 1.25–16.24). Univariate analysis identified suburban areas (P = 0.02) and medium to large-sized dogs (P = 0.00) as secondary risk factors. Among the dogs that tested positive on ELISA or qPCR, 16 were subsequently confirmed to have CanL through qPCR test of lymph node aspirates and skin scrapings. The majority of these cases were found in suburban areas (68.75%), with 43.75% detected during springtime. Additionally, 50% of the cases involved medium-sized dogs. Conclusion Seroprevalence and molecular prevalence of CanL in Beijing was 4.87% and 3.26% respectively, with a higher prevalence observed in spring and among younger dogs (0-2Y), emphasizing the importance of comprehensive studies to address public health threats.