Global distribution of Leptospira serovar isolations and detections from animal host species: a systematic review and online database

Abstract

Objectives: Leptospira, the spirochaete causing leptospirosis, can be classified into >250 antigenically distinct serovars. Although knowledge of the animal host species and geographic distribution of Leptospira serovars is critical to understand the human and animal epidemiology of leptospirosis, currently data are fragmented. We aimed to systematically review the literature on animal host species and geographic distribution of Leptospira serovars to examine associations between serovars with animal host species and regions, and to identify geographic regions in need of study.

Methods: Nine library databases were searched from inception through 9 March 2023 using keywords including Leptospira, animal, and a list of serovars. We sought reports of detection of Leptospira, from any animal, characterized by cross agglutinin absorption test, monoclonal antibody typing, serum factor analysis, or pulsed-field gel electrophoresis to identify the serovar.

Results: We included 409 reports, published from 1927 through 2022, yielding data on 154 Leptospira serovars. The reports included data from 66 (26.5%) of 249 countries. Detections were from 144 animal host species including 135 (93.8%) from the class Mammalia, 5 (3.5%) from Amphibia, 3 (2.1%) from Reptilia, and 1 (0.7%) from Arachnida. Across the animal host species, Leptospira serovars that were detected in the largest number of animal species included Grippotyphosa (n=39), Icterohaemorrhagiae (n=29), Pomona (n=28), Australis (n=25), and Ballum (n=25). Of serovars, 76 were detected in a single animal host species. We created an online database to identify animal host species for each serovar by country.

Conclusions: We found that many countries have few or no Leptospira serovars detected from animal host species and that many serovars were detected from a single animal species. Our study highlights the importance of efforts to identify animal host species of leptospirosis, especially in places with a high incidence of human leptospirosis. We provide an updated resource for leptospirosis researchers.

Keywords: Leptospira; animals; epidemiology; serovar; systematic review.

Figure 1

Flow diagram of the article review process for the systematic review of reports on Leptospira serovar isolations and detections in animal host species published 1927–2022 Legend: *Multiple reasons for exclusion possible

Figure 2

Frequency of number of reports per Leptospira serovar detected from animal hosts, per UN region (A), and frequency of unique animal host species in which each Leptospira serovar was detected (B) in the systematic review of reports on Leptospira serovar isolations and detections in animal host species published 1927–2022 Legend: A: Reports that described different regions are counted multiple times. Serovar Pomona was described in 62 reports; serovar Hardjo was described in 53 reports.

Figure 3

Heat map of detected Leptospira serovars in 16 animal host orders in the systematic review of reports on Leptospira serovar isolations and detections in animal host species published 1927–2022

Figure 4

Frequency of number of reports that detected Leptospira serovars per UN region, stratified for Rodentia (A), Artiodactyla (B), and Carnivora (C) in the systematic review of reports on Leptospira serovar isolations and detections in animal host species published 1927–2022 Legend: *Serovars that were detected in only one report are not shown.