Molecular and Serological Prevalence of Leptospira spp. in Feral Pigs (Sus scrofa) and their Habitats in Alabama, USA.

Md Monirul Hoque,Anil Poudel,Vienna Brown,Chengming Wang,Anwar Kalalah,Sara Bolds,Steven Madere,B. Graeme Lockaby,Subarna Barua,Steven Kitchens,Stuart Price,Folasade Adekanmbi

doi:10.3390/pathogens9100857

Abstract

Leptospirosis is a widespread zoonosis and has been recognized as a re-emerging infectious disease in humans and a variety of wild and domestic animal species. In order to understand the prevalence and diversity of Leptospira spp. in feral pig populations of Alabama, we trapped 315 feral pigs in Bullock County east-central Alabama, and collected 97 environmental samples from riparian areas in Bullock County and Macon County east-central Alabama. Two previously published PCRs followed by DNA sequencing and BLASTn were performed to identify pathogenic Leptospira species in the kidney of feral pigs (3.2%, 10/315) as well as environmental samples collected from the habitats of feral pigs (2.1%, 2/97), but not in the whole blood samples (n = 276) or spleen (n = 51). An ELISA determined that 44.2% of serum samples (122/276) were antibody-positive for Leptospira. The identification of two pathogenic Leptospira species from environmental samples and the high sero-positivity in feral pigs suggests potential pathogen shedding from feral pigs to environments, and to humans and domestic animals. In order to better understand the risk to human health associated with feral swine presence, further studies are warranted to explore the interrelationship between Leptospira spp. shedding in the urine of feral pigs and bacterial culture to explore pathogenicity. Multi-locus sequencing typing (MLST) and microscopic agglutination tests (MAT) should be performed in future studies to make a definite determination of pathogenic Leptospira in feral pigs in Alabama.

Highlights

Leptospirosis is a bacterial disease of global importance that affects humans and a variety of wild and domestic animal species
The main objectives of this study were to examine the prevalence of leptospirosis in feral swine populations in Alabama, and examine the presence of pathogenic Leptospira in stream water and stream bed sediments as the habitats of feral pigs, including a privately owned tract of land and a national forest
We collected whole blood and tissue specimens from a total of 315 feral swine at the privately owned land (POL), with paired whole blood and kidney specimens from 276 feral pigs

Summary

Introduction

Leptospirosis is a bacterial disease of global importance that affects humans and a variety of wild and domestic animal species. Pedersen et al (2015) [13] tested whole blood from 2055 wild pigs collected across the United States for antibody presence to six strains of Leptospira known to infect humans and domestic animals. While Kaller et al (2015) [15] recorded the presence of leptospires in surface waters within the Kistachie National Forest in western Louisiana, their data did not reveal spatial linkages between Leptospira and the presence of feral pigs Human risk of this disease is strongly linked to environmental conditions and is higher in the tropics due to elevated humidity and temperature. The main objectives of this study were to examine the prevalence of leptospirosis in feral swine populations in Alabama, and examine the presence of pathogenic Leptospira in stream water and stream bed sediments as the habitats of feral pigs, including a privately owned tract of land and a national forest

Sample Compositions

Molecular Detection of Leptospira Species

Detection of Anti-Leptospira IgG Antibody

Discussions

Study Areas

Trapping of Feral Pigs and Collection of Tissues

Collection of Environmental Samples

Extraction of Nucleic Acids

Statistical Analysis