Small Mammals as Carriers/Hosts of Leptospira spp. in the Western Amazon Forest.

Luciana Dos Santos Medeiros,Anahi Souto Vieira,Maria Isabel Nogueira Di Azevedo,Filipe Anibal Carvalho-Costa,André Luis De Moura Botelho,Narianne Ferreira De Albuquerque,Bernardo Rodrigues Teixeira,Paulo Sérgio D'Andrea,Rui Carlos Peruquetti,Gabriel Martins,Walter Lilenbaum,Susan Christina Braga Domingos,Charle Ferreira Crisóstomo

doi:10.3389/fvets.2020.569004

Abstract

Leptospira is a bacteria that causes leptospirosis and is transmitted through water, soil, or mud that is contaminated by the urine of infected animals. Although it is mainly associated with the urban environment, Leptospires also circulate in rural and wild environments. This study aimed to investigate the role of small mammals in leptospirosis epidemiology in the western Amazon, Brazil. In total, 103 animals from 23 species belonging to the orders Didelphimorphia and Rodentia were captured. Blood, kidney, and urine samples were collected and Microscopic Agglutination Test (MAT), lipL32 PCR, secY sequencing, and culturing were conducted. MAT was reactive on 1/15 sera, and no bacterial isolate was obtained. PCR yielded 44.7% positive samples from 16 species. Twenty samples were genetically characterized and identified as L. interrogans (n = 12), L. noguchii (n = 4), and L. santarosai (n = 4). No statistical association was found between the prevalence of infection by Leptospira spp. in small mammals within carrier/hosts species, orders, study area, and forest strata. Our results indicate a high prevalence of pathogenic Leptospira spp. in several rodent and marsupial species and report the first evidence of Leptospira spp. carrier/hosts in the Brazilian Western Amazon.

Highlights

Leptospirosis is a zoonotic infectious disease caused by the bacteria from the Leptospira genus [1] and transmitted through water, soil, or mud contaminated by the urine of infected animals
The studied areas were forests in the state of Acre, Brazil, western Amazon on Acre river basin, and represented different levels of conservation and land use (Figure 1). These areas included: [1] Floresta do Seringal Cachoeira (FSC) (10◦49′S, 68◦21′W), in the municipality of Xapuri, a continuous and conserved primary forest with 24,200 ha, a medium anthropic impact and land use for ecotourism and traditional activities of latex and castanha-doBrasil extractions; [2] Reserva Florestal Humaitá (RFH) (9◦43′S, 67◦48′W), in the municipality of Porto Acre, is a wide fragment of ∼2,000 ha of primary and secondary rain forest, submitted to moderate anthropic action, surrounded by farms, roads and a large river. This area belongs to the Federal University of Acre (UFAC) and is a preserved area designated for research; [3] Floresta Experimental Catuaba (FEC) (10◦04′S, 67◦37′W), in the municipality of Senador Guiomard, comprising 900 ha of primary and secondary rain forest
Of 15 serum samples subjected to Microscopic Agglutination Test (MAT), only one (6.6%) was positive, a sample from the marsupial Marmosa (Micoureus) rutteri that was reactive to two L. interrogans serogroups (Australis and Autumnalis) at a titer of 1:100 each

Summary

Introduction

Leptospirosis is a zoonotic infectious disease caused by the bacteria from the Leptospira genus [1] and transmitted through water, soil, or mud contaminated by the urine of infected animals. It is mainly reported in the urban environment, leptospirosis circulates in rural and wild environments, with a wide variety of mammal species acting as carrier/hosts of the bacterium [2]. Small Mammals as Carriers of Leptospira in the wild and in the transmission to humans, the possibility of transmission between wild and domestic animals has been a major concern among conservationists and livestock authorities in many areas, especially in the Amazon [5,6,7]. The emergence of zoonosis can greatly impact the abundance of some carrier/host populations, in some extreme cases leading to local extinctions [8]

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