An epidemiological comparative study on diagnosis of rodent leptospirosis in Mazandaran Province, northern Iran.

Mohammad Reza Pourshafie,Ehsan Mostafavi,Soheila Moradi Bidhendi,Hossein Nahrevanian,Pejvak Khaki,Mohammad Mehdi Gouya,Hamed Hanifi,Jamshid Darvish,Behzad Esfandiari

doi:10.4178/epih/e2015012

Abstract

OBJECTIVES:Leptospirosis is a zoonosis caused by leptospires, in which transmission occurs through contact with contaminated biological fluids from infected animals. Rodents can act as a source of infection for humans and animals. The disease has a global distribution, mainly in humid, tropical and sub-tropical regions. The aim of this study was to compare culture assays, the microscopic agglutination test (MAT), polymerase chain reaction (PCR), and nested PCR (n-PCR), for the diagnosis of leptospirosis in rodents in Mazandaran Province, northern Iran.METHODS:One hundred fifty-one rodents were trapped alive at 10 locations, and their urine and kidney samples were collected and used for the isolation of live Leptospira. The infecting serovars were identified and the antibody titres were measured by MAT, using a panel of 20 strains of live Leptospira species as antigens. The presence of leptospiral DNA was evaluated in urine and kidney samples using PCR and n-PCR.RESULTS:No live leptospires were isolated from the kidney and urine samples of the rodents. Different detection rates of leptospirosis were observed with MAT (21.2%), PCR (11.3%), and n-PCR (3.3%). The dominant strain was Leptospira serjoehardjo (34.4%, p=0.28), although other serotypes were also found. The prevalence of positive leptospirosis tests in rodents was 15.9, 2.6, and 2.6% among Rattus norvegicus, R. rattus, and Apodemus sylvaticus, respectively.CONCLUSIONS:Leptospirosis was prevalent in rodents in Mazandaran Province, northern Iran. MAT was able to detect leptospires more frequently than culture or PCR. The kidney was a more suitable site for identifying leptospiral DNA by n-PCR than urine. Culture was not found to be an appropriate technique for clinical diagnosis.

Highlights

Leptospirosis is one of the most important common zoonotic diseases
Epidemiological parameters In Mazandaran Province, microscopic agglutination test (MAT) found that 21.2% of all rodent samples tested positive for Leptospira serotypes, of which 11.9% were in the Nowshahr district, 6.6% were in the Nour district, and 2.6% were in the Sari district
76.8% belonged to the species Rattus norvegicus, 6.0% belonged to the species R. rattus, and 17.2% belonged to the species Apodemus sylvaticus

Summary

Introduction

Leptospirosis ( known as rice field fever) is one of the most important common zoonotic diseases. Most pathogenic leptospires can remain alive in water and soil for months and can enter into humans or other animal hosts through scratches in the skin [1,2]. In Iran, the temperate and humid climate zone ranges from the plains along the Caspian Sea to the northern foothills of the Alborz mountain range. In this region, rice planting is the predominant occupation of the rural population, and the majority of farmers keep one or more livestock animals in their

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