A study of ticks and tick-borne livestock pathogens in Pakistan.

Shahid Karim,Zia Uddin Sindhu,Nabanita Mukherjee,Jaclyn Williams,Muhammad Jawadul Hassan,Khemraj Budachetri,Dmitry Apanskevich,Zafar Iqbal,Muhammad Sohail Sajid,Shafiq Ullah,Abdullah Arijo,Raja Muhammad Dilpazir Khan,Asma Kausar,Steven Adamson,Muhammad Azam Kakar,Abid Ali,Scot E Dowd,Rosemary C Sang

doi:10.1371/journal.pntd.0005681

Abstract

BackgroundAs obligate blood-feeding arthropods, ticks transmit pathogens to humans and domestic animals more often than other arthropod vectors. Livestock farming plays a vital role in the rural economy of Pakistan, and tick infestation causes serious problems with it. However, research on tick species diversity and tick-borne pathogens has rarely been conducted in Pakistan. In this study, a systematic investigation of the tick species infesting livestock in different ecological regions of Pakistan was conducted to determine the microbiome and pathobiome diversity in the indigenous ticks.Methodology/Principal findingsA total of 3,866 tick specimens were morphologically identified as 19 different tick species representing three important hard ticks, Rhipicephalus, Haemaphysalis and Hyalomma, and two soft ticks, Ornithodorus and Argas. The bacterial diversity across these tick species was assessed by bacterial 16S rRNA gene sequencing using a 454-sequencing platform on 10 of the different tick species infesting livestock. The notable genera detected include Ralstonia, Clostridium, Staphylococcus, Rickettsia, Lactococcus, Lactobacillus, Corynebacterium, Enterobacter, and Enterococcus. A survey of Spotted fever group rickettsia from 514 samples from the 13 different tick species generated rickettsial-specific amplicons in 10% (54) of total ticks tested. Only three tick species Rhipicephalus microplus, Hyalomma anatolicum, and H. dromedarii had evidence of infection with “Candidatus Rickettsia amblyommii” a result further verified using a rompB gene-specific quantitative PCR (qPCR) assay. The Hyalomma ticks also tested positive for the piroplasm, Theileria annulata, using a qPCR assay.Conclusions/SignificanceThis study provides information about tick diversity in Pakistan, and pathogenic bacteria in different tick species. Our results showed evidence for Candidatus R. amblyommii infection in Rhipicephalus microplus, H. anatolicum, and H. dromedarii ticks, which also carried T. annulata.

Highlights

Pakistan, a predominantly farming nation, has an agriculture sector representing 20.9% of the country’s total gross domestic product and employs 43.4% of the country’s total workforce
Our results showed evidence for Candidatus R. amblyommii infection in Rhipicephalus microplus, H. anatolicum, and H. dromedarii ticks, which carried T. annulata
We investigated the presence of pathogenic rickettsial infections and the presence of the protozoan T. annulata in the tick species we collected

Summary

Introduction

A predominantly farming nation, has an agriculture sector representing 20.9% of the country’s total gross domestic product and employs 43.4% of the country’s total workforce. According to the 2013/14 Pakistan Livestock Census [1], the livestock sector within the agricultural economy doubled from 25.3% in 1996 to 55%. The role of the livestock sector in the rural economy is crucial, as 30–35 million people in the rural population rely on this sector for their livelihoods. Livestock farming plays a vital role in the rural economy of Pakistan, and tick infestation causes serious problems with it. Research on tick species diversity and tick-borne pathogens has rarely been conducted in Pakistan. A systematic investigation of the tick species infesting livestock in different ecological regions of Pakistan was conducted to determine the microbiome and pathobiome diversity in the indigenous ticks

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Results

Discussion

Conclusion