Molecular detection of Rickettsia africae in Amblyomma ticks collected in cattle from Southern and Central Mozambique.

Elisa Taviani,Vlademiro Magaia,Luis Neves,Nidia Cangi

doi:10.3855/jidc.11625

Elisa Taviani, Vlademiro Magaia + Show 2 more

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https://doi.org/10.3855/jidc.11625

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Abstract

Rickettsia are Gram-negative and obligate intracellular bacteria, which cause typhus and spotted fever-like diseases in humans. In Africa, Rickettsia africae of the Spotted Fever Group Rickettsia (SFGR) is the etiologic agent of the African Tick-Bite Fever. The disease is transmitted by ticks of the genus Amblyomma, which serve as vectors and reservoirs of Rickettsia. In this study, we aimed to detect Rickettsia species in ticks collected from cattle in south and central Mozambique. DNA from 412 adult ticks and 22 pools of larvae were extracted and tested for the presence of Rickettsia genes gltA, ompA and ompB by PCR, followed by sequencing and phylogenetic analysis. Our results showed that in adult ticks, 79.5% (n = 330), 66% (n = 274) and 67% (n = 275) samples were positive for gltA, ompA and ompB genes, respectively. Among the 22 pools of larvae analysed, 77.2% (n = 17) were positive for the three genes tested. The infection rates ranged from 43% to 100% for Rickettsia by gltA in all locations studied, with maximum values of 100% observed in the districts of Maputo province namely Changalane, Boane and Matutuine district. The phylogenetic analysis of amplified sequences revealed that samples under study grouped with R. africae for the 3 genes. The study showed that Spotted Fever Group Rickettsia represented by R. africae widely circulate in Amblyomma ticks collected in south and central regions of Mozambique.

Highlights

Rickettsia are Gram-negative and obligate intracellular bacteria, which cause typhus and spotted fever-like diseases in humans
This genus is divided into three taxonomic groups defined according to the distinctive diseases they cause, namely, the typhus group (TG), spotted fever group Rickettsia (SFGR) and scrub-typhus groups (STG), each comprising several Rickettsia species [3]
When looking at the Rickettsia infection rates in adult tick per district, A. hebraeum ticks ranged from 43% to 100%, with the highest values (100%) detected in ticks collected in districts of the Maputo province, namely Changalane, Boane and Matutuine

Summary

Introduction

Rickettsia are Gram-negative and obligate intracellular bacteria, which cause typhus and spotted fever-like diseases in humans. Methodology: DNA from 412 adult ticks and 22 pools of larvae were extracted and tested for the presence of Rickettsia genes gltA, ompA and ompB by PCR, followed by sequencing and phylogenetic analysis. Conclusion: The study showed that Spotted Fever Group Rickettsia represented by R. africae widely circulate in Amblyomma ticks collected in south and central regions of Mozambique. The genus Rickettsia comprises obligate intracellular bacteria [1], among which 22 species have been proven to be pathogenic to humans [2,3] This genus is divided into three taxonomic groups defined according to the distinctive diseases they cause, namely, the typhus group (TG), spotted fever group Rickettsia (SFGR) and scrub-typhus groups (STG), each comprising several Rickettsia species [3]. STG rickettsiae comprise the mite-transmitted Orientia tsutsugamushi previously called R. tsutsugamushi [12], of which chiggers are the main vectors [13]

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