Range expansion of the economically important Asiatic blue tick, Rhipicephalus microplus, in South Africa.

Nkululeko Nyangiwe,Ivan G Horak,Sonja Matthee,Luther Van Der Mescht

doi:10.4102/jsava.v88i0.1482

Abstract

The Asiatic blue tick, Rhipicephalus microplus, a known vector of bovine babesiosis and bovine anaplasmosis, is of great concern in the cattle industry. For this reason, detailed knowledge of the distribution of R. microplus is vital. Currently, R. microplus is believed to be associated mainly with the northern and eastern Savanna and Grassland vegetation in South Africa. The objective of the study was to record the distribution of R. microplus, and the related endemic Rhipicephalus decoloratus, in the central-western region of South Africa that comprises Albany Thicket, Fynbos and Savanna vegetation. In this survey, ticks were collected from 415 cattle in four provinces (Eastern Cape, Northern Cape and Western Cape and Free State provinces) and from the vegetation in the Eastern Cape province of South Africa between October 2013 and September 2015. More than 8000 ticks were collected from cattle at 80 localities of which R. microplus was present at 64 localities and R. decoloratus at 47 localities. A total of 7969 tick larvae were recorded from the vegetation at 20 localities of which 6593 were R. microplus and 1131 were R. decoloratus. Rhipicephalus microplus was recorded in each of the regions that were sampled. Rhipicephalus microplus is now present throughout the coastal region of the Eastern Cape province and at multiple localities in the north-eastern region of the Northern Cape province. It was also recorded in the western region of the Western Cape province and one record was made for the Free State province. The observed range changes may be facilitated by the combined effects of environmental adaptability by the tick and the movement of host animals.

Highlights

It is well established that ticks and tick-borne diseases (TBDs) significantly impact domestic animal health and the livestock farming industry globally (Busch et al 2014; De Castro 1997; Jonsson & Piper 2007)
It was recorded in the western region of the Western Cape province and one record was made for the Free State province
There are two tick species that act as vectors of the causative agents of bovine babesiosis in South Africa: Rhipicephalus decoloratus, which is endemic to Africa and transmits Babesia bigemina (African redwater) and R. microplus, which is originally from southern Asia and acts as a vector for B. bigemina and B. bovis, the causative organism of Asiatic redwater in cattle

Summary

Introduction

It is well established that ticks and tick-borne diseases (TBDs) significantly impact domestic animal health and the livestock farming industry globally (Busch et al 2014; De Castro 1997; Jonsson & Piper 2007). In Africa, it is estimated that animal losses because of high tick infestations and the control of TBDs such as babesiosis and anaplasmosis cost countries such as Kenya, Tanzania and Zimbabwe between $5 and $6 million per annum (McLeod & Kristjanson 1999). South Africa has a large commercial cattle farming industry and spends considerably more on TBDs per annum (approximately $21 million) (McLeod & Kristjanson 1999). There are two tick species that act as vectors of the causative agents of bovine babesiosis in South Africa: Rhipicephalus decoloratus (the African blue tick), which is endemic to Africa and transmits Babesia bigemina (African redwater) and R. microplus (the Asiatic blue tick), which is originally from southern Asia and acts as a vector for B. bigemina and B. bovis, the causative organism of Asiatic redwater in cattle. The tick has subsequently spread across southern, eastern and western Africa and to date the affected countries include South Africa (Howard 1908; Tønnesen et al 2004), Zimbabwe (Mason & Norval 1980), Swaziland (Weddernburn et al 1991), Zambia (Berkvens et al 1998), Ivory Coast and Benin (De Clercq et al 2012; Madder et al 2007), Tanzania (Lynen et al 2008), Mozambique (Horak et al 2009), Burkina Faso, Mali and Togo (Adakal et al 2013) and Namibia (Nyangiwe et al 2013b)

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Discussion

Conclusion