WINDHOEK – The disease-carrying and invasive pantropical blue tick was discovered in Namibia for the first time, according to researcher Nkululeko Nyangiwe of the Department of Conservation Ecology and Ethomology at Stellenbosch University (SU).
This parasite linked to ‘cattle fever’ or babesios, was probably imported by way of livestock from South Africa. This is the finding of research conducted by Nyangiwe, which appeared in the international science journal Experimental and Applied Acarology, which publishes peer-reviewed original papers describing advances in basic and applied research on mites and ticks. His supervisor Dr Sonja Matthee also of the SU Department of Conservation Ecology and Entomology, Prof Conrad Matthee of the SU Department of Botany and Zoology and Prof Ivan Horak of the University of Pretoria participated in the study. It forms part of Nyangiwe’s more extensive doctoral research project on the distribution of the invasive pantropical blue tick (Rhipicephalus microplus) in the Eastern Cape Province of South Africa.
The tick was found earlier this year on several breeds of cattle on four of the 18 privately owned farms sampled across the central region of Namibia. In Windhoek, the Chief Veterinary Officer in the Ministry of Agriculture, Water and Forestry, Dr John Shoopala, confirmed the presence of the blue tick. He urged farmers to be vigilant and to report any suspicions about the presence of the tick, which is related to the African blue tick. It is one of the most important ticks found on livestock around the world. It is a parasite of cattle, but it also occurs on sheep, goats and some wild animals in regions where cattle are farmed.
Heavy tick burdens on animals can decrease production and damage hides. This hard tick can transmit the organisms causing babesiosis (also called ‘cattle fever’) and anaplasmosis (known in South Africa as gall sickness) to cattle. Dr Shoopala said although there are no trade barriers associated with the presence of ticks in Namibia, the impact on production would be felt by producers.
“Thus with livestock being the main contributing sector to the agricultural Gross Domestic Product (GDP), the presence of this invasive tick in the country is an unwelcome occurrence in the industry,” he said. Moreover, according to him control measures are also laborious, because treatment with acaricide does not provide resistance to tick re-infestation on the animal.
The small numbers of the invasive tick collected in Namibia, compared to those of the endemic African blue tick found on the same animals, may imply that the introduction events were recent. Based on records by farmers, it was probably introduced into Namibia prior to November 2010 when a ban on the importation of cloven-hoofed animals from South Africa came into place due to an outbreak of foot-and-mouth disease.
“The four farmers from whose cattle it was collected had previously brought in cattle from the Eastern Cape and North West provinces of South Africa where the pantropic blue tick is present,” explained Nyangiwe. “One farmer had also bought cattle in Namibia that had a South African history,” said the doctoral student. It remains unclear whether the pantropical blue tick will become invasive, as previous studies in Southern Africa have shown it sometimes co-occurs quite readily with the endemic African blue tick.
“Acaricide resistance can also hamper control efforts by farmers,” warned Dr Matthee. Dr Shoopala wants farmers to treat all newly acquired animals on arrival, followed by a quarantine period of 3 to 4 weeks and a second treatment prior to release on the farm. Restricting movement of animals to the dry months can also help reduce tick transmission.
He says without partial distribution, the Directorate of Veterinary Services cannot predict the economic implications with certainty. At least if there was a clear indication about which farms were affected, suitable control measures could be put in place, he noted.
The pantropical blue tick originates from Asia and has become a successful invasive species in amongst others Latin America, Mexico, Australia and Madagascar. It is now common along the eastern coastal belt of Africa, the northern and eastern parts of South Africa, Swaziland, Mozambique, Zimbabwe and Zambia, and recently invaded the Ivory Coast and Benin in West Africa. It has until now not been recorded in Namibia, Angola, Lesotho or Botswana.
Previous studies suggest the distribution of this tick in Africa is related to warm summers and high annual rainfall, and its ability to survive during cold or dry winters. “These broad climatic requirements, together with the trade in live cattle and goats may facilitate its introduction and establishment in previously uninfected countries,” noted Dr Matthee.
By Deon Schlechter