Tick-borne diseases cost the industry as much as $168 million on the continent, with a mortality of 1.1 million cattle every year. To many it is a pesky blood-sucking creature that you can pick up on a walk or off of your dog or cat, but to Africa’s pastoralists they present one of the biggest challenges they face.
Ticks are arachnids (and hence are more closely related to spiders than to insects) which are responsible for losses caused by their attachment to animal hides, by the injection of toxins, and/or by the transmission of diseases that reduce production or cause mortality. In Africa there are over 650 tick species.
They cause considerable economic losses in the eastern, central and southern Africa region because nearly 900 million people rely on livestock for their livelihoods. Estimates have put costs as high as $168 million, with a mortality of 1.1 million cattle every year.
Ticks can also affect other livestock economies; for example, the damage caused by tick bites also diminishes the value of skins and hides for the manufactures of leather. Tick bite marks are among the various factors causing the non-availability of good quality raw material for the leather industry, causing between 20 and 30% depreciation in normal value in the market.
The biggest hit
The most damaging effect of ticks however is their ability to transmit diseases, some of which can be fatal to the host. Four groups of tick-borne diseases (TBD) are of importance to the livestock industry: anaplasmosis, babesiosis, cowdriosis and theileriosis. In Africa, all four of these types of disease pose a threat to livestock production.
The diagnosis of TBDs has improved tremendously in the last decade, but the latest technologies are not always affordable or available to field workers. High costs also inhibit tick control. The most widely used method for the effective control of ticks is the direct application of acaricides (pesticides that kill members of the arachnid subclass Acari) to host animals, usually using a dip tank.
However acaricides are expensive and can be detrimental to the environment. In Mozambique for example it can cost up to $14 per cattle dipped while in Tanzania the cost of dipping a single dairy cow can be as high as $36 per year.
Even when they have access to dips or sprays, in order to optimise the use of acaricides, farmers need to understand the biology and ecology of the tick species on their land and how to use the pesticide.
Not doing it right
In Kenya for example, only 67% of rural farmers and 38% of peri-urban farmers were found to be applying acaricide correctly. In fact, over the last 30 years, the African Insect Science for Food and Health organisation (ICIPE) has reported that this method of control has become less reliable for many reasons, including; reduced government spending on livestock and extension, the cost of acaricides, acaricide resistance, poor management of dips and spray races, and poor monitoring of the movement of cattle and quarantine of infected animals.
So for many pastoralists they simply resort to removing the ticks by hand. In Nigeria for example, the Fulani pastoralists traditionally control ticks by manual removal three times a week during the wet season (from April to October) and twice a week during the dry season (from November to March). In fact in certain parts of the country dip tanks or acaricides have never even been used.
East Coast Fever
One particularly devastating tick-borne disease is East Coast Fever, caused by the protozoan parasite, Theileria parva. East Coast fever disease is the single biggest killer of cattle in 11 countries in Eastern and parts of Central Africa and it is widely regarded as the most serious animal health constraint to increasing the productivity of cattle in eastern, southern and central Africa – mostly because the disease causes high mortality (greater than 80%) in susceptible cattle populations, with the more productive European and improved zebu breeds being particularly susceptible.
For four decades, the Nairobi-based International Livestock Research Institute (ILRI) and its predecessor, the International Laboratory for Research on Animal Diseases (ILRAD), conducted research on East Coast fever.
A “live” vaccine that protects cattle in Africa against East Coast fever has been developed – though there are various versions of the infection-and-treatment immunisation vaccine which have been developed, each differing in the strains of theilerial parasites used in the vaccine. The most widely used version is known as the “Muguga cocktail”.
However, there is still another hurdle in the fight to control ticks, production of the live East Coast fever vaccine is complicated, time-consuming and expensive. To produce one million doses of vaccine requires 130 cattle that have not previously been exposed to the disease, 500 rabbits and at least 600,000 ticks.
The entire process of making the batch takes up to 18 months. The product then requires a cold chain and careful handling to deliver it and have it administered by trained veterinarians on farms and ranches.
The good news is that the commercial production of the “Muguga cocktail” has now been taken up by the Centre for Ticks and Tick-borne Diseases (CTTBD), in Malawi, and the vaccine is expected to be distributed in up to 11 countries in Eastern and Central Africa where the disease is endemic.
The last challenge however will be getting this vaccine to the people who need to access it most, where significant barriers exist in terms of access, cost and administrating the vaccine.
Published: 11 May 2015. By Samantha Spooner
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