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Cattle production: East Coast fever and the brown ear tick

diseases; dipping

The control and management of ticks, and tick-borne diseases, is complex and difficult, but not impossible. Success depends on commitment, co-operation, funds, some knowledge and a healthy dose of common sense.

East Coast fever (ECF) and its vector, the brown ear tick, present the most serious disease challenge cattle farmers face in the sub-region.

It’s too big for one stock farmer to handle, so look for help where you farm and find power in the group.

The group can share problems, information and facilities (dip tanks, spray races, crush pens) and has it has better buying, and bargaining, power. Dips, vaccines and medicines are expensive.

A number of groups have some clout when it comes to lobbying government for much-needed and deserved assistance.

Also read: Farmer unity – a powerful influence on state policy

THE NATURE OF THE PROBLEM

If you want to frighten a cattle farmer, mention a disease outbreak. As his animals die, the farmer watches his livelihood die with them.

Worse, if he has no weapons to defend his herd, and the disease strikes not one, but many animals. And, even worse if that disease is a constant, lurking danger.

This is East Coast fever. Most of Africa’s small-scale cattle farmers face it every day of their lives.

An animal dies every 30 seconds from ECF.

UNDERSTAND THE TICK

East Coast fever’s vector, the brown ear tick, needs 3 cow hosts to complete its life cycle. Understanding the tick, its life cycle, habitat requirements and survival strategies is essential to managing this killer disease. Photo: Afrivip from Ticks of Domestic Animals in Africa; Walker et al. 2003.
  • The brown ear tick likes warm, moist, shady environments.
  • Open and semi-closed woodlands and scrub Savanna in the tropical and moist sub-tropical areas is ideal habitat – open, dry grassland is not.
  • It is a 3-host (multihost) tick.
  • At every stage of the life cycle (larvae – nymph –adult) the tick attaches to a new host to feed.
  • They are rapid feeders and need only 4 to 7 days to engorge (fill with blood) before they detach and drop off.
  • Every stage may be infected with ECF.
  • Larvae will pick up the parasite from an animal, and infected nymphs and adults will pass the parasite back to their cattle hosts.
  • After its blood meal the tick (larvae, nymph or adult) drops off and moults into the next stage.
  • Adult females detach when they are engorged (full of blood), drop off and lay thousands of eggs.
  • Brown ear ticks can survive between stages, without food, for a long time. Larvae can live for 7 to 10 months without a meal.
  • Nymphs can survive for 6 to 15 months, and adults 14 months to 2 years.
  • If temperature, rainfall and day length conditions are ideal, the ticks can complete a life cycle (1 generation) in 3 months.
  • Where there are marked seasonal changes (winter, summer, autumn, spring), adult ticks will sit out the dry season waiting for the start of the rains before they look for a host. Larvae are most prevalent in autumn and winter, and nymphs in winter and spring.
  • Farmers should dip in winter to stop population expansion in summer.
  • In regions where there are 2 rainy seasons and the seasons are less marked (as in the tropics) there may be 3 generations, often overlapping, of ticks in a year.
  • There is no easy way to tackle a problem like this, and in the next 2 articles we look at dipping and dips to combat ECF.

Also read: Know you enemy – East Coast fever

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