Online Reporter
Agriculture Reporter
One of the most serious roundworm infections of cattle, sheep and goats wireworm disease is caused by the internal parasite Haemonchus contortus, which is found in the fourth stomach (abomasum) and small intestines of the animals.
The parasite feeds on blood and infected animals become anaemic and may die in poor condition.
Occurrence
Wireworm disease occurs all over Zimbabwe and is most common during the rainy season.
All age groups can become infected, but most serious effects are observed in lambs and kids. Animals get infected when they ingest infective larvae together with plants or water.
Clinical signs
Acute wireworm disease is seen primarily when young animals become heavily infected.
The animals die showing signs of severe anaemia. In chronic cases the clinical signs
are as follows:
• Pale mucous membranes
• Swellings under the jaw (bottle jaw)and occasionally along the ventral aspect of the abdomen
• Progressive weakness
• Diarrhoea or constipation may occur
Control
• Provision of clean pastures, i.e. pastures that have not been grazed by ruminants for at least eight weeks.
• Dose animals a day before putting them onto clean pastures.
• Rotational grazing aided by the strategic use of anthelminthics has proven to be an effective control measure for wireworms.
• During the rainy season, sheep and goats should be treated every three weeks.
• If the rain continues for 10 to 14 days, reduce this to two weeks.
• During dry months, six-week intervals should be sufficient.
• Cattle require less frequent dosing.
• Treatment at the beginning of the rains and at the beginning of winter is generally sufficient.
• It is important to avoid using one type of remedy all the time to prevent resistance of the parasite to specific drugs.
• Remedies should be alternated yearly.
• It should be kept in mind that drugs alone are not able to keep the infection level low without rotational grazing.
