By Prof Hamadi Boga
Agricultural authorities in African countries tend to put emphasis on tick-borne diseases as a major threat to animal health. Most livestock disease control programmes target East Coast Fever, Anaplasmosis and heartwater, and others such as Foot and Mouth Disease. However, scientists are warning of the growing threat of the neglected parasites such as leeches and liver flukes to livestock production.
The Director of Uganda’s Mbarara Zonal Agricultural Research and Development Institute (MbZARDI), Dr Halid Kirunda, cites the 2021 statistics compiled by abattoirs in the country, which put the economic loss caused in cattle as a result of damaged liver at 60 percent. The infested liver is unwanted and is usually destroyed upon slaughter of the cattle. Depending on the degree of infestation, liver fluke may cause a reduced meat and milk production in cattle. Fertility can suffer and beef cattle affected by fluke may take an extra 80 days to reach market weights.
Liver flukes are hosted by snails and so where there is a suitable habitat for the snail such as springs, marshy areas, water courses, water troughs and irrigated pasture, the animals are predisposed. Other areas of occurrence are grazing paddocks.
Identification and diagnosis
Liver fluke can produce either acute or chronic disease. Acute disease is the most common chronic disease in cattle and can occur any time but is most common during rainy season.
Acute disease tends to follow a relatively short term intake of a massive number of fluke cysts. This causes substantial liver damage, which results in weight loss and general ill-thrift, leading to reduced production of meat and milk This leads to signs such as bottle jaw swelling below the jaw, weight loss and general ill-thrift and anaemia which can be seen through pale gums and membranes around the eyes.
Prevention
Farmers are expected to adopt an integrated approach to liver control by avoiding introducing animals with liver fluke onto the farm. Saturate all animals that come from a liver fluke area and keep them in a quarantine paddock for a day or two. Always request an animal health statement when purchasing stock so you are aware of the disease status level of assurance that is being provided by the stock vendor. Fence ‘flukey’ areas to prevent access by livestock and keep water troughs clean and free from snails.
Monitor the fluke status of livestock using either faecal samples to check for fluke eggs, a blood test, or reports on liver condemnations of animals sent for slaughter as well as avoid taking the cattle for water consumption in swamps with presence of snails.
Leech infestation in livestock
According to studies in Ethiopia, leech infestation of livestock is common in the highlands, where small streams and ponds are used to water livestock and the problem occurs mainly during dry seasons.
The mucous membranes of the nostrils and mouth are common predilection sites for aquatic leeches in the bodies of domestic animals. Coughing, blood in the nose and mouth, respiratory problems, emaciation and anaemia, and reduced milk yield have been reported in leech-infested animals. The common sources of leeches are small rivers, wells, irrigation canals and standing water bodies. Livestock become infected with the parasite when they drink water from leech-infested water bodies and graze on leech-infested deforested areas.
Leeches are more common during the dry season, especially from midDecember to June. Cattle are the most vulnerable species, regardless of sex or age. The effects of leech infestation Leech infestation has direct impact on animal health and indirect impact on financial and social aspects.
In addition, sick animals there is challenge especially cattle of causing reduced milk yield, emaciation and respiratory problems and in rare cases deaths are the causes of loss of livestock production. Clinical symptoms include cutaneous bleeding, blood-tinged saliva and shortness of breath.
Management
Farmers use both traditional and modern medication methods to alleviate the problem. The traditional intervention method they use is done manually by removal and the treatment option they preferred to alleviate the problem was smoking of dried and rolled tobacco leaf powder.