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With increase in rainfall, pay attention to cases of bovine leptospirosis

25 January 2021

Embrapa

The intensification of rains in this period is conducive to the proliferation of different disease-causing microorganisms, such as leptospirosis, which affects several species of animals, including cattle.

 The infection causes abortions in cows at the end of pregnancy in the chronic form of the disease. In the acute phase, in young cattle and adults, renal damage occurs that can lead to renal failure and death.

According to veterinarian Raul Mascarenhas, from Embrapa Pecuária Sudeste (São Carlos - SP), the losses for the rancher are mainly associated with abortion.

“As it occurs only at the end of gestation, the cow will probably remain for more than a year without producing milk. Another damage is the loss of the calf, which can be a dairy female or an animal of high genetic value,” explains Mascarenhas.

The veterinarian points out that by avoiding cases of abortion, the producer already pays the investment of one year in preventive measures adopted.

Leptospirosis is caused by the bacterium Leptospira spp, transmitted to animals by eating contaminated pasture or contact with contaminated water or waterlogged soil. In conditions of low environmental humidity and direct incidence of sunlight, this bacterium only remains alive for 30 minutes.

Already in conditions of high humidity and neutral or slightly alkaline pH, Leptospira can survive for weeks or months. In an aqueous environment, it is able to move around until it finds a host, which is why bovine leptospirosis is more frequent in this rainy season.

The veterinarian recommends making the diagnosis routinely in the herd in cases of the presence of Leptospira spp in animals on a farm and also knowing which serogroup is predominant. This is done through blood tests.

"Why is it important? Suppose that when doing blood tests on animals, the most common serogroup found is ' Icteriohaemorrhagiae ', common in rodents. Therefore, rats have an important role in the transmission of the disease in this herd. Or it may be that the predominant serogroup is " Hardjo ", the most common of cattle. In this case, the transmission of the disease occurs mainly through the cattle themselves,” he explains.

With this information, the producer will be able to define the best control and prevention strategy. If the problem is Leptospira transmitted by rats, the rancher will have to make a more efficient control of rodents, keeping the environments clean from food scraps, use of traps, conditioning and protection of feed in deposits, frequent cleaning of the facilities, etc.

If the transmission is occurring among the cattle themselves, Mascarenhas advises the producer to focus on measures to prevent infection, such as reducing and enclosing wetlands, vaccination and treatment of the animals.

Vaccination against leptospirosis does not prevent infection, but reduces symptoms. When necessary, this preventive measure must be adopted at least every six months. However, depending on the monthly average of cases of abortions in the herd, this application should be performed at shorter intervals, every four or three months.

In addition, as there is an association of leptospirosis with the rainy season, it is recommended to schedule one of the vaccinations for one month before the beginning of that period. Treatment is done with the antibiotic streptomycin.



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