“The stress experienced by the animal owing to infestation leads it to stop feeding, lose weight and become less fertile,” she told Agência FAPESP. “Infestation occurs when the tick feeds on the animal’s blood, since as it does so it inoculates the animal with antihemostatic, anti-inflammatory and immunomodulatory substances contained in its saliva,” said Tatiana Teixeira Torres, who conducted the study with geneticists Valéria Lis Le Gall and Guilherme Marcondes Klafke.Īccording to Torres, these substances modify the host’s physiology around the bite, causing loss of blood and a reduction in immunity and irritation. The research was supported by FAPESP and the National Council for Scientific and Technological Development (CNPq). In Brazil, this parasite is currently resistant to a greater or lesser extent to all the commercial pesticides used by cattle farmers.Īn article published recently in Scientific Reports describes a study in which Brazilian researchers affiliated with the Department of Genetics and Evolutionary Biology at the University of São Paulo’s Bioscience Institute (IB-USP) and the Desidério Finamor Institute of Veterinary Research (IPVDF) in Eldorado do Sul (Rio Grande do Sul State) identified mechanisms of the cattle tick’s resistance to ivermectin, one of the drugs most widely used to combat R. The cattle tick is controlled by pesticides, invariably leading to the selection of resistant strains. The horn fly (Haematobia irritans) causes losses of US$2.5 billion (18.3%), while the damage done by the botfly (Dermatobia hominis), screw-worm fly (Cochliomyia hominivorax) and stable fly (Stomoxys calcitrans) amounts to US$1 billion (7.5%).

None does more damage than the southern cattle tick (Rhipicephalus (Boophilus) microplus), which accounts for annual losses amounting to US$3.2 billion (23.2%).

Next come external parasites, which live on the skin of cattle or visit them to feed. The worst damage is caused by internal parasites, such as gastrointestinal worms, which cause losses amounting to US$7.1 billion (51% of the total).

In other words, the damage caused by parasites in terms of mortality, weight loss, impaired fertility and reduced yield is more than double the value of the annual exports. This loss is estimated to have reached at least US$13.9 billion in 2014. The numbers could be even higher if it were not for the huge annual economic loss caused by parasites. In the same year, Brazil was the world’s leading exporter of beef, shipping a total of US$6.28 billion. Brazil’s commercial cattle herd totaled 217.7 million animals in 2017, according to the country's Ministry of Agriculture.

Parasites in city all deaths