Epizootiological aspects of Anaplasma marginale in Mexico.
The epizootiology of anaplasmosis (caused by Anaplasma marginale) in Mexico is discussed. The disease is common and highly virulent in 3 areas adjacent to the Gulf of Mexico, comprising Tizimín (in Yucatán state), San Rafael (in Veracruz) and Linares (in Nuevo León), where the seropositivity of cattle varies from 58 to 73%. Intensive tick control programmes are carried out in these areas. Treatment of cattle is based on clinical diagnosis. Only official institutions are provided with diagnostic equipment for epidemiological studies such as card agglutination test, complement fixation test and ELISA. The prevalence of anaplasmosis in Mexico has been variously reported as 7.9% in the north, 25.9% on the Altiplano, 14.6% on the Pacific coast and 51.4% on the coast of the Gulf of Mexico.