New concepts on limiting factors of ovine and caprine malignant theileriosis [OCMT] in Iran

ABSTRACT

In spite of presence of the vector ticks and susceptible hosts of Ovine Malignant Theileriosis in all parts of Iran, the endemic areas of the disease are restricted to certain foci in the South and center of the country. Finding the reason of this point, this study was conducted in seven experiments to transmit Theileria lestoquardi from carrier sheep to susceptible host by Hyalomma anatolicum anatolicum. The carrier sheep were collected from three different areas including Fars, Ham and Tehran provinces and the vector ticks were collected from Fars. Ilam and Urmia. The results showed that the ticks from non-endemic areas could potentially transmit the parasite. Therefore the assumption that the restricted foci of the disease are due to adaptation of the parasite in the endemic areas to the local vector tick is not much valid. It may be concluded that in some areas [non-endemic] the limiting factor is low temperature and in the others, the extreme high temperature that reduce tick ratio per animal. Ovine and Caprine Malignant Theileriosis [OCMT] occurs in certain foci of Iran with a mean annual temperature between 20 - 25°C. The clinical signs and the variation of parasitemia were recorded in the experimentally infected animals