Correlation between the infection rate of the vector tick, Haemaphysalis longicornis and the parasitaemia of cattle infected with Theileria sergenti.

The infection rate of Theileria sergenti in salivary glands of nymphal Haemaphysalis longicornis which had dropped from cattle showing different piroplasm parasitaemias was examined by the methyl green-pyronin staining method. The results suggested that there was some correlation between parasitaemia and the subsequent infection rate in salivary glands of ticks. It seemed possible that the parasitaemia in cattle, especially the number of parasitized erythrocytes in blood imbibed by ticks, might be an important influence on the number of infected acini of ticks.