Remarks on theilerioses and Theileria

Abstract

1. Areas in which theileriasis occurs are characterized by conditions in which the native cattle do not show clinical manifestations of the disease, but introduced cattle suffer from an epizootic manifesting itself seasonally with varied intensity.2. The degree of virulence exhibited and the species of tick acting as vectors have only an indirect significance as an indication of species of the parasite.3. The facts relating to the development of Theileria in the tissues of infected animals and relation of this to developmental stages in the circulating blood are still far from clear.4. The development cycle of Theileria in the red cells of the circulating blood of sick animals is described, and proof given that this is characterized by the formation of anaplasmatic forms developing into ring-shaped forms in T. annulata and T. dispar, and probably in all forms except, possibly, T. parva.5. It is very desirable from the point of view of world economy that a special commission to study theileriasis in the different areas in which it occurs should be established on an international basis.