Are there drugs to prevent cattle getting Ngana?

Trypanocidal drugs for use in cattle are limited to the salts of just three compounds:-

diminazene aceturate (Berenil®, Hoechst; Veriben®, Sanofi; and various other generic formulations)

homidium bromide (Ethidium®, Laprovet) and homidium chloride (Novidium®, Mérial) and;

isometamidium chloride (Samorin® /Trypamidium®, Mérial; Veridium®, Sanofi).

Drugs may be used chemotherapeutically for the treatment of existing trypanosome infections or chemotherapeutically to prevent infection. Some drugs may be used for either purposes, while those which are eliminated rapidly are limited to therapeutic use.

Diminazene aceturate is the most widely used chemotherapeutic agent, but has almost no prophylactic activity. Isometamidium chloride is the most widely used and effective chemoprophylactic drug, and also has chemotherapeutic activity. Homidium salts are used mainly for chemotherapy, but do have some prophylactic activity (Leach and Roberts, 1981).