Nasta's research on experimental chemoprophylaxis and immuno-prophylaxis of tuberculosis was cutting edge. Unlike doxycycline it is not used in chemoprophylaxis. The effect of chemoprophylaxis following rodent bites or scratches on the disease is unknown. Patients may be offered chemoprophylaxis with penicillin. The use of chemoprophylaxis is limited primarily by two factors&colon; risk and financial costs. Doxycycline is used primarily for chemoprophylaxis in areas where chloroquine resistance exists. Sulfonamides are not recommended for chemoprophylaxis because of rare but severe skin reactions experienced. Using chemoprophylaxis as a treatment against early signs of tuberculosis has proven to be effective. The main methods of controlling surra has been drug chemotherapy, and chemoprophylaxis in animals.