A SIMULATION OF LEPTOSPIROSIS CONTROL IN DUTCH DAIRY HERDS

A state-Transition model was developed to examine the 'farm-to-farm spread of bovine Leptospira hardjo infections epidemiologically and economically, by using a computer spreadsheet program. The model offers the opportunity to consider five different control strategies with varying effectiveness and participation levels of farms. It was designed with so-called default settings, but all 67 input variables can be modified easily to suit different conditions and areas (making it a flexible tool for decision making and research activities). The model runs on a personal computer with the MS-DOS operating system. Results of calculations with the most likely input values showed that with extremely high participation levels of farms, only a combination of dihydrostreptomycin treatment and a vaccination scheme (both carried out after an outbreak of the disease) is economically attractive. With lower participation levels, more likely for the Dutch situation, a publicity campaign on how to reduce the spread of the disease and how to reduce the risk for dairy cows seems to be a better option. Further research is desired to model the indirect losses owing to potential export bans and human infections. © 1990.