Studies on the epidemiology and control of rabies
The work described in this dissertation falls into two main parts;Firstly, the epidemiology of rabies in Iowa is discussed in the first three sections. A retrospective study has shown a close association between rabies in skunks and rabies in domestic and other wild animals. Skunks were recognized as the main reservoir hosts to be considered in planning and targeting control measures in all species. The epidemiology of rabies in raccoons was investigated in two geographical locations. In both locations, there was a correlation in this species between the sero-positive rate and age as well as between the sero-positive rate and weight. This is an indication of continuous exposure to the infection throughout the life of the animals. This also was reflected in the difference in the percentage of positive sera between juvenile and adults. The juvenile raccoons have shown a positive rate which is one-third that of the adults. Female raccoons have shown a higher percentage of positive sera than males in general. There were some differences among both weight and age groups in the positive rates in each sex. In Guthrie County, the spring percentage of positive sera was higher than the percentages in summer or the fall. However, in Cerro Gordo County, the spring percentage of positive sera was lower than in summer. The skunks from Cerro Gordo County have shown a lower positive rate in the spring than in the summer. In skunks, the females also showed a higher positive rate than the males. However, a negative correlation between weight and positive rate was detected in the skunks. In both species, the probably time of transmission of the infection was considered to be during over-winter communal denning when the population density were high, and during the early spring breeding season;Secondly, the activity of 3 chemotherapeutics was evaluated against rabies virus in vitro. Amantadine HCl, ribavirin and rifampin were found effective when used in the first 8-12 hr after infection. Also, these drugs were effective when used continuously for 24-36 hr, with ribavirin showing a wider range of active concentrations than amantadine HCl, which in turn showed wider range than rifampin. Amantadine HCl, and rifampin were more toxic to cell cultures at higher concentrations.