The role of heterogeneity in the persistence and prevalence of Sin Nombre virus in deer mice.

Many diseases persist at a relatively low prevalence, seemingly close to extinction. For a chronic disease in a homogeneous population, reducing the transmission rate by a fraction proportional to the prevalence would be sufficient to eradicate the disease. This study examines how higher prevalence of the Sin Nombre virus in male deer mice (Peromyscus maniculatus) might contribute to disease persistence. Analyzing data from over 2,000 individual mice captured in 19 sites over 4 years, we found prevalences of 18.5% in males and 8.8% in females. By examining recaptures, we determined that males are more likely to contract the infection because of higher susceptibility or higher encounter rates. Comparing across 86 sampling periods, we found a higher proportion of males when population densities were low. A capture-recapture analysis indicates that males live longer than females. A mathematical model based on the measured parameters and population size trajectories suggests that the combined heterogeneity in encounters, susceptibility, and mortality may buffer the disease from extinction by concentrating disease in the subgroup most likely to transmit the disease. This buffering effect is not significantly stronger in a fluctuating population, indicating that these forms of heterogeneity might not be the key for disease persistence through host population bottlenecks.

Arthritis: preferred learning methods among Arizona therapists.

Arizona occupational and physical therapists were surveyed about their needs for education in arthritis. Responses to statements regarding attitudes, knowledge, willingness to learn, and preferred methods of learning were subjected to chi-square analysis. The results showed that a significant number of both occupational and physical therapists are deficient in knowledge about the disease and maintain negative attitudes about patients with rheumatoid arthritis. Both groups indicated a high interest in continuing education about arthritis. The preferred method of learning was self-study guides.