Predicting the local dynamics of epizootic rabies among raccoons in the United States

Abstract

Mathematical models have been developed to explore the population dynamics of viral diseases among wildlife. However, assessing the predictions stemming from these models with wildlife databases adequate in size and temporal duration is uncommon. An epizootic of raccoon rabies that began in the mid-Atlantic region of the United States in the late 1970s has developed into one of the largest and most extensive in the history of wildlife rabies. We analyzed the dynamics of local epizootics at the county level by examining a database spanning more than 20 years and including 35,387 rabid raccoons. The size, number, and periodicity of rabies epizootics among raccoons were compared with predictions derived from a susceptible,

Animal Rabies in Massachusetts, 1985–2006

“…After 1992, specimen submissions increased to almost eightfold, and the number of positive animals increased to 45-fold. Similar to observations in other jurisdictions (Fischman et al, 1992;Krebs et al, 1994;Wilson et al, 1997;Guerra et al, 2003;Krebs et al, 2004), raccoons and skunks with the raccoon strain virus became the predominant animals positive for rabies, and the diversity of submitted and positive animals continued to increase significantly. In the period 1985-1991, bats accounted for 50/52 (96%) rabiespositive animals, with two foxes with bat strain rabies.…”

“…Fall is associated with fewer encounters and higher likelihood that an encounter would be with a rabid animal demonstrating abnormal behavior. Similar seasonal variation in rabies incidence in animals with the introduction of raccoon strain rabies has been observed in other areas (Jenkins et al, 1988;Fischman et al, 1992;Torrence et al, 1992;Krebs et al, 2000;Guerra et al, 2003).…”

“…More raccoons were positive than skunks, but the spillover of raccoon strain rabies into skunks is significant, and in some areas, including Massachusetts, rabid skunks with raccoon strain have outnumbered rabid raccoons, raising a concern about skunk-to-skunk transmission of the raccoon virus variant (Krebs et al, 2000). Cat rabies in the United States reflects spillover of the dominant terrestrial rabies virus where it occurs (McQuiston et al, 2001).…”

“…A recent hot spot occurred on Cape Cod following the breach of the vaccine barrier in 2004. Epizootic spread and temporal-spatial clustering have been characteristic of the spread of raccoon rabies in the eastern United States (Fischman et al, 1992;Childs et al, 2000;Recuenco et al, 2007). The clusters of intensified activity in local areas also contribute to the cyclic pattern.…”

The community-wide dilemma of hospital-acquired drug resistance

“…These threats are largely the consequence of the emergence of novel pathogens into the human population (e.g., SARS-CoV and HIV), the transport of pathogens into novel areas (e.g., West Nile Virus), or the evolution of resistance among pathogens once believed controllable (e.g., antimicrobial-resistant forms of tuberculosis). In the wake of this enormous problem, there has been a renewed effort at constructing mathematical models of the infectious disease process in an attempt to predict disease emergence and the evolution of antimicrobial resistance (2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). Models of antimicrobial resistance have largely focused on the likelihood and conditions under which resistant pathogenic forms will arise and spread and the identification of measures that should be taken to limit emergence (9)(10)(11).…”