arXiv subjects

Christopher Kribs

Publications and source records attributed to Christopher Kribs.

2 recordsLinked to original sources

arXiv2026

A Model of Annual Tick Population Density in the Eastern United States as a Function of Questing Behavior and Host Availability

Understanding the ecological processes that regulate populations of the blacklegged tick, Ixodes scapularis, is essential for explaining regional differences in tick abundance and the risk of tick-borne diseases. In this study, we develop a stage-structured nonlinear system of difference equations by ordering and composing the seasonal biological events that govern tick and host life cycles. The model incorporates ratio-dependent host-attachment, allowing host-finding success to depend jointly on host availability and tick abundance. Parameter estimates from both northeastern and southeastern ecosystems in the United States are used to examine how regional differences in host community composition and questing behavior influence tick population dynamics. Analysis shows that a $+1$/$-1$ bifurcation pair occurs at the demographic persistence threshold, producing an exchange of stability between the extinction and positive fixed points together with the emergence of an unstable cohort-based 2-cycle. Quantitative results show that ratio-dependent host-finding success limits population growth by restricting successful feeding, while questing behavior alters both the frequency and composition of host encounters. Together, these mechanisms regulate tick persistence and long-term abundance, providing a demographic foundation for understanding variation in tick abundance and Lyme disease risk.

math.DS↗

arXiv2019

Comparison of screening for methicillin-resistant Staphylococcus aureus (MRSA) at hospital admission and discharge

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant contributor to the growing concern of antibiotic resistant bacteria, especially given its stubborn persistence in hospitals and other health care facility settings. In combination with this characteristic of S. aureus (colloquially referred to as staph), MRSA presents an additional barrier to treatment and is now believed to have colonized two of every 100 people worldwide. According to the CDC, MRSA prevalence sits as high as 25-50% in countries such as the United Kingdom and the United States. Given the resistant nature of staph as well as its capability of evolving to compensate antibiotic treatment, controlling MRSA levels is more a matter of precautionary and defensive measures. This study examines the method of "search and isolation," which seeks to isolate MRSA positive patients in a hospital so as to decrease infection potential. Although this strategy is straightforward, the question of just whom to screen is of practical importance. We compare screening at admission to screening at discharge. To do this, we develop a mathematical model and use simulations to determine MRSA endemic levels in a hospital with either control measure implemented. We found that screening at discharge was the more effective method in controlling MRSA endemicity, but at the cost of a greater number of isolated patients.

q-bio.PE↗