Characterization of rat pinworm (Syphacia muris) epidemiology as a means to increase detection and elimination

Rodent pinworms persist in many institutions, suggesting deficiencies in eradication and diagnostic processes. When pinworms are detected, treatment success is common, but false-negative test results during health surveillance or after treatment likely contribute to the continued presence of this parasite. PCR testing is not always practical, and increased information regarding the life cycle and general epidemiology of pinworm infestations could improve the sensitivity of traditional nonPCR detection methods and improve eradication efforts. We therefore investigated a pinworm (Syphacia muris) infestation in Sprague-Dawley rats (Rattus norvegicus) to develop a more accurate testing strategy. In addition, we sought to determine the duration of egg viability by using an in vitro hatching protocol to assess environmental persistence. Finally, we tested the ovicidal efficacy of a disinfectant used at our institution. Eggs were shed in higher numbers in the midafternoon as compared with other times of the day, and the sex of the host had no consistent effect on egg shedding. Egg shedding showed periodicity over time, with shedding decreasing to 0 at 2- to 3-wk intervals. Neither cecal examination nor tape tests alone reliably predicted pinworm infestation, and results of the 2 tests did not necessarily coincide. Eggs aged for as long as 7 mo remained viable, indicating a potential for recontamination from the environment. Finally, gaseous chlorine dioxide was an effective ovicidal agent, with a kill rate of 99.7%. These results suggest that strategies for S. muris eradication can be optimized to increase detection and elimination.

Use of an aquarium as a novel enrichment item for singly housed rhesus macaques (Macaca mulatta)

Locomotor stereotypies are behaviors often seen in singly housed rhesus macaques (Macaca mulatta) and are considered to represent a maladaptive response to captive environments. Active and passive enrichment items are commonly used to mitigate these and other abnormal behaviors. Active enrichment items allow physical manipulation and may be temporarily successful in reducing stereotypies, but their beneficial effects usually are confined to relatively short periods of active use. Passive enrichment items that do not involve physical manipulation are less well studied, and the results are mixed. This study evaluated an aquarium with live fish for use as a novel passive enrichment item in a common facility setting as a means to decrease locomotor stereotypy. We hypothesized that the introduction of the aquarium would decrease the frequency of locomotor stereotypy in a group of singly housed rhesus macaques (n = 11) with a known history of abnormal behaviors. Unexpectedly, locomotor stereotypy increased with the introduction of the aquarium and then decreased over time. Furthermore, when the aquarium was removed, the frequency of stereotypy decreased to below baseline levels. These unexpected results are best explained by neophobia, a common phenomenon documented in many animal species. The increase in abnormal behavior is likely to result from the addition of a novel object within the environment. This study demonstrates that, in the context of reducing abnormal behavior, presumably innocuous enrichment items may have unexpected effects and should be evaluated critically after their introduction to a captive population.