Distribution patterns and aggregation modelling of helminth parasites of wild rats in Mount Makiling Forest Reserve and adjacent areas, Philippines
2019
Estano, L.A.
A number of studies had been done on parasite diversity in rats, however, there is a dearth of information on their pattern of distribution in hosts population. This study aimed to determine the parasite helminth fauna and their distribution patterns in wild rats in Mount Makiling Forest Reserve (MMFR) and adjacent areas. Collection of rat samples was done in various sampling sites categorized as residential, agricultural and agro-forest. Three species of wild rats were captured namely, Rattus tanezumi, Rattus norvegicus and Rattus exulans. Of the total 90 wild rats collected, 86.7 % were found infected. The helminth parasites identified were four (4) cestodes (Hymenolepis diminuta, Hymenolepis nana, Taenia pisiformis and Strobilocercus fasciolaris), six (6) nematodes (Nippostrongylus brasiliensis, Strongyloides ratti., Capillaria hepatica, Trichuris muris, Angiostrongylus cantonensis, and Rictularia sp.), and one (1) trematode (Echinostoma ilocanum). Juveniles exhibited low prevalence (61.5 %) while adult and sub-adult showed higher prevalence at 91.3% and 90.7% respectively (significant at p 0.05). The prevalence was higher during wet (89.74%) than in dry season (86.27%), however the difference was not significant at p 0.05. Moreover, prevalence rate was higher in male (94.3%) than in female (81.8%) but not significant at p 0.05. The parasites were found to be highly aggregated using Poulin Index where the resulting measurement of aggregation of the negative binomial distribution and is less than 1. A mathematical mechanistic model was used to show population dynamics of hosts and their parasites. The model revealed that aggregation has beneficial effects on the population of helminth parasites, that is aggregation tends to allow increase of parasite in a host population but not affecting the latter's population size.
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