Parasite populations in the brown ratRattus norvegicusfrom Doha, Qatar between years: the effect of host age, sex and density

Abstract

AbstractA total of 179 urban rats were sampled in the city of Doha in Qatar across the winter seasons (February–April) of 2002 and 2003. Only two parasites were identified, with overall prevalences of 35.8% and 41.3% for the cestodeHymenolepis diminutaand the fleaXenopsylla astiarespectively. The prevalence ofH. diminutawas markedly influenced by both year of study and host age, being higher in 2003 and amongst older rats. The abundance of infection ofH. diminutawas influenced by the year of study, host age and sex. Worm burdens in adult rats were almost twice as heavy in males compared with females and adults of both sexes harboured heavier infections than juveniles. The prevalence ofX. astiawas influenced by both year and host age, being higher in juvenile rats in 2002 and in adults in 2003. The abundance ofX. astiawas significantly higher in 2003 and both male and female rats showed similar abundances, but in 2003 females were more heavily infested. Reasons for this are discussed in relation to the differing foraging strategies shown by male and female rats. The prevalence and abundance profiles for bothH. diminutaandX. astiawere higher overall in 2003 due to a significant increase in the rat population density, although this did not reflect in any increase in parasite species richness. Rats that were infected withH. diminutawere almost twice as likely to be infected withX. astiathan those without the cestode, but when controlled for the effects of year, host age and sex, no quantitative interactions were detected between the two parasite species.