Background and Aim: Rodents are ubiquitous animals that host ectoparasites and transmit zoonotic diseases. We conducted a cross-sectional study on the seasonal variation, period prevalence (Pp), and relative risk of ectoparasitic infestations in rodents collected in North Sinai, Egypt, from September 2019 to August 2020.

Materials and Methods: We captured 380 rodents during the study period. Rodents were euthanized to perform species identification, and 2930 external parasites were collected and identified using light microscopic examination with systemic keys depending on morphological characters.

Results: Rattus norvegicus (brown rat), Rattus rattus frugivorus (white-bellied rat), Rattus rattus alexandrines (gray-bellied rat), and Mus musculus domesticus (house mouse) were captured at the highest frequencies during summer (n=186), followed by spring (n=84), fall (n=71), and winter (n=39), with a higher proportion of males captured in all seasons. Analysis of the infestation Pp revealed highly significant increases (p<0.01) in ectoparasites during the winter. Temperature, humidity, and dew point were significantly (p<0.01) correlated with the numbers of captured and infested rodents. Parasitological examinations showed the higher risks of flea (Echidnophaga gallinacea, Xenopsylla cheopis, and Leptopsylla segnis) and lice (Hoplopleura hirsuta, Hoplopleura ocanthopus, Hoplopleura oenomydis, and Polyplax spinulosa) infestations during winter and mite (Laelaps nuttalli, Dermanyssus gallinae, Ornithonyssus bacoti, and Myobia musculi) infestations during summer.

Conclusion: We conclude that ectoparasitic infestation prevalence and risk varies with predominating macroclimatic conditions. Strict preventive and biosecurity measures should be applied to combat rodent-related problems.

Keywords: ectoparasites, North Sinai, period prevalence, relative risk, rodents.