Zoonotic parasites of brown rats in selected ricefields surrounding Lake Mainit, Philippines

Abstract

Zoonotic parasites in brown rats (Rattus norvegicus) can be transmitted through environmental contaminations and cause diseases to humans. This study was conducted to determine the prevalence and intensity of zoonotic parasites among R. norvegicus in selected ricefields surrounding Lake Mainit, Philippines. A total of 50 brown rats were trapped in metal cages baited with bread or fish or both and subjected to parasite examination under the dissecting microscope. The results documented two species of ectoparasites and five species of endoparasites recovered from brown rats. The prevalence rate of infection was recorded highest in the hookworm Nippostrongylus brasiliensis (74%) and the rat tapeworm Hymenolepis nana (34%). Results also show that N. brasiliensis obtained the highest Mean Intensity (MI) of infection (MI=40). Among ectoparasites, the sucking louse Polyplax spp. and the mite Laelaps spp. were also infesting brown rats with a prevalence of 48% and 17%, respectively. A positive weak significant association (r=0.331; p=0.035) between the parasite’s intensity and the rat’s weight was recorded. Barangay Matin-ao holds the highest MI of infection, while Barangay San Isidro has the lowest (p=0.001). Risk factors associated with parasite infection varied from one place to another. The existence of these rats carrying parasites represents a potential risk to nearby residents. Hence, it is essential to address environmental and public health awareness against future zoonotic transmission through ubiquitous brown rats.