The urban mouse, Mus domesticus, and its role in the transmission of Toxoplasma gondii infection

Abstract:
As part of an investigation into the potential public health threats posed by infestations of the urban house mouse (Mus domesticus) in the UK, 200 mice were trapped and screened for the presence of a number of zoonotic diseases. Results indicated that none of the mice were infected with Strongyloides stercoralis, Trichuris trichiura, Hymenolepsis nana, Campylobacter, Escherichia coli 0157, Listeria, Shigella, Salmonella, Yersinia or Coxiella burneti. Four mice tested positive for Cryptospordium, and two for Chlamydia. Forty-two percent were infested with fleas. Serological testing confirmed that 1% of the mice were infected with Toxoplasma gondii. When infection was determined by detection of T. gondii-specific DNA using the SAG1-PCR, an infection rate of 58.5% was found. This is considerably higher than the infection rates reported by previous authors. Mice (along with most warm blooded animals) act as intermediate hosts of this parasite, but cats are the only known definitive host. The only known definitive host is the cat. Public health importance of Toxoplasma gondii lies in its ability to cause serious pathology in certain vulnerable groups, such as pregnant women (e.g. foetal pathology/abortion) and the immunocompromised (e.g. fatal encephalitis). Human infection is via ingestion of food and/or water contaminated with oocysts excreted by cats, by consumption of tissue cysts in undercooked meat and by vertical transmission from mother to foetus. Current approaches to the control of mice in urban areas are discussed in the light of these high infection rates.