Parasitology



Detection of high levels of congenital transmission of Toxoplasma gondii in natural urban populations of Mus domesticus


P. A. MARSHALL a1, J. M. HUGHES a2, R. H. WILLIAMS a2, J. E. SMITH a3, R. G. MURPHY a1 and G. HIDE a2c1
a1 Built and Human Environment Research Institute, School of Environment and Life Sciences, University of Salford, Salford M5 4WT, UK
a2 Centre for Parasite Biology, Molecular Epidemiology and Ecology, Biosciences Research Institute, School of Environment and Life Sciences, University of Salford, Salford M5 4WT, UK
a3 School of Biology, University of Leeds, Leeds LS2 9JT, UK

Article author query
marshall p   [PubMed][Google Scholar] 
hughes j   [PubMed][Google Scholar] 
williams r   [PubMed][Google Scholar] 
smith j   [PubMed][Google Scholar] 
murphy r   [PubMed][Google Scholar] 
hide g   [PubMed][Google Scholar] 

Abstract

The relative importance of different transmission routes of Toxoplasma gondii has been a matter for debate. This ubiquitous parasite is generally thought to be transmitted by infective oocysts excreted by the definitive host, the cat. Ingestion of undercooked meat has also been considered an important route of transmission in many mammals while congenital transmission has generally been considered relatively rare. Experimental studies demonstrate the ability of T. gondii to be transmitted congenitally, but few studies have investigated the frequency of this transmission route in natural populations. We use PCR amplification of the SAG1 gene to investigate the frequency of congenital transmission in a wild population of mice (Mus domesticus) and show that congenital transmission is occurring in 75% of pregnancies in this population. Furthermore, for infected pregnant mice, transmission occurs to at least one foetus in 100% of cases while variable penetrance of congenital infection is observed. These high levels of congenital transmission in this wild population of mice, taken together with other recent data on congenital transmission in sheep, suggests that this phenomenon might be more widespread than previously thought.

(Received March 15 2003)
(Revised July 18 2003)
(Accepted July 29 2003)


Key Words: Toxoplasma gondii; Mus domesticus; PCR; SAG1; congenital; transmission.

Correspondence:
c1 Biosciences Research Institute, School of Environment and Life Sciences, University of Salford, Salford M5 4WT, UK. Fax: +0161 295 5015. E-mail: g.hide@salford.ac.uk


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