title: Helminth parasites in black rats (Rattus rattus) and brown rats (Rattus norvegicus) from different environments in the Netherlands.
abstract: BACKGROUND
  Rattus norvegicus (brown rat) and Rattus rattus (black rat) are known carriers of bacteria, viruses, and parasites of zoonotic and veterinary importance. Moreover, rats may play a role in the transmission of muscle larvae of the zoonotic nematode Trichinella spiralis to farm animals. We aimed to study the intestinal and intramuscular helminths in wild rats from three different environments to assess the relevance of rats as carrier of zoonotic parasites for public health.
  
  
  METHODS
  Wild brown rats (117 individuals) and black rats (44 individuals) were captured at farms, in suburban and in rural environments in the Netherlands. Intestinal helminths were isolated and identified morphologically. Artificial digestion was used to isolate muscle larvae.
  
  
  CONCLUSIONS
  Morphological analysis of rat intestinal contents yielded six nematode species (Syphacia muris, Heterakis spumosa, Aonchotheca murissylvatici, Trichuris muris, Nippostrongylus brasiliensis, and Strongyloides sp.), three cestode species (Hymenolepis diminuta, H. nana and Hymenolepis (=Rodentolepis) fraterna), and four trematode species (Plagiorchis muris, Plagiorchis proximus, Echinostoma chloropodis, and Notocotylus imbricatus).Black rats at farms displayed the lowest intestinal helminth species variation (six species) and carried overall on average 0.93 species simultaneously. In comparison, brown rats at farms carried seven helminth species and 1.91 species simultaneously. Brown rats from suburban environments displayed the highest species variation (11 species) at 1.82 simultaneous helminth species. Absence of trematodes from rats at farms may suggest limited exchange of rats between farms and surrounding wet rural environments. We report four species of veterinary (Syphacia muris) or zoonotic relevance (Hymenolepis diminuta, Hymenolepis nana and Plagiorchis muris). We did not find Trichinella muscle larvae, consistent with long-term prevalence in Dutch wild rats.
authors.affiliation: National Institute for Public Health and the Environment, Bilthoven, the Netherlands; frits.franssen@rivm.nl.
authors.forename: Frits
authors.initials: F
authors.lastname: Franssen
authors.affiliation: National Institute for Public Health and the Environment, Bilthoven, the Netherlands.
authors.forename: Arno
authors.initials: A
authors.lastname: Swart
authors.affiliation: Institute for Risk Assessment Sciences (IRAS), Utrecht University, Utrecht, the Netherlands.
authors.forename: Frans
authors.initials: F
authors.lastname: van Knapen
authors.affiliation: National Institute for Public Health and the Environment, Bilthoven, the Netherlands.
authors.forename: Joke
authors.initials: J
authors.lastname: van der Giessen
keywords: Hymenolepis; Rattus norvegicus; Rattus rattus; Syphacia; Trichinella; black rat; brown rat; intestinal helminths