Gastropods as intermediate hosts of Pneumostrongylus tenuis Dougherty of white-tailed deer

Abstract

From May to October, 1966, gastropods from three different habitats on Navy Island, Ontario, were examined for larvae of Pneumostrongylus tenuis. Of 9940 examined individually, 4.2% contained larvae. A mean of 2.9 larvae was recovered from each infected gastropod. Deroceras laeve and Zonitoides nitidas were the most abundant and commonly infected species. The incidence of infective larvae in adult D. laeve from a wet forested area rose to 25% by late June but dropped to 1.5% during July, coinciding with the disappearance of adult slugs. The level of infection in Z. nitidus (4.3%) remained relatively constant. The wet forested habitat where gastropods were abundant, commonly infected, and active from May to October was probably most important for transmission. Experiments showed that snails already containing larvae can be reinfected and there is some evidence that they are repeatedly infected in nature. Larval development was retarded in aestivating snails. Numbers of larvae recovered and their rate of development differed in various species of experimentally infected gastropods. Snails of the family Polygyridae were the most suitable intermediate hosts studied. Larvae passed by deer were situated in the film of mucus covering faecal pellets. In this location, larvae may be dispersed by high spring water or heavy rainfall. Snails became infected when exposed to larvae in wet and dried soil. Larvae on pellets survived freezing at −15 to −20 °C for up to 306 days.

Distribution and Ecology of Meningeal Worm, Parelaphostrongylus Tenuis (Nematoda), in Northcentral North America

“…Gastropods become relatively inactive when moisture is low (Burch, 1956), and deer feces and surface soil (both with first-stage larvae of P. tenuis) become dry. The likely result is increased mortality of P. tenuis larvae and curtailed transmission (see Lankester and Anderson, 1968). Beetle (1989) indicated that extremes of temperature, short periods between killing frosts and little moisture likely contribute to fewer gastropods.…”

“…Parelaphostrongylus tenuis, called meningeal worm, is a common parasitic nematode of white-tailed deer (WTD; Odocoileus virginianus), throughout the deciduous mixed-hardwood forests of eastern North America (Lankester, 2001). It has been reported as far west as western Manitoba (Bindernagel and Anderson, 1972) in Canada and western Nebraska in the United States (Oates et al, 2000).…”

Climate and Habitat Influence Prevalence of Meningeal Worm Infection in North Dakota, Usa

“…Seasonal temperature and precipitation influence the range and prevalence of meningeal worm infection via gastropod distribution and larval survival (Lankester and Anderson 1968;Shostak and Samuel 1984;Forrester and Lankester 1998;Wasel et al 2003). We obtained data on precipitation and temperature from 160 weather stations in North Dakota for the period 1963-2005 (National Oceanic and Atmospheric Administration 2015).…”

“…The meningeal worm has an indirect life cycle requiring one of several species of terrestrial gastropods as intermediate hosts (Lankester and Anderson 1968). It can cause fatal neurologic disease in several species of accidental hosts, including moose (Alces alces), elk (Cervus canadensis), and mule deer (Odocoileus hemionus; Lankester 2001), although its life cycle is generally only completed in white-tailed deer (Anderson and Prestwood 1981).…”

“…Gastropod abundance is linked to cool, wet microclimates in wooded habitats (Lankester and Anderson 1968;Kearney and Gilbert 1978;Raskevitz et al 1991), and woodlands and croplands in association with woodlands promote abundant white-tailed deer populations (Cote et al 2004;Smith et al 2007). Prevalence of infection is also positively related to growing-season precipitation (Wasel et al 2003); increased growing-season precipitation enhances the ability of habitats to support terrestrial gastropods (Burch 1962;Bickel 1977) and may increase meningeal worm larval survival by helping maintain a moist mucous coating on the outside of deer feces containing larvae (Shostak and Samuel 1984).…”