Factors driving lungworm spread and the need for ongoing diagnosis and prevention

The spread of Angiostrongylus vasorum across the UK in recent years alongside drug companies having products licensed for its treatment and prevention, has led to raised awareness of this parasite among veterinary professionals and the public alike. This raised profile has been beneficial in reducing canine morbidity and mortality associated with infection, especially in parts of the country where it has not previously been endemic or routinely diagnosed. Veterinary nurses play a key role in giving accurate risk-based parasite prevention advice to clients. When advising clients on the need for angistrongylosis prevention as part of an overall parasite control programme, nurses need to consider the factors driving spread of the parasite and the resulting geographic and lifestyle factors likely to increase exposure risk.

Foxes act as a wildlife reservoir host for A. vasorum worms in the UK but any canid can be infected including domestic dogs. First stage larvae (L1) pass out in the faeces and require gastropod molluscs (slugs and snails) as intermediate hosts for further development. Infection occurs in canids when infective third stage larvae (L3) are ingested. This occurs most commonly through deliberate or accidental consumption of infected slugs or snails (Morgan et al, 2005) or paratenic hosts such as amphibians and possibly birds. Infection has also been demonstrated under experimental conditions to occur from ingestion of larvae present in slime trails (Conboy et al, 2015), but the effect of this in natural transmission is unlikely to be significant. Infected slugs have been found to contain between 1 and 54 L3 larvae, with less than 1% of these larvae leaving live slugs (Lange et al, 2018).