The common frog (Rana temporaria) as a potential paratenic and intermediate host forAngiostrongylus vasorum

Abstract

Common frogs (Rana temporaria) were exposed either to third-stage larvae (L3) or to first-stage larvae (L1) of Angiostrongylus vasorum. Following exposure to L3, viable larvae could be detected in the frogs for at least 2 weeks. Following exposure to L1, the frogs developed viable L3 in their tissues within 30 days. In a test of the infectivity of these larvae, one fox was fed frogs previously infected with L3 and another fox was fed frogs previously infected with L1. On autopsy it was found that adult A. vasorum populations had been established in both foxes. Thus, it could be concluded that frogs can act not only as paratenic hosts but also as intermediate hosts for A. vasorum.

Combined Serological Detection of Circulating Angiostrongylus vasorum Antigen and Parasite-specific Antibodies in Dogs from Hungary

“…The adult parasite lives in the pulmonary arteries and right cardiac ventricle of dogs, foxes and other wild carnivores, which are infected through the ingestion of obligatory intermediate hosts (snails or slugs) (Guilhon and Bressou 1960;Guilhon and Cens 1973) or paratenic hosts (Bolt et al 1993) containing the infectious third stage larvae. Clinical signs in dogs most frequently include respiratory signs such as coughing and dyspnoea, but a broad range of further signs indicating coagulopathies or neurological dysfunctions (Chapman et al 2004;Staebler et al 2005;Wessmann et al 2006;Koch and Willesen 2009), may be the signs most obvious to clinicians and animal owners.…”

Pathological Findings in Dogs Naturally Infected with Angiostrongylus Vasorum in Newfoundland and Labrador, Canada

“…4 Frogs can also serve as paratenic and intermediate hosts. 2 In the definitive host, adult female nematodes in pulmonary arteries shed eggs that are subsequently transported downstream to smaller capillaries in the lung parenchyma. The eggs develop and hatch, releasing first stage larvae (L1) that penetrate capillary and alveolar walls, and move into alveoli and larger airways.…”

PCR detection of Angiostrongylus vasorum in faecal samples of dogs and foxes

“…Finally, this PCR may potentially be used for larval identification in intermediate hosts ); however, this remains to be assessed. Intermittent larval excretion, prepatent and low-grade infections are a fundamental obstacle to all methods based on faecal analysis (Bolt et al 1993;Oliveira et al 2006;Verzberger-Epshtein et al 2008), which may explain why no A. vasorum larvae were detected in five foxes although adult worms were recovered at PM. The intermittent excretion necessitates the examination of samples from three consecutive days, as suggested by Willesen et al (2004).…”

“…The first-stage larvae (L1) hatch and penetrate into the lung alveoli and then migrate up to the bronchi, where they are coughed up, swallowed and passed into the environment via the faeces of the host. Snails and slugs become infected by foraging on the faecal deposits and thereby serve as intermediate hosts (Bolt et al 1993). Over the past decade, the prevalence of A. vasorum in wildlife has increased in several European countries (Morgan et al 2005;Van Doorn et al 2009;Helm et al 2010), the most important definitive hosts being domestic dogs and foxes (Koch and Willesen 2009), whilst the modes of transmission to the final host are still unclear (Morgan et al 2005).…”