The effect of some biological and physical factors on infection of Biomphalaria glabrata with Angiostrongylus cantonensis

Abstract

Several biological and physical factors which may influence infection of Biomphalaria glabrata snails with the first stage larvae of Angiostrongylus cantonensis were studied. These factors were: the size of snails, the number of first stage larvae to which snails were exposed, the age of larvae, individual exposure compared with mass exposure of snails, the length of exposure period and the effect of temperature and light. The results showed that young snails, 2 mm in diameter, became infected with significantly smaller numbers of third stage larvae than larger snails (4, 8, 12 and 16 mm). No significant differences in the intensity of infection were evident between the larger size groups. The number of third stage larvae recovered from snails was directly related to the number of first stage larvae to which the snails were exposed. The mean percentage recovery per snail was more or less constant regardless of the infective dose. First stage larvae showed a slight reduction in their survival rate within 7 and 4 days, at 24 degrees C and 26 degrees C respectively, after which a sharp decrease in their survival rate occurred. However, the infectivity of larvae was progressively reduced from the second day at these two temperatures. The mean intensity of infection in snails was independent of whether the infection was by mass or individual exposure. The average number of first stage larvae entering a snail was greatest during the first half hour of exposure, this decreased considerably during the second half hour, and thereafter the number of larvae which entered a snail was low. It was concluded that 26 degrees C was the optimal temperature for infection and that the presence or absence of light had no effect on the infection.

Development of Angiostrongylus costaricensis Morera and Céspedes 1971 (Nematoda: Angiostrongylidae) larvae in the intermediate host Sarasinula marginata (Semper 1885) (Mollusca: Soleolifera)

“…A similar pattern was also observed in Angiostrongylus cantonensis (Yousif and Lammler 1975;Ishii 1984;Hori et al 1985;Lv et al 2006), Angiostrongylus vasorum (Guilhon and Gaalon 1969), Umingmastrongylus pallikuukensis (Kutz et al 1999;Kutz et al 2001), Protostrongylus spp (Samson and Holmen 1984), Elaphostrongylus rangiferi (Skorping 1984;Schjetlein and Skorping 1995), Cystocaulus ocreatus (Gerichter 1948), Muellerius capillaris (Gerichter 1948;Rose 1957) and Parelaphostrongylus odocoilei (Jenkins 2006) for which a strong association between temperature, larval development and infection rates in invertebrate hosts was shown. Other factors have also been mentioned as possible interference agents in b 23 µm a 21 µm c 12 ∝m d 20 µm Fig.…”

“…Studies have demonstrated that the nematode larval development in mollusks may be influenced by environmental factors such as humidity, temperature, estivation, intern factors such as infection intensity, and specific characteristics of the host like age, size, and susceptibility (Cheng and Alicata 1965;Gerichter 1948;Guilhon and Gaalon 1969;Halvorsen and Skorping 1982;Hori et al 1985;Ishii 1984;Kutz et al 1999;Rachford 1976;Rose 1957;Samson and Holmen 1984;Solomon et al 1996;Yousif and Lammler 1975;Wallace and Rosen 1969;Kutz et al 2001;Lv et al 2006;Jenkins 2006).…”

The effect of temperature and host age on the infectivity and development of Angiostrongylus vasorum in the slug Arion lusitanicus

“…Yousif and Lammer (1975) observed that the infection rate of A. cantonensis in aquatic Biomphalaria glabrata snail was negligible below 20°C but high at 26°C, and Skorping (1982) found that the mean number of Elaphostrongylus rangiferi larvae in the intermediate host Arianta arbustorum increased markedly with increasing temperatures, from 10 larvae at 4°C to 50 larvae at 28°C. In both studies, low temperature may have reduced the activity of both the slugs and the parasitic larvae (Yousif and Lammer 1975;Skorping 1982;Kozlowski 2007).…”

“…Wallace and Rosen (1969) stated that the intensity of A. cantonensis infection is relatively low in small snail species and similarly, Yousif and Lammer (1975) found that the infection of B. glabrata with A. cantonensis is significantly lower in small-sized snails than in larger ones. Likewise, Ibrahim (2007) demonstrated both increasing prevalence and intensity of A. cantonensis with host size, and Conejo and Morera (1988) found higher infection rates of A. costaricensis in a larger specimen.…”

“…Transmission to the intermediate host is likely to be influenced by temperature conditions and age of both the larvae and the intermediate hosts (Wallace and Rosen 1969;Yousif and Lammer 1975;Skorping 1982;Hori et al 1985). As such, the time from excretion in faeces until exposure to the gastropod and the environmental temperature may determine the successful transmission.…”