[A comparative study of three methods in detecting Angiostrongylus cantonensis larvae in lung tissue of Pomacea canaliculata].

Objective: To compare the efficiency of three methods, lung-microscopy, tissue homogenate and enzyme digestion in the detection of Angiostrongylus cantonensis larvae from the lungs of snails.

Methods: 60 Pomacea canalicular infected by the first-stage larvae of A. cantonensis were divided into 2 groups and the lung of each snail from the two groups was separated from the soft body. All the lungs were examined under microscope and larval nodes were counted. Each lung from one group was ground and that from the other was artificially digested by enzyme, the number of larvae in each lung was recorded. The efficiency of three methods was compared. Enzyme digestion was also used to estimate number of larvae in lung and in other body parts.

Results: By using enzyme digestion as the standard method, the detection rate of lung-microscopy, tissue homogenate and enzyme digestion was 96.7%, 93.4% and 100% respectively (chi2=2.069, P>0.05), while the lung-microscopy was significantly faster (Z=4.782, P<0.01). The number of larvae in snail lung was positively correlated with that in other part (r=0.847, P<0.01).

Conclusions: The lung-microscopy in larvae detection is similarly efficient to the other two methods but faster, which is therefore more suitable for snail screening in the field.