Echinostoma ilocanum is widespread among the Philippine Islands but only 3% of over 30,000 stools were found to be positive for eggs. The prevalence rates were highest in Ilocana populations of northern Luzon; 11% of over 7,000 stools examined, however, rates as high as 44% were found. Pila luzonica is eaten uncooked by some people and metacercariae from these snails developed into adults in a number of laboratory animals. Rats, mice and hamsters were the most susceptible with patent infections developing as early as 7 days and lasting for 328 days. There seems to be little disease in humans and animals infected with this parasite.