Eating habits associated with Echinostoma malayanum infections in the Philippines.

A survey of 61 residents belonging to 12 pre-selected families (having at least one member positive for echinostomiasis malayanum) from Barangay Malibago, Echague, Isabela (northern Luzon) suggested that infections with Echinostoma malayanum follow a "familial trend". The parasite is endemic because the raw ingestion of Lymnaea (Bullastra) cumingiana, the second intermediate host in the Philippines, is a learned habit passed down from one generation to the next. A questionnaire on eating habits revealed that Lymnaea (Bullastra) cumingiana or "birabid" was usually prepared raw or half-cooked after treatment with salt or "bagoong" (salted fish paste). It was abundant in rice fields during the wet months of the year, thus implying a seasonal infection pattern since eating frequency was affected by availability. Those who ate this snail reported a long duration of indulgence with this habit. In contrast, Pila luzonica or "kuhol", the second intermediate host of E. ilocanum, is subjected to similar eating practices but is rarely ingested raw or "half-cooked". Other than snails, shrimps, fish (Tilapia sp.) and meat are also eaten raw. This suggests that the local population is potentially susceptible to other food-borne helminthiases. Extensive use of mass media and public health education is necessary to awaken the awareness of the people to the potential hazards associated with their traditional eating habits.