Transmission: a Case Study of the Vuon-Ao-Chung Agricultural System on the Mekong Delta of Vietnam

Planting rice on the Mekong Delta, Vietnam.
Image taken from the Jeroen Neele Photo Gallery
The agent F. buski is transmitted by fecal-oral route between mammalian hosts, via an intermediate snail host. The organism is in its infective stage after passing through the snail and lives on water plants that are eaten raw by humans and pigs, or peeled with the teeth (caltrop and water chestnuts are peeled with the teeth).

From 1995 to 1997, agricultural researchers from various Asian Institutions conducted a survey to assess the presence and economic implications of helmenthic disease in the Mekong Delta region of Vietnam. One particular area of focus involved the transmission of F. buski within the Vuon-Ao-Chung (VAC) system, which combines small industries of agriculture, pig raising, and fish raising. These systems are not economically efficient and produce little, if any, income. Farmers are even further debilitated economically by high rates of parasitic disease among the livestock. Thus, agricultural and animal activities are closely related and occur on small plots of land. Many farmers probably use pig feces as a source of cheap fertilizer as well. With an understanding of the F. buski lifecycle, it is easy to see that the parasite could thrive in such an environment.

The researchers discovered F. buski eggs in the feces of four pigs from four farms. All infected pigs had been fed mainly with supplimental water spinach feed grown locally. Gyraulu and Indoplanorbis snails, which serve as intermediate hosts to the parasite, were detected in marshlands, ponds, small rivers and rice fields near the pig pens in the VAC systems. The researchers concluded that the parasite had been transmitted among the pigs by feeding on the contaminated water plants. They also concluded that humans were also at risk of infection since many ate locally grown water spinach as well.

Fattening pigs enjoying the leaves of Trichanthera
gigantea in the Mekong Delta in Vietnam.
Image taken from Cantho University, Vietnam

Yoshihara, Shinobu, Nguyen Phuoc Hung, Nguyen Huu Hung, and Chau Ba Loc. "Helminths and Helminthiosis of Pigs in the Mekong Delta Vietnam with Special Reference to Ascariosis and Fasciolopsis buski Infection." Japan Agricultural Research Quarterly. Vol. 33, No. 3 (1999). Online. Internet. 28 April 2002.