Background
Asian schistosomiasis is caused by the blood fluke Schistosoma japonicum. Infection with this helminth can cause long-term chronic health problems due to eggs becoming lodged in body tissues, particularly the liver leading to hepatosplenomegaly and liver fibrosis. In children infection is linked with growth and cognitive stunting. The life cycle of this helminth is complex, comprising the definitive mammalian host as well as an intermediate molluscan host. Transmission occurs when eggs are excreted in the faeces of infected definitive hosts. The eggs hatch on contact with water into miracidia, which then penetrate the molluscan host undergoing asexual reproduction. Cercariae, the infective stage, emerges from the snail and directly penetrates the skin of an infective host. S. japonicum occurs in China, the Philippines, and Indonesia, and is zoonotic with 46 different mammalian hosts potentially acting as reservoir hosts of infection. Previous work has identified water buffalo in both China and the Philippines, where they are referred to as carabao, as the major reservoir hosts contributing to human infections in endemic areas. Control efforts to target these hosts have included animal chemotherapy with praziquantel, vaccines, and removal of animals and replacement with tractors, the latter of which has only occurred in China. However, to date animal chemotherapy and vaccines have not been included in any national control programs, and animal replacement does not occur in the Philippines. There have also been very limited studies examining other potential hosts in the Philippines, which may also contribute to transmission, with the most recent occurring in 50 villages of Samar province. However, that study used insensitive techniques, as proven by previous projects in our lab, which identified the native carabao as major reservoir hosts. Animal vaccination and chemotherapy is part of ongoing projects. Here, we would like to explore other interventions such as education of animal owners and livestock management to prevent animal infections and thereby decreasing environmental contamination with parasite eggs. This step would be developed in partnership with local farmers.
Aim
In this project, we aim to examine in more detail using highly sensitive diagnostics animal definitive hosts in an endemic area of the Philippines, and develop novel interventions for preventing animals contributing to transmission. Aim 1: To examine animal hosts (cattle, carabao, dogs, pigs, goats, rodents) in Leyte, a schistosomiasis endemic region of the Philippines, utilizing sensitive molecular (qPCR, dPCR) and coprological (FEA-SD) diagnostics. Aim 2: To conduct surveys and questionnaires of animal owners about how the animals are kept, how they receive or interact with water, and other animal management information. Aim 3: To develop novel animal management practices in consultation with local animal owners to animals from contributing to transmission and thus reducing human infections. Aim 4: To investigate and develop a model for economic loss from animals due to infection with schistosomiasis.