Guide released in the fight against parasites in America

A regional office of the World Health Organization (WHO) has developed guidelines to help eliminate the health burden associated with parasites.

Fascioliasis is a parasitic disease that affects humans and various animals. It is caused by the trematode Fasciola hepatica in Latin America and the Caribbean. The World Health Organization classifies it as a neglected tropical disease. In 2012, experts estimated that there were 2.6 million infected people.

The Pan American Health Organization (PAHO) aims to eliminate fascioliasis as a public health problem in the Americas by 2030.

As part of this work, guidelines have been developed providing information and guidance to support countries in reaching and achieving that goal.

About fascioliasis
Human fascioliasis is restricted to environments where certain characteristics and socio-economic determinants necessary for infection are present. Such areas are typically associated with small-scale farmers and rural communities. People acquire Fasciola infection by ingesting metacercariae in aquatic plants, food and water. Metacercariae are the infective final larval form of a trematode.

The Fasciola transmission cycle is complex and involves many mammals as definitive hosts. Transmission requires freshwater snails as intermediate hosts and the ingestion of contaminated plants or water. It is associated with poor sanitation and inadequate food hygiene.

The life cycle of Fasciola is approximately 14 to 23 weeks. The period between the ingestion of the metacercariae and the elimination of the eggs in the feces is approximately two months, but varies depending on the host and the level of infection. In humans it can take three to four months. Adult parasites in humans are estimated to live between 9 and 13 years of age.

The parasite can infect all age groups, but children up to 15 years of age and young adults are the main groups experiencing acute and chronic consequences of the disease, including anemia, jaundice and damage to the bile ducts of the liver.

Prevention steps
Interventions to eliminate fascioliasis as a public health problem include preventive chemotherapy, veterinary measures including treatment of domestic animals, and fencing of pasture areas and freshwater bodies suspected of being infected. Longer term actions include promoting information, education and communication, control or management of intermediate host snails and pasture drainage.

According to the guidelines, all steps should be adapted to the current situation and the objectives and resources of each country.

Control measures include using water that is free of human and animal fecal contamination when growing vegetables and avoiding the use of raw plants and vegetables in food preparation. If possible, cook vegetables at 60 degrees C (140 degrees F). Cooling and freezing are not efficient methods.

The guidelines state that authorities should facilitate the use of safe water, conduct inspections during animal slaughter and monitor the dissemination of health-promoting and educational messages. It is also important to involve communities in analyzing the problem, planning solutions and implementing, monitoring and evaluating actions.

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