Fasciola infection in guinea-pigs in the peruvian highlands

Abstract

Fasciolosis is found in many regions throughout the world including the rural areas of Cajamarca, Peru where high prevalences have been reported in cattle, sheep, goats and pigs (Tones, 1980). The disease i~ also an important zoonosis in people living in the countryside (Rodriguez, 1983). Cajamarca, a valley at latitude 7°10 ' • O ! south, longltude 78 30 west and at a height of 2,536 m above sea level, has a favourable environment for the development of Fasciola hepatica. Large areas of pasture, adequate humidity (relative humidity 74%) and warmth (mean temperature 14°C) encourage the spread of the intermediate host, Lymnaea viatrix. The intermediate host snail is more prevalent in the lower pastures in still or slow moving water. In many South American countries, guinea-pigs (Cavia spp.) are bred for food, both in the cities and the countryside. A rodent native to South America, the guinea-pig (or cuy) has been known since the time of the Incas. A wild-type called the Sacha-Cuy is still believed to occur in the Amazon and Western Andes it has a small tail, is brown in colour and is more prolific than its domesticated cousin (Zevallos, 1975). Bred in peasant houses, the guinea-pig is often raised within the owner's kitchen but may also be kept in separate accommodation. Guinea-pig owners may rear from 2 to 15 animals although some have much larger numbers: a guinea-pig weighing 800 g may fetch US$3 to 4 in the local market. Food consists of alfalfa (Medicago sativa), ryegrass (Lolium spp. ) and/or waste from the kitchen (tuber, vegetable, cereal and fruit skins amongst others). Ryegrass comes from the same fields where cattle graze and alfalfa is cut from fields mainly dedicated to cattle rearing (cattle are not grazed directly on alfalfa pastures in Cajamarca) and both are fed fresh to the guinea-pigs (Aliaga, 1993) giving rise to the possibility of infection with Fasciola. In a study carried out from January to April 1988, analysis of faecal samples using a rapid sedimentation method (Lumbreras, 1962) indicated prevalences of 24 to 35% (24/100 samples and 35/100 samples) in guinea pigs kept by people living on the hillsides and from 52 to 53% (52/100 samples and 53/100 samples) in guinea-pigs reared in the valley itself. Of the positive cases, 28% had egg counts of 16 eggs per gram or more (Machuca and Gamarra, 1988). The faeces of the guinea-pigs, often with high egg concentrations, are spread on the pastures as fertiliser where conditions allow the life cycle to be completed. Adequate control of fasciolosis may, therefore, require control in all affected spedes including guinea-pigs.