Fascioliasis due to the digenean species Fasciola hepatica has recently proved to be an important public health problem, with human cases reported in countries of the five continents, including severe symptoms and pathology, with singular epidemiological characteristics, and presenting human endemic areas ranging from hypo- to hyperendemic. One of the singular epidemiological characteristics of human fascioliasis is the link of the hyperendemic areas to very high altitude regions, at least in South America. The Northern Bolivian Altiplano, located at very high altitude (3800-4100 m), presents the highest prevalences and intensities of human fascioliasis known. Sequences of the internal transcribed spacers ITS-1 and ITS-2 of the nuclear ribosomal DNA of Altiplanic Fasciola hepatica and the intermediate snail host Lymnaea truncatula suggest that both were recently introduced from Europe. Studies were undertaken to understand how the liver fluke and its lymnaeid snail host adapted to the extreme environmental conditions of the high altitude and succeeded in giving rise to high infection rates. In experimental infections of Altiplanic lymnaeids carried out with liver fluke isolates from Altiplanic sheep and cattle, the following aspects were studied: miracidium development inside the egg, infectivity of miracidia, prepatent period, shedding period, chronobiology of cercarial emergence, number of cercariae shed by individual snails, survival of molluscs at the beginning of the shedding process, survival of infected snails after the end of the shedding period and longevity of shedding and non-shedding snails. When comparing the development characteristics of European F. hepatica and L. truncatula, a longer cercarial shedding period and a higher cercarial production were observed, both aspects related to a greater survival capacity of the infected lymnaeid snails from the Altiplano. These differences would appear to favour transmission and may be interpreted as strategies associated with adaptation to high altitude conditions.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0031182001008034

Fasciola hepatica and lymnaeid snails occurring at very high altitude in South America.

https://www.cell.com/parasitology/pdf/S0169-4758(98)01245-9.pdf

Progress in development of liver fluke vaccines.

The worldwide importance of human infection by Fasciola hepatica has been recognized in recent years. The endemic region between Lake Titicaca and the valley of La Paz, Bolivia, at 3800-4100 m altitude, presents the highest prevalences and intensities recorded. Large geographical studies involving Lymnaea truncatula snails (malacological, physico-chemical, and botanic studies of 59, 28 and 30 water bodies, respectively, inhabited by lymnaeids; environmental mean temperature studies covering a 40-year period), livestock (5491 cattle) and human coprological surveys (2723 subjects, 2521 of whom were school children) were conducted during 1991-97 to establish the boundaries and distributional characteristics of this endemic Northern Altiplano region. The endemic area covers part of the Los Andes, Ingavi, Omasuyos and Murillo provinces of the La Paz Department. The human endemic zone is stable, isolated and apparently fixed in its present outline, the boundaries being marked by geographical, climatic and soil-water chemical characteristics. The parasite distribution is irregular in the endemic area, the transmission foci being patchily distributed and linked to the presence of appropriate water bodies. Prevalences in school children are related to snail population distribution and extent. Altiplanic lymnaeids mainly inhabit permanent water bodies, which enables parasite transmission during the whole year. A confluence of several factors mitigates the negative effects of the high altitude.

The Northern Bolivian Altiplano: a region highly endemic for human fascioliasis.

Field and experimental bovine infection sera were used in immunoblots of sporozoite and schizont lysates of Theileria parva to identify candidate diagnostic antigens. Four parasite antigens of Mr 67,000 (p67), 85,000 (the polymorphic immunodominant molecule, PIM), 104,000 (p104), and 150,000 (p150) were selected for a more detailed analysis. The p67 and p104 antigens were present only in the sporozoite lysates, whereas PIM and p150 were found in both sporozoite and schizont lysates. The four antigens were expressed as recombinant fusion proteins and were compared with each other in an enzyme-linked immunosorbent assay (ELISA) and in the whole-schizont-based indirect fluorescent antibody test (IFAT) in terms of their ability to detect antibodies in sera of experimentally infected cattle. The PIM-based ELISA provided a higher degree of sensitivity and specificity than did the ELISA using the other three recombinant antigens or the IFAT. Further evaluation of the PIM-ELISA using experimental sera derived from cattle infected with different hemoparasites and field sera from endemic and nonendemic T. parva areas showed that the assay had a sensitivity of > 99% and a specificity of between 94% and 98%.

/pdf/an-enzyme-linked-immunosorbent-assay-for-detection-of-559dlz39e4.pdf

An enzyme-linked immunosorbent assay for detection of Theileria parva antibodies in cattle using a recombinant polymorphic immunodominant molecule

Early immunodiagnosis of fasciolosis in ruminants using recombinant Fasciola hepatica cathepsin L-like protease.

Herd evaluation by enzyme-linked immunosorbent assay for the determination of Fasciola hepatica infection in sheep and cattle from the Altiplano of Bolivia

Fasciola hepatica: host responders and nonresponders to parasite glutathione S-transferase.

Se estudio el potencial inmunodiagnostico de un FAST-ELISA para la deteccion de anticuerpos contra de fasciolosis en ninos de Cajamarca, Peru. Sueros de 4 ninos no infectados fueron negativos mientras que 13 ninos infectados fueron positivos a la prueba de FAST-ELISA. Doce de los ninos infectados serorevirtieron con disminucion de anticuerpos cuatro meses luego de terapia con dehidroemetina. Estos resultados indican la utilidad de la prueba de FAST-ELISA para deteccion de infeccion y prediccion de cura en ninos con fasciolosis.

Maricelis Soler de Galanes

Papers

Herd evaluation by enzyme-linked immunosorbent assay for the determination of Fasciola hepatica infection in sheep and cattle from the Altiplano of Bolivia

Fasciola hepatica: host responders and nonresponders to parasite glutathione S-transferase.

Immune diagnosis of human fasciolosis in children from Cajamarca, Perú