BACKGROUND Amphimerus spp. is a liver fluke that infects humans and domestic animals. It is highly prevalent in some
Ecuadorian communities. Currently, diagnosis is based on the microscopic observation of eggs in faeces, but this has variable
sensitivity. More sensitive methods are needed for diagnostic testing.
OBJECTIVE The main objective of this work was to develop an enzyme-linked immunosorbent assay (ELISA) using crude
antigens from
Amphimerus spp. adult worms to detect anti-
Amphimerus IgG in human sera.
METHODS Crude somatic antigens were obtained from adult
Amphimerus spp. worms. Human sera from 119 patients were
tested: 48 from individuals with a confirmed
Amphimerus spp. infection, 78 from non-infected Ecuadorians living in the endemic
region, 60 from persons living in non-endemic areas (20 Ecuadorians, 20 Europeans, and 20 Africans), and 33 who had other
parasitic and non-parasitic infections.
PRINCIPAL FINDINGS Results were analysed using the receiver-operator characteristic (ROC) curve analysis with an area under
curve (AUC) value of 0.967. The accuracy of the ELISA was high. The sensitivity was 85.0% [95% confidence interval (CI): 80.3-89.7%] and the specificity was 71.0% (95% CI: 65.2-76.8%). Some cross reactivity was detected against
Paragonimus mexicanus,
Fasciola hepatica
, Schistosomiasis,
Taenia solium,
Strongyloides stercoralis
,
Mansonella
spp., and
Vampirolepis nana.
MAIN CONCLUSIONS We have developed the first ELISA technique that detects anti-
Amphimerus IgG in human sera with good
sensitivity, repeatability and reproducibility. However, more specific antigens are needed to further enhance performance of this
assay. Regardless, this ELISA test could be useful for early diagnosis and prompt treatment of human
Amphimerus spp. infections.
