WHO sets new diagnostic targets for Echinococcus granulosus in humans, dogs and sheep

The World Health Organization has published new target product profiles for in vitro diagnostic tests for cystic echinococcosis, aiming to stimulate the development of simpler, faster and more affordable tools for humans, dogs and sheep. The profiles address a major One Health gap: diagnosis in people still relies heavily on imaging, while reliable field tests for canine and livestock infection remain scarce or unavailable.

Cystic echinococcosis (CE), or hydatid disease, is caused by Echinococcus granulosus sensu lato. WHO estimates that in 2021 the parasite was responsible for about 848,000 cases, 5,230 deaths and 415,000 disability-adjusted life-years worldwide. The parasite circulates mainly between dogs and livestock. Dogs act as definitive hosts and shed eggs in faeces, contaminating soil, food and water. Sheep and other herbivores become intermediate hosts, while humans are accidentally infected by ingesting eggs from contaminated hands, food or water.

Three diagnostic priorities

WHO defines three separate target product profiles: one for human case management, one for canine echinococcosis, and one for sheep and goats. The objective is not to prescribe a specific technology, but to tell diagnostic developers what performance, cost and operational characteristics programmes actually need. content

For humans, the new test would complement imaging when a focal lesion compatible with CE cannot be confidently confirmed or excluded. WHO's ideal profile calls for at least 95% clinical sensitivity and 98% specificity, with a result in under 30 minutes. The target price is ≤US$2 per test, with US$5 as the minimum acceptable target.

Dogs are central to transmission surveillance

The canine profile is designed to identify areas with at least 1% prevalence in the dog population, monitor control programmes and map active transmission. Ideally, the test should work at point of care, require little or no equipment and use faeces, including samples collected from the environment. WHO sets ambitious ideal performance targets: ≥99% sensitivity and ≥99% specificity, detection of infection from as little as one adult worm, and results in less than 30 minutes. Minimum acceptable targets are 80% sensitivity, 95% specificity and detection of infections with at least 50 adult worms. The target price is particularly low: ≤US$0.50 per canine test ideally and ≤US$3 at minimum.

A rapid test is also needed for sheep and goats

For sheep and goats, WHO wants a test able to identify areas with ≥5% infection prevalence, again for monitoring control programmes and mapping transmission. The target population is animals at least one year old in areas where E. granulosus transmission is suspected. The ideal assay should detect at least one viable cyst, reach ≥99% sensitivity and ≥99% specificity, deliver results within 30 minutes and operate in basic field conditions.

WHO's publication highlights the scale of the current diagnostic gap. In dogs, microscopy cannot distinguish E. granulosus eggs from other taeniids, while copro-ELISA and copro-PCR can lack specificity or reproducibility. In livestock, routine diagnosis still depends mainly on carcass inspection after slaughter, and no serological test is currently available for sheep and goats.