Researchers find gaps in EU parasite surveillance

Adequate surveillance programs for most foodborne parasites in Europe are lacking, according to a recently published study.

Researchers found although human and animal data are available for five selected parasites, the surveillance and reporting requirements vary among and within regions and countries, and among national experts and European bodies.

In 2012, the Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (WHO) ranked 24 foodborne parasites to provide risk assessors with help to prioritize their control globally with Taenia solium ranking highest.

When a similar approach was applied to Europe in 2016, the top five parasites of concern were Echinococcus multilocularis, Toxoplasma gondii, Trichinella spiralis, E. granulosus, and Cryptosporidium spp.

Information on surveillance systems was collected from 35 European countries and analyzed according to the five different regions. Findings were published in the journal Parasite Epidemiology and Control. For many foodborne parasites, human surveillance is passive in most countries and regions in Europe and notification differs between them.

Recording infections
Trichinella spiralis is reportable in 34 countries with active surveillance in susceptible animals under EU rules. However, outbreaks continue to occur, mainly linked to meat from pigs reared under non-controlled housing conditions and hunted wild boar.

Infections caused by Echinococcus multilocularis, E. granulosus, and Toxoplasma gondii rarely cause acute clinical disease. Cystic echinococcosis and alveolar echinococcosis have long incubation periods, ranging from five to 15 years, making it extremely difficult to study outbreaks or determine the source of sporadic cases.

Cryptosporidiosis has an incubation period of five to seven days so outbreaks are more readily noticed. However, reporting is a problem in many countries because of a lack of routine diagnostics and speciation of human and animal cases.

Alveolar echinococcosis is notifiable in north, east and South East Europe, but in only four countries in Western Europe and speciation is not routinely done, so cases are mainly reported as “echinococcosis.”

E. granulosus in slaughter animals is underreported in many countries because of the low sensitivity of meat inspection, lack of confirmation and speciation of suspected lesions, and absence of data registration systems.

Surveillance of Cystic echinococcosis and alveolar echinococcosis in humans and animals is variable and fragmented with potential underreporting. Suspected cases are not confirmed in many countries. Improved diagnosis and reporting of human cases is needed with emphasis on the highly endemic countries in southern Europe, according to the study.

Plugging gaps
Researchers recommended mandatory and separate notification of E. granulosus and E. multilocularis infections in humans and relevant animals in all countries to get clearer insight into the extent of the problem so trends can be analyzed.

Reporting of congenital toxoplasmosis is absent in many EU countries. There is no mandatory control to prevent infections via consumption of meat from infected livestock. This reinforces the need for risk-based surveillance systems in livestock to reduce infections from meat, said experts.

Mild cases of Trichinella spiralis may be missed because active surveillance is lacking and outbreaks continue to occur, mainly associated with meat products from pigs reared under non-controlled housing conditions and hunted wild boar.

There are considerable differences in reporting, resulting in a skewed impression in the distribution of Cryptosporidium. Several countries claimed to have voluntary reporting, but it is unclear what this entails, and how the data are recorded or to whom they are accessible.

The study was based on work in the European Cooperation in Science and Technology (COST) action on foodborne parasites which ran for four years and ended in 2019.

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