Significant Risk of Echinococcus multilocularis in Norway

This is one of the conclusions of a risk assessment by the Norwegian Scientific Committee for Food and Environment (VKM).

Background

VKM’s Panel on Biological Hazards has updated its scientific assessment on the potential for introduction to, and establishment of, Echinococcus multilocularis in mainland Norway. This work was initiated by the Panel itself.

Echinococcus multilocularis, commonly referred to as the fox tapeworm, is a parasite that lives in the intestines of canids. Rodents are the main intermediate hosts, but the parasite can also infect humans. The disease, alveolar echinococcosis, is rare, can be extremely severe, and is difficult to treat. Without treatment, it is typically fatal within 10 years.

The previous Scientific Opinion on this parasite by VKM was published in 2012. This update evaluates whether the conclusions reached in the previous Opinion were valid and whether the situation has changed. New information, particularly regarding spread of the parasite in Sweden, has been included.

The conclusions of the previous Scientific Opinion are considered to remain valid, and introduction of this parasite by infected canids to Norway remains possible.

There is a significant possibility that the fox tapeworm will be introduced to Norway and have become established before we detect it," says Lucy Robertson, scientific lead for the project. "Transmission of Echinococcus multilocularis from Sweden to Norway via foxes is likely a matter of time, but we cannot predict when it will occur. This is troubling, as we observe in other countries where the parasite has established itself in foxes and rodents that humans eventually become infected."

Methodology

Data were collected through literature searches and reviews of published monitoring reports. The material provides an update of existing literature on:

• Monitoring of foxes and wolves for Echinococcus multilocularis in mainland Norway

• Spread of Echinococcus multilocularis in Sweden, but also elsewhere in Europe and North America

• Contamination of fresh produce with the parasite, including fresh produce imported to Norway

VKM also considered the potential effectiveness of various control measures.

Results

More than a decade after Echinococcus multilocularis was detected in Sweden (2011), the prevalence remains low and geographically limited in that country, indicating a slow spread. There are no data indicating that the parasite is any closer to the border with Norway. It has still not been detected in mainland Norway, and analyses of fresh produce on the Norwegian market has also not identified the parasite.

Regulations currently, require that dogs entering Norway are treated with anti-parasitic drugs that eliminate this parasite. However, there is no documentation on the extent to which dog owners comply with these rules or whether checks are performed at land and sea borders.

Uncertainty

The primary uncertainties in the assessment stem from the limited data available due to the restricted outbreak in Sweden. Additionally, there is a lack of information about the number of untreated dogs entering Norway.

This risk assessment was self-initiated and conducted by VKM’s Panel on Biological Hazards.

VKM conducts risk assessments both upon request and on its own initiative,but does not decide how risks should be managed.