We are on the cusp of another wonderful season for outdoor activities, such as camping, hiking, and fishing. The bountiful nature of Hokkaido can provide you with exciting and unforgettable adventures with your friends. However, Hokkaido can also provide you with a very dangerous parasite called Echinococcus.

In this month's issue, I'll give you some information about this parasite and tips for your outdoor life in Hokkaido.

What Is Echinococcus?

Echinococcus multilocularis is the causative agent of the highly pathogenic. Alveolar Hydatid disease (AHD), which can be fatal if untreated. This parasite, which is found throughout Hokkaido, needs different mammals as its host at each growing stage. Wild carnivores such as red foxes are the definitive hosts for E. multilocularis that harbors the adult tapeworm (about 4mm) in the small intestine. The foxes get infected when they eat field mice, which are infected by the tapeworm larvae. The larvae mature into adult form in the intestine of the foxes. These foxes are not harmed by the tapeworm at all and don't have any symptoms of AHD. They do, however, produce egg-infected feces, and the eggs (about 0.03mm) are eaten by the mice (the intermediate hosts of E. multilocularis), and migrate via the bloodstream into the mouse's liver, where the eggs mature into the larvae and they form cysts.

How Can I Be Infected?

Humans become infected when we get into this life cycle of the parasite, such as when we swallow eggs in contaminated water or food as the field mice do. We can be exposed to the eggs in the following two ways:

1. By taking in water or food, such as vegetables, herbs, and fruits, contaminated with the feces of the infected foxes.

2. By having direct contact with infected foxes or household animals, such as dogs and cats. (These pets shed the eggs in their feces, so their fur may be contaminated. Don't forget the fact that the egg is too small to see!)

If we swallow the eggs, they are carried from the intestine to our liver, where cysts form. Cysts can also form in the lungs, as well as in the brain, bones, skeletal muscles, kidney, and other tissues.

What Are the Symptoms?

Cyst-like larvae grow in the organs and cause AHD. AHD usually attacks the liver, and the liver cyst may remain undetectable for 10 ~ 20 years or more until it becomes large enough to be noticeable.

Symptoms include abdominal swelling, the production of pressure effects or other symptoms resulting from the cysts leaking or if they rupture. There may be right upper quadrant pain, nausea, and vomiting as well. The effects of pressure may result in biliary obstruction, which could result in jaundice and itchy skin rash. These symptoms are very similar to liver cirrhosis and liver cancer.

How Can I Find Out If I Have Echinococcus?

Hokkaido, which is the endemic area of Echinococcus, provides free check-ups for residents. If you have properly registered with the city hall, you are entitled to a blood test for antibodies for the parasite at the Asahikawa Public Health Center. The exact date of the test this year will be announced in the 'Koho Asahikawa Shimin' July issue. If the result of the antibody test positive, then you'll undergo a second test, including two kinds of blood tests and an abdominal ultrasound. These tests are all provided by Asahikawa City and you don't have to be covered by any health insurance to receive them.

What Is the Treatment?

Currently the definitive treatment is surgical removal of cysts. After surgery, medication may be necessary to keep the cyst from growing back.

How Can I Prevent the Infection?

The following precautions are very important to avoid infection.

Never, ever drink the water of a stream or a marsh unless it has been boiled.
Wash your hands after touching anything anywhere a fox may have been.
Don't eat wild fruits or vegetables unless washed very carefully or cooked.
Don't have contact with wild red foxes or any other canines.
Don't keep wild canines around your house.
Don't allow your dogs and cats to wander freely or eat wild rodents.

The Echinococcus infection has the potential to affect the economy of Hokkaido because of its impact on the agricultural and tourist industries. However, epidemiological knowledge can prevent you from contracting the infection. Keep these tips in mind as you enjoy your summer adventures in Hokkaido!