Pigs at a farm near Tokyo have been infected with the swine fever virus, the agriculture ministry said Friday, as Japanese authorities have been struggling for a year to contain the highly contagious disease.

It was the first hog cholera case reported in the Kanto region of eastern Japan since the epidemic started in the central prefecture of Gifu in September 2018.

A pig raised by the farm in Chichibu, Saitama Prefecture, died after being shipped Wednesday to a meat-processing plant in neighboring Yamanashi Prefecture with 36 other animals. Another three pigs were also found with problems in their internal organs, according to the Ministry of Agriculture, Forestry and Fisheries.

The prefectural government of Saitama decided to cull the around 680 pigs at the farm on Saturday.

The disease affects only pigs and wild boars, and has a high fatality rate. It does not affect humans even if meat from an infected animal is consumed.

Infected wild boars, suspected of spreading the virus, have been found in Gifu and several other prefectures.

The outbreak is the first in Japan since 1992. The country declared the virus eradicated in 2007.

Following the case reported in Gifu, infections have also been confirmed in Aichi, Mie and Fukui prefectures.