The health ministry said Wednesday two more people have been confirmed dead due to a viral infection transmitted by a mite bite, bringing the death toll in Japan to three.

Both were men, one living in Ehime Prefecture and the other in Miyazaki Prefecture. They died last fall from the infection, known as severe fever with thrombocytopenia syndrome, the ministry said. They had no recent record of overseas travel.

The ministry confirmed in January that an adult woman in Yamaguchi Prefecture died last fall from the syndrome.

It brushed aside concerns that the new viral infection has been spreading in Japan, saying the number of deaths only increased as local authorities re-examined overlooked cases.

No effective vaccine has been found to prevent the viral infection, which was first reported in China around 2009. Genetic studies showed the virus that killed the three Japanese occurred in Japan and did not come from China, the ministry said.