Taiwan records first domestic cases of Mpox clade Ib strain

Taipei, Aug. 26 (CNA) Taiwan's Centers for Disease Control (CDC) on Wednesday reported two new cases of Mpox involving the clade Ib strain, marking the first domestic cases of the variant, which is believed to be more transmissible and more easily spread through close physical or intimate contact.

Both patients were men in their 30s who had not been vaccinated and had engaged in high-risk sexual behavior with unspecified partners, according to contact tracing. However, the sources of their infections remain unclear, CDC spokesperson Lin Ming-cheng (林明誠) told reporters.

The first patient sought medical attention in late July after developing a fever, as well as rashes and pustules on his abdomen and groin. He tested positive for Mpox after his doctor suspected the disease, Lin said.

The second patient sought treatment in early August after developing rashes on his trunk and legs, followed by a fever and muscle soreness. He also tested positive after his doctor suspected Mpox and conducted testing, Lin said.

As of Aug. 23, Taiwan had recorded 28 Mpox cases, including 19 domestic and nine imported cases, according to the CDC. The figure was lower than the 48 cases reported in 2024 and 31 in 2025 in the same period.

A total of nine cases, including the two newly reported domestic cases, have been identified as the clade Ib strain since Taiwan recorded its first imported case in May 2026.

The CDC said global experience shows that people infected with either clade Ib or clade II can develop symptoms including fever, swollen lymph nodes, rashes and blisters.

Clade Ib is more easily transmitted within households, while people with weakened immune systems, including children, pregnant women and those with chronic illnesses, are more likely to develop severe symptoms, the agency said.

The CDC said many people who have contracted Mpox had engaged in high-risk sexual behavior, while nearly 90 percent had not been vaccinated.

Vaccination remains the most effective way to prevent Mpox, including infection with the clade Ib and clade II strains, the agency said.

Those eligible for publicly funded vaccines include people who have engaged in high-risk sexual behavior in the past year, people who have been diagnosed with a sexually transmitted disease, and people who have had sexual contact with anyone in either of those categories.