Madagascar leads global mpox clade I caseload in 2026 after introducing the virus from mainland Africa

Summary

Madagascar has become the country with the highest number of confirmed clade I Mpox cases outside the Democratic Republic of Congo as of June 2026, with 689 confirmed cases as of June 14, according to WHO's multi-country situation report 64. The outbreak began in December 2025, when the first cases were detected; the circulating strain was confirmed as clade Ib on January 6, 2026, marking Madagascar's first-ever mpox outbreak. Genomic analysis confirmed a single introduction from mainland Africa, most likely from East-Central Africa, followed by sustained community transmission. The outbreak produced the first cross-border spread to a non-African territory when La Réunion, a French overseas department, confirmed a case on January 22, 2026, in a traveller from Madagascar, followed by a second confirmed imported case in February.

The split

Malagasy and Francophone African health media covered the outbreak as a public health emergency requiring international support, noting Madagascar's limited laboratory capacity and the logistical challenges of surveillance across a large island with fragmented healthcare infrastructure. French media covered the La Réunion imported cases and the risk of further spread to mainland France and other French overseas territories. WHO and ECDC coverage emphasised clade Ib's more transmissible characteristics relative to clade IIb. East African public health analysts tracked whether the Madagascar outbreak represented a separate transmission chain from the DRC-centred clade Ib epidemic, or whether there would be cross-Indian Ocean spread.

By the numbers

• 689, confirmed clade I mpox cases in Madagascar as of June 14, 2026 (WHO)
• 0, deaths reported in the initial outbreak phase (January 2026 data)
• December 2025, date Madagascar declared the outbreak
• January 6, 2026, date clade Ib was confirmed as the circulating strain
• January 22, 2026, La Réunion confirmed case (first non-African territory)
• 1, single genomic introduction event, followed by sustained community transmission

Why it matters

The emergence of Mpox clade Ib in Madagascar is significant because clade Ib has shown greater transmissibility than earlier clade II variants in DRC, Uganda and neighbouring countries. Madagascar's position as a major Indian Ocean hub with air connections to France, Réunion, Comoros, Mauritius and Mozambique creates a broader geographic exposure risk. The outbreak also highlights the limits of the clade-II-focused JYNNEOS vaccine stockpiles, which provide protection against clade I but were primarily deployed in 2022-24 for the global clade IIb emergency, creating questions about remaining supply for Indian Ocean and Southern African deployment.

What to watch

• WHO situation report updates through the second half of 2026
• Whether clade Ib spreads beyond Madagascar in the Indian Ocean island group
• JYNNEOS vaccine supply availability for Madagascar and potential island-chain deployment
• Genomic surveillance in mainland East and Southern Africa for the same clade Ib strain