Mayotte, a French island in the Indian Ocean, said Sunday it had identified a total of 26 cases of cholera, stretching its care capabilities to the limit.

On Friday, Mayotte had reported its first three locally acquired cases of the disease, which came in addition to 10 imported cases detected over the past month.

After patient numbers doubled in 48 hours, the medical staffing situation at the Mayotte main hospital was “highly critical”, said Olivier Brahic, the head of the ARS health authority.

ARS said it had opened a second cholera unit at the hospital after the first unit, with a capacity of 14, had been overwhelmed.

Cholera is an infectious disease typically causing severe diarrhoea, vomiting and muscle cramps, which spreads easily under insufficient sanitation conditions.

ARS has announced a campaign to identify further cases, administer antibiotics and vaccinate people.

Mayotte’s imported cases have arrived mostly from the neighbouring Comoros, which has been battling a cholera epidemic since the start of the year.

Many migrants travel through the Comoros on their way to Mayotte from the Democratic Republic of Congo, itself facing a cholera epidemic that killed hundreds last year.

Mayotte is France’s 101st and poorest administrative region and anti-immigrant groups have launched protests against new arrivals despite a vow from Paris to tighten citizenship rules.

Part of the Comoros archipelago, Mayotte voted to remain part of France in 1974, when the other three islands sought and won independence.