An outbreak of African swine fever in Nigeria’s largest pig farm co-operative in the south-west of the country has been confirmed.
Some 300,000 pigs have been killed, farmer Ayo Omirin told the BBC.
The most affected farm provides a source of livelihood to some 3,000 farmers.
Although it is harmless to humans, the viral disease can kill pigs within a few days, according to the World Organisation for Animal Health (OIE).
It has been 12 years since the last case of African swine fever hit Oke Aro farm, its president Adewale Oluwalana said.
The virus can be passed on by direct contact with infected pigs and wild boars, through infected animal feed and on clothing and farm equipment.
At least six million pigs were culled after the virus hit Asian countries last year.
Pig rearing is one of the main routes out of poverty for many people in Nigeria, meaning this outbreak threatens the livelihoods of thousands of families, the BBC’s Ronke Alo reports.
The outbreak has hit Oke Aro farm, a co-operative settlement managed by the Lagos State government, said to be the largest pig farm in West Africa.
At least 99% of the pig pens have been affected, Mr Omirin told the BBC.
The farm is a key supplier of pig products but it struggles to meet the demands of more than 50 million consumers in the region.
“We have lost four farmers as a result of shock, two of them slumped and died on the farm,” Mr Omirin said.
A sensitisation exercise is under way to advise farmers on how to protect the surviving livestock, said Jide Lawal, Lagos State agriculture spokesman.
He said the state government had distributed food aid to affected farmers and also sent a team to fumigate farms in the south-west region.