IRRUA, Nigeria - Nigeria is battling against an unprecedented outbreak of Lassa fever, a cousin of Ebola, that has already killed 110 people this year.
Even as doctors grapple to contain the threat, health watchdogs are struggling to understand why the deadly virus has spread so dramatically.
The Nigeria Centre for Disease Control (NCDC) has confirmed 353 Lassa cases since January 1, compared with 143 cases for the whole of 2017.
But the possible reasons for this surge are many, said NCDC director Chikwe Ihekweazu.
"The harder you look, the more you find," he said, citing a change in the virus' environment, viral mutation - and better reporting of cases by the public in response to awareness campaigns.
Lassa fever is an acute viral haemorrhagic disease that can be transmitted to humans from infected rat faeces or urine.
Like the notorious Ebola - though somewhat less contagious - it can also be passed from one person to another via contact with infected bodily fluids.
Full protective gear for medical personnel is vital and isolation is essential.
A visit to the Lassa fever isolation ward at the Irrua Specialist Teaching Hospital in southern Edo State - the only such unit in a country of 190 million people - provides a snapshot of the practical difficulties in tackling the peril.
Before the unit was built in 2008, suspect blood samples were sent to South Africa for an accurate diagnosis - but when the results came back it was already too late, doctors say.
Despite its unique status, the Lassa facility, staffed by a dozen Nigerian employees and a handful of European tropical medicine specialists, is struggling.
In normal times, it treats just a couple of dozen patients each year. But since the start of 2018, the unit has already admitted more than 150.
At least 78 dead in Lassa fever outbreak in Nigeria https://t.co/buDVRJhQ5N Poor health infrastructure and response have contributed to its continual spread. #Nigeria #Lassafever #GlobalHealth pic.twitter.com/U9NZZqqdbf— Kunal D Patel (@kunalthedreamer) March 9, 2018