Rats responsible for lingering Lassa fever in Nigeria, says study.
The most extensive and rapid genomic analysis of the Lassa virus conducted so far has shown that rats are responsible for the largest outbreak of Lassa fever in Nigeria this year.
Published on October 17, 2018 in the New England Journal of Medicine, the report allays fears that Lassa had mutated into a super-bug that spreads swiftly among people. The viral genomes harvested from 220 patients were surprisingly diverse, indicating that most people have not been infected from other people.
The unprecedented speed of this analysis has helped officials to combat the spread of Lassa fever, while its genetic information will assist researchers as they develop vaccines against the scourge.
Other diseases transmitted by rats include, but not limited to bubonic plague salmonella; rat-bite fever; leptospirosis; tapeworms and murine typhus.
However, the World Health Organisation (WHO) has described the ongoing Lassa fever outbreak in the country as the worst and largest ever.
Latest figures from the Nigeria Centre for Disease Control (NCDC), from January 1 to October 14, 2018, no fewer than 2,706 suspected cases and 137 deaths have been reported from 22 states.
According to the study, people can contract Lassa virus from direct contact with the African soft-furred rat (Mastomys natalensis), by eating them, while infected rodents could indirectly transmit the virus by salivating or urinating on rice, cassava and other crops stored in barrels or left to dry in the sun. The infection can also pass from person to person through bodily fluids, which is how most health workers contract the virus.
Author of the study and Director, African Centre of Excellence for Genomics of Infectious Diseases (ACEGID) at Redeemer’s University in Osun State, Dr. Christian Happi, began sequencing viral genomes isolated from patients with Lassa fever.
He said if the virus spreads from person to person, its genome would be nearly identical among individuals living near one another, explaining that the first 14 genomes examined were diverse, suggesting that each person was infected by a different lineage of the virus.
He also shipped blood samples to the Broad Institute of Massachusetts Institute for Technology (MIT) and Harvard in Cambridge, Massachusetts, where the researchers analysed 129 virus genomes isolated from patients this year, and 91 others collected from Nigeria between 2015 and 2017.
Fewer than 10 percent were similar enough to indicate that they had probably passed from person to person.