Nigeria's big Lassa outbreak blamed on rats, not human-human spread
A genomic analysis indicates that Nigeria’s big Lassa fever outbreak this year has been driven by transmission from rats, not by human-to-human spread, easing worries about a possible Lassa superbug, according to a study described yesterday in the New England Journal of Medicine (NEJM).
Nigeria recorded 523 Lassa cases with 135 deaths from Jan 1 through Oct 7 of this year, according to a press release from the US National Institute of Allergy and Infectious Diseases (NIAID), which supported the study.
The Lassa virus is spread in West Africa by Mastomys natalensis rodents, also known as African soft-furred rats. People can become infected through contact with the rats’ urine or feces, and the virus can spread from person to person through contact with bodily fluids.
Public health officials were concerned that the Nigerian outbreak could be driven by a new or more virulent Lassa strain, possibly fueling increased human transmission, NIAID said. To find out, researchers analyzed Lassa virus genomes from 129 patients in this year's outbreak and 91 patients infected from 2015 through 2017.
"They discovered that Lassa genomes from 2018 were drawn from a diverse range of viruses previously observed in Nigeria rather than from a single dominant strain," NIAID said. "This indicates that a single virus strain was not driving the surge in cases in 2018." In addition, dating of the most recent ancestors of the 2018 samples suggested the outbreak involved many independent transmissions from rats to humans rather than from humans to humans.
Further, phylogenetic analysis revealed that viral diversity was affected by geography, with major rivers appearing to serve as barriers to migration of different strains, the NEJM report said.
A Nature news story yesterday said the "unprecedented speed" of the genomic analysis has helped health officials fight the spread of Lassa virus. The study was led by Christian Happi, PhD, director of the African Center of Excellence for Genomics of Infectious Diseases at Redeemer's University in Ede, Nigeria.
Oct 17 NEJM report
Oct 17 NIAID press release
Oct 17 Nature news story
CDC notes Jamestown Canyon and Powassan virus infections
In a review of arbovirus illness activity in the United States for 2017, researchers from the US Centers for Disease Control and Prevention (CDC) today said more cases of Jamestown Canyon and Powassan virus neuroinvasive disease were reported than in any previous year. They published their findings today in Morbidity and Mortality Weekly Report (MMWR).
Of 2,291 arbovirus cases reported to the CDC, 70% were neuroinvasive. West Nile virus was responsible for 92% (2,097), with a rate of neuroinvasive disease that was similar to the average for previous years. Others included Jamestown Canyon (75), La Crosse (63), Powassan (34), St. Louis encephalitis (11), unspecified California serogroup (6), and eastern equine encephalitis (5). The cases were reported from 641 counties in 47 states and the District of Columbia. Rates of neuroinvasive disease were highest in South Dakota, Mississippi, Arizona, Texas, and Illinois.
The Jamestown Canyon virus cases, two of which were fatal, were reported in 10 states, mainly in the Northeast and Upper Midwest, with Louisiana, Maine, and North Carolina reporting their first cases in 2017.
Powassan virus cases were reported in 10 states, also mainly in the Northeast and Midwest. Increases in both illnesses could be due to increased awareness and testing, but increased virus activity can't be ruled out, researchers said.
In another notable finding for 2017, eastern equine encephalitis from organ transplantation was reported for the first time and occurred in three patients.
Oct 18 MMWR report
APIC, CDC unveil tools to quickly identify infection prevention gaps
To help health facilities quickly spot infection prevention gaps and take action in real time, the Association for Professionals in Infection Control and Epidemiology (APIC) and the CDC today released free, downloadable Quick Observation Tools (QUOTs).
In a statement, APIC said the QUOTs are a set of ready-to-use assessment forms arranged around common themes, environments, and patient populations. The tools are designed to allow healthcare workers to check infection prevention at the patient-care level in a matter of minutes. The 20 sets of QUOTs are based on scientific recommendations, and each contains as many as 10 individual observation worksheets for use separately or together.
Ryan Fagan, MD, medical officer at the CDC, said the goal is to empower a range of health professionals, not just infection preventionists, to curb infections in their own patient care areas. "These tools are designed to be completed in just a few minutes each with a simple set of observations and should be repeated over time to track improvements."