News Scan for Nov 26, 2019

News brief

Sierra Leone probes Lassa cluster linked to exported Dutch cases

The recent Lassa fever infections, one of them fatal, of two Dutch citizens working in Sierra Leone, along with related high-risk exposures in three United Kingdom citizens, are part of a healthcare Lassa cluster, according to new details about the event in the World Health Organization (WHO) African regional office's weekly outbreaks and emergencies update.

The first patient in the cluster is a male Dutch doctor who worked in Masanga hospital in Sierra Leone's Tonkolili district. His symptoms, which were nonspecific, began on Nov 11, and he was initially treated with antimalarials and antibiotics. When his symptoms did not improve, he was evacuated by air ambulance to the Netherlands on Nov 19, but without barrier nursing procedures. Tests in the Netherlands revealed Lassa virus the next day, and the man died on Nov 23.

On Nov 21, a second Lassa case was confirmed in a female Dutch health worker who worked alongside the doctor during two surgical procedures. Her symptoms began on Nov 11, and her samples tested positive for Lassa virus. She has been evacuated to the Netherlands under barrier-nursing procedures.

On Nov 22, a lab in Sierra Leone confirmed a third Lassa fever case, which involves a local nurse anesthetist who had worked alongside the first two case-patients. Three more suspected cases have been identified in Sierra Leone, all in health workers at Masanga hospital. All but one had assisted with the two surgeries. The two patients had maternal-related procedures, and both died following their surgeries and are considered to be the source of the outbreak and are considered probable Lassa cases.

So far, 48 contacts have been identified and are being monitored in Denmark, Germany, Sierra Leone, the Netherlands, Uganda, and the UK.

Sierra Leone, one of the countries where Lassa fever is endemic, has convened an emergency task force to address the outbreak and with the support of global health partners has launched an investigation in areas linked to the cluster. The WHO emphasized that the cases underscore the importance of applying standard precautions when taking care of all patients, regardless of perceived infection risk.
Nov 25 WHO African regional office report

Samoa measles cases surge; study highlights isolation challenges

A surge of measles activity in Samoa over the past several weeks has grown to 2,437 cases, 32 of them fatal, the government said yesterday on Twitter. It noted that 243 of the cases had been reported in just the last 24 hours. So far, 505 cases involve babies ages 0 to 11 months. Of the total, 1,823 are in children under age 19.

The government said since a measles vaccination campaign began on Nov 20, the health ministry has immunized 24,000 people.

UNICEF noted recently that measles vaccine coverage in Samoa for 2018 was only 40% for the first dose, and 28% for the second dose. Other South Pacific countries are also battling measles outbreaks, including Tonga and Fiji.
Nov 25 Samoan government Tweet

In other measles developments, researchers from Singapore who examined the records of children admitted to a pediatric emergency department (ED) over a 7-year period found that most who needed to be hospitalized had nonspecific symptoms and often no rash during the early illness stages, making it hard to adequately isolate patients. The team published its findings in the December issue of the Pediatric Infectious Disease Journal.

Their study included 277 patients who were hospitalized for measles from Jan 1, 2010, through December 2016. Of those, 177 (63.9%) weren't isolated initially in the ED, and 33.2% weren't placed in isolation wards when they were admitted.

Of the total, 75 (27.1%) didn't have a rash on initial ED evaluation. Those patients were seen earlier in their illness, compared to kids who had rashes. The children who didn't have rashes tended to be younger, with many admitted for poor feeding.

"This calls for the importance of universal push for global vaccination to increase herd immunity to prevent measles infection," they wrote.
December J Pediatr Infect Dis abstract

Flu Scan for Nov 26, 2019

News brief

Study: Baloxavir-resistant influenza A can spread without virulence loss

An analysis of flu viruses during Japan's 2019 flu season suggests that 2009 H1N1 and H3N2 viruses can rapidly acquire the I38T mutation in the polymerase acidic (PA) protein, which has been linked to reduce susceptibility to baloxavir marboxil, a new antiviral. A team based Japan reported their findings yesterday in Nature Microbiology.

Baloxavir, which targets the flu virus' polymerase complex, is approved for use in Japan, the United States, and Hong Kong. Earlier studies had identified the mutation linked to baloxavir resistance and hinted that such viruses can spread person-to-person and reduce replication fitness. However, the mutation's impact on viral fitness wasn't known.

For the study, the team looked for the mutation before and after patients were treated with baloxavir in Japan. Before treatment, two patients had flu viruses that carried the I38T mutation. One was from a household of a patient who had been treated with baloxavir.

They assessed the impact on virus replication for four influenza A viruses that harbored the mutation, finding that the mutation impacts the replication of 2009 H1N1, though compensatory mutations can develop. However, the mutation in H3N2 viruses didn't seem to affect fitness.

Virulence testing that compared the effect of mutant viruses with wild-type viruses in hamsters, mice, and ferrets found that virulence was similar for both. Transmissibility experiments with ferrets found that transmission is similar for both the mutant and wild-type viruses, suggesting that the mutant versions have the potential to spread.

Researchers concluded that flu viruses circulating in humans can rapidly acquire the baloxavir-resistance mutation without a loss in viral fitness, and that widespread use of the drug could result in influenza A viruses carrying the resistance mutation. "The proper use of this drug and continued close monitoring for the emergence or prevalence of seasonal influenza A virus PA-I38T variants is extremely important," the group wrote.
Nov 25 Nat Microbiol abstract

WHO: Flu levels still low in North America, rising in Middle East

In its latest global flu update, the World Health Organization (WHO) said flu levels are at inter-seasonal levels throughout most of Northern Hemisphere, but activity is rising in the Middle East.

"Respiratory illness indicators started to increase in some countries of the WHO European region, Eastern Asia, and in North America, but influenza detections remain below seasonal thresholds," the WHO said.

Influenza A is still the dominant strain globally, with fairly equal proportions of influenza 2009 H1N1 and H3N2 among the "A" strains, the WHO said. Of the sub-typed influenza A viruses, 47% were influenza H1N1 and 53% H3N2.

In the Middle East, Bahrain, Kuwait, and Saudi Arabia reported increased influenza A activity. Reports of influenza remain low throughout Southern Asia, Central America, and the Caribbean.
Nov 25 WHO update