News Scan for Apr 20, 2018

Romaine warning widens
US flu ebbs further
Yellow fever in Brazil
Avian flu outbreaks
Wild ducks as H5N8 carriers

CDC expands E coli warning to all Yuma-grown romaine lettuce

The US Centers for Disease Control and Prevention (CDC) today expanded its warning to consumers to include all types of romaine lettuce from the Yuma, Ariz., growing area, based on new information from Alaska that sick people ate lettuce from whole heads of romaine.

In addition to advising against eating chopped romaine, which was originally tied to a multistate Escherichia coli O157:H7 outbreak, the CDC advises consumers to also avoid whole heads and hearts of romaine from the Yuma growing region. The CDC's initial warning also includes salads and salad mixes that contain chopped romaine.

Newly reported illnesses from Alaska will be included in the next case count update, the CDC said. For now, the outbreak total remains at 53 cases from 16 states.

In Alaska, state and local health officials interviewed sick people at a correctional facility about the food they ate and other exposures they had before symptoms began. Sick patients reported eating romaine lettuce, and trace-back investigations point to whole-head romaine sources from the Yuma, Ariz., growing area.

In earlier updates on the outbreak and the investigation, federal officials said the Yuma area generally supplies romaine to the United States during November through March each year. Produce industry groups have said nearly all of the romaine harvested and shipped now is from California areas not implicated in the outbreak. So far, no specific grower, supplier, distributor, or brand has been identified.
Apr 20 CDC outbreak update


End of flu season still sees pediatric deaths, high hospitalization rate

For the second week in a row, outpatient visits for influenza-like illness (ILI) fell below the national baseline of 2.2%, according to the latest flu surveillance update from the CDC, but flu deaths in children continue to be reported, and hospitalization rates have been record-breaking.

Despite the low levels of flu activity, the CDC noted 5 new pediatrics deaths, bringing the season's total to 156. This flu season has been one of the most deadly for kids in recent years, surpassing even the 2014-15 season, which saw 148 pediatric deaths.

Only 5 states are reporting widespread flu activity, down from the previous week's 7. The states are Connecticut, Delaware, Massachusetts, New York, and Rhode Island. Only Arizona experienced high ILI, with Alaska and South Dakota reporting moderate ILI.

Influenza B was the dominant strain last week, following the trend seen at the end of flu seasons. Of positive flu specimens gathered at clinical labs, 65.7% were influenza B. 

Overall hospitalizations are still high, at 103.7 lab-confirmed cases per 100,000 population, up from 101.6 the week before. In patients 65 and older it reached 446.4 per 100,000 population, up from 437.0 the week before. The vast majority of hospitalizations (73.8%) were due to infections with influenza A viruses.

In an accompanying summary of flu activity, the CDC said hospitalization rates this season have been record-breaking, exceeding end-of-season hospitalization rates for 2014-15, another season dominated by the H3N2 virus.
Apr 20 CDC FluView


Brazil reports more yellow fever infections and deaths

In a weekly update on its yellow fever outbreak, Brazil yesterday reported 30 more lab-confirmed cases and 11 more deaths from the disease, according to a statement from the country's health ministry. The new developments put the case total at 1,157 and the number of deaths to 342.

As of April 17, the ministry has received reports of 5,131 suspected cases and has ruled out 2,951, with 1,023 still under investigation. The three hardest hit states, where most of the illnesses have been reported, are Minas Gerais, Sao Paulo, and Rio de Janeiro.

Though the number of cases this season, which runs through Jun 30, has outpaced the previous one, the incidence this season is lower, because the mosquito-borne virus is circulating in metropolitan regions of the country with larger populations. Incidence this season is 3 per 100,000 population compared with 6.2 per 100,000 during the 2016-17 season.

Brazil has extended a yellow fever vaccination recommendation to the whole country with a goal of completing the campaign by April 2019, but uptake so far is well below the 95% target.
Apr 19 Brazilian MOH update


High-path avian flu outbreaks reported from four countries

Over the past week, four countries—China, South Africa, Taiwan, and Togo—have reported highly pathogenic avian influenza involving different strains, according to the latest notifications from the World Organization for Animal Health (OIE).

China's outbreak involved H7N9, which struck a layer farm in Ningxia province in the north. The outbreak began on Apr 3, killing 585 of 13,578 birds.

Meanwhile, South Africa reported several more H5N8 outbreaks involving both poultry and other types of birds. The two poultry outbreaks involved farms, one of them housing domestic ducks and quails, at locations in North West province. One event began on Mar 13, and the start date for the other was Apr 6. Taken together, the virus killed 584 of 41,012 birds. Also, the country reported four more H5N8 outbreaks involving wild birds in Western Cape province and one in hobby ducks at a location in Limpopo, its northernmost province. Between Jan 23 and Mar 22 the virus killed 14 wild birds and 11 of 85 hobby ducks.

In Taiwan, authorities reported four more H5N2 outbreaks, part of activity involving the virus that has been underway since 2015. All four events involved poultry farms with start dates ranging from Apr 2 to Apr 10. Species included native and breeding chickens. Deaths were reported in 7,242 of 62,935 birds.

Elsewhere, Togo reported an H5N1 outbreak at an agropastoral farm where layers, broilers, and swine were raised in Maritime region in the far south of the country. The event began on Mar 27, killing 3,629 of 5,001 susceptible birds. So far the source of the virus isn't known. Togo's last H5N1 outbreak was reported in October 2017.
Apr 19 OIE report on H7N9 in China
Apr 18 OIE report on non-poultry H5N8 in South Africa
Apr 18 OIE report on H5N8 in South African poultry
Apr 19 OIE report on H5N2 in Taiwan
Apr 18 OIE report on H5N1 in Togo


Study finds more support for wild ducks as H5N8 carriers

Wild ducks species may be driving the long-distance spread of highly pathogenic H5N8, according to researchers from the Netherlands who experimentally infected water birds and chickens to spot any virulence differences between infection from a H5N8 virus from 2014 and a H5N1 virus from 2005.

The team noted that the global spread of H5N8 to several continents in 2014 and 2015 raised questions about whether the virus was better adapted to wild birds than earlier H5 viruses. They reported their findings in an early online edition of Emerging Microbes and Infections.

The species they tested included Eurasian wigeons, common teals, mallards, and common pochards, all of them migratory birds that are abundant and play an important role in the ecology of avian influenza viruses.

H5N8 caused subclinical infections in all four of the species, but virus excretion was highest in Eurasian wigeons, providing the strongest evidence yet that they are long-distance carriers of the virus. More than half of pochards infected with the 2005 H5 virus had clinical illness. In chickens, the H5N8 virus caused systemic disease and high mortality, similar to the 2005 H5 virus.

The researchers concluded that a switch in virus excretion level, highest in wigeons for the 2014 virus, after being higher for pochards and mallard for the 2005 virus, and decreased clinical severity from the 2014 virus suggests that the earlier H5 viruses have adapted to wild waterfowl populations. They emphasized that their study only looked at a limited number of bird species and that others may be involved in H5 epidemiology, and more research is needed to explore additional contributors as well as spatial and temporal connections between migratory flyways.
Apr 18 Emerg Microb Infect abstract

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