News Scan for May 04, 2016

News brief

Sierra Leone study: Nearly half of Ebola survivors' household contacts infected

In a study conducted in Sierra Leone, nearly half of household contacts of Ebola virus disease (EVD) survivors contracted the illness, with the risk strongly associated with the level of exposure, according to a report published yesterday in Emerging Infectious Diseases.

The study was done by researchers from the London School of Hygiene and Tropical Medicine and the charity Save the Children. They talked with 937 household members of 94 Ebola survivors who were discharged from Sierra Leone’s Kerry Town Ebola Treatment Centre from November 2014 through March 2015.

Of the 937 people, 448 (48%) had had EVD. After adjusting for confounding and clustering, the researchers found that the risk of infection was highly correlated with the level of exposure, ranging from 83% for touching the corpse of an Ebola victim down to 8% for minimal contact, such as sitting in the same room with a patient.

The adjusted risk also varied by age: 43% for children under 2 years, 30% for those 5 to 14 years; 41% for those 15 to 19, 51% for adults 20 to 29 years, and more than 60% for adults over 30.

Compared with the risk for those in their 20s, exposure-adjusted relative risks were lower for those of ages 5 to 9 (0.70), 10 to 14 (0.64), and 15 to 19 (0.71), but not for children under age 2 (0.92) or ages 2 to 4 (0.97).

"Overall, after exclusion of primary and co-primary case-patients, we found a high household attack rate, higher than found in previous studies, perhaps reflecting the urban setting and the bias toward households with multiple cases," the researchers wrote.

They said the lower risk among 5- to 14-year-olds may suggest decreased susceptibility to Ebola in that age-group. "Lower attack rates or case-fatality rates in children have been found for other viral diseases, including varicella, smallpox, and West Nile virus disease," they observed. "For EVD, different cytokine and chemokine responses related to survival have been noted for adults and children."

Having a spouse who contracted EVD first was not found to be a risk factor after adjustment for age, the report says. "Consequently, sexual transmission did not appear to be an important factor in the acute phase."
May 3 Emerg Infect Dis report


Study: Healthy people an increasingly significant reservoir for ESBLs

The rate of gut colonization with extended-spectrum beta-lactamase (ESBL)–producing organisms, a risk factor for ESBL infections, is significant not only in hospitalized but in healthy people worldwide, suggesting important ramifications for infection control and antibiotic management, say the findings of a study published yesterday in Clinical Infectious Diseases.

The Brown University and Boston University authors carried out a systematic review and meta-analysis of studies containing data for fecal colonization with ESBL class A bacteria in healthy individuals in each of the World Health Organization regions of the world. Included in the analysis were 66 studies out of 17,479 evaluated.

Pooled prevalence of fecal colonization with ESBL-producing Enterobacteriaceae was found to be 14%, and the prevalence showed an increasing trend annually of 5.38% (P = 0.003). Asian and African regions had the highest prevalence of colonization, ranging from 15% to 46%; Central, Northern, and Southern Europe had lower but significant prevalence (3%, 4%, and 6%, respectively), as did the Americas (2%).

The most prevalent ESBL enzymes were CTX-Ms, class A enzymes that accounted for 69% of colonization in the study. The use of antibiotics within the prior 4 months was associated with a high risk of colonization (relative risk [RR]=1.63), as was use of antibiotics within the prior 12 months (RR=1.58). Colonization was also associated with a history of international travel (RR=4.06).

The authors did not find a statistically significant correlation between hospitalization and colonization status. ESBL infections have traditionally been linked with hospitals but are increasingly occurring as community-acquired infections and "have recently emerged as a major threat for public health," said the authors.

A commentary also published yesterday in Clinical Infectious Diseases says, "Future questions to be addressed include the true impact of colonization on infection as well as the need for active surveillance screening given the controversial nature of this practice with other [multidrug resistant organisms]."

The authors add, "The role of gut decolonization strategies or possibly FMT [fecal microbiota transplant] to limit transmission and infection represent intriguing potential therapeutic interventions but, most importantly, strict adherence to hand hygiene protocols should be emphasized in an attempt to reduce transmission."
May 3 Clin Infect Dis study abstract
May 3 Clin Infect Dis commentary

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Flu Scan for May 04, 2016

News brief

Low-pathogenic H5N1 virus prompts turkey culling in Missouri

Authorities have destroyed a flock of 39,000 turkeys on a farm in southwestern Missouri following the detection of a low-pathogenic H5N1 avian influenza virus in the birds, according to a report that US officials filed with the World Organization for animal Health (OIE) on May 2.

The virus was found through routine surveillance testing, and none of the birds were sick, says the report from the US Department of Agriculture (USDA). The virus is closely related to low-pathogenic H5N1 isolates found in US wild birds, officials said.

The virus was detected Apr 26 on a farm in Jasper County, near Missouri’s southwestern corner, and the finding was confirmed 4 days later by a USDA laboratory, according to the report. The pathogen was found in samples from healthy turkeys.

In addition to culling all the turkeys on the farm, authorities have quarantined the site and are conducting an epidemiologic investigation and enhanced surveillance and testing in the area, the report says. The Missouri Department of Agriculture is working with the USDA Animal and Plant Health Inspection Service on the effort.

Partial sequencing of the virus’s hemagglutinin and neuraminidase proteins shows it is 98% similar to a 2011 H5N1 isolate from a mallard duck in Ohio. It also bears 99% similarity to an isolate found in a blue-winged teal in Louisiana in 2014.

One turkey farm in Jasper County was hit in March 2015 by the highly pathogenic H5N2 avian flu virus that struck hundreds of turkey and chicken farms in the Midwest that spring. The outbreak killed and forced the culling of tens of millions of birds, most of them in Iowa and Minnesota.
May 2 OIE report
Mar 10, 2015,
CIDRAP News story on H5N2 outbreak in Missouri


H5N6 sickens another in China, WHO notes hospital spread with H7N9

A 65-year-old woman from China's Anhui province is hospitalized in critical condition with an H5N6 avian influenza infection, the country's 13th such case since 2014, according to a statement yesterday from Hong Kong's Centre for Health Protection (CHP). Also, the World Health Organization (WHO) weighed in on 17 recent cases from China, including an instance of possible human-to-human transmission between hospital patients.

An investigation revealed that the woman had contact with poultry before she came down with symptoms on Apr 24. She was hospitalized on Apr 27 and is listed in critical condition.

The pace of H5N6 illnesses in China has picked up in recent months, with 10 cases reported since the end of December. The last few cases were reported in April. Though a handful of Asian countries have reported H5N6 in poultry, China is the only one to report human infections. In an earlier risk assessment, the World Health Organization (WHO) said it is closely monitoring the situation and that most patients had been exposed to live poultry before they got sick.
May 3 CHP statement

In other avian flu developments, the WHO said yesterday that on Apr 18 China notified it of 17 more lab-confirmed H7N9 cases, 5 of them fatal. All of the cases had been noted in official statements from China's provincial health departments or in government monthly infectious disease updates.

The WHO said onset dates ranged from Feb 21 to Mar 20, with patient ages ranging from 26 to 86 years. Eleven of the patients were men, and 15 of the patients had been exposed to live poultry before their symptoms began.

One healthcare-related cluster was reported among the group: An 85-year-old woman from Zhejiang province who reportedly had no poultry exposure but had shared the same hospital ward with an earlier confirmed case-patient died from H7N9 on Mar 8. Her hospital contact was a Zhejiang province man who had been exposed to live poultry and was also a household contact of a confirmed case. The WHO said human-to-human transmission can't be ruled out and that more virologic information is expected.
May 3 WHO update


Flu vaccination protective against premature birth in Laos

Maternal influenza vaccination improves birth outcomes to the tune of preventing about 1 in 5 preterm births during times of high flu circulation, according to an observational study carried out in Laos and published yesterday in Clinical Infectious Diseases.

The authors, from the US Centers for Disease Control and Prevention and several institutions in Laos, enrolled 5,103 women giving birth at three hospitals in Laos from April 2014 through February 2015. Flu vaccination status was determined by means of vaccine cards, and the proportions of small-for-gestational-age and preterm (<37 weeks gestation) neonates as well as mean birth weight were calculated.

A total of 2,172 (43%) of the women had been vaccinated. Of the 4,854 women who had live births, 10.2% had infants classified as preterm. The proportion born to vaccinated and unvaccinated mothers differed significantly (7.5% vs 12.8%, respectively; P < 0.001; crude relative risk [RR] = 0.58, 95% confidence interval [CI], 0.48-0.71); adjusted RR = 0.70 (95% CI, 0.57-0.87). The protective effect of vaccine remained only among infants born during periods of high influenza activity.

The population prevented fraction was 18.0%. No effect of vaccination was noted on the proportion of infants born small for gestational age (4.7% and 3.8%, P = 0.16, for vaccinated and unvaccinated mothers, respectively) or in mean birth weight.

Laos, which has a high rate of poor birth outcomes that has improved little in the past 10 years, has since 2012 offered free influenza vaccinations to high-risk populations, including pregnant women.

The authors concluded, "Many low and middle income countries have high rates of poor birth outcomes, and in tropical regions these countries may experience year-round influenza virus circulation. Adding influenza vaccine to the current package of antenatal services may be beneficial in countries such as Laos."
May 3 Clin Infect Dis study abstract


Northern Hemisphere flu activity ebbs as it inches up in southern half

The WHO's most recent influenza report shows that flu activity is continuing to decrease in the Northern Hemisphere as it rises slightly in the Southern Hemisphere.

In addition, influenza B has increased in North America, Northern Temperate Asia, Southeast Asia, and in parts of Europe.

In the Southern Hemisphere, particularly in Central and South America, flu activity, influenza-like illness (ILI), and severe acute respiratory infections (SARIs) have slowly been on the rise. Most of the increase can be attributed to 2009 H1N1, the WHO said. Brazil, for instance, has had higher-than-expected levels of H1N1 activity, and Paraguay and Argentina have experienced increased ILI and SARI activities.

Influenza A is also more prevalent in North Africa and West Africa, WHO said, but its activity is still declining. The other regions of Africa have had low levels of flu activity in general.  

Unlike last week, all areas in Asia are experiencing low levels in flu activity.

Overall, 46.9% of strains are influenza A and 53.1% are influenza B, according to the WHO. Of these, influenza 2009 H1N1 is the dominant A strain at 84.8%, with H3N2 accounting for 15.2%. The B-Victoria lineage makes up 82.3% of the B strain, with the rest of the isolates of the Yamagata lineage.
May 2 WHO update

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