News Scan for May 04, 2016

Ebola spread in households
ESBL colonization

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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