News Scan for Sep 30, 2013

Vaccine exemptions and pertussis
Resistant enterococci in ICUs
Dengue outbreak in Pakistan
Polio in Pakistan

Study: Vaccine exemptions helped fuel California pertussis outbreak

Clusters of children who had nonmedical exemptions (NMEs) from vaccines appears to be one of several factors that played a role in California's 2010 pertussis (whooping cough) epidemic, researchers reported today in Pediatrics.

Other studies have shown that NMEs cluster geographically and that such clusters play a role in disease outbreaks, but several factors—especially waning acellular vaccine immunity—likely contributed to the spike in pertussis rates, according to a team, from Maryland, Georgia, and California.

The researchers first analyzed state department of education data on NMEs for kids entering kindergarten from 2005 through 2010 and health department data on pertussis illness onsets in 2010. Then they looked for clusters of NMEs, as well as spatial and temporal pertussis clusters, with an eye toward identifying any overlap between the NME and pertussis clusters.

They found 39 clusters of high NME rates and two pertussis clusters. NME and pertussis clusters were both associated with high socioeconomic characteristics, including lower population density and higher median household income. Census areas in exemption clusters were 2.5 times more likely to be in a pertussis cluster during the outbreak period (odds ratio = 2.47; 95% confidence interval [CI], 2.22-2.75).

And more pertussis cases occurred within NME clusters compared with outside the clusters (incident rate ratio = 1.20; 95% CI, 1.10-1.30). Researchers found that the association was significant, even after adjusting for demographic factors.

The team concluded that NME clustering may have been one of several factors that contributed to California's 2010 pertussis outbreak, and that large numbers of unvaccinated or undervaccinated people can lead to pertussis outbreaks. They noted that sustained community transmission in the face of limited vaccine effectiveness and waning immunity can put young infants and other susceptible people at increased risk.
Sep 30 Pediatrics abstract


Meta-analysis: About 9% colonized with VRE on ICU admission

About 9% of patients are colonized with vancomycin-resistant enterococci (VRE) on admission to an intensive care unit (ICU), and about the same proportion will acquire VRE during their ICU stay, according to a 37-study meta-analysis published in PLoS One.

Brown University scientists searched PubMed and EMBASE databases through May 2013 for studies that reported the prevalence of VRE on admission to an ICU and performed a meta-analysis to assess rates and trends of VRE colonization. The 37 studies involved 62,959 patients.

Their pooled prevalence estimate of VRE colonization rate at ICU admission was 8.8% (95% CI, 7.1%-10.6%). For a more conservative estimate, they excluded studies with results in the 90thpercentile as potential outliers and got an adjusted VRE prevalence of 7.9% (95% CI, 6.3%-9.6%). The rate did not vary significantly from 1995 to 2010.

For US ICUs, the estimated prevalence was 12.3%. Reported colonization rates were lower elsewhere in the world: Europe, 2.7%; Australia 4.4%; and Asia, 5.3%.

VRE acquisition rates in ICUs were obtained from 26 studies. The rates varied widely, from 1.1% to 29.4%, with an estimated pooled VRE acquisition rate of 8.8% (95% CI, 6.9%-11.0%), which did not vary when eliminating the 90th-percentile studies.

Egger's test, however, was significant, suggesting a bias from small studies. After exclusion of studies that had fewer than 1,000 population at risk, the combined estimate was 4.8% (95% CI, 2.8%-7.2%).

Among VRE-colonized patients, VRE infection rates in the ICU varied even more dramatically, from 0% to 45%.
Sep 27 PLoS One study


WHO reports more than 6,000 recent dengue cases in Pakistan

More than 6,000 suspected dengue fever cases have been reported recently in the Swat district of Khyber Pakthunkhwa province in Pakistan, a regional office of the World Health Organization (WHO) reported yesterday.

From Aug 7 to Sep 25, 6,376 suspected cases, including 23 deaths, were reported in the district, the WHO's Regional Office for the Eastern Mediterranean (EMBRO) said in a statement. "Laboratory test[s] performed at the National Institute of Health (NIH) in Islamabad, Pakistan, confirmed the diagnosis and detected three sero types of dengue fever (DEN-1, DEN-2 and DEN-3) as the causative strain of this current outbreak," the statement said.

Sporadic cases have also been reported in Punjab, Sindh, and Balochistan provinces, according to EMBRO. District health and WHO officials have increased response activities, including public-awareness and risk-mitigation campaigns.

The WHO does not advise any travel or trade restrictions targeting the Swat district or Pakistan, the statement said.
Sep 29 WHO EMBRO statement


Pakistan confirms 5 more polio cases

Five new cases of polio have been confirmed in Pakistan, bringing the 2013 total for the country to 36, according to a story in Pakistan-based The News International today.

The new cases include three children from North Waziristan agency who are 7, 13, and 17 months of age; one from Khyber agency who is 6 months of age; and one from Peshawar (age not given).

The infected children in North Waziristan had not received any vaccine because of a Taliban-imposed ban on polio vaccination that has been in force for 15 months. The child from Khyber had received no doses either; the vaccination status of the Peshawar child was not given.

Vaccination workers have been the targets of terrorism in Pakistan, with multiple murders of workers and their security forces fiercely curtailing immunization efforts. The country is one of three in the world in which polio is still endemic, in addition to Afghanistan and Nigeria.
Sep 30 News International story
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