News Scan for Oct 13, 2016

News brief

Study finds long-distance migrant birds key to US H5N8 outbreak in 2015

The 2014-15 outbreak of H5N8 avian flu in Europe and then North America was likely driven by long-distant migrant birds and an unusually "promiscuous" clade, a study published today in Science found.

Scientists from 32 global institutions who form the Global Consortium for H5N8 and Related Influenza Viruses analyzed migration patterns of wild birds that were found to be infected with H5N8. They also constructed phylogenetic trees of viruses collected from 16 different countries from 2004 to 2015 to track virus evolution.

Their data suggest that H5N8 was most likely carried by long-distance flights of infected migrating birds from Asia to Europe and North America via their Arctic breeding grounds. The authors write that the virus likely spread along two main migration routes: (1) from the east Asia coast/Korean peninsula, north to the Arctic coast of the Eurasian continent, then west to Europe and (2) from the Korean peninsula, then east across the Bering Strait and south along the northwest coast of North America.

Their genetic analysis also found that "the hemagglutinin of clade virus was remarkably promiscuous, creating reassortants with multiple neuraminidase subtypes." That led to rapid evolution of the highly pathogenic H5N8 strain.

Lead author Samantha Lycett, PhD, of the University of Edinburgh, said in a university news release, "Bird flu is a major threat to the health and wellbeing of farmed chickens worldwide. Our findings show that with good surveillance, rapid data sharing and collaboration, we can track how infections spread across continents."

In a commentary on the study in the same issue, Colin A. Russell, PhD, with the Department of Veterinary Medicine at the University of Cambridge, wrote, "Enhancing surveillance in wild birds where migratory flyways overlap, particularly the Arctic, could provide an early-warning system for the spread of new viruses. However, these overlaps cover huge geographic areas" and involve massive bird populations.

"We urgently require detailed assessments of where surveillance is most needed and could have the greatest impact."

The H5N8 strain first started causing outbreaks in Southeast Asia in 2014, then spread to Europe and North America, causing 48 million US poultry deaths and more than $3 billion in economic loss in 2015.
Oct 13 Science study
Oct 13 University of Edinburgh news release
Oct 13 Science commentary


US cost of nonvaccination calculated at more than $7 billion annually

Overall costs of health-related expenditures plus lost income and productivity of low vaccine uptake in adults for vaccine-preventable diseases in the United States amounts to over $7 billion per year, according to a study published yesterday in Health Affairs.

The researchers developed a cost-of-illness model for 14 vaccine-preventable diseases associated with 10 vaccines and multiplied the cost per patient by the number of cases in persons aged 19 years or older for 2015. The total economic burden across the population was nearly $9 billion (plausibility range $4.7 billion to $15.2 billion).

Based on vaccination uptake rates in 2015, the investigators calculated that $7.1 billion, almost 80%, of the total was accounted for by cases of the diseases in unvaccinated individuals.

The authors say their study "presents a more comprehensive analysis of the economic burden of vaccine-preventable disease among US adults than previously conducted" and "highlights the importance of increasing adult vaccine uptake" in the country. They express hope that their cost estimates "spur creative policy solutions" toward increasing vaccination rates and raise appreciation for the value of vaccination in people's minds as they make more informed choices.

The diseases included in the analysis were hepatitis A and B, shingles, human papillomavirus, influenza, measles, mumps, rubella, meningococcal disease, pneumococcal disease, tetanus, diphtheria, pertussis, and varicella.
Oct 12 Health Affairs abstract

Antimicrobial Resistance Scan for Oct 13, 2016

News brief

WHO: Global TB reduction efforts lag, disease burden higher than thought

The World Health Organization (WHO) warned today that efforts to reduce the global burden of tuberculosis (TB) need to move faster to meet international targets, and that detection and treatment gaps remain a significant roadblock in the fight against multidrug-resistant TB (MDR-TB).

According to the WHO's Global Tuberculosis Report 2016, there were an estimated 10.4 million new TB cases in 2015, with 60% of those cases occurring in just six countries—India, China, Indonesia, Nigeria, Pakistan, and South Africa. The 2015 numbers, which include new surveillance and survey data from India, show that the global TB burden is higher than previously estimated. Of the estimated 10.4 million new cases, only 6.1 million were detected and officially notified.

An estimated 1.4 million people died from TB last year. Although the number of TB deaths fell by 22% between 2000 and 2015, it remains one of the top 10 causes of death worldwide.

The report estimates that 480,000 people developed MDR-TB in 2015. But while that number did not change from 2014, an additional 100,000 people were diagnosed as having rifampicin-resistant TB (RR-TB). Rifampicin is one of the four first-line drugs used to treat the disease. India, China, and Russia accounted for 45% of the MDR/RR-TB cases.

The MDR-TB estimates are likely low, however, given that only 30% of the 3.4 million new bacteriologically confirmed and previously treated TB cases notified globally were reported to have had drug susceptibility testing for rifampicin, the WHO said. In addition, only 20% of those patients eligible for MDR-TB treatment (125,000) received it in 2015. The global cure rate for MDR-TB remained at 52%.

The WHO's End TB Strategy, which was approved by the World Health Assembly in 2014, calls for a 90% reduction in TB deaths and an 80% reduction in the TB incidence rate by 2030, compared with 2015. The new report shows the world has a long way to go to meet those targets and is short on money, with investments in low- and middle-income countries falling $2 billion short of the $8.3 billion needed. The WHO says that funding gap could increase to $6 billion by 2020 if current funding levels don't increase.

"We face an uphill battle to reach the global targets for tuberculosis," WHO Director-General Margaret Chan, MD, MPH, said in a press release. "There must be a massive scale-up of efforts, or countries will continue to run behind this deadly epidemic and these ambitious goals will be missed."
Oct 13 WHO Global Tuberculosis Report 2016
Oct 13 WHO press release


Study documents drug resistance in Corynebacterium striatum

A study yesterday identifies Corynebacterium striatum as an emerging drug-resistant threat that is associated with increased use of parenteral antimicrobial drugs.

The case-control study, published in Emerging Infectious Diseases, retrospectively identified 179 C striatum isolates in a clinical database and used patient records to obtain clinical relevance, in vitro susceptibility, and length of parenteral antimicrobial use. Then, in a subset of 38 patients who had hardware-associated osteomyelitis or infections of implanted cardiac devices, the researchers performed matched case-control analysis to examine length of parenteral therapy in C striatum cases compared with patients who had coagulase-negative staphylococci.

Susceptibility testing showed that 87 of 121 clinical isolates (71%) from patients infected with C striatum were resistant to all oral antimicrobial drugs tested, including penicillin, tetracycline, clindamycin, erythromycin, and ciproflaxin. The case-control analysis found that patients infected with C striatum were on parenteral antimicrobial drugs more than twice as long as the patients with coagulase-negative staphylococci (69 ± 5 days vs 25 ± 4 days). In addition, the researchers found that serious adverse events associated with parenteral antimicrobial drugs were more likely to be found in the C striatum patients.

The authors say the findings highlight the need to identify Corynebacterium to the species level and perform susceptibility testing for any isolate believed to be clinically meaningful. Furthermore, the high levels of resistance found in C striatum to easily tolerated oral antibiotics indicate the need for development of new oral antimicrobial agents.
Oct 12 Emerg Infect Dis article

This week's top reads