News Scan for Feb 11, 2016

Global dengue burden
Antibiotic resistance in Europe
MCR-1 spread in French livestock
Saudi MERS risk

Models reveal rapid two-decade global rise in dengue infections

The global incidence of dengue has increased sharply since 1990, resulting in climbing rates of disability, particularly in Southeast Asia, while mortality rates appear lower than expected, according to a study yesterday in The Lancet Infectious Diseases.

Researchers funded by the Bill and Melinda Gates Foundation used data from the Global Burden of Disease Study 2013 to run models on dengue incidence, mortality, and related disability in 130 countries between 1990 and 2013.

The global number of dengue cases rose from 8.3 million in 1990 to 58.4 million in 2013. Dengue incidence was highest in Southeast Asia, where 34.3 cases per 1,000 population were reported in 2013.

The investigators also estimated that dengue infection was responsible for 566,000 years lived with disability, largely due to chronic fatigue, in 2013.

Global mortality models estimated that dengue death rates have risen only slightly in the past 20 years, from 8,657 deaths in 1990 to 9,110 in 2013. A total of 576,900 years of life were lost due to dengue mortality in 2013.

Global dengue mortality incidence was greatest in infants and young children (post-neonatal to 9 years), yet declined from 1990 to 2013, while mortality rates rose moderately in all other age groups.

Many of the fatal dengue cases in 2013 occurred in Southeast Asia (5,376 deaths) and South Asia (2,132 deaths). Death rates in tropical and central Latin America and the Caribbean increased from 1990 to 2013, while remaining fairly low compared to overall global mortality burden. Most dengue-related deaths (7,018) in 2013 occurred in individuals belonging to the lower middle-class income group.

The researchers acknowledge that their models resulted in estimates of mortality incidence that are significantly lower than the World Health Organization's estimate of 10,000 to 20,000 deaths caused by dengue each year.

A commentary by Annelies Wilder-Smith, MD, PhD, and Peter Byass, PhD, in the same issue of Lancet Infectious Diseases discusses the difficulties inherent in estimating global incidence and mortality for dengue, highlighting global discrepancies between diagnostics, reporting systems, and surveillance. The commentators said global dengue mortality is likely underestimated, noting that further models could counter this by accounting for population density and clinical reporting differences in high-incidence countries.
Feb 10 Lancet Infect Dis study
Feb 10 Lancet Infect Dis commentary


Annual European survey finds high levels of drug-resistant Campylobacter

The major findings of an annual antimicrobial resistance survey by European Union agencies included a high level of Campylobacter resistance to important antibiotics and some evidence of Salmonella resistance to colistin, a "last resort" drug.

"Scientists warn that resistance to ciprofloxacin, an antimicrobial that is critically important for the treatment of human infections, is very high in Campylobacter, thus reducing the options for effective treatment of severe foodborne infections," says a press release from the European Food Safety Authority (EFSA). The 2014 survey was conducted by the EFSA and the European Centre for Disease Prevention and Control (ECDC).

"In Campylobacter from humans, a high to very high proportion of isolates were resistant to ciprofloxacin and tetracyclines, whereas resistance to erythromycin was low to moderate," the report says. In broiler chickens, 69.8% of Campylobacter isolates were resistant to ciprofloxacin, while 60.2% of human isolates showed resistance to the drug.

As for Salmonella, resistance to widely used antimicrobials was common in isolates from humans (tetracyclines, 30%; sulfonamides, 28.2%; ampicillin, 28.2%) and poultry, according to the press release.

Evidence of resistance to colistin was found in Salmonella and Escherichia coli in poultry, the report says. Mike Catchpole, the ECDC's chief scientist, commented in the press release, "This is worrying because it means that this last-resort drug may no longer be effective for treating severe human infections with Salmonella."

The investigators found regional differences in resistance, with the highest levels in eastern and southern Europe. "In northern Europe, there is lower resistance in bacteria from poultry, particularly in countries with low use of antimicrobials in animals," Marta Hugas, head of EFSA's Biological Hazards and Contaminants Unit, said in the release.
Feb 11 ECDC press release
Full ECDC report


French team finds MCR-1 spread in livestock

French researchers have found more evidence of the MCR-1 antibiotic-resistance gene in livestock, according to a report today on sampling from turkeys, chickens, and pigs published in the latest edition of Eurosurveillance.

MCR-1, which disables the last-line antibiotic colistin, was first described by Chinese researchers in November. The older drug isn't used much anymore in humans but is commonly used in raising food animals. Since release of the Chinese report, researchers in several countries have found the gene in their sample collections, along with worrisome signs that it can appear alongside other resistance genes. Last month French researchers reported the detection in Escherichia coli samples from the country's veal calves, some from as far back as 2005.

In the new report, researchers from the French Agency for Food, Environmental, and Occupational Health Safety (ANSES) looked at 1,696 isolates collected from 2007 to 2014 in the French livestock antimicrobial-resistance surveillance program. Most were susceptible to colistin, but of 23 isolates that were above the cutoff value for resistance, all harbored the MCR-1 gene. Two were isolated from healthy pigs between 2011 and 2013. Seven of the MCR-1 detections were from broiler samples collected in 2013 and 2014, and 14 were from turkeys in 2014. Four of the positive turkey isolates showed resistance to several other antibiotics.

The authors concluded that their findings support the spread of MCR-1 in French livestock and the practice of using colistin in agriculture should be revisited, both due to the potential for treatment failure in animals and to preserve the usefulness of the antibiotic in humans.
Feb 11 Eurosurveill report


MERS mortality risk associated with increased age, comorbidities

Fatal Saudi MERS-CoV cases were associated with increased age, inpatient infection, and a variety of comorbidities, according to an epidemiological study yesterday in the International Journal of Infectious Diseases.

Researchers at Monash University in Melbourne, Australia, analyzed descriptive data on 939 patients diagnosed with MERS-CoV (Middle East respiratory syndrome coronavirus) between September 2012 and July 2015 in the Saudi Arabia.

Most case-patients were 40 years or older (657, or 70%). Locations most affected by MERS incidence were Riyadh (369 cases, or 39.3%), Jeddah (197 cases, or 20.8%), and the Eastern Region (125 cases, or 13.3%). More than half of the total cases (67, or 53.6%) reported in the Eastern Region were diagnosed in 2015.

Of the 421 patients for whom comorbidities were reported, 224 (53.2%) had diabetes, and 200 (47.5%) had hypertension. Comorbidities associated with a higher mortality risk included cancer (adjusted odds ratio [AOR] 5.98, 1.64-21.79), cardiac disease (AOR 2.80, 1.52-5.16), hypertension (AOR 1.41, 0.80-2.48), pulmonary disease (AOR 1.10, 0.48-2.54), and renal disease (AOR 1.06, 0.56-2.03).

Advanced age (80 years and older) was also associated with likelihood of MERS-related mortality (AOR 4.07, 1.41-11.78), as was nosocomial infection (AOR 2.61, 1.41-4.82). Length of time between onset of symptoms and hospitalization did not significantly affect outcome.

Limitations acknowledged by the investigators include missing data on diagnosis and treatment in some of the case reports and the fact that it is difficult to draw conclusions on risk factors for mortality without the ability to observe a control group.
 Feb 10 Int J Infect Dis study

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