News Scan for Oct 04, 2017

News brief

Scientists develop rapid susceptibility test for urinary tract infections

California researchers have developed a rapid test to detect antibiotic susceptibility in urinary tract infections (UTIs) in less than 30 minutes, which could allow patients to be diagnosed and prescribed effective antibiotics during just one healthcare visit, according to a study today in Science Translational Medicine.

The team of scientists used an ultrafast single-molecule DNA amplification and quantification method called digital real-time loop-mediated isothermal amplification (dLAMP), which directly counts bacterial genomes in urine samples instead of relying on lab cultures, which can take days. The researchers diluted and incubated the samples for 15 minutes before dLAMP testing, which takes about 7 minutes. The dLAMP analysis calculated the ratios of DNA concentration between untreated samples and those treated with antibiotics to determine susceptibility and resistance levels among UTI pathogens.

The researchers validated the test using 51 clinical samples that had already been confirmed as either susceptible or resistant to ciprofloxacin or nitrofurantoin.

UTIs, which almost always are treated with antibiotics, account for about 8 million primary care visits a year, and antibiotic resistant infections are a growing threat, the authors note.

They conclude, "Here, we solved three problems to determine phenotypic antibiotic susceptibility in clinical samples within 30 min. First, we used digital quantification of a DNA marker to reduce the antibiotic exposure time to 15 min. Second, we showed that dAST [digital antimicrobial susceptibility testing] is robust to the presence of commensal bacteria and clinical urine matrices. Third, we developed and optimized a rapid, high-resolution measurement method for quantifying NA [nucleic acid] targets that shortens the measurement step to less than 10 min."
Oct 4 Sci Transl Med abstract

High flu levels continue in Australia, parts of Asia

Flu activity in Australia has plateaued at the national level, with variable activity in different parts of the country, and in other parts of the Southern Hemisphere flu is declining, the World Health Organization (WHO) said in its latest global flu update.

Other hot spots include Southeast Asia, where flu levels are high and all subtypes are circulating. Countries reporting high flu activity include Laos, southern China, and Thailand. Meanwhile, flu appears to be decreasing in Southern Asia, where the 2009 H1N1 virus has been more common.

In Western Asia, flu activity is rising in Qatar, with 2009 H1N1 and H3N2 subtypes cocirculating. Some countries in Western Africa are reporting flu detections, with strains present in the region, the WHO said.

In temperate parts of the Northern Hemisphere, flu activity is still at low levels.

At the global level, influenza A made up 82.6% of flu positives at labs in the first half of September. Of subtyped influenza A viruses, 88.9% were H3N2, and of the characterized B viruses, 65.3% belonged to the Yamagata lineage.
Oct 2 WHO global flu update

Study bolsters Lone Star tick as vector for human Bourbon virus cases

An analysis of Lone Star ticks in an area of Missouri not far from where the first Bourbon virus infection was reported in 2014 in a Kansas resident suggests that the ticks are a vector of the virus. A team from the US Centers for Disease Control and Prevention and Missouri Western State University reported their findings yesterday in Emerging Infectious Diseases.

Their retrospective analysis included nearly 40,000 ticks that had been collected in the spring and summer of 2013 from six sites in northwestern Missouri as part of surveillance for Heartland virus, another tickborne disease. Five of the sites were owned by people infected by Heartland virus and the other was state recreational land. The area where the ticks were collected is about 150 miles from Bourbon County, Kansas, where the first US illness was detected, in a man older than age 50 who got sick after being bitten by ticks in the spring of 2014 and died from his illness. A few cases have also been reported from Missouri and Oklahoma.

Tests identified Bourbon virus in three pools of Lone Star ticks: one containing adult males and the others nymphs. Infection prevalence appeared to be higher in adults than in nymphs. Given that Lone Star ticks are known to aggressively feed on people and are abundant in Kansas and Oklahoma—where two human cases have been detected—the researcher said the findings add evidence that the species is a vector of Bourbon virus to humans. They added that the virus still hasn't been found in nonhuman vertebrates and that its natural history is still unknown.
Oct 3 Emerg Infect Dis report

Zika Scan for Oct 04, 2017

News brief

Monoclonal antibody treatment protects monkeys from Zika infection

Neutralizing monoclonal antibodies engineered from three humans infected with Zika virus protected non-human primates from contracting the mosquito-borne disease, according to a new study published in Science Translational Medicine.

Monoclonal antibodies have been an area of interest since the current Zika epidemic began in 2015, because they can be developed more quickly than traditional vaccines and would avoid an antibody-dependent effect (ADE) observed in other flavivirus vaccines.

To conduct the study, researchers mixed antibodies from three humans infected with Zika, engineered to eliminate the potential for ADE, to create a cocktail injected into macaques. The animals were then challenged with Zika virus, and the cocktail prevented viral replication in all the animals.

The authors said these results pave the way for human trials, even in pregnant women, the group health officials most want to protect, given the damage the virus can cause in unborn babies.

"The administration of human neutralizing monoclonal antibodies (nmAbs) in pregnant women to prevent ZIKV infection could be especially beneficial because they are generally considered safe and maternal antibodies cross the placenta and are the predominant means of fetal immunity," the authors write.
Oct 4 Sci Transl Med study

Zika surveillance outside Americas identifies travelers as disease sentinels

An analysis of Zika virus in travelers outside of the Americas designed to look at patterns in Africa, Asia, and Pacific regions found that patients were sentinel markers of Zika activity in five countries: Indonesia, Philippines, Thailand, Vietnam in Cameroon. An international group of researchers who are part of the GeoSentinel Surveillance Network reported their findings yesterday in PLOS One.

They looked at records from 64 travel and tropical medicine clinics in 29 countries, focusing on returning travelers with confirmed or probable Zika infection acquired in Africa, Asian, and Pacific regions from January 2012 through December 2016. Illnesses were contracted in Asia (18), the Pacific (10), and Africa (1).

The system flagged the first confirmed Zika infection in the Pacific island nation of Kiribati in 2015, along with a probable case from the Southeast Asian nation Timor-Leste in April 2016.

The team also looked at the timing of Zika advisories from some of the world's major health organizations, finding that travel advisories were variable, due to uncertainties about risk. They concluded that travelers play a key role in the global spread of Zika virus and serve as sentinels of disease activity. They added that though the clinics don't capture all imported cases, tracking infections in returning travelers can be a helpful part of local surveillance.
Oct 3 PLOS One study