News Scan for Aug 15, 2019

More DRC Ebola cases
Australian flu activity analysis
Rotavirus vaccine impact
Lyme serologic testing

WHO notes 10 more Ebola cases in DRC

According to the World Health Organization's (WHO) online dashboard, 10 new cases of Ebola have been confirmed in the Democratic Republic of the Congo (DRC), raising the outbreak total to 2,852, and 380 suspected cases are still under investigation.

Fatalities have passed the 1,900 mark, to stand at 1,905, after seven new deaths from the virus were confirmed today.

According to the latest Disease Outbreak News from the WHO, transmission rates remain steady in the last week, with an average of 81 new cases per week in the last 6 weeks.

While there are no further cases of Ebola in Goma or outside the DRC, the WHO said transmission among health workers is still common.

"New infections continue to be reported among personnel working in community health posts and other facilities. In the last 21 days, 11 new cases were reported among health workers from Beni (3), Mandima (2), and one each in Katwa, Mabalako, Mambasa, Masereka, Mutwanga, and Vuhovi," the WHO said.

Health workers make up 5% of cases in this outbreak.
WHO Ebola dashboard
Aug 15 WHO Disease Outbreak News



Report: Australia flu surges likely due to several factors

An analysis of intense interseasonal flu outbreaks in Australia during the 2018-2019 season, which led to an early start to its 2019 season, found that the causes were complex, and included climate, virological, and immunity factors. Researchers from Australia reported their findings today in Eurosurveillance.

During the country's last interseasonal months, from November 2018 to May 2019, lab-confirmed flu cases were five times higher than the previous 3-year average, with children disproportionately affected. Health officials also saw higher than normal numbers of institutional outbreaks, hospitalizations, and deaths. They note that it's not uncommon to see late summer outbreaks in tropical and subtropical parts of the country; however, more than 70% of the population lives in Australia's temperate regions.

The 2009 H1N1 virus predominated throughout 2018 and into early 2019, after which H3N2 activity increased rapidly, with influenza B circulating at low levels.

The spike in interseasonal activity dovetailed into an early and severe start to Australia's 2019 flu season, already its second biggest in the last 20 years. The developments triggered distribution of a record 12.5 million vaccine doses, which would cover about half of the country's population. Activity appeared to have peaked in early July in most parts of the country.

Reasons for the widespread interseasonal outbreaks are probably complex and due to multiple factors, including hotter and drier weather in most of the country. Also, researchers noted that Australia's 2018 season was mild, which could have increased the number of susceptible people. Co-circulation of both influenza A subtypes and emerging clades that spread later than the winter months may have also led to higher infection rates, perhaps due to a fitness advantage or because they evaded existing immunity. Another factor could be that the 2018 flu vaccine provided suboptimal protection against the strains.

The team concluded that Australia's outbreak show the need for year-round flu surveillance, even in parts of the world with temperate climates.
Aug 15 Eurosurveill report


Study finds modest benefit from extra dose of rotavirus vaccine

In an effort to address why the rotavirus vaccine isn't as effective in children in low-income countries as it is in their peers in high- and middle-income countries, researchers found that giving children an extra dose only provides a modest improvement. A group from Yale School of Public Health and the Institute of Infection and Global Health at the University of Liverpool published their findings yesterday in Science Translational Medicine.

They looked at rotavirus vaccinations and diarrhea cases reported in children in the main hospital in Blantyre, Malawi. The country introduced rotavirus vaccine in 2012, which is given to at ages 6 and 10 weeks. They also had 12 years of prevaccination data and 5 years of postvaccination data from the Malawi-Liverpool-Wellcome Trust Clinical Research Program in Blantyre. Their goal was to investigate the magnitude and duration of protection from the current vaccine and potential waning immunity. They also conducted computer modeling simulations to gauge strategies for improving vaccine effectiveness.

Their findings suggested that a third dose of rotavirus vaccine at 9 months would provide only a 5% to 16% reduction in overall rotavirus-associated gastroenteritis over the first 3 years.

Researchers also found other possible reasons for the lower effectiveness in low-income countries, such as a high rate of rotavirus transmission in Malawi, which could impact protection and delay cases among vaccinated infants to the second year of life. Other causes of gut inflammation and interference from other vaccines could also affect the vaccine's effectiveness, they wrote.

Nigel Cunliffe, MD, PhD, a study coauthor with the University of Liverpool, said in a Yale press release, "Strategies to enhance the immune response to initial vaccination, including the use of next-generation vaccines that are currently in development, may lead to enhanced and more durable vaccine impact."
Aug 14 Sci Transl Med abstract
Aug 14 Yale University
press release


CDC updates Lyme serologic test recommendations

For 25 years, the Centers for Disease Control and Prevention (CDC) have recommended a two-tier test for Lyme disease diagnosis; using a sensitive enzyme immunoassay (EIA) as a first test, followed by a western immunoblot assay for specimens yielding positive or equivocal results.

Since 1994, all future Lyme tests approved for use must be more sensitive or specific than the two-tier model.

In the latest edition of Morbidity and Mortality Weekly Reports (MMWR), authors write that newly approved tests that use EIA for the second test are also now acceptable for clinical use when diagnosing Lyme.

"On July 29, 2019, FDA cleared several Lyme disease serologic assays with new indications for use based on a modified two-test methodology. The modified methodology uses a second EIA in place of a western immunoblot assay. Clearance by FDA of the new Lyme disease assays indicates that test performance has been evaluated and is "substantially equivalent to or better than' a legally marketed predicate test," the authors wrote.

Lyme disease, caused by the bacteria Borrelia burgdorferi, is transmitted through the bites of black-legged ticks. The tick bite often leaves a telltale "bull's eye" rash, and patients who test positive for Lyme are usually treated with a course of antibiotics.

According to the CDC, Lyme disease causes more than 300,000 illnesses each year in the United States. It is the most commonly occurring vector-borne disease in the US, and the sixth most commonly reported notifiable infectious disease.
CDC Lyme disease home page
Aug 15 MMWR report

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