News Scan for May 05, 2016

News brief

Saudi Arabia reports asymptomatic MERS infection in Riyadh

Saudi Arabia's Ministry of Health (MOH) today reported an asymptomatic MERS-CoV infection in a man in Riyadh who is a household contact of a previous MERS patient.

The new MERS-CoV (Middle East respiratory syndrome coronavirus) case—just the country's fifth in 2 weeks after a surge of cases in March and early April—involves a 39-year-old foreign man who is not a healthcare worker. The MOH provided no further details about the man or his household contact, as is its wont.

The new case brings the country's MERS total since 2012 to 1,381, including 590 deaths. Seven MERS-CoV patients are still undergoing treatment.
May 5 Saudi MOH update

 

Study: Single dose of oral cholera vaccine protects older kids and adults

One dose of killed oral cholera vaccine reduced cases of the disease by 40% in a cholera-endemic area, according to a study today in the New England Journal of Medicine.

Researchers from Bangladesh, South Korea, and the United States evaluated the efficacy of a single dose of the killed oral cholera vaccine Shanchol in 102,552 people ages 1 year and older living in Dhaka, Bangladesh, compared with a group of 102,148 people who received a placebo. Shanchol is currently administered in a two-dose schedule, and in 2015 the regimen's efficacy was determined to be 53% over 2 years.

During 6 months of follow-up, 101 cases of cholera occurred in the study groups, 37 of which caused severe dehydration. The vaccinated group experienced a lower rate of cholera episodes (0.37 cases per 1,000 people) compared with the placebo group (0.62 per 1,000), and vaccine protective efficacy for all cholera cases was 40%. The protective effect for a single dose was higher for severely dehydrating cholera cases, which were reduced by 63% in vaccinated people.

A single dose appeared to convey little protection for children under the age of 5, however. Vaccine efficacy for children ages 1 to 4 years was 16% (95% confidence interval [CI], -49%-53%) for all cholera cases and 28% (95% CI, -221%-84%) for severely dehydrating disease. Protective efficacy against all cholera episodes in children ages 5 to 14, in contrast, was 63% (95% CI, -39%-90%), and in people 15 years and older it was 56% (95% CI, 16%-77%).

While a two-dose regimen of killed cholera vaccine remains ideal, a single dose appears sufficient for older children and adults when the recommended schedule proves difficult or impractical, the authors said. They added that children under the age of 5 should receive two doses whenever possible.
May 5 N Engl J Med study

 

Report notes H5N6 mutations in humans, some worrisome

The genetic makeup of H5N6 avian flu isolates from two people infected in Guangdong province, China, in December 2015 differs fairly substantially from human isolates from the same province in 2014 and shows evidence of increased resistance, a worrisome sign, according to a letter yesterday in Emerging Infectious Diseases.

Chinese researchers said that although the hemagglutinin and neuraminidase genes were similar in the 2015 and 2014 viruses, all six internal genes differed.

The PB-2 gene from one of the 2015 isolates appears to have been derived from an H6N6 virus isolated from a duck, while all its other genes were derived from H5N6 viruses that have been circulating in poultry since 2013. The other 2015 isolate showed high nucleotide identity with an H5N6 human virus collected in 2015 in Yunnan province. Its six internal genes appear to have come from H9N2 viruses in animals.

"These findings show that the circulating H5N6 virus in southern China has reassorted with enzootic H6N6 and H9N2 viruses, resulting in new H5N6 viruses that are capable of infecting humans," the authors wrote.

In addition, the 2014 human H5N6 isolates had no mutations associated with reduced sensitivity to adamantane antiviral drugs, but two of the three isolates from 2015 (the two from Guangdong and one from Yunnan) have the 31N amino acid in their M2 gene, suggesting that they have acquired resistance.

"Thus, this virus lineage could be a great threat to public health," the authors conclude.
May 4 Emerg Infect Dis letter

Ebola Scan for May 05, 2016

News brief

Guinea study finds Ebola RNA in semen up to 9 months after infection

A study of Ebola virus disease survivors in Guinea has added to previous evidence that the virus can persist for as long as 9 months in the semen of survivors, reinforcing the concern about a risk of sexual transmission for months after recovery.

An international team of researchers tested 98 semen samples from 68 Ebola survivors in Conakry and Macenta, Guinea, from March through October 2015, according to their May 3 report in the Journal of Infectious Diseases. Polymerase chain reaction (PCR) results for Ebola RNA were positive for 10 samples collected from eight men up to 276 days (9 months) after their first symptoms.

The proportion of specimens that tested positive decreased over time, with positive results for 28.6% of specimens (4 of 14) obtained between 1 and 3 months after disease onset, 16.7% (3 of 18) collected at 4 to 6 months, and 6.5% (2 of 31) obtained at 7 to 9 months, the report says.

The researchers did not determine whether the samples contained infectious virus. "Semen probably does not remain infectious during the whole period, and viral isolation and sequencing will soon be performed . . . to determine the infectivity of samples," they wrote.

In a study published in October 2015, Ebola RNA was found in the semen of 11 of 43 Ebola survivors who were tested between 7 and 9 months after their illness. And reports published in 2015 suggested that an Ebola case in a Liberian woman was probably caused by sexual transmission from her husband, an Ebola survivor.

The World Health Organization (WHO) has recommended that Ebola survivors abstain from sex or use condoms for up to 6 months after Ebola infection if semen testing is unavailable.
May 3 J Infect Dis report
Accompanying May 3 J Infect Dis commentary
Related CIDRAP News reports: Apr 5, 2016, and Oct 14, 2015

 

Post-epidemic Ebola cases in Liberia ascribed to lingering silent infection

A small Ebola outbreak that occurred in Liberia several months after its epidemic was declared halted was due to some unknown, persistently infected source, rather than an environmental source or cases in a neighboring country, according to findings from a large international team of scientists.

Active Ebola transmission in Liberia was stopped in February 2015, notes the report, published Apr 29 in Science Advances. Subsequently, one case was confirmed in March 2015, and a cluster of seven cases popped up in June of the same year.

The authors used epidemiologic and genomic data to investigate the source of that second post-epidemic flare-up, which occurred in Needowein, Margibi County. They said they found links between the Needowein cluster and a cluster of cases that had occurred nearly a year earlier in the nearby Barclay Farm community.

The researchers couldn't pinpoint the source, however. They found that Ebola virus genomes from two Barclay Farm patients differed from Ebola genomes from the Needowein outbreak by only one nucleotide, suggesting direct transmission, but the Barclay Farm patients had died in August 2014.

Another possible link was a woman from Barclay Farm who had a presumed Ebola infection and who moved to Needowein, but her case was never confirmed, the report says. The authors speculate that the source of the virus might have been an unidentified Ebola survivor with ties to the Barclay Farm cluster.

The report notes that Liberia was again declared free of Ebola in September 2015, but three more linked cases were confirmed in November. And just over a month ago, on Apr 1, the WHO reported yet another new case in Liberia. The WHO warned in March that sporadic cases are likely to occur because of lingering infections in survivors.

Previous reports have shown that the virus can linger in immune-protected parts of the body, such as the eyes and testes, and sexual transmission has been suspected as the source of some recent illness clusters (see item above).
Apr 29 Science Advances report
Apr 1 CIDRAP News story on most recent Ebola case in Liberia

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