Chinese study points to asymptomatic migratory birds as source of H5N8
Asymptomatic migratory birds may play a role in geographic dissemination as well as facilitate the viral evolution and reassortment of highly pathogenic H5N8 avian influenza, Chinese researchers reported yesterday in Emerging Infectious Diseases.
The authors captured and tested migratory birds during their wintering period in the coastal wetlands of Shanghai, which lies at the Yangtze River estuary and serves as a "crucial stopover" for migratory birds in East Asia, from October 2013 through December 2014.
They identified 26 novel H5N8 viruses in total, 19 in swabs from ducks (16 from common teals, 2 from falcated ducks, and 1 from a spot-billed duck) in 2013, and 7 in swabs from Eurasian curlews in 2014. In addition, H5N1 avian flu was detected in common teals, 3 showing mixed infection and 1 showing only that subtype.
Homology BLAST searches showed striking similarity between the H5 and N8 genes in 18 of the H5N8 viruses in ducks and isolates from poultry in Zhejiang province, adjacent to Shanghai. The searches also showed high similarity between H5 and N8 viruses in all 7 of the curlews to isolates from wild ducks in South Korea in early 2014. Matrix genes of all novel H5N8 viruses were found to be closely related to isolates from birds in China, Japan, and South Korea.
Phylogenetic analysis showed similarity between the H5N8 viruses in the 18 ducks and in poultry from eastern China and Korea. It also showed similarity between the H5N8 in the 7 curlews and in Korean, European, and North American birds.
The authors note that the H5N1 and H5N8 coinfection found in several of the migratory ducks "suggests that rapid and active mutation and reassortment of H5 subtypes may take place in these hosts." They conclude that "To monitor and then control the epidemics of H5 subtype viruses, it is urgent that more intensive surveillance be carried out in poultry and wild birds and that information be promptly shared among countries."
Apr 26 Emerg Infect Dis study
Study: Single inhalation of laninamivir can provide protection against influenza
A single 40-milligram (mg) dose of the long-acting neuraminidase inhibitor laninamivir octanoate, known to be effective and convenient as treatment for influenza, may also be an effective option for postexposure prophylaxis, Japanese researchers reported yesterday in Clinical Infectious Diseases.
In the double-blind study, analysis was done of 801 participants from 50 primary care clinics in Japan from November 2014 to March 2015. Eligible participants were family members who had cohabited with a flu patient (index patient) within 48 hours of symptom onset. Nasopharyngeal swabs were taken in index patients on day 1 and in family members on days 1, 3, and 11. If the latter individuals developed fever or other flu symptoms between days 1 and 10, they returned to the study site for a diagnostic swab and evaluation.
Enrollees were randomly assigned to receive one of three regimens through self-activated inhalation: 40 mg of laninamivir on one day and an identically packaged placebo on the second day, 20 mg of laninamivir on both of 2 days, or placebo on 2 days.
Laninamivir significantly reduced the incidence of flu: Clinical influenza, defined as a positive swab, fever, and at least two flu symptoms (eg, headache, chills, cough), occurred in 4.5% of those receiving either the single 40-mg dose or the two 20-mg doses of laninamivir and 12.1% of those receiving placebo only. Symptomatic flu occurred in 8.6%, 9.3%, and 18.9% of people in the three groups, respectively, and laboratory-confirmed flu in 11.7%, 13.0%, and 25.3%, respectively. Protective efficacy was comparable in the two laninamivir regimens, and all regimens were well tolerated.
As pointed out by the authors, a single inhalation of laninamivir as prophylaxis for flu "may have great advantages over drugs that require daily administration, such as oseltamivir and zanamivir, particularly for healthcare workers in a pandemic setting."
Apr 26 Clin Infect Dis abstract
WHO details latest 3 cases of MERS-CoV in Saudi Arabia
The latest three cases of MERS-CoV in Saudi Arabia include one healthcare worker and two household contacts of case-patients already reported, the World Health Organization (WHO) said today.
One patient is a 58-year-old symptomatic woman from Abha who tested positive for MERS-CoV (Middle East respiratory syndrome coronavirus) Apr 22 after having tested negative 2 days earlier. She is a household contact of a MERS patient but has no other known exposures. She has comorbidities and is currently in critical condition but is not receiving mechanical ventilation.
Another patient is a 31-year-old man from Riyadh who was admitted for MERS symptoms Apr 16 to the same hospital where he works and where he cared for a MERS patient. He has no comorbidities and no other known risk factors for MERS. He is stable and is on home isolation.
The third patient is a 24-year-old man from Hofuf who tested positive for MERS on Apr 18. He is asymptomatic but was identified during contact tracing as a household contact of a MERS patient. He has no comorbidities and is on home isolation. He has a history of frequent contact with camels and is known to have consumed their raw milk.
The WHO has been notified of 1,728 laboratory-confirmed MERS-CoV cases globally with at least 624 deaths since September 2012. The Saudi ministry of health has counted 1,377 cases with 587 deaths in that country, with no new cases reported since Apr 23.
Apr 27 WHO statement
