Image copyright Yasushi Abe Image caption The Agona district chief says the body of a baby who died of pneumonia on 26 February was taken to Agona
A total of eight cases of a new coronavirus variant have been confirmed in Japan.
The cluster, of victims in the Agona district of Kawasaki, is not linked to the H7N9 virus outbreak that killed 16 people between April 2012 and February 2015.
Most of the victims had lung infections and three died.
Only one of the eight cases was suffering from a previously undetected health problem, Public Health Minister Setsuden Toba said.
He said it was possible the virus might have become airborne, as nearly all of the patients were reported to have reported coughing, running nose and poor lung function before their symptoms developed.
Image copyright Japan Agency for Medical Research Image caption The new virus variant had been identified in Oman in 2017
All eight patients are aged over 65 and fell ill on or between 26 February.
Authorities believe the virus may have been transmitted from a three-year-old girl who became ill and died in February.
The Agona district chief says the body of a baby who died of pneumonia on 26 February was taken to Agona to perform a traditional rite of mourning.
“At this point, we don’t know how the child became infected, but we are ready to step up testing and investigate further,” chief district chief Takaharu Seko told AFP news agency.
Image copyright Japan Agency for Medical Research Image caption Most of the victims had lung infections and three died
The Agona district chief made the announcement after meeting Japan’s Chief Cabinet Secretary Yoshihide Suga.
The World Health Organization has previously referred to the Agona case as the first confirmed transmission of an influenza virus in people via respiratory droplets.
The Tokyo public broadcaster NHK says the Agona cluster began in August last year.
Kanato Arie, a medical doctor who practises in Kawasaki, told NHK the latest cluster could be linked to previous contacts of the Agona cluster, which included a couple who moved from the region last year.
Kawasaki is 200km (124 miles) south of Tokyo.
Some 15 people from Kawasaki also fell ill last month. There is no indication of direct infection between these patients and those from Agona.
In the first and second cluster, the affected were hospitalized at the same hospital and a funeral home, according to NHK.
Image copyright AFP
Image copyright PA Image caption The victims were found to have no known links to the area of Kawasaki
Coronavirus strain found
Seko also said the Agona cluster had been identified in the Oman that last year. The virus variant, called AH virus A2, was identified in that country on 8 January 2017.
Coronaviruses cause common colds and flu.
Lupus of the lung is a rare but serious type of pulmonary disease, with symptoms including severe coughing, laboured breathing and shortness of breath.
It is caused by L-clue, a virus responsible for many cases of lupus and various types of hepatitis C.
From 1950 to 2014, the Middle East Respiratory Syndrome (MERS) virus claimed 650 lives in the Middle East.
The strain originated in camels and spread to humans, triggering a deadly epidemic in 2012 and 2013.
Image copyright AP Image caption Officials have called for a thorough investigation into how the infections occurred
Policies and infections
Coronaviruses have been known to cause human infection in animals for many years, the World Health Organization says.
“Most commonly they cause a common cold, although viruses other than coronaviruses cause less than 1% of disease in people,” a WHO website says.
“Influenza viruses are sometimes the source of human infections because they spread among animals.”
The report, however, notes that “symptoms are similar in people and animals, but their pathogenesis is different”.
New guidelines to reduce exposure to animal-borne viruses in the workplace were published in 2017 after MERS was suspected in a number of cases across the Middle East.
The guidelines urge a health worker’s exposure to respiratory or throat specimens be minimised at work sites where the risk of infection is high.
Efforts to control the transmission of other diseases among people at work are also being monitored.