Second family cluster found in Wuhan novel coronavirus outbreak

A few more details emerged from the probe into a novel coronavirus (2019-nCoV) outbreak linked to a market in Wuhan, China, including news of another family cluster—who may have been exposed to the same source—and more information on positive environmental specimens taken from the market.

In another development, an expert group that compared what's currently known about 2019-nCoV and SARS and MERS-CoV said the new virus poses a significant threat to global health, but so far the clinical illness appears to be milder than both SARS (severe acute respiratory syndrome) and MERS-CoV (Middle East respiratory syndrome coronavirus).

Evidence of human-to-human spread

Yesterday, Wuhan's health department noted a family cluster of a husband who worked at the market and his wife, who had not been at the market, which appears to be the first indication of limited human-to-human spread.

Today, the South China Morning Post (SCMP) reported that Wuhan authorities told visiting Hong Kong health officials that three members of the same household were among the 41 cases. They include a father, his son, and a cousin who ran a seafood stall at the market at the center of the investigation and got sick at the same time, suggesting that they may have been exposed to the same source. The market also sold live animals such as poultry, bats, and marmots, along with wildlife parts.

The report also gave new information on environmental testing at the seafood market, following reports yesterday that some samples were positive for 2019-nCoV. One of the Hong Kong experts quoted in the SCMP story, Chuang Shuk-kwan, MBBS, said so far, only sample collected from the seafood section of the market tested positive, but experts don't think the chance of a seafood source is high and are looking for the source in animals.

In a media briefing transcript posted today by Hong Kong's government, she said some of the cases were also clustered around the area of the market where seafood was sold. "So, they are chasing it, where the source is. But the investigation is still ongoing so there is no conclusion yet."

A Chinese tourist tested positive for 2019-nCoV a few days ago while visiting Thailand, after frequenting a different market in Wuhan, heightening suspicions that the source of the virus may be other markets, as well. Preliminary environmental testing at other markets has not turned up any positives.

Experts air questions on latest coronavirus threat

In a commentary published in the International Journal of Infectious Diseases, members of the Pan-African Network on Emerging and Re-emerging Infections, which includes scientists involved in SARS and MERS-CoV investigations, said 2019-nCoV may be related to the sale of wild animals as game food at the seafood market. And the clinical infections, when compared to SARS and MERS-CoV, seem to be milder in severity, lethality, and transmissibility. "There is currently no clear evidence of human to human transmission," they wrote.

Many questions remain, such as specific animals or other reservoirs, transmission route, incubation period, risk factors for infection, and survival rates, for example. "Once there is any clue to the source of animals being responsible for this outbreak, global public health authorities should examine the trading route and source of movement of wild animals from other parts to Wuhan and prevent further such trade which is posing risk to human health," the team wrote.

The rapid identification and containment of the 2019-nCoV in a relatively short time period is reassuring and a commendable achievement by China public health authorities.

They noted that while SARS-CoV disappeared, MERS-CoV continues with sporadic cases and still many unanswered questions, such as the source, transmission, and epidemic potential. "The Wuhan outbreak is a stark reminder of the continuing threat of zoonotic diseases to global health security," they wrote, adding that more funder and governmental investments are needed to support a collaborative global "one-health" approach to the battle against zoonotic diseases.

See also:

Jan 15 SCMP story

Jan 15 Hong Kong government briefing transcript

Jan 14 Int J Infect Dis abstract

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