Pneumonia in Wuhan: A Novel Coronavirus Emerges in China
“For the first time in history we can track the evolution of a pandemic in real time.”
“You can't take a knife on a plane anymore, but you can get on carrying a virus.”
On December 31, 2019, Chinese authorities reported to the World Health Organization (WHO) that 59 patients with pneumonia had been hospitalized in Wuhan, China. The outbreak had begun in early December. Seven of these patients were reported to be seriously ill. As of January 5, no further cases have been reported, and recently, the original number of cases was scaled back to 41. On January 11, however, the first fatality, a 61-year-old man, was reported. Amazingly, on that same day, Chinese researchers reported that they had sequenced the genome of the virus causing the outbreak—a newly recognized coronavirus. Evidence so far suggests that this novel virus, named nCoV-2019, isn’t easily spread person-to-person.
Why China? You may recall that China has been the source of several serious emerging infections in recent years—most notably, the pandemic of severe acute respiratory syndrome (SARS) in 2002—also caused by a new coronavirus. It seems that every few years, outbreaks of bird flu have emerged in China that threatened the world with another catastrophe like the 1918-1919 flu pandemic that killed 50-100 million people globally.
You may also recall from reading previous posts in this blog, that a majority of emerging infections in the past 50 years have been zoonotic, that is, they are spread from animals to humans. This was the case in the SARS pandemic (Chinese horseshoe bats were ultimately found to be the reservoir of the coronavirus, and palm civets in animal markets in Guangdong served as intermediate hosts). The bird flu outbreaks are often traced to poultry markets.
The current Wuhan outbreak appears to have arisen in a seafood market, which also sells bats, marmots, snakes, and poultry. It was closed down January 1, 2020. Intensive epidemiological investigations are underway to find the animal source of the outbreak (my bet is bats). Also, the clinical features of the illness and risk factors, such as, gender, age, occupation, underlying diseases, as well as specific animal contacts are in the early stages of investigation.
Lessons from other coronaviruses. As their name implies, under an electron microscope the virions are reminiscent of a royal crown or solar corona, and their genetic material is composed of single-stranded RNA. Counting the Wuhan agent, seven types of coronavirus are known to infect humans. Four are relatively trivial offenders—they cause the common cold. But the other three, including nCoV-2019, cause serious pulmonary infections. From the genome sequencing data, nCoV-2019 appears most related to the other two beta coronaviruses: SARS-CoV and MERS-CoV.
In many ways, the SARS pandemic was the most remarkable of all the emerging infections. The first cases appeared in Guangdong, China in November 2002, and the government was initially slow to alert the WHO. But once the international community of public health experts, epidemiologists, and virologists started working together the pandemic was declared contained by July 2003. The former director of the WHO, Margaret Chan, suggested this was the first time in history that a pandemic could be tracked in real time. This accomplishment was a great public health triumph, despite its costs: 8,096 cases and 774 deaths in 39 countries, and an estimated $54 billion hit to the global economy.
As its name suggests, Middle East Respiratory Syndrome, caused by MERS-CoV, arose in Saudi Arabia. Since its recognition in June 2012, close to 2,500 cases with a case fatality rate of 35%, have been reported in 27 countries. It, too, is a zoonotic infection and, perhaps not too surprisingly, camels appear to be the primary reservoir of this coronavirus.
In addition to reminding us of the critical importance of proximity to animals in emerging infections, another key lesson underscored by SARS-CoA and MERS-CoA is the huge role that air travel plays in transporting infectious agents around the world. Thus, officials in many countries throughout Asia are now on high alert for travelers who might have contracted a respiratory infection in Wuhan, China.
Sure enough, on January 8 a woman who had traveled by air from Wuhan to Thailand was hospitalized with pneumonia due nCoV-2019. Her illness was detected at the airport where a thermal screening device uncovered her fever. Surprisingly, she had not visited the seafood market frequented by the other cases. This single case was enough to trigger an emergency meeting by the WHO.
Celebrating a really important moment in public health. The amazing speed at which the world’s public health and infectious disease experts came to grips with the SARS pandemic may be outpaced by achievements so far in dealing with the outbreak in Wuhan. It seems fortuitous that this new coronavirus got its start in humans in Wuhan, the home of one of China’s top laboratories, the Wuhan Institute of Virology. While there was some finger pointing at China in the early months of the SARS pandemic, authorities at the WHO and elsewhere suggest this time we should clap our hands to celebrate the openness and technological achievements of China.