|Corona Virus, electron micrograph, Wikipedia
The most dangerous infectious diseases are those that have both high mortality and morbidity rates—that is, they are both highly infectious and deadly. The most infectious diseases are generally spread easily from person to person through the air (e.g., common cold, influenza) and their proliferation is facilitated by crowded living conditions, as exist in slums and pilgrimages, like the annual Hajj, which will soon be under way in Saudi Arabia.
It is therefore alarming that a new SARS-like virus has turned up in Saudi Arabia. It has already killed at least one resident and left a visitor from Qatar in critical condition, according to the San Francisco Chronicle. The new disease is caused by a coronavirus, the same type of virus that causes SARS (Severe Acute Respiratory Syndrome), which killed 800 people during a 2003 epidemic that began in Asia, but quickly spread throughout the world as a result of an infected super spreader boarding an airline.
The virus samples from the Arabian victim and the visitor from Qatar (now being treated in London) are almost identical, according to the World Health Organization (WHO). The WHO is not yet recommending travel restrictions. They do not know the source of the new virus (SARS jumped species from wild civets to humans) or whether it will be easily transmissible between people. They are saying that there is no evidence yet that it is transmissible between people (both victims could have picked up the disease from contact with animals). Furthermore, they do not yet know how virulent the virus is. It may be that both victims had underlying health conditions that made them more susceptible to the virus or its symptoms.
With the Hajj pilgrimage rapidly approaching and the millions of people who will be flooding into Saudi Arabia from around the world, the potential for a deadly pandemic is significant. If the new disease turns out to spread easily between people, thousands of pilgrims could take the new germ with them back to their home countries, rapidly seeding most of the planet in a matter of weeks. People do not die from the common cold, which can also be caused by coronaviruses. Therefore, the fact that one person has already died and another is in critical condition suggests that this new coronavirus may be more akin to SARS, which had a 10% mortality rate.