27th December 2012
If germs hung a recruiting sign for their hosts, it would probably be a version of the World War I poster of Uncle Sam pointing: We want YOU to help us reproduce. All hosts were equally eligible for service, infectious-disease researchers thought. Assuming the recruits weren’t immune due to a prior infection or vaccination, anyone should have roughly the same potential to spread a disease’s pathogens. But then came severe acute respiratory syndrome, or SARS.
This pandemic started as just another strange pneumonia from southern China, but in 2003 it turned into a global outbreak that infected 8,098 people and killed 774. Key to the disease’s spread, researchers found, was a small but crucial portion of the population that became known as “superspreaders,” people who transmitted the infection to a much greater than expected number of new hosts. The more scientists learn about superspreaders, the more they are beginning to realize that this tiny segment of the population is the driving force behind the emergence and spread of infectious diseases.