Pandemics: Potential Sources and Global Effects
Professor Dr. Reinhard Burger
Robert Koch Institute
The institute I work with, the Robert Koch Institute, is responsible for protection against infectious diseases in Germany. Looking back at the last 20 or 30 years, you will see that a new infectious agent was discovered in almost every year—or you could say that every year a new infectious agent discovered the human population.
THE HUMAN AND FINANCIAL COSTS OF PANDEMICS
Thinking in that way, and recognizing how much people travel around the world and how influenza is very easily transmitted through aerosols and smear and has a short incubation period, it should not be astonishing that even minor, relatively limited epidemics just as the SARS epidemic can have financial or economic consequences in the range of $50 billion. Regarding human costs, Professor Klenk has already mentioned the enormous number of deaths caused by the major pandemics of the last century, and I would like to add that these pandemics, particularly the1918 Spanish flu, affected young, healthy people, not just the very young and the elderly population. In a country such as Germany, just to give you an idea of the normal influenza impact, there are about six million cases in a bad year, like the 2004-2005 winter season, with about 2.5 million people unable to work, about 30,000 people requiring hospitalization, and between 10,000 and 20,000 deaths. This is not the result of a pandemic, but a typical influenza outbreak.
SOURCES OF A POSSIBLE PANDEMIC
All influenza experts agree that another influenza pandemic is inevitable and probably imminent. Currently the risk of avian influenza being transmitted to human beings is probably low and, as Professor Klenk mentioned, there are relatively few human cases if you consider the unprecedented enormous number of infected animals. But avian influenza could be the origin of an influenza pandemic and then we would have to deal with large numbers.
While Germany or Sweden could well be the source, at present the most likely source for such a pandemic virus is of course southeast Asia, because the sheer number of animals infected is very large and contact between human beings and infected animals is much closer there than in the transatlantic area. You have backyard chickens—poultry is an important source of food—and you have people living closely together in the same house and a warm climate, all of which increase the concern for spread in the host range, which includes stone martens and other kinds of birds and cats.
WHO, the World Health Organization, defines the risk of spread with six different color levels ranging from cream to dark red. Right now we are in phase 3, yellow, which means there is no or limited human-to-human transmission. However, in early June a family in Indonesia was reported to have the largest cluster of influenza infections so far, with six deaths in a single family, so we are perhaps on the verge of moving to level 4, in which increased localized human-to-human transmission is in evidence. Intensive efforts are now underway to determine if this cluster of cases involved transmission from human to human or if it came from an identical source, for example, the family might have prepared and eaten an infected chicken. But the chance of eliminating the disease from the bird population currently is zero—it is endemic.
POTENTIAL GLOBAL EFFECTS
If a pandemic should occur, it would affect the daily life of populations all around the world for months. There would not only be special demands on medical, emergency, and relief workers and affect their health but intensive personal hygiene measures would have to be taken and public gathering places such as schools and events such as this one would be affected. In all likelihood there would be shortages in medical care because medical personnel would be sick and because no effective vaccine would be available in time. It is probably also unrealistic to expect assistance or material help from other countries because everybody will be concerned with their own welfare.
Epidemiologists are discussing whether a pandemic virus could be detected and identified very early, i.e., when there are fewer than 10 or 20 cases. But even if this were to happen, sufficient quantities of antiviral agents would need to be available locally and the problem of resistance would most likely keep the effectiveness of early quarantine measures low.
I believe very strongly that the risk of an influenza pandemic is a very clear and present risk because the virus can change its genetic makeup very rapidly. Efforts are now being concentrated on reducing morbidity and mortality in the population, but this requires international cooperation because viruses do not observe borders. Efficient, effective cooperation needs to take place because viral agents travel quickly—the 1918 virus traveled the world in a few months when there was no air traffic. Antiviral drugs or vaccines must also be equally available to all states.