The A(H1N1) virus behind the swine flu outbreak pales in comparison with fearsome pathogens that kill millions of people worldwide each year, experts said.
Seasonal flu strikes 57,000 to 96,000 people a week in the world, leaving in its wake 4,800 to 9,600 dead, according to the World Health Organization.
AdvertisementIn comparison, the A(H1N1) virus has infected 1,085 people and killed 26 worldwide in the past 10 days, the WHO said.
"This infection is behaving like what we call a seasonal flu, like a more typical, conventional influenza outbreak," said James Nataro, an epidemiologist at the University of Maryland. "It's not behaving like the influenza pandemic of 1918."
The 1918-19 pandemic of "Spanish flu," described as the biggest plague of the 20th century, killed between 20 and 50 million people.
The number of cases and deaths attributed to A(H1N1) remains low compared to those registered every year as a result of seasonal flu, the physician said, noting the moderate virulence of the virus.
"So right now, we are trying to maintain some cautious optimism in the face of a frenzy of activity," Nataro told AFP.
According to the WHO, nearly 90 percent of deaths from infectious disease are caused by six infections - tuberculosis, pneumonia, diarrhea, measles, malaria and AIDS - which are most prevalent in less developed countries.
AIDS kills more than two million people a year and has infected more than 33 million people worldwide.
Tuberculosis, which has made a comeback in recent years, kills 1.5 million people yearly, and more than half a million of the 9.27 million cases that appear each year are antibiotic-resistant strains that have appeared since 2006, notably in China.
A virtually incurable form of tuberculosis, known as "intensively resistant," has developed in 37 countries, including Russia and four other former Soviet republics, in the past two or three years.
Measles, the most contagious of the infectious diseases, causes some 900,000 deaths a year in developing countries for lack of vaccinations.
Malaria, caused by a parasite transmitted by the bite of anopheles mosquito, affects 300 to 500 million people, killing between 1.5 and 2.7 million mostly young children every year in Africa.
Next to the great insect bites, the most dangerous virus is the ebola virus, which is transmitted by blood, sperm or saliva and has a mortality rate that can reach 90 percent.
It first appeared in 1976 in the Republic of the Congo, where it caused fulminating hemorrhagic fever. Outbreaks of the virus have been reported from time to time and as recently as 2008, but they have been contained to small clusters.
Ebola's devastating power inspired the 1995 movie Outbreak with Dustin Hoffman, which described an epidemic of a type 4 virus, which includes ebola, dengue and the H1N1 flu responsible for the great pandemic of 1918.
Viruses are classed in four categories according to the danger they represent, taking into account their capacity to propagate and their mortality rate.
The greatest danger to humans comes from the enormous genetic variability of a common pathogen like the flu virus, according to infectious disease specialists.
That is why the A(H1N1) virus needs to be closely followed, said Neal Cohen, an epidemiologist at Hunter College in New York.
"There is the possibility of further mutation in the structure of this virus, and we need to watch for that. And whether it mutates or not, there is a possibility we will see this virus return in the fall or winter," he said.
"Our experience in the past with SARS and avian flu makes us better prepared for a pandemic, and this virus has been mild in the United States so far. Yet we still need to follow the epidemiological trail in Mexico and here."