Looking back on the worst pandemics of the past hundred years

The word “˜pandemic’ has penetrated popular parlance in the past few days as news of the spread of swine flu in North America and Europe grabs headlines. What is a pandemic?

Pandemics are widespread outbreaks of contagious disease. What separates a pandemic from an epidemic is the number of people affected. Pandemics are worldwide and affect healthy people just as severely as those with compromised immune systems.

The Black Death is far and away the best-known pandemic in history. Commonly thought to be caused by the bubonic plague, the disease was spread by the burgeoning merchant class of the day, and killed about 75 million worldwide in the mid-1300s. About two-thirds of the victims lived in Europe.

Pandemics have struck in modern times, too. There have been at least three in the last hundred years.

SPANISH FLU, 1918

The worst pandemic of the 20th century, the Spanish flu affected up to 40 per cent of the world’s population. According to the World Health Organization, the flu resulted in more than 50 million deaths – far more than the number of people who died in the First World War.

The flu first emerged in the spring of 1918 in war-ravaged Europe, as well as the United States. Troops carried the illness to Africa and Asia. The first wave of the Spanish flu was extremely contagious but had a relatively low death toll. The second wave, which emerged a few months later, resulted in a ten-fold increase in fatalities.

The majority of victims were between 20 and 50 years old. In many cases, they began feeling ill in the morning and died before sundown. Many of those who survived the first few days ended up dying of complications such as pneumonia.

ASIAN FLU, 1957

This flu killed between one and four million people worldwide. It spread from Southeast Asia to Europe and North America in just four months. Every region in the world had reported cases by the fall of 1957. Limited supplies of a vaccine were available at that time. A second wave struck early in 1958.

Infection rates were highest among school children, young adults and pregnant women, but elderly people proved the most vulnerable.

HONG KONG FLU, 1968

This flu killed about 34,000 people worldwide. Overall, however, the Hong Kong flu was less severe and spread more slowly than earlier versions.

That being said, it was a serious problem in the United States, where it was introduced by troops returning from the war in Vietnam. The illness spread from California to the rest of the country in just three months.

The elderly and those suffering from other medical conditions proved the most susceptible.

PANDEMIC SCARES

SEVERE ACUTE RESPIRATORY SYNDROME (SARS), 2002

This severe respiratory disease, caused by a virus, led to close to 800 deaths. It first emerged in China and spread worldwide before it was contained in 2004.

Four small outbreaks were reported between July 2003 and May 2004. Three of them were linked to laboratory releases of the virus, and were quickly contained.

Canada was one of the countries most affected, with thousands of people being put under quarantine. Toronto was hit hardest, with many hospitals going into lockdown and tourism taking a nose-dive.

AVIAN FLU, 1997

This flu normally infects just birds and pigs, but it emerged in humans in Hong Kong in 1997, when six people there died. The disease emerged again in February 2003 and in December 2003. Almost 300 people have died from the illness to date.

Bird flu still rates high on the list of potentially catastrophic pandemics in the minds of many microbiologists and public health officials.