In 1796 a bold English doctor named Edward Jenner inoculated an 8-year-old boy with material from a cowpox sore on a milkmaid's hand. Two months later Jenner reinoculated the boy with matter from a human smallpox pustule.

Jenner called his successful new anti-smallpox technique "vaccination."

It took almost two centuries for the human race to fully apply it.

Today, however, billions of tragic cases of smallpox and billions of vaccinations later, the director-general of the World Health Organization will formally declare, "I personally believe smallpox has now been eradicated throughout the world."

If he is right -- and it is two years since the last known natural occurrence of this once-global scourge -- man has for the first time wiped out a major disease.

It was just two years ago today that Ali Maow Maalin, a hospital cook in Merca, Somalia, was reported severely ill with a high fever and the typical smallpox rash. Somali and WHO teams quickly isolated him under guard and sought out and vaccinated 161 people who had been in some contact with him. None got smallpox.

Maalin was thus the last smallpox victim in an area on the horn of Africa -- Somalia and Ethiopia and their nomadic desert regions -- that turned out to be the site of smallpox's last stand.

As recently as the summer of 1977, little more than two years ago, there were still more than 2,500 cases in Somalia.

In the mid-1950's the disease was still ever-present -- "endemic" is the public health doctor's word -- in 33 countries, including India, Pakistan, Indonesia, Brazil, Rhodesia and South Africa.

And a few generations ago, the sight of pockmarked faces, marked for life by this disease's deep scars, was still common in the United States.

"Smallpox has been called one of the most loathsome diseases," says Dr. Donald Henderson of Johns Hopkins University. "I know that no matter how many visits I made to smallpox wards filled with seriously ill and dying patients, I always came away shaken."

Henderson made many such visits. Now dean of the School of Hygiene and Public Health at Johns Hopkins, he led the World Health Organization's final campaign against the great killer and disfigurer. For a decade, until going to Hopkins in February 1977, he was chief medical officer of WHO's smallpox eradication campaign.

At the end of the campaign, when no more cases could be found despite great effort and a WHO offer of $1,000 for any report, he said "we knew we had done it, but we couldn't believe it."

The campaign he supervised was highly sophisticated and intelligent.

In 1966, on a motion by the Soviet Union, the World Health Assembly, the representative body of WHO, voted to try to eliminate smallpox in 10 years.

"Privately," Henderson has said, "I believe very few" thought it was really possible.

But there were new tools, including a freeze-dried vaccine that doesn't require refrigeration. It made mass immunization possible in torrid areas like the Sahara, Brazilian jungles, tropical African rain forests and Ganges plain.

There was money: $9.65 million in international funds, in addition to many nations' internal spending, U.S. money of course predominated: $23.3 million contributed directly, as well as the largest share of WHO's $34 million budgetary allotment.

There were also new strategies. Particularly effective was a stopgap devised in 1968 by a young American health officer named William Foege when there was a delay in delivery of supplies in Nigeria.

If we can't vaccinate everyone, said Foege, why not do all those in a limited area surrounding each known case? It turned out that this "search and contain" strategy, inevitable known later as "search and destroy," could effectively eliminate smallpox in large nations without vaccinating the whole population. Dr. Foege now directs the U.S. Center for Disease Control in Atlanta.

Though Somalia's last case was the last natural occurence of smallpox there has since been a notable instance -- and two related deaths.

A medical photographer who worked above a British laboratory that stockpiles smallpox virus caught the disease and died last September.The head of the lab where the dangerous live virus reseach was conducted, virologist Henry Bedson, evidently blamed himself. He was found dead, a suicide.