A Disease Is Eradicated When All The Microbes That Cause It Have Been Eliminated. Once Eliminated, There Is No Further Need For Preventive Vaccines. So Far, Small Pox Has Fallen, But Several Other Diseases May Be On Their Way Out.

In fall of 1977, one Mr. Ali Maow Maalin of Somalia acquired an odd, if uninvited, distinction: he was the final person on earth to catch the dreaded disease smallpox. There have been no cases since. The disease is considered eradicated, and it is the first major disease to be so eliminated.

Smallpox is a killer, and in times passed, over half the world would contract it, and as many as half of those would die. Vaccination has been available in most places since the 19^th century; even earlier. Despite this, in the 20^th century alone, half a billion, that was a ‘b,’ died of smallpox.

By the 1950’s various eradication campaigns were well underway, and later in that decade, North America, and all but four countries in South America were free of the disease.

A worldwide effort was undertaken starting in the late fifties. The death rate at that time was around two million a year .The campaign sputtered for about 10 years, then the World Health Organization, part of the United Nations, got involved, which brought both funding and people. By 1975, smallpox persisted only in Ethiopia and Somalia. Smallpox was finally eliminated there, and the battle was finally won.

Why Not Eradicate All Diseases?

Smallpox is a good target for eradication. The infection spreads only person to person, or via their contaminated clothing or bedding. There is no intermediate animal involved, and the virus survives only in humans, and there are no “carriers”. Vaccinate and isolate, and eventually the pathogen will die.

Other diseases are more complex. Bubonic plague, the infamous “black death”, which wiped out almost a third of Europe in medieval times, is still around, with about 500 cases being reported annually, and a hundred or so deaths. However, plague, a bacterial infection, has a cycle involving animals, living alternately between rats and fleas, and can survive indefinitely there. So bubonic plague is not likely to be eradicated, even if human cases could be prevented entirely for some period.

Which Diseases Are In the Cross Hairs?

Polio is a very attractive target. It either spreads person to person, or via food or water that has been contaminated by waste product from an infected person. So polio eradication is as much a civil engineering project as anything else.

The polio epidemics of the past were brought to a screeching halt in the mid 50’s. No one around at the time will ever forget the fear of the disease, which had reached epidemic level, and the famous televised announcement where Dr. Salk pronounced that polio was conquered. But as was the case with smallpox, not everyone had access to vaccines. A coalition of groups undertook the sometimes difficult project of getting the vaccines to the entire planet and has had great success, with the entire western hemisphere, Europe, China, India, and all of Southeast Asia having become 100% free from polio.

It seemed polio’s days were, at last, numbered. It has, unfortunately, made a resurgence, largely due to fatwas (religious edicts) in several Moslem countries against the vaccine. Amazing, sometimes, what some minds will concoct. Still polio is at least contained, and hopefully sealed off, and the day will come, perhaps one country at a time, when polio will be no more.

Malaria kills far more, and there is no effective vaccine. Malaria is caused by a parasite, a protozoa, larger and more complex than a bacteria.

The parasite is carried by mosquitos, who get it by biting an infected person, so there is a cycle that could, in principal, be broken. This is a tougher one though. People, especially if untreated, can carry the disease for years. However, if people are treated, and access to mosquitos blocked, the disease tends to permanently die out.

Malaria was once found worldwide. It has been eradicated in Europe, North America, and the Caribbean, and parts of South America, Asia and Southern Africa, but remains endemic in many areas. It could succumb. There are attacks on many fronts: treatments, mosquito nets, control of still waters, etc.

There is additional success to report.

The Western Hemisphere has been free from measles since 2002, and in April 2015, rubella (German measles) was deemed eradicated from the Western Hemisphere as well.

The Battle Is Never Over.

Bacteria and viruses are masters of adaptation. They are forever watching and waiting for an opportunity to mutate into the next fearsome pathogen. They are greatly assisted in this matter by environments where:

• There is close contact with penned animals-many pathogens jumped from animal versions to human ones.
• Lack of proper sanitation-many disease , cholera for instance, is transmitted only via contaminated water,
• Dense populations-the more people, the more disease can spread.
• Lack of access to safe water. A surprisingly large number of people do not have a supply of drinking water they can depend on.
• Unsafe food standards. Another opportunity for pathogens to gain a foothold.

Remove or improve these, and fewer and fewer new diseases will be seen. We are optimistic.

As to Mr. Maalin of Somalia, the final smallpox victim: He made a full recovery.