Canadian Medical Association Journal 1996; 155: 1492-1494
© 1996 Canadian Medical Association
There are good reasons for putting the virus out of its misery. Variola causes smallpox, which just three decades ago was endemic in 31 countries, infecting between 10 million and 15 million people a year and killing nearly 2 million of them. Millions more were disfigured or permanently blinded.
The annual toll began to decline only when an effective vaccine was developed and when determined immunization programs were launched worldwide. It took 10 years and cost more than $300 million (US), but eventually the global war against smallpox was won.
The virus has not been seen in its wild state for almost two decades, and the last known case of smallpox occurred in Somalia in October 1977. Almost 3 years later, on May 8, 1980, the virus was officially declared to have been eradicated from the natural world, a victory that has produced huge medical and financial benefits. No longer is there a need to pay the high costs of prevention -- the immunization programs,
border controls and surveillance efforts that once were our only bulwark against smallpox -- nor do we have to treat smallpox patients or shoulder considerable losses in productivity.
The accumulated financial dividend from the demise of smallpox has already been estimated at nearly $2.5 billion (US), or more than eight times the cost of eradicating the virus. Public health does not get more cost-effective than this.
Still, although it has been wiped out in the natural world, the variola virus does exist. It is stored at the Centers for Disease Control and Prevention in Atlanta and at the Russian State Research Centre of Virology and Biotechnology at Koltsovo.
There's a reason for preserving the virus under controlled conditions, thus ensuring its availability for research, but scientists believe that cloned DNA fragments of the variola genome will provide the same information. And keeping the beast alive is a risky undertaking. Should the virus escape from either of its laboratory prisons it would pose a serious threat in a world where many people now lack immunity to smallpox.
And so, last May the World Health Assembly, the governing body of the World Health Organization (WHO), voted unanimously to destroy the last two existing stocks of the variola virus. The proposed date is June 30, 1999, and after that smallpox will truly enter the history books at the top of a new chapter devoted to diseases that have been defeated once and for all.
Of the six, polio is nearest to extinction. In fact, it has already been wiped out in the Americas, where the last case appeared in August 1991 in a young Peruvian boy. Three years later, the poliovirus was formally declared to have been eradicated from North, South and Central America and the Caribbean. Other parts of the world are nearing the same goal, and it is still possible that the planet will be free of polio by 2000, the target set by WHO.
Today, the news about polio is mixed and the same is true of the five other diseases covered by a 20-year-old WHO initiative, the Expanded Program on Immunization (EPI), which was undertaken in collaboration with UNICEF.
Launched in 1974, EPI has already produced astonishing increases in immunization coverage around the world. Along the way, it has benefited from the efforts of many governments and private organizations, particularly Rotary International; its Polio Plus program was launched in 1985 and has already contributed $230 million (US) to global immunization efforts. Two decades ago, fewer than 5% of children in the developing world were being vaccinated; by 1990, 80% of the world's children under age 1 were being immunized against the diseases targeted by the EPI. It is estimated that up to half a million potential polio cases are now being prevented annually.
There's certainly good news about measles. Prior to the introduction of a measles vaccine 30 years ago, almost all children could expect to be infected at some point. There were 130 million cases of measles a year, resulting in 78 million deaths. Thanks to immunization programs today's record is vastly better, yet measles is still responsible for more deaths each year than any other vaccine-preventable disease. Outbreaks continue to occur in most developing countries, and the disease remains among the leading causes of child mortality worldwide. Each year about 45 million cases of measles are recorded, producing more than 1 million deaths.
Meanwhile, as with other EPI diseases, there has been a recent decline in vaccination coverage against measles even though it should be rising. Donor countries have become complacent and cut back funding to developing countries, and some diseases have rebounded.
Diphtheria is one, for it has been resurfacing in areas from which it had largely been eliminated. In 1994 almost 48 000 cases were reported in the newly independent states of eastern Europe, resulting in 1742 deaths. This trend is expected to worsen, and the disease is spreading farther afield. Finland recorded four cases in 1994 -- its first in 30 years. Germany had six, leading to one death.
No place is safe. According to recent estimates, between 20% and 60% of the adult population of North America and Europe are no longer protected against diphtheria, owing to a weakening of immunity following childhood vaccinations or foregone booster shots.
Neonatal tetanus is another persistent affliction. With the exception of polio, it's the EPI disease closest to worldwide eradication, but it isn't dead yet. In the early 1980s, fewer than 5% of women in developing countries were receiving the recommended course of at least two antitetanus vaccinations, and tetanus accounted for nearly 25% of all infant deaths worldwide. By 1993, the number dying from tetanus in the first 3 weeks of life had been reduced by about half. The bad news is that approximately half a million babies still die annually from this disease, mainly in Asia and sub-Saharan Africa.
"Tetanus is a warning beacon," says Dr. Ralph Henderson, assistant director general of WHO. "Wherever it occurs, it demonstrates abject failure of the health system."
"Tuberculosis is humanity's greatest killer, and it is out of control in many parts of the world," says Dr. Arati Kochi, manager of WHO's TB program. "The disease, preventable and treatable, has been grossly neglected, and no country is immune to it."
TB is reappearing at sometimes alarming rates in regions such as Europe and the US, where it had been in retreat. The US reported a 12% increase in cases between 1986 and
1991. In Italy, there was a 28% jump between 1988 and 1990. Switzerland had a 33% increase from 1986 to 1990.
The quickening rate of international travel is partly to blame. In the US, about 25% of all TB cases occur in foreign-born people, and that proportion is rising. But other factors are involved too, including urban poverty and homelessness. Meanwhile, TB-control programs have been allowed to deteriorate in many countries or have been dismantled altogether.
Worst of all, recent efforts to deal with renewed outbreaks of the disease have often been badly conceived or poorly administered. In many cases, TB patients fail to complete their full course of treatment, which usually takes 68 months. When this happens they continue to harbour TB, but with a difference. The surviving bacillus has now had the opportunity to develop a resistance to one or more of the common antibiotic drugs used in TB treatment. These new drug-resistant strains are more difficult to treat -- at times, all but impossible -- and so pose a far greater threat to public health. Already, about 50 million people are infected with strains that resist treatment by at least one of the common antituberculosis drugs.
"Perhaps the greatest tragedy of tuberculosis is that we have highly cost-effective tools for its prevention and treatment that we are not using," says Professor Richard Feacham, dean of the London School of Hygiene and Tropical Medicine.
During the next decade, some 300 million people will be infected with the TB bacillus; 90 million of them will develop the disease and 30 million will die from it. TB already claims more adult lives each year than malaria and all other tropical diseases combined, and it also kills almost 300 000 children a year.
TB alone does not excite the greatest alarm among public-health officials in developing countries -- that distinction belongs to TB in combination with HIV. The two infections create a lethal cocktail by multiplying the harmful effects of one another. The deadly combination has overwhelmed the health care systems in many poor countries at the same time financial support from the industrialized world is drying up.
There is a solution to the growing TB threat -- directly observed treatment, short-course (DOTS). People with TB are directly observed throughout their treatment to ensure they comply with their prescribed drug regimen. It works. A DOTS program in New York City has cut TB cases there by 21% since 1992 and the number of new drug-resistant cases has declined by 25% during the same period.
According to Kochi, an additional expenditure of $360 million (US) a year would pay for a global TB-control program based on the DOTS approach. It could save 12 million lives over the next decade and help to stave off catastrophe.
"If infectious persons are not cured, new infections will continue at the rate of one per second," warns a recent WHO statement. "As faulty TB programs further the spread of drug-resistant strains, we will come closer to returning to the day when we will once again have no treatment for TB, except isolation in sanatoriums."
It may seem an impossible task, especially on a planet plagued by war, poverty, natural disasters and political instability, but our record so far is genuinely impressive. Without immunization, the death toll from these diseases would be far higher, 5 million a year instead of 1.8 million. Some 3.2 million lives are already being saved annually and the cost is amazingly low, between $12 and $15 (US) per child. At these prices, it would take $1.4 billion (US) annually to immunize fully all the developing world's newborn children. That's about the cost of two Boeing 747 airliners.
We already know that these diseases can be beaten: smallpox has been routed worldwide and polio has been eradicated from the Americas. True, the Expanded Program on Immunization has faltered somewhat recently, but its major goals are still within reach.
Like other countries and agencies, Canada has made important contributions to the struggle. Since 1986 Canada's International Immunization Program (CIIP) has been administered by the Canadian Public Health Association, with total funding of $89 million. Currently, Canada supports 60 immunization projects in 28 countries; during an earlier phase, CIIP supported 95 projects in 47 countries.
Beating these diseases won't be easy: it will require renewed political commitment and increased financial support. But as this Year of the Vaccine draws to a close, we should remember that polio can be eradicated worldwide by the end of this century, neonatal tetanus can be eliminated and deaths from measles can be drastically reduced. Important inroads against tuberculosis can be achieved.
Many countries, agencies and people remain determined to fight this battle through to the millennium. If we win it, the whole world will share the benefits.