Page images
PDF
EPUB
[graphic][ocr errors][merged small][merged small][subsumed][subsumed][subsumed][ocr errors][ocr errors][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed][subsumed]

There is general agreement among experts that the world was fortunate in having a mild worldwide influenza outbreak to test the early warning network. It did not work perfectly. The action required to make the system even more effective was clearly indicated.

For example, some reports of epidemics to WHO and the dispatch of virus strains to the international centers were delayed or neglected altogether, even when there were signs that an epidemic or unusual strain or virus had appeared. More effective operation of the existing network is clearly called for.

As another example, many countries and territories, even those with. the necessary laboratories have not named such a laboratory to be officially responsible for cooperating in what must be truly a worldwide program if it is to be effective. Recall, as noted above that the recent pandemic began on the Chinese mainland, an area not covered by the WHO program, and that as a consequence there was a 2month delay in learning of the new virus.

Once news of the unusual epidemic was received by the U.S. Army and the WHO influenza center laboratories the warning system. worked well. The virus was isolated, sent to the appropriate reference center and identified as an entirely new strain within 3 weeks, and the information being broadcast to the rest of the world immediately. This was a notable achievement. However, it cannot be stressed too often that if the information had been received promptly from China, the rest of the world would have had 2 more months in which to prepare.

Clearly every country, with the necessary laboratories, should cooperate in this program, and efforts should be made to establish laboratories where they do not now exist.

4. INTERRELATIONSHIPS OF RESEARCH AND DISEASE CONTROL

The WHO influenza program is an instructive example of the way in which research and practical public health measures are intertwined.

The program was started by WHO in 1947 primarily as a research project to learn more about the epidemiology of influenza. The laboratory network is now, as has been pointed out above, an essential part of the worldwide public health defense against influenza. The original research laboratory network now operates in close relationship with national public health authorities. This is necessary so that the influenza centers can know of, be informed of, and promptly initiate studies of, outbreaks in remote areas. They thus may keep health authorities informed of the appearance of unusual epidemics throughout the world and of the appropriate technical countermeasures.

So far as influenza is concerned, the 1957 worldwide epidemic was the first to occur since modern methods for study of the virus became available. A number of studies have therefore been planned and are being coordinated by WHO in the hope of learning more of the epidemiology and prospects of control of influenza.

For example the WHO Influenza Center in the Netherlands discovered in June that antibodies to the new virus were present in some persons of over 70. WHO was immediately informed, with the result that it was possible to arrange the collection of sera from elderly persons in some other areas not yet involved in the epidemic. The

studies have confirmed the Dutch findings, a result which would have been impossible if collection of the sera had been delayed until the epidemic had reached the area. This discovery may prove to be of great importance since a possible interpretation is that the new virus is related to the virus responsible for the 1889-90 pandemic.

There is a possibility that certain domestic animals, particularly swine, may play a role in the epidemiology of human influenza. Arrangements were therefore made by WHO to collect sera from swine and other domestic animals in 25 countries in different parts of the world before the epidemic reached them. Later, after the epidemic had passed, further sera were collected from the same animals and the two are being compared for antibodies against the Asian strain.

On a broader scale, it is now becoming clear that the influenza centers, which were necessarily virus laboratores, form a natural nucleus from which WHO may help to evolve more extensive virus studies on a worldwide basis.

B. MALARIA ERADICATION

A decade ago, about 3 million people a year died from malaria. About another 300 million suffered the weakening effects of malaria. Despite the high figure of annual deaths, and though it is often a major cause of infant mortality, malaria is important mainly because it produces chronic invalidism. It is insidious rather than dramatic except when, for reasons imperfectly understood until recently, epidemics flare up, as in Ceylon in 1934-35 or in Brazil in 1938-39. It leads to an increased number of deaths from other causes, impairs physical and mental development, and affects birth rates and the survival of newborn. It has serious repercussions on agriculture, commerce, and industry. Wherever it exists, human progress is retarded or inhibited. The development of many potentially fertile areas of the world is barred by its presence. Other areas, in which human activities have encouraged the breeding of the mosquito vectors of malaria, have been developed and later abandoned. The disease was, and has been from time immemorial, one of the major health problems of mankind. But little could be done except to suppress the symptoms of the disease through use of quinine. Economic toll

Malaria is an expensive visitor in any country. In 1909 it was estimated that malaria was costing the United States $100 million a year. By 1938 these annual costs had risen to $500 million.

In an epidemic of malaria in southern Egypt in 1942 to 1943, one plantation alone suffered a monetary loss equivalent to $600,000. A petroleum company in Venezuela estimated that malaria cost the company $494,500 over a 6-year period due to personnel illness. attributed to the disease.

Even with the eradication of malaria from the United States in 1945-48, it still levies an enormous hidden tax on the people because imports such as basic minerals, hardwoods, coffee, cocoa, vegetable oils, waxes, and certain fruits which come from the malarious Tropics are priced at least 5 percent higher than they would need be if it were not for the cost of malaria.

In India the estimated 25 percent decrease in the working capacity of labor in the malarious areas produces an estimated annual loss of about $450 million to the economy of that country.

1. THE TWO TECHNICAL ADVANCES

Two technological breakthroughs completely altered the world outlook. DDT was developed, and this opened the possibility of stopping malaria by massive killing off of the mosquitos which spread the disease. Second, drugs which kill in the victims' body the parasite responsible for the disease were developed. The disease could be cured, rather than its effects suppressed.

The two technical advances presented a series of strategic questions to WHO. Were the technical advances such as to warrant an effort to rid the world of malaria? Was malaria a disease of such significance that it would rank high on a priority list of threats to the health of the world? Should reliance be placed on curing individuals through mass treatment campaigns, or on breaking the chain of infection by killing off the anopheline mosquitos which carry the disease?

2. EARLY STRATEGIC DECISIONS

There was no doubt as to the seriousness of the disease, but the approach to be used presented difficult problems.

Controlled experiments in the use of two new antimalarial drugs, chloroquine (aralen) and proguanil (paludrine) were proposed, but WHO placed its faith in the use of DDT against adult mosquitoes as the main instrument for malaria control. The decision was made not only on grounds of efficiency, but also for economic reasons. Malaria, poverty, low population density, and lack of development are inseparable in the rural tropics. The administration of antimalarial drugs, at least weekly, would demand organization that does not exist and could not be set up in most of the affected areas. Prevention of mosquito breeding by attacking the larval forms in water becomes more expensive per person the lower the human population density. In contrast, the use of DDT as a house spray, once or twice a year, demands a comparatively small, mobile organization. Its cost, which depends on the number of houses to be sprayed, remains about the same per head whatever the population density, except in rare circumstances.

Other chemicals, notably benzene hexachloride (BHC) and dieldrin, have been developed, supplementing, not replacing, DDT. Difficulties, foreseen and unforeseen, have had to be overcome, but WHO's original policy of relying on residual insecticides for world malaria control has never been superseded.

3. OPERATIONAL PROCEDURES

With some of the basic questions settled, difficult operational problems had to be solved. In 1947 and 1948, these principles were as follows:

(1) Demonstration teams were to visit any malarious country requesting assistance. The basic composition of a team was a malariologist and an entomologist, with the addition of a sanitarian or a sanitary engineer.

(2) With a view to creating local malaria organizations, the expert committee recommended that governments should appoint nationals to understudy each member of the international

team.

(3) At the same time, it was recommended that WHO should provide expert lecturers for existing schools of malariology, assist in setting up courses in malariology in regions not yet provided with such facilities, provide fellowships for individual training abroad, and circulate literature both on technical subjects and on the health education of the public. Here, in concrete terms, is an example of the way in which extension of disease control programs depend on the training of people.

The program expanded satisfactorily. Seven teams were operating by the end of 1949, all in Asia-four in different provinces of India, one in Afghanistan, one in Pakistan, and one in Thailand. Preparations for an eighth, in Iran, were underway. Expansion of activities continued smoothly in 1950, by the end of which year nine demonstation teams were at work. Those previously established had expanded their areas of operation, and in India and Pakistan during 1950 the number of persons protected from malaria was increased fourfold. In the demonstration areas of Thailand and Pakistan, and in at least one area of India, there was evidence that the transmission of malaria had actually been interrupted.

4. A REVOLUTIONARY DEVELOPMENT

At about this time, two events occurred which completely changed the world strategy for dealing with malaria.

The first development, a favorable one, related to the technique of DDT spraying. Greece, which had converted its malaria-control program (begun with assistance from the Rockefeller Foundation) into a nationwide DDT spraying campaign since 1946, found difficulty in procuring the DDT necessary to maintain coverage over the whole area. It was decided, instead of reducing the dosage in all areas, to continue spraying in some areas, but to discontinue it altogether in others.

The results proved that discontinuance of spraying in such circumstances did not result in a recrudescence of malaria, although some cases did occur. The local malaria service established a special organization of "epidemiological surveillance." This picked up cases easily enough, evidently before they infected enough mosquitos for the disease to become widespread again.

This accidental discovery had tremendous implications. It now seemed feasible to eradicate malaria by programs limited in time. This in turn meant that countries which could not afford a continuing program could consider an all-out effort for a limited period.

5. MEANING OF MALARIA ERADICATION

Here the meaning of "malaria eradication" and other terms must be spelled out to permit an understanding of later WHO programs. Malaria eradication means the ending of the transmission of malaria and the elimination of the reservoir of infective cases in a campaign limited in time. This must be distinguished clearly from two other concepts.

« PreviousContinue »