The control of infectious diseases and the possibility of their complete disappearance is a contemporary conception. It was gestating from the end of the 19th century to better understand its causes and transmission mechanisms and with the development of preventive means such as vaccines.
Massive vaccination campaigns raised great hopes and the concept of “preventable diseases” emerged. The gradual development of effective antimicrobial treatments, such as sulfa drugs and antibiotics, strengthened faith in medicine. The possibility of defeating infectious diseases as the main cause of mortality seemed achievable. The leading role would go to chronic and degenerative diseases.
It was in this context that the hope for eradication emerged : the total suppression of a disease on a global scale. The infectious agent would only continue to exist confined in laboratories under the supervision of international health authorities.
From a historical perspective, attempts to eradicate diseases have generally been unsuccessful (hookworm, yellow fever, malaria). Only smallpox has been officially eradicated (1980).
The program for the eradication of smallpox began in 1966. The choice of this disease, in a context in which its incidence was already decreasing, was due to a series of circumstances. The virus only has humans as a reservoir. There are no asymptomatic carriers. There are also no chronic cases.
Political circumstances were also favorable. The United States and the Soviet Union collaborated in the middle of the Cold War. The Soviet ability to produce vaccines on a large scale was coupled with the well-crafted organizational schemes of the Americans. In addition, the World Health Organization (WHO) was used extensively. Their prestige was at stake after failing to eradicate malaria.
The triumph over smallpox has been criticized, as the eradication program reinforced a type of vertical and reductionist type of technical approach. By focusing on a single disease, no attention was paid to other conditions. Neither were social contexts taken into account.
In reality, the success of smallpox eradication was achieved outside of the overall strategy proposed by WHO: primary health care. With a transversal and holistic orientation, it was considered the most appropriate way of organizing health services.
Limitations in the smallpox eradication strategy indicated the need for some changes. It is necessary to combine massive vaccination campaigns against various diseases. Stable surveillance systems should also be strengthened to allow case detection and investigation, as well as immediate action in the event of new disease outbreaks.
On this basis, WHO set itself new challenges. The most important has been the eradication of poliomyelitis, which began many years after having an effective vaccine. The strategy, launched in 1988, has been successful in some regions, such as the Americas (1994), the Western Pacific (2000) and Europe (2002).
A very recent fundamental novelty in this long eradication process has been the declaration of the African Region as a wild polio-free zone on August 25, 2020, once the requirements have been met, especially due to the absence of polio cases in Nigeria. , the last country to report cases, in the last three years.
However, it has not achieved its overall objective, given the difficulties in developing vaccination campaigns in war contexts that create problems of access to certain areas. Afghanistan and Pakistan continue to suffer endemic cases, and the WHO considers that the risk of outbreaks at the international level is still high.
Eradicable or re-emerging?
Optimism around the elimination of infectious diseases waned after the successful eradication of smallpox. In the 1980s, people began to speak of “emerging infectious diseases” (new, such as AIDS) and “re-emerging” (which increase their incidence, such as tuberculosis and syphilis). The great importance of malaria, which kills almost 275,000 children under 5 years of age annually, is another sign of the failure of eradication strategies.
The current theoretical and epidemiological schemes were insufficient and new approaches have been necessary. In this framework, the concept of “pathocenosis” is useful: diseases, far from acting in isolation, configure a reality of exchanges and mutual determination.
Thus, the eradication of one or more diseases supposes the rupture of the ecological balance with other germs present in a certain population. This facilitates the emergence of new diseases due to pathogens that until then were of little importance.
Other factors have facilitated the development of infectious diseases. Among them are antibiotic resistance, irreversible damage to the environment, zoonoses, globalization of health, socio-economic inequalities and cultural issues. The diseases caused by viruses that have emerged at the beginning of the 21st century and COVID-19 are good testimony to this.
Isolated scientific and technical actions have not been effective. Only a holistic and coordinated approach can tackle health problems that 50 years ago seemed to be disappearing. In this context, there has been talk of the “return of epidemics”. It will be necessary to put in place some programmatic principles that go beyond the approach that the eradication strategies assumed. Imprisoned by technoscience and the commercialization of health, without attention to context, they have been unsuccessful.
Enrique Perdiguero-Gil, Professor of History of Science, Miguel Hernández University and Rosa Ballester Añón, Emeritus Professor of History of Science, Miguel Hernández University
This article was originally published on The Conversation. Read the original.
