Smallpox and its eradication in the Democratic Republic of Congo: lessons learned.

Smallpox eradication is considered to be one of the most remarkable accomplishments of the 20th century. Lessons learned from the campaign during the 1960s and 1970s in the Democratic Republic of Congo (DRC) can provide important information for the development of other eradication programs including polio. The DRC is the third largest country in Africa; the population suffers from extreme poverty, deteriorating infrastructure and health systems, and long periods of civil strife. Despite these challenges, DRC's smallpox eradication campaign was successful, eradicating smallpox only 41 months after initiation. DRC had been polio free since 2001; however, in 2006, imported cases were identified in the country. Polio transmission has since been re-established and DRC now has the second greatest number of reported polio cases in the world. Challenges which existed during the smallpox campaign in DRC are still present today; additionally, the polio vaccine itself poses unique challenges which include requiring multiple doses to confer immunity. In the fight against polio in DRC, it will be important to draw from the smallpox eradication experience. A number of important themes emerged during the campaign that could be beneficial to eradicating polio and future eradication programs that may follow. During the smallpox campaign, a standard vaccination program was implemented, surveillance was intensified, and there were strong collaborative programs with community involvement. These successful elements of the smallpox campaign should be adapted and applied in DRC in polio eradication programs.

Clinco-epidemiological features of monkeypox patients with an animal or human source of infection

Clinical and laboratory examinations were carried out on a total of 388 monkeypox patients in Zaire from 1981 to 1986. An animal sources of infections was suspected in 245 (72 percent) and interhuman transmission for the remaining 93 patients. Among those whose infection was presumably acquired from an animal source, the most affected groups were children aged 3-4 years (27 percent) and 5-6 years (20 percent), while only 4 percent of cases were over 15 years old; there was a considerable preponderance of males (58 percent) over females (42 percent), especially in the age group 5-14 years. Among those presumably infected by person-to-person transmission, the age distribution was more uniform, adult patients tending to be relatively more common, and there were more females (57 percent) than males (43 percent). Based on comparisons of the frequency and intensity of clinical signs and symptoms among patients infected from an animal source and those who were infected by another patient, there was no evidence that the disease becomes more severe and the transmitted virus more virulent or more easily transmissible from person to person after one or more passages through human hosts

Human monkeypox: Secondary attack rates

Data on human monkeypox collected in Zaire during the six years 1981-86 were analysed to assess the extent of interhuman transmission of monkeypox virus. Among the 2278 persons who had close contact with 245 monkeypox patients infected from an animal sources, 93 fell ill and were presumed to have been infected from the known human sources: 69 of these were spread in the first generation, 19 in the second, and the remaining five cases in the third and fourth generation. The secondary attack rates were correlated with the age, sex, place of residence, and vaccination status of the contacts. There was an overall 3 percent probability of becoming ill following infection from a know human source. The affected household was the main focal point for interhuman transmission of monkeypox virus. The highest attack rate (11.7 percent) occurred among unvaccinated household contacts in the age group 0-4 years. However, the majority of susceptible persons who had been close to patients in the confined space of poorly ventilated huts failed to develop illness. There was no evidence of an increase in the secondary attack rate between 70-80 and 81-86. The inefficient spread from person to person, even in conditions of maximum exposure, supports the concept that monkeypox virus is poorly adapted for sustained transmission between humans and that such transmission does not pose a significant health problem

Smallpox and its eradication / F. Fenner ... [et al.]

The definitive history of the worlds most triumphant achievement in medicine and public health. In 31 chapters, this monumental work recounts the history of one of humanity's worst diseases, moving from ancient times, through the discovery of vaccination, to the spectacular WHO-led campaign that finally vanquished the disease. Authored by experts personally involved in the eradication campaign, the book gives posterity a minutely detailed account of both how the disease once reigned and what was necessary, step by step and country by country, to eliminate the ancient scourge once and for all. Virtually everything ever known about the disease, and everything that happened during the global eradication campaign, has been collected and preserved in this richly illustrated account. For scientists and clinicians, Smallpox and its Eradication will serve as a complete and final review of knowledge on the clinical features, virology, pathology, immunology, and epidemiology of variola major and minor. For students of public health and medical history, the book offers access to a wealth of previously unpublished data and personal experiences that make up the saga of a public health event unprecedented in scope and unparalleled in the magnitude of its achievement. For posterity, Smallpox and its Eradication will serve, above all, as an inspiring reminder of the knowledge and efforts that transformed smallpox from a universally dreaded disease to one the world could safely forget

Tasks in the wake of smallpox eradication

The last case of endemic smallpox occurred a decade ago but not everybody was convinced that eradication had been achieved. It was essential to investigate rigorously all reported instances of suspected smallpox and to make known the findings so that public confidence would be built up. Laboratory stocks of various virus have been reduced and the destruction of the final ones is now in prospect. Vaccination against the disease is virtually a thing of a past; in 1986 the World Health Organization's Committee on Orthopoxvirus Infections suggested that it should be terminated even for military personnel. Vigilance continues in respect of animal poxviruses that might conceivably become important in humans