Tropical Health Matters

Almost 40 years ago efforts got underway to eradicate another human infectious disease from the face of the earth. Smallpox eradication. Defined as the total elimination of the disease from every country, had been successful, facilitated by the basic technology of an effective vaccine. There were difficult times with the organization and management aspects of smallpox eradication, but the organizers of the campaign were able and willing to adapt their strategies as they learned more about the epidemiological, social, and cultural aspects of the disease.

Praise has been given to guinea worm efforts because of the start contrast between 3.5 million cases in the mid-1980s to only 13 so far verified in 2024. Interestingly, progress has been inching, as one author put it, toward zero for at least 10 years, long after the earlier target date of 1995. Clearly a disease that was theoretically “simple” to eliminate through the provision of clear, safe water supplies, was not so simple after all.

Despite his recent health and family challenges President Jimmy Carter has never waivered from his support to eradicate guinea worm as reported by CNN.  The Carter Center’s 2023 report showed a remarkable reduction in Guinea worm cases, bringing the ancient parasitic disease closer to being eradicated.  Alix Boisson-Walsh provides details in a Lancet Infectious article entitled “Diseases Guinea worm disease inched closer to eradication in 2023.”  The Carter Center shared these highlights for 2023:

• Eradication of Guinea worm disease remains in sight with only 13 provisional human cases reported worldwide in 2023.
• The Carter Center announced Thursday. The number matches the lowest annual total of human cases ever reported, following 13 cases in 2022 and 15 in 2021.
• When The Carter Center assumed leadership of the global Guinea Worm Eradication Program in 1986, an estimated 3.5 million human cases occurred annually in 21 countries in Africa and Asia.

• The grisly parasitic disease has been reduced by 99.99% since eradication efforts began and is poised to become the second human disease and the first parasitic disease eradicated in history.
• Reports of animal infections slightly increased due to expanded surveillance in Angola and Cameroon.

• All figures for humans and animals are provisional until officially confirmed, typically in March. Guinea worm is poised to become the second human disease in history to be eradicated, following smallpox, as well as the first parasitic disease and the first without a medicine or vaccine. Community-based and innovative behavioral change and local mobilization are the key drivers of success.

Building on seven World Health Assembly resolutions and hosted by The Carter Center, Reaching the Last Mile, the UAE, and the WHO, representatives of impacted countries (Angola, Chad, Ethiopia, Mali, South Sudan, Sudan, Democratic Republic of the Congo, and Cameroon) and organizations renewed their commitment to eradicating the debilitating disease by 2030 by signing the Abu Dhabi Declaration on the Eradication of Guinea Worm Disease, in 2022 and pledged to commit resources, energy, and policy initiatives to eradicate Guinea worm disease.

Four decades of disease eradication work may seem like a long time, but like smallpox, guinea worm has been around for millennia. CDC notes that, “In 1959, the World Health Organization (WHO) started a plan to rid the world of smallpox,” and “the 33^rd World Health Assembly declared the world free of this disease on May 8, 1980.”

Malaria eradication efforts started, stalled and resumed beginning with the National Malaria Eradication Program in the USA on July 1, 1947. Subsequently, “the World Health Organization (WHO) submitted at the World Health Assembly in 1955 an ambitious proposal for the eradication of malaria worldwide.” We are still aiming for 2030 and beyond to rid the world of malaria country-by-country.

In 1998 Walter R. Dowdle outlined three indicators that were considered to be of primary importance in eradicating a disease. These included “an effective intervention is available to interrupt transmission of the agent, practical diagnostic tools with sufficient sensitivity and specificity are available to detect levels of infection that can lead to transmission, and humans are essential for the life-cycle of the agent, which has no other vertebrate reservoir and does not amplify in the environment.” In 2000, Aylward and colleagues also posed three criteria including “(1) biological and technical feasibility, (2) costs and benefits, and (3) societal and political considerations.”  Andrews and Langmuir post the awkward reality that “If … the decline in new cases is halted by circumstances which slow it down to a fluctuating equilibrium at some point approaching but not quite reaching zero, the disease may be declared administratively to be under control, though it is certainly not eliminated.”

The persistence of low-level human transmission of guinea worm may appear encouraging when compared to he initial estimate of 3.5 million infections, but we hope that the political and social commitment will persist so that the dwindling cases will eventually reach zero. Additional effort is needed now that one of Dowdle’s criteria has been breached, another vertebrate reservoir (domestic dogs, cats and others who share unsafe water sources with humans). The costs and benefits can be questioned as eradication is drawn out over time. Guinea worm has always epitomized the concept of NTDs wherein not just the disease but the people who suffer from it are neglected. Eradication will only come when that neglect stops.

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