Ten people worldwide. That is how many were infected with guinea worm in 2025, a parasite that has ruined lives in tropical regions for millennia. What makes this number historic: humanity has driven this disease to the edge of extinction without a vaccine and without medication, through behavioral change alone.
What is guinea worm?
Dracunculus medinensis, Latin for the "little dragon of Medina," is a parasitic roundworm that can grow up to a meter long inside the human body. Larvae live in water fleas in stagnant water. Humans become infected by drinking contaminated water. After an incubation period of about a year in the body, the female worm bores through tissue and often emerges through the foot or lower leg. This process is painful and lasts for weeks. The only treatment: to wind the worm out a few centimeters each day onto a stick. If it breaks, sepsis and permanent damage to joints and tendons threaten. No cure exists.
The disease primarily affects smallholder farmers and herders in the middle of harvest season. Those infected often cannot work for weeks. Evidence of infection appears in Egyptian papyri and the Old Testament.
From 3.5 million to ten: The starting point in 1986
When the Carter Center took over coordination of the global eradication program in 1986, an estimated 3.5 million people per year suffered from guinea worm disease in 21 countries across Africa and Asia. Key partners included the World Health Organization (WHO), the US Centers for Disease Control (CDC), UNICEF, and the Gates Foundation. The situation was difficult: there was no vaccine, no effective drug, and the disease affected regions with minimal health infrastructure.
The program therefore concentrated on three measures. First, water filtration: simple cloth filters or tube filters trap water fleas. The Carter Center has distributed millions of such filters, many in straw-like format. Second, case reporting: trained community volunteers report new infections immediately, ensuring infected individuals stay away from water sources. Third, treating water sources with the pesticide temephos, which kills water fleas without making water unsafe for humans. According to the Carter Center, this program has prevented over 100 million infections.
2025: Three countries, ten cases, 33 percent fewer than the year before
In 2025, the ten reported cases occurred in three countries: four in Chad, four in Ethiopia, and two in South Sudan. This represents a 33 percent decline compared to 2024 (15 cases). Angola, Cameroon, the Central African Republic, and Mali reported zero human cases for the second consecutive year. The WHO has already certified 200 countries as guinea worm-free. Six countries remain uncertified.
In comparison: Only smallpox has ever been eradicated
The only disease ever erased from the textbook of human history is smallpox. In 1980, the WHO declared it eradicated, three years after the last documented natural case in October 1977 in Somalia. Smallpox had one decisive advantage: since 1796, a vaccine has existed. The WHO's mass vaccination campaign was the central tool of eradication.
Polio is the next eradication target for the global community. Since 1988, the WHO has reduced case numbers by more than 99.9 percent, from about 350,000 to roughly 95 cases in 2024, all in Pakistan and Afghanistan. Here too, a vaccine is the primary instrument. Guinea worm would be the first parasitic disease and the first disease without a pharmaceutical tool to vanish. This comparison point is significant: behavioral change alone has never eradicated an epidemic in the history of medicine.
What slows the final step: Dogs in Chad
The largest remaining problem is biological. In Chad, far more animals than humans are infected with Dracunculus parasites: in 2025, 147 infected dogs, cats, and otters were registered there, 445 in Cameroon, and 70 in Angola. Animals contract the parasites by eating infected fish or water insects and excrete larvae, contaminating water sources. The classical eradication model, which relies on human behavioral change, does not work for animal reservoirs. The Carter Center has expanded the program to animals, attempting to keep dogs away from stagnant water. An effective treatment for animal infection does not yet exist.
Three years without transmission: The roadmap to 2027
For official WHO eradication certification, a country must demonstrate three consecutive years without confirmed transmission, followed by comprehensive epidemiological verification. The Carter Center expects that certification could be achieved as early as 2027, more realistically 2028 or 2029. In the optimistic scenario, case numbers would fall to zero in 2026 and remain there through 2029. The animal reservoir in Chad makes this scenario uncertain: as long as dogs contaminate water sources, relapses are possible. The three open risks are animal reservoirs, inadequate surveillance in conflict zones, and political instability in the remaining endemic countries.