The Top 5 Deadliest Diseases with 100% Fatality Rates: From Laughing Sickness to Fatal Insomnia

4. Kuru (The Laughing Sickness)

• What It Is: Kuru is a rare and fatal brain disease caused by prion infection, historically linked to ritualistic cannibalism. The disease was prevalent among the Fore people of Papua New Guinea in the mid-20th century.
• Fatality Rate: 100%.
• Key Symptoms: Early signs include tremors, poor coordination, and mood changes. Later symptoms involve severe speech difficulties, the inability to eat or stand, and bursts of uncontrollable laughter, which earned it the nickname “laughing sickness.”
• How It Works: Kuru spread through the consumption of infected human brains during funerary rituals. Prions from infected tissue triggered the disease.
• Duration: Victims typically died within 6–12 months of symptom onset.
• Rarity: With the cessation of cannibalistic practices, kuru has virtually disappeared. No cases have been reported outside New Guinea.
• Why It’s Deadly: Like other prion diseases, kuru has no cure. Its unique transmission method has rendered it nearly extinct.