In May 2019, we investigated monkeypox in a traveler from Nigeria to Singapore. The public health response included rapid identification of contacts, use of quarantine, and postexposure smallpox vaccination. No secondary cases were identified. Countries should develop surveillance systems to detect emerging infectious diseases globally.
Keywords: Monkeypox; Nigeria; Singapore; communicable disease control; disease outbreaks; imported infectious diseases; monkeypox virus; orthopoxvirus; viruses; zoonoses.