Secondary, or human-to-human, transmission is relatively limited. Infection can result from close contact with respiratory secretions, skin lesions of an infected person or recently contaminated objects. Transmission via droplet respiratory particles usually requires prolonged face-to-face contact, which puts health workers and household members of active cases at greater risk. The longest documented chain of transmission in a community was six successive person-to-person infections. Transmission can also occur via the placenta from mother to fetus (congenital monkeypox).

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