Monkeypox in Non-Human Primates

In nonhuman primates, the disease ranges from mild to fatal. Old and New World primates, as well as apes are susceptible, with most severe disease seen in cynomolgus macaques, orangutans and infants of all species. In mild cases, 1-4 mm cutaneous papules progress to pustules, crust over, and ultimately drop off, leaving small scars. The histology is similar to that seen in humans, with epidermal hyperplasia and central necrosis (typical "pock" formation), with ballooning degeneration of keratinocytes and large eosinophilic intracytoplasmic inclusions. In more severe disease, facial edema, oral ulcers, lymphadenopathy, and rarely disseminated disease with visceral lesions may be seen.

A related orthopoxvirus, tanapox, causes "benign epidermal monkeypox (BEMP)". Although the cutaneous lesions are similar, this disease does not result in systemic illness and does not infect New World monkeys. Lesions are generally seen on the face, digits, and perineum.

Related poxviruses include Yabapox, an arthropod-borne disease most commonly seen in macaques, and molluscum contagiosum. All four viruses are transmissible from animals to man.