Epidemiology/Transmissibility:

• 1^st identified in monkeys in 1958
• 1^st human case reported in 1970
• Endemic in areas of Africa
• Typically, only see sporadic cases outside of Africa in people who have traveled to certain regions or have been in close contact with those travelers
• From the 1970s up until 2003, sporadic cases were identified in central and western Africa
• Before 1980, case-fatality rate was 17% and secondary transmission was the cause in 9% of cases
• From 1981 to 1986, the case-fatality rate was 10% and secondary transmission was the cause in 28%
• From 1996 to 1997, the largest outbreak of human monkeypox occurred, which had a case-fatality rate of 1.5% and secondary transmission was the cause in 78%
• The 2003 outbreak, was the first documented cases in the western hemisphere with a case-fatality rate of 0% and secondary transmission was the cause in 0%
• Cases of Monkeypox in 2022 from May 6^th – 20^th [2]:
  • UK: 20 (Confirmed)
  • Spain: 23 (Unconfirmed)
  • Portugal 5 (Confirmed) + 15 (Unconfirmed)
  • US 1 (Confirmed)
• Precise prevalence and incidence are limited (But both have increased since the discontinuation of routine smallpox vaccination)
• Wide range of hosts which has allowed a reservoir in wild animals and some sporadic cases in humans
• In contrast to smallpox, monkeypox associated with low transmissibility between human beings
• Mode of transmission remains poorly characterized:
  • Large respiratory droplets most likely mode of transmission
  • Direct contact through bodily fluids also possible
  • The likelihood of transmission between individuals without prolonged close contact is considered to be low

Hosts/Reservoirs:

• Primary reservoir is thought to be squirrels, non-human primates, prairie dogs, rabbits, and rats
• Primary reservoir for human infection remains unknown

Who to Suspect:

• Travelers to known endemic areas
• Anyone in contact with a traveler to a known area

Clinical Features:

• Clinically monkeypox is almost indistinguishable from smallpox, chickenpox, and other causes of vesiculopustular rashes
• Typical incubation period 10 – 14 days (up to 21 days)
• Infectious period occurs during the 1^st week of the rash
• 2-day prodrome manifested by fever, malaise, and lymphadenopathy typically occurs before development of rash
• Lymphadenopathy is key distinguishing characteristic of human monkeypox compared to smallpox
  • 90% of patients infected with monkeypox develop lymphadenopathy (Typically in submandibular, cervical, postauricular, axillary, or inguinal areas)
• Rash begins as maculopapular lesions of 2 to 5mm in diameter
  • Typically, centrifugal pattern (from the torso outwards)
  • Can be monomorphic (like smallpox) or pleiomorphic (like chickenpox)
• Skin lesions typically progress from popular, to vesicular, to pustular, and crust phases over a 14-to-21-day period
• In patients with smallpox vaccination the rash will be milder and only ≈50% will have lymphadenopathy
• Most patients will not become seriously ill
• In the 2003, US outbreak (81 confirmed cases) there were zero deaths [1]
• Mortality seems to be higher in children, young adults, and immunocompromised individuals
  • Generally, cases are mild, and people tend to recover within weeks