Monkeypox

Monkeypox resembles smallpox or chickenpox, but lymphadenopathy is more prominent. Humans develop disease after contact with infected animals or humans. Serial transmission in humans does not usually go beyond secondary cases. Case fatality rate was 1-14% in children not vaccinated against smallpox.

CASES/YEAR
1 (US); 300 (Global)
CATEGORY
AGENT TYPE
Viruses
OTHER NAMES
Monkey pox virus; Monkeypoxvirus;
ACUITY
Acute-Moderate
INCUBATION
About 12 days; [Harrison ID, 762]
INITIAL SYMPTOMS
Rash, fever, and lymphadenopathy;
PRECAUTIONS
Airborne until monkeypox confirmed and smallpox excluded; Contact until lesions crusted; "See www.cdc.gov/ncidod/monkeypox for most current recommendations. Transmission in hospital settings unlikely. Pre- and post-exposure smallpox vaccine recommended for exposed HCWs." [CDC 2007 Guideline for Isolation Precautions]
COMMENTS
In April, May, and June of 2003, 87 cases of monkeypox were reported in the states of Illinois, Indiana, Kansas, Missouri, Ohio, and Wisconsin. Mildly ill in most cases, the majority of patients had direct contact with infected prairie dogs. The prairie dogs were purchased at the same wholesale pet store that had housed sick exotic African rodents. Common symptoms included rash, fever, and cough. The animal investigation traced the infection back to Gambian giant rats imported from Ghana where monkeypox is endemic. [MMWR. 7/11/03] Small, sporadic outbreaks of monkeypox have been reported in villages in the rainforests of Central and West Africa. Humans, squirrels, and primates appear to be reservoirs. Humans develop disease after contact with infected animals or humans. Serial transmission in humans occurs, but does not usually go beyond secondary cases. The secondary attack rate is about 8%. The illness resembles smallpox or chickenpox, but lymphadenopathy is more prominent. Case fatality rate was estimated at 1-14% in children not vaccinated against smallpox. [CCDM, p. 565-6] Unlike smallpox, monkeypox causes lymphadenopathy (submandibular or cervical and less often axillary or inguinal) in up to 83% of unvaccinated patients. Pneumonia is a complication. [Guerrant, p. 371] Encephalitis is rare. [PPID, p. 1235t] Some patients have "upper respiratory tract lymphadenitis with dysphagia and airway compromise." [PPID, p. 1815] The rash evolves synchronously and involves the palms and soles. [Guerrant, p. 371]
DIAGNOSTIC
See http://www.cdc.gov/ncidod/monkeypox/diagspecimens.htm. Skin biopsy; Paired sera; Serum IgM; [PPID, p. 1235
SCOPE
West and Central Africa; [CCDM]
SIGNS & SYMPTOMS
  • >fatigue, weakness
  • >fever
  • >myalgia
  • E dysphagia
  • E pharyngitis
  • G diarrhea
  • G nausea, vomiting
  • H lymphadenopathy
  • N confusion, delirium
  • N headache
  • N lethargy
  • R cough
  • S papules or plaques
  • S pustule
  • S rash (exanthem)
  • S rash on palms
  • S skin blister or vesicles
  • *encephalitis
  • *pneumonia
ANTIMICROBIC

No

VACCINE

Yes

ENTRY
Inhalation, Animal Bite
SOURCE
Person-to-Person
RESERVOIR
Monkeys, Rodents, Human, Wild Animals
RISK FACTORS
  • Care for patients (droplet/airborne)
  • Handle infected rodents (bite)
  • Handle infected rodents (not bite)
  • Travel to endemic area
TREATMENT
No antimicrobial therapy;
DRUG LINK
REFERENCES FOR CASES/YEAR
1. (US) 87 cases in US in 2003; Guesstimate: 1 case/year;
2. (Global) Occurs in remote villages of Central & West Africa; [Fact sheets from WHO 2013] Since 1970 cases have been reported in DRC, Liberia, Ivory Coast, Sierra Leone, Nigeria, Benin, Cameroon, Gabon, Central African Republic, and South Sudan; 338 cases reported in Zaire from 1981-1986; 250 serosubstantiated cases found in DRC from February 1996 to October 1997; [PPID, p. 1814] Guesstimate: 300 cases/year;