title: Evaluation of human-to-human transmission of monkeypox from infected patients to health care workers.
abstract: BACKGROUND
  In 2003, human monkeypox was first identified in the United States. The outbreak was associated with exposure to infected prairie dogs, but the potential for person-to-person transmission was a concern. This study examines health care worker (HCW) exposure to 3 patients with confirmed monkeypox.
  
  
  METHODS
  Exposed HCWs, defined as HCWs who entered a 2-m radius surrounding case patients with confirmed monkeypox, were identified by infection-control practitioners. A self-administered questionnaire and analysis of paired serum specimens determined exposure status, immune response, and postexposure signs and symptoms of monkeypox.
  
  
  RESULTS
  Of 81 exposed HCWs, 57 (70%) participated in the study. Among 57 participants, 40 (70%) had > or =1 unprotected exposure; none reported signs or symptoms consistent with monkeypox illness. One exposed HCW (2%), who had been vaccinated for smallpox within the past year, had serological evidence of recent orthopoxvirus infection; acute- and convalescent-phase serum specimens tested positive for anti-orthopoxvirus IgM. No exposed HCWs had signs and symptoms consistent with monkeypox.
  
  
  CONCLUSIONS
  More than three-quarters of exposed HCWs reported at least 1 unprotected encounter with a patient who had monkeypox. One asymptomatic HCW showed laboratory evidence of recent orthopoxvirus infection, which was possibly attributable to either recent infection or smallpox vaccination. Transmission of monkeypox likely is a rare event in the health care setting.
authors.affiliation: Bioterrorism Preparedness and Response Program, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA. Alf6@cdc.gov
authors.forename: Aaron T
authors.initials: AT
authors.lastname: Fleischauer
authors.forename: James C
authors.initials: JC
authors.lastname: Kile
authors.forename: Molly
authors.initials: M
authors.lastname: Davidson
authors.forename: Marc
authors.initials: M
authors.lastname: Fischer
authors.forename: Kevin L
authors.initials: KL
authors.lastname: Karem
authors.forename: Robert
authors.initials: R
authors.lastname: Teclaw
authors.forename: Hans
authors.initials: H
authors.lastname: Messersmith
authors.forename: Pamela
authors.initials: P
authors.lastname: Pontones
authors.forename: Bradley A
authors.initials: BA
authors.lastname: Beard
authors.forename: Zachary H
authors.initials: ZH
authors.lastname: Braden
authors.forename: Joanne
authors.initials: J
authors.lastname: Cono
authors.forename: James J
authors.initials: JJ
authors.lastname: Sejvar
authors.forename: Ali S
authors.initials: AS
authors.lastname: Khan
authors.forename: Inger
authors.initials: I
authors.lastname: Damon
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Kuehnert
mesh_terms: D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D002648:Child; D004196:Disease Outbreaks; D005260:Female; D006282:Health Personnel; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D017758:Infectious Disease Transmission, Patient-to-Professional / Q000706:statistics & numerical data*; D008297:Male; D008875:Middle Aged; D045908:Mpox, Monkeypox / Q000635:transmission*; D012900:Smallpox Vaccine; D011795:Surveys and Questionnaires
chemical_list: D000914:Antibodies, Viral; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D012900:Smallpox Vaccine