Evaluation of human-to-human transmission of monkeypox from infected patients to health care workers.
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.
Fleischauer
Aaron T
AT
Bioterrorism Preparedness and Response Program, National Center for Infectious Diseases, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA. Alf6@cdc.gov
Kile
James C
JC
Davidson
Molly
M
Fischer
Marc
M
Karem
Kevin L
KL
Teclaw
Robert
R
Messersmith
Hans
H
Pontones
Pamela
P
Beard
Bradley A
BA
Braden
Zachary H
ZH
Cono
Joanne
J
Sejvar
James J
JJ
Khan
Ali S
AS
Damon
Inger
I
Kuehnert
Matthew J
MJ
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
D000914:Antibodies, Viral; D007074:Immunoglobulin G; D007075:Immunoglobulin M; D012900:Smallpox Vaccine