Major increase in human monkeypox incidence 30 years after smallpox vaccination campaigns cease in the Democratic Republic of Congo.
Studies on the burden of human monkeypox in the Democratic Republic of the Congo (DRC) were last conducted from 1981 to 1986. Since then, the population that is immunologically naïve to orthopoxviruses has increased significantly due to cessation of mass smallpox vaccination campaigns. To assess the current risk of infection, we analyzed human monkeypox incidence trends in a monkeypox-enzootic region. Active, population-based surveillance was conducted in nine health zones in central DRC. Epidemiologic data and biological samples were obtained from suspected cases. Cumulative incidence (per 10,000 population) and major determinants of infection were compared with data from active surveillance in similar regions from 1981 to 1986. Between November 2005 and November 2007, 760 laboratory-confirmed human monkeypox cases were identified in participating health zones. The average annual cumulative incidence across zones was 5.53 per 10,000 (2.18-14.42). Factors associated with increased risk of infection included: living in forested areas, male gender, age < 15, and no prior smallpox vaccination. Vaccinated persons had a 5.2-fold lower risk of monkeypox than unvaccinated persons (0.78 vs. 4.05 per 10,000). Comparison of active surveillance data in the same health zone from the 1980s (0.72 per 10,000) and 2006-07 (14.42 per 10,000) suggests a 20-fold increase in human monkeypox incidence. Thirty years after mass smallpox vaccination campaigns ceased, human monkeypox incidence has dramatically increased in rural DRC. Improved surveillance and epidemiological analysis is needed to better assess the public health burden and develop strategies for reducing the risk of wider spread of infection.
Rimoin
Anne W
AW
University of California, Los Angeles School of Public Health, Los Angeles, CA 90095, USA. arimoin@ucla.edu
Mulembakani
Prime M
PM
Johnston
Sara C
SC
Lloyd Smith
James O
JO
Kisalu
Neville K
NK
Kinkela
Timothee L
TL
Blumberg
Seth
S
Thomassen
Henri A
HA
Pike
Brian L
BL
Fair
Joseph N
JN
Wolfe
Nathan D
ND
Shongo
Robert L
RL
Graham
Barney S
BS
Formenty
Pierre
P
Okitolonda
Emile
E
Hensley
Lisa E
LE
Meyer
Hermann
H
Wright
Linda L
LL
Muyembe
Jean-Jacques
JJ
D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D002648:Child; D002675:Child, Preschool; D002980:Climate; D015023:Democratic Republic of the Congo / Q000453:epidemiology; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D045908:Mpox, Monkeypox / Q000453:epidemiology* / Q000276:immunology; D012423:Rural Health / Q000706:statistics & numerical data; D012899:Smallpox / Q000276:immunology / Q000517:prevention & control*; D012900:Smallpox Vaccine / Q000276:immunology*; D013997:Time Factors; D055815:Young Adult
D012900:Smallpox Vaccine
Trop Geogr Med. 1987 Jan;39(1):56-63
3037740
J Trop Med Hyg. 1987 Feb;90(1):31-8
3029395
IARC Sci Publ. 1987;(82):1-406
3329634
Vaccine. 2007 Feb 9;25(8):1513-25
17126963
Emerg Infect Dis. 2001 May-Jun;7(3):434-8
11384521
Bull World Health Organ. 1972;46(5):633-9
4340223
Virology. 2005 Sep 15;340(1):46-63
16023693
Lancet. 1986 Jan 11;1(8472):98-9
2867342
N Engl J Med. 2006 Aug 31;355(9):962-3
16943415
Vaccine. 2006 Nov 17;24(47-48):7009-22
17052815
N Engl J Med. 2004 Jan 22;350(4):342-50
14736926
Emerg Infect Dis. 2005 Apr;11(4):539-45
15829191
Nat Med. 2005 Sep;11(9):1005-11
16086024
Am J Trop Med Hyg. 2005 Aug;73(2):428-34
16103616
Bull World Health Organ. 1988;66(6):747-52
2853010
Trop Geogr Med. 1988 Apr;40(2):73-83
2841783
Trop Geogr Med. 1987 Apr;39(2):115-22
2820094
Int J Epidemiol. 1988 Sep;17(3):643-50
2850277
Bull World Health Organ. 1985;63(6):1055-68
3879673
Bull World Health Organ. 1984;62(5):703-13
6096036
J Clin Microbiol. 2004 May;42(5):1940-6
15131152
Am J Epidemiol. 1987 Dec;126(6):1082-92
2825518
Bull World Health Organ. 1968;39(2):277-83
5303409
Arch Pediatr Adolesc Med. 2005 Nov;159(11):1022-5
16275790
Lab Invest. 2004 Sep;84(9):1200-8
15208646
Bull World Health Organ. 1980;58(2):165-82
6249508
J Clin Microbiol. 2004 Feb;42(2):601-9
14766823