title: Major increase in human monkeypox incidence 30 years after smallpox vaccination campaigns cease in the Democratic Republic of Congo.
abstract: 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.
authors.affiliation: University of California, Los Angeles School of Public Health, Los Angeles, CA 90095, USA. arimoin@ucla.edu
authors.forename: Anne W
authors.initials: AW
authors.lastname: Rimoin
authors.forename: Prime M
authors.initials: PM
authors.lastname: Mulembakani
authors.forename: Sara C
authors.initials: SC
authors.lastname: Johnston
authors.forename: James O
authors.initials: JO
authors.lastname: Lloyd Smith
authors.forename: Neville K
authors.initials: NK
authors.lastname: Kisalu
authors.forename: Timothee L
authors.initials: TL
authors.lastname: Kinkela
authors.forename: Seth
authors.initials: S
authors.lastname: Blumberg
authors.forename: Henri A
authors.initials: HA
authors.lastname: Thomassen
authors.forename: Brian L
authors.initials: BL
authors.lastname: Pike
authors.forename: Joseph N
authors.initials: JN
authors.lastname: Fair
authors.forename: Nathan D
authors.initials: ND
authors.lastname: Wolfe
authors.forename: Robert L
authors.initials: RL
authors.lastname: Shongo
authors.forename: Barney S
authors.initials: BS
authors.lastname: Graham
authors.forename: Pierre
authors.initials: P
authors.lastname: Formenty
authors.forename: Emile
authors.initials: E
authors.lastname: Okitolonda
authors.forename: Lisa E
authors.initials: LE
authors.lastname: Hensley
authors.forename: Hermann
authors.initials: H
authors.lastname: Meyer
authors.forename: Linda L
authors.initials: LL
authors.lastname: Wright
authors.forename: Jean-Jacques
authors.initials: JJ
authors.lastname: Muyembe
mesh_terms: 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
chemical_list: D012900:Smallpox Vaccine
references.citation: Trop Geogr Med. 1987 Jan;39(1):56-63
references.pmid: 3037740
references.citation: J Trop Med Hyg. 1987 Feb;90(1):31-8
references.pmid: 3029395
references.citation: IARC Sci Publ. 1987;(82):1-406
references.pmid: 3329634
references.citation: Vaccine. 2007 Feb 9;25(8):1513-25
references.pmid: 17126963
references.citation: Emerg Infect Dis. 2001 May-Jun;7(3):434-8
references.pmid: 11384521
references.citation: Bull World Health Organ. 1972;46(5):633-9
references.pmid: 4340223
references.citation: Virology. 2005 Sep 15;340(1):46-63
references.pmid: 16023693
references.citation: Lancet. 1986 Jan 11;1(8472):98-9
references.pmid: 2867342
references.citation: N Engl J Med. 2006 Aug 31;355(9):962-3
references.pmid: 16943415
references.citation: Vaccine. 2006 Nov 17;24(47-48):7009-22
references.pmid: 17052815
references.citation: N Engl J Med. 2004 Jan 22;350(4):342-50
references.pmid: 14736926
references.citation: Emerg Infect Dis. 2005 Apr;11(4):539-45
references.pmid: 15829191
references.citation: Nat Med. 2005 Sep;11(9):1005-11
references.pmid: 16086024
references.citation: Am J Trop Med Hyg. 2005 Aug;73(2):428-34
references.pmid: 16103616
references.citation: Bull World Health Organ. 1988;66(6):747-52
references.pmid: 2853010
references.citation: Trop Geogr Med. 1988 Apr;40(2):73-83
references.pmid: 2841783
references.citation: Trop Geogr Med. 1987 Apr;39(2):115-22
references.pmid: 2820094
references.citation: Int J Epidemiol. 1988 Sep;17(3):643-50
references.pmid: 2850277
references.citation: Bull World Health Organ. 1985;63(6):1055-68
references.pmid: 3879673
references.citation: Bull World Health Organ. 1984;62(5):703-13
references.pmid: 6096036
references.citation: J Clin Microbiol. 2004 May;42(5):1940-6
references.pmid: 15131152
references.citation: Am J Epidemiol. 1987 Dec;126(6):1082-92
references.pmid: 2825518
references.citation: Bull World Health Organ. 1968;39(2):277-83
references.pmid: 5303409
references.citation: Arch Pediatr Adolesc Med. 2005 Nov;159(11):1022-5
references.pmid: 16275790
references.citation: Lab Invest. 2004 Sep;84(9):1200-8
references.pmid: 15208646
references.citation: Bull World Health Organ. 1980;58(2):165-82
references.pmid: 6249508
references.citation: J Clin Microbiol. 2004 Feb;42(2):601-9
references.pmid: 14766823