title: Epidemiology of rubella virus cases in the pre-vaccination era of Ethiopia, 2009-2015.
abstract: Rubella is a common mild rash illness caused by rubella virus. The majority of infections occur in children and young adults. The infection is the cause of a serious birth defect known as Congenital Rubella Syndrome (CRS) when a woman acquires infection early in pregnancy. Ethiopia has not yet established rubella virus surveillance and has not yet introduced rubella vaccine into the routine immunization program. We characterize the epidemiology of laboratory confirmed rubella virus cases collected through measles surveillance from 2009 to 2015 to better understand the burden of the disease in the country.
  
  
  
  A descriptive analysis was made to characterize rubella cases reported through the national measles case based surveillance system. The measles case definition was used to capture potential rubella cases. A suspected measles case was a person with generalized rash and fever with cough, or coryza or conjunctivitis. Those cases whose sera were negative for measles IgM antibodies were tested for rubella IgM antibody. A confirmed rubella case was a person who tested positive for rubella IgM. Only laboratory confirmed rubella cases were analyzed in this article.
  
  
  
  Between 2009 and 2015, a total of 28,284 serum/plasma samples were collected and tested for measles IgM antibody and 11,151 (39.4%) were found positive. A total of 17,066 measles IgM negative or indeterminate samples were tested for rubella virus IgM and 2615 (15.3%) were found positive during the same period. Of 2615 confirmed rubella cases, 52.2% were females. The age of confirmed cases ranged from one month to 42 years with a mean age of 7.3 years. Three-fourth of all confirmed rubella cases were aged less than 10 years. The number of laboratory confirmed rubella cases linearly increased from 83 in 2009 to 856 in 2013 but dropped to 222 and 319 in 2014 and 2015 respectively. Higher number of cases occurred in the hot dry season (January through June) and in the central and western part of Ethiopia with 127 lab-confirmed outbreaks in the study period.
  
  
  
  Based on our analysis, rubella was found to be endemic throughout Ethiopia. Children below the age of 10 years were the most affected. The burden of rubella cases varied from year to year but had a seasonal peak in March. To better understand the magnitude of rubella prior to vaccine introduction, establishing rubella surveillance system, conducting sero-prevalence studies among child bearing age females and establishing CRS sentinel surveillance among young infants are critical.
authors.affiliation: Ethiopian Public Health Institute, Arbegnoch Street, P. O. Box 1242, Addis Ababa, Ethiopia. mekonengetahun@gmail.com.
authors.forename: Mekonen
authors.initials: M
authors.lastname: Getahun
authors.affiliation: Ethiopian Public Health Institute, Arbegnoch Street, P. O. Box 1242, Addis Ababa, Ethiopia.
authors.forename: Berhane
authors.initials: B
authors.lastname: Beyene
authors.affiliation: WHO Country Office, Addis Ababa, Ethiopia.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Gallagher
authors.affiliation: WHO Country Office, Addis Ababa, Ethiopia.
authors.forename: Ayesheshem
authors.initials: A
authors.lastname: Ademe
authors.affiliation: Ethiopian Public Health Institute, Arbegnoch Street, P. O. Box 1242, Addis Ababa, Ethiopia.
authors.forename: Birke
authors.initials: B
authors.lastname: Teshome
authors.affiliation: Ethiopian Public Health Institute, Arbegnoch Street, P. O. Box 1242, Addis Ababa, Ethiopia.
authors.forename: Mesfin
authors.initials: M
authors.lastname: Tefera
authors.affiliation: Ethiopian Public Health Institute, Arbegnoch Street, P. O. Box 1242, Addis Ababa, Ethiopia.
authors.forename: Anjelo
authors.initials: A
authors.lastname: Asha
authors.affiliation: Ethiopian Public Health Institute, Arbegnoch Street, P. O. Box 1242, Addis Ababa, Ethiopia.
authors.forename: Aklog
authors.initials: A
authors.lastname: Afework
authors.affiliation: Ethiopian Public Health Institute, Arbegnoch Street, P. O. Box 1242, Addis Ababa, Ethiopia.
authors.forename: Esete
authors.initials: E
authors.lastname: Assefa
authors.affiliation: Ethiopian Public Health Institute, Arbegnoch Street, P. O. Box 1242, Addis Ababa, Ethiopia.
authors.forename: Yoseph
authors.initials: Y
authors.lastname: HaileMariam
authors.affiliation: WHO Country Office, Addis Ababa, Ethiopia.
authors.forename: Yonas
authors.initials: Y
authors.lastname: HaileGiorgis
authors.affiliation: Ethiopian Public Health Institute, Arbegnoch Street, P. O. Box 1242, Addis Ababa, Ethiopia.
authors.forename: Hiwot
authors.initials: H
authors.lastname: Ketema
authors.affiliation: Ethiopian Public Health Institute, Arbegnoch Street, P. O. Box 1242, Addis Ababa, Ethiopia.
authors.forename: Dejenie
authors.initials: D
authors.lastname: Shiferaw
authors.affiliation: Ethiopian Public Health Institute, Arbegnoch Street, P. O. Box 1242, Addis Ababa, Ethiopia.
authors.forename: Ayenachew
authors.initials: A
authors.lastname: Bekele
authors.affiliation: Ethiopian Public Health Institute, Arbegnoch Street, P. O. Box 1242, Addis Ababa, Ethiopia.
authors.forename: Daddi
authors.initials: D
authors.lastname: Jima
authors.affiliation: Ethiopian Public Health Institute, Arbegnoch Street, P. O. Box 1242, Addis Ababa, Ethiopia.
authors.forename: Amha
authors.initials: A
authors.lastname: Kebede
mesh_terms: D000293:Adolescent; D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D002648:Child; D002675:Child, Preschool; D017281:Cost of Illness; D004196:Disease Outbreaks; D005002:Ethiopia / Q000453:epidemiology; D005260:Female; D006801:Humans; D017589:Immunization Programs / Q000639:trends; D007223:Infant; D008297:Male; D008457:Measles / Q000097:blood / Q000453:epidemiology / Q000821:virology; D008875:Middle Aged; D011247:Pregnancy; D015995:Prevalence; D012409:Rubella / Q000097:blood / Q000453:epidemiology* / Q000821:virology; D012411:Rubella Vaccine; D012412:Rubella virus; D012621:Seasons; D018571:Sentinel Surveillance; D014611:Vaccination / Q000639:trends; D055815:Young Adult
chemical_list: D000914:Antibodies, Viral; D012411:Rubella Vaccine; C040901:rubella antibodies
keywords: 2009–2015; Ethiopia; Pre-vaccine era; Rubella