title: Rubella in Sub-Saharan Africa and sensorineural hearing loss: a case control study.
abstract: Rubella infection can affect several organs and cause birth defects that are responsible for congenital rubella syndrome (CRS). Congenital hearing loss is the most common symptom of this syndrome, occurring in approximately 60% of CRS cases. Worldwide, over 100 000 babies are born with CRS every year. There is no specific treatment for rubella, but the disease is preventable by vaccination. Since 1969, the rubella vaccine has been implemented in many countries, but in Africa, only a few countries routinely immunize against rubella. The aim of this study was to estimate the rate of infection from the wild-type rubella virus in São Tomé and Príncipe by determining rubella seroprevalence with a DBS method. The goal of this study was to reinforce the need for implementation of the rubella vaccine in this country. As secondary objectives, the validation of a DBS method was first attempted and an association between seroprevalence and hearing loss was assessed.
  
  
  
  We collected samples from individuals observed during humanitarian missions in São Tomé and Príncipe. All individuals underwent an audiometric evaluation, and a drop of blood was collected for the dried blood spot (DBS). We define two groups: the case group (individuals with unilateral or bilateral hearing loss (HL)) and the control group (individuals with two normal ears). Patients were excluded if they suffered from conductive HL, if they showed evidence of possible causes of HL, if they had developmental delay or if they refused to participate in the study.
  
  
  
  Among the 315 subjects, we found 64.1% individuals with IgG for the rubella virus, 32.1% without immunity for the rubella virus and 3.8% who were borderline. In the control group, 62.6% were positive for the rubella IgG, whereas in the case group, 72% were positive. Analyzing both groups, with ages ranging from 2 to 14 years of age and from 15 to 35 years of age, we found a seroprevalence of 50.3% to rubella in the younger group and 82.1% in the older group, with a significant difference between cases and control group noted within the younger patients (p = 0.025).
  
  
  
  Rubella is a disease that can be prevented. Rubella infections are still very common in São Tomé and Príncipe, and women of child-bearing age are still at risk for rubella infection during pregnancy, justifying the urgency of vaccination against rubella. A statistically significant association between the group of children under 14 years of age with HL and immunity for rubella was observed in this country, although this study did not allow us to establish a cause-effect relationship between rubella infection and SNHL.
authors.affiliation: Otolaryngology Department, NOVA Medical School/Faculty of Medical Sciences, Universidade Nova de Lisboa, Campo dos Mártires da Pátria, 130, 1169-056, Lisboa, Portugal. cristinacaroca@netcabo.pt.|Hospital CUF Infante Santo, Avenida Infante Santo, 34, 6°, 1350-079, Lisboa, Portugal. cristinacaroca@netcabo.pt.|Centre for Toxicogenomics and Human Health (ToxOmics), NOVA Medical School / Faculty of Medical Sciences, Universidade Nova de Lisboa, Campo dos Mártires da Pátria, 130, 1169-056, Lisboa, Portugal. cristinacaroca@netcabo.pt.
authors.forename: Cristina
authors.identifier: 0000-0001-8096-8895
authors.initials: C
authors.lastname: Caroça
authors.affiliation: CEDOC, NOVA Medical School/ Faculty of Medical Sciences, Universidade Nova de Lisboa, Lisboa, Portugal.
authors.forename: Vera
authors.initials: V
authors.lastname: Vicente
authors.affiliation: Hospital CUF Infante Santo, Avenida Infante Santo, 34, 6°, 1350-079, Lisboa, Portugal.
authors.forename: Paula
authors.initials: P
authors.lastname: Campelo
authors.affiliation: CEDOC, NOVA Medical School/ Faculty of Medical Sciences, Universidade Nova de Lisboa, Lisboa, Portugal.
authors.forename: Maria
authors.initials: M
authors.lastname: Chasqueira
authors.affiliation: Escola Superior de Tecnologia da Saúde de Lisboa, Avenida D. João II, Lote 4.69.01, 1990-096, Lisboa, Portugal.|BioISI-Biosystems and Integrative Sciences Institute, Faculty of Science of the University of Lisbon, Lisbon, Portugal.|ESS/IPS, School of Health, Polytechnic Institute of Setúbal, Setúbal, Portugal.
authors.forename: Helena
authors.initials: H
authors.lastname: Caria
authors.affiliation: Otolaryngology Department, NOVA Medical School/Faculty of Medical Sciences, Universidade Nova de Lisboa, Campo dos Mártires da Pátria, 130, 1169-056, Lisboa, Portugal.|Centre for Toxicogenomics and Human Health (ToxOmics), NOVA Medical School / Faculty of Medical Sciences, Universidade Nova de Lisboa, Campo dos Mártires da Pátria, 130, 1169-056, Lisboa, Portugal.
authors.forename: Susana
authors.initials: S
authors.lastname: Silva
authors.affiliation: CEDOC, NOVA Medical School/ Faculty of Medical Sciences, Universidade Nova de Lisboa, Lisboa, Portugal.|Clinical Pathology Laboratory-Labco, Hospital da Luz, Avenida Lusíada, 100, 1500-650, Lisboa, Portugal.
authors.forename: Paulo
authors.initials: P
authors.lastname: Paixão
authors.affiliation: Otolaryngology Department, NOVA Medical School/Faculty of Medical Sciences, Universidade Nova de Lisboa, Campo dos Mártires da Pátria, 130, 1169-056, Lisboa, Portugal.|Hospital CUF Infante Santo, Avenida Infante Santo, 34, 6°, 1350-079, Lisboa, Portugal.
authors.forename: João
authors.initials: J
authors.lastname: Paço
mesh_terms: D000293:Adolescent; D000328:Adult; D017954:Africa South of the Sahara / Q000453:epidemiology; D016022:Case-Control Studies; D002648:Child; D002662:Child Health Services; D002675:Child, Preschool; D005260:Female; D006319:Hearing Loss, Sensorineural / Q000453:epidemiology* / Q000517:prevention & control; D006801:Humans; D008297:Male; D008493:Medical Missions; D012409:Rubella / Q000097:blood / Q000453:epidemiology* / Q000517:prevention & control; D012411:Rubella Vaccine / Q000008:administration & dosage; D016036:Seroepidemiologic Studies; D014611:Vaccination; D055815:Young Adult
chemical_list: D012411:Rubella Vaccine
keywords: Congenital Rubella Syndrome; Hearing loss; Rubella; Sub-Saharan Africa; World Health Organization