Contribution to the study of epidemiological factors associated with sensorineural hearing loss in the population of São Tomé and Príncipe

Abstract

ABSTRACT: Otorhinolaryngology, like other medical and non-medical services, can contribute to its humanitarian support. At the end of 2010, the ORL department of CUF Infante Santo Hospital, led by Professor João Paço, was invited to participate in humanitarian missions in one of the Portuguese-speaking countries, former Portuguese colony - Democratic Republic of São Tomé and Príncipe. Without any knowledge of the main ENT pathologies we started this adventure. From research on sub-Saharan African countries, an increase in deafness was expected from chronic otological infections. The mission was organized to have audiological assessment, ENT assessment and surgical interventions. It was in February 2011 that we started the adventure through the hot lands of São Tomé and Príncipe. Deafness was one of the main problems found, but contrary to what we expected, deafness was mainly sensorineural, affecting a high percentage of children, some without language acquisition and with bilateral profound deafness. At the end of the first mission, the results led to the curiosity to understand the reason for the increased prevalence of sensorineural deafness, irreversible and with socio-cultural repercussions important for the development of a country. The absence of clinical records, laboratory exams, imagiologic or audiologic tests led us to a greater clinical challenge of etiological cause of hearing loss in this country. The present doctoral project was born at the end of the first mission. Admission to the doctoral course was accepted in July 2011, and a challenge to research began. The initial research project has undergone several modifications due to there are several diagnostic and economic constrictions. In June 2013, in the scope of the doctoral course, during genetics curricular unit, and due to difficulties in carrying out complementary examinations in the island, born the idea was born to study the association between neurossensorial hearing loss and some of some of the most frequent hemoglobinopathies of the region. These hemoglobinopathiesare known to give some protection for the development of one of the major scourges of the country – Malaria. For that, was carried-out the collection of blood samples on Dried Blood Spot or Guthrie paper from São Tomé and Príncipe for analysis in Portugal. Since São Tomé and Príncipe is an island that has been colonized for many years by Portuguese, we could hypothesize for the existence of an associated genetic factor, and for that reason the evaluation of the main mutations of our people should be investigated. Since São Tomé and Príncipe is an island that has been colonized for many years by Portuguese, we hypothesize the existence of the same genetic factors, and for that reason the evaluation of the main mutations from Portuguese population was investigated. In this country, they had a significant improvement in primary health care, since the implementation of humanitarian aid by the IMVF in cooperation with the Camões Institute. São Tomé and Príncipe have good vaccination coverage, but some vaccines that may have an impact on the appearance of deafness, such as rubella, were not implemented until this project. Rubella is a known etiologic factor for congenital deafness. In São Tomé and Príncipe it is not possible to determine the existence of the disease by laboratory tests, being a pathology often forgotten at diagnosis. For this reason, the research project also contemplated the serological study of rubella in order to confirm the existence of the disease in the community and demonstrate the need to implement adequate measures - vaccination. Knowing that there is not only an etiological factor for deafness, the birth of this project undoubtedly is stimulating for a clinician and a researcher. The curiosity that awakens and the attempt to stop this scourge that interferes so much with the development of a community, leads to the effort which is always rewarded. Analyzing the main effects of the risk factors evaluated, it was found that female gender is in high risk to have HL than male gender; rubella disease could lead to HL if it is during gestational period and represents a double risk to HL. In this sample, self-report of malaria infection augments the risk of HL, around three times more; sickle cell disease (HbSS) have almost two and half folder risk to develop HL and sickle cell trait is protecting to HL; regarding G6PD non-B variant in association with gender, even though it was not found to be statistically significant, male gender almost duplicated the risk to develop HL; the mutations in GJB2 and GJB6 of control group, unilateral and bilateral did not reveal significant difference. There was a wide variability in mutations found, which led to conclude that it is not possible to define a standard and can be justified by the existence of multiple people to colonize the island. Simultaneously with the etiological research project, there is a need to the diagnosis to minimize the effects of deafness. The acquisition of equipment for audiological evaluation (audiogram and auditory evoked potentials) and the acquisition and adaptation of hearing aids to children and young adults with work activity were born with the help of patronage, in order to reduce the effects of social isolation. This project gave rise to another humanitarian project - "Projecto sem Barreiras" of the Fundação Calouste Gulbenkian with the IMVF and Universidade Católica Portuguesa which included the national implementation of the Sign Language of São Tomé and Príncipe (LGSTP) and the Neonatal Auditory Screening of São Tomé and Príncipe (RANSTP), with the acquisition of acoustic oto-emission equipment. Undoubtedly a project that was born with Professor João Paço, cherished by all, with the ambition to contribute to the development of a country - Democratic Republic of São Tomé and Príncipe and scientific knowledge.