RESUMO
BACKGROUND: Minimal influenza surveillance has been carried out in sub-Saharan Africa to provide information on circulating influenza subtypes for the purpose of vaccine production and monitoring trends in virus spread and mutations. OBJECTIVE: The aim of this study was to investigate a surveillance program in Kenya to isolate and characterize influenza viruses. RESULTS: In the 2006-2007 influenza season, nine influenza A viruses were isolated. All were of H3N2 subtype with key amino acid (aa) changes indicating that they were more closely related to recent World Health Organization recommended vaccine strains than to older vaccine strains, and mirroring the evolution of circulating influenza A globally. Hemagglutination inhibition data showed that the 2006 Kenya isolates had titers identical to the 2005-2006 H3N2 vaccine strain but two- to threefold lower titers to the 2006-2007 vaccine strain, suggesting that the isolates were antigenic variants of the 2006-2007 vaccine strains. Analysis of aa substitutions of hemagglutinin-1 (HA1) protein of the 2006 Kenyan viruses revealed unique genetic variations with several aa substitutions located at immunodominant epitopes of the HA1 protein. These mutations included the V112I change at site E, the K 173 E substitution at site D and N 278 K change at site C, mutations that may result in conformational change on the HA molecule to expose novel epitopes thus abrogating binding of pre-existing antibodies at these sites. CONCLUSION: Characterization of these important genetic variations in influenza A viruses isolated from Kenya highlights the importance of continuing surveillance and characterization of emerging influenza drift variants in sub-Saharan Africa.
Assuntos
Vírus da Influenza A Subtipo H3N2/genética , Vírus da Influenza A Subtipo H3N2/isolamento & purificação , Influenza Humana/virologia , Adolescente , Adulto , Sequência de Aminoácidos , Anticorpos Antivirais/sangue , Criança , Pré-Escolar , Análise por Conglomerados , Feminino , Testes de Inibição da Hemaglutinação , Glicoproteínas de Hemaglutininação de Vírus da Influenza/genética , Humanos , Lactente , Vírus da Influenza A Subtipo H3N2/imunologia , Quênia , Masculino , Dados de Sequência Molecular , Filogenia , RNA Viral/genética , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Adulto JovemRESUMO
A descriptive epidemiologic study using pretested questionnaires was conducted in East Africa in 1989/90 and looked at various types of pesticides in current usage in the region especially with regard to their procurement, distribution and utilization. Hospital records were examined for reported cases of pesticide poisoning as well as assessing the knowledge and the awareness of health care providers on the recognition and potential of pesticide poisoning. The main pesticide importers in the region were the Ministries of Agriculture whereas distribution was dominated by co-operative unions. Although pesticide regulatory mechanisms existed, their weak structures enabled the importation and usage of pesticides no longer in use in the countries of origin. Incidents of abuse were noted, as in the use of organochlorine pesticides on food crops and reported poisoning cases in the district hospitals where Kenya and Tanzania reported 455 and 736 cases respectively. Though tentative, more than 40 % of the health care professionals interviewed could not recognise pesticide poisoning cases. Therefore to avert pesticide related morbidity and mortality in the region, pesticide regulatory bodies need strengthening while pesticide users, the general public and health care workers should be educated on pesticides.