Influenza virus infections among outpatients seeking health care at selected hospitals in Morogoro, Mbeya and Zanzibar, Tanzania

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Sokoine University of Agriculture


Respiratory infections cause significant morbidity and mortality worldwide and are the second leading causes of death in Tanzania. Several studies involving national sentinel surveillance for influenza and epidemiology of influenza have been conducted in Tanzania. However, there is dearth in the information on the aetiology of respiratory diseases. This study screened for influenza viruses in subject with influenza-like illnesses in selected areas of Tanzania. A total of 735 subjects were recruited at hospitals in Morogoro, Mbeya and Zanzibar and the collected sample were screened for influenza viruses using reverse transcription polymerase chain reaction (RT-PCR). Out of the tested samples, 13% (93/735) were positive for influenza virus. Influenza A accounted for 56% (52/93) of the detected viruses. Majority of positive cases (19/93; 20%) were from individuals <9 years and 20 to 35 years old categories. There was a significant difference in the proportion of influenza positive sample by month (χ2=67.9 p<0.05). Two peaks of infection were observed from March to May and from November to January. Four representative influenza isolates were sequenced and genetically characterized. The BLAST search showed that A/Tanzania/BMH1674/2019 isolate from Zanzibar had 99.86% nucleotide identity with Texas/109/2019 strain from Texas in United States. All of the three influenza B viruses from Zanzibar and Morogoro were 100% identical and belong to the influenza B victoria lineage. This study have revealed that influenza A virus was the most prevalent in 2019 and most of the isolates in our study are not independent evolution variants, as they shared high nucleotide similarity with characterized reference strains from the neighbouring countries and other part of the world.


Masters Thesis


Influenza, Virus, Infections, Health care, Morogoro