Coxsackievirus A24: A Causative Agent of Acute Haemorrhagic Conjunctivitis Outbreak in Dar es Salaam, Tanzania, between January and February 2024

BackgroundOn 15 January 2024, the Ministry of Health (MOH) reported a notable outbreak of acute viral conjunctivitis in the city of Dar es Salaam. In this study we investigated the causative agent of acute conjunctivitis outbreak which occurred in Dar es Salaam between Jan 2024 and Feb 2024. MethodologyWe conveniently collected a pair of eye swab samples from twenty-five patients presenting with symptoms of acute conjunctivitis at clinics in Dar es Salaam during the outbreak. One for bacterial culture and another for molecular detection. MacConkey and Blood agar were used to culture patient samples to identify possible bacterial causes. A Multiplex Real-time RT-PCR targeting Adenovirus, Metapneumovirus, Human Enterovirus and Parainfluenza. Positive samples with Ct value less than 30 for enterovirus were subjected to genomic sequencing by Illumina Miseq after library preparation and enrichment by Illuminas Respiratory Pathogen ID/AMR enrichment panel kit as per manufacturers instructions (RPIP kit), followed by bioinformatics and phylogenetic analysis. ResultsOut of 25 samples, nine samples were positive for human enterovirus by Real-time PCR. Of the nine positive samples four were sequenced and Coxsackievirus A24 variant, was identified as the most probable cause of the outbreak. Phylogenetic analysis showed that samples collected during the outbreak (28AO and 26HB) belong to a clade with Coxsackievirus A24 sequences from France Mayotte from a 2024 outbreak, also close to sequences from neighbouring East African countries (Uganda, Kenya) as well as South American countries (Brazil, Mexico, and French Guiana). ConclusionThis study demonstrated the utility of genomic epidemiology in identifying Coxsackievirus A24 as the pathogen responsible for the outbreak and its circulation within the East African region.