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Uganda: Child with encephalitis diagnosed with novel orthobunyavirus - Ntwetwe virus

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  • Uganda: Child with encephalitis diagnosed with novel orthobunyavirus - Ntwetwe virus

    Published Date: 2018-06-11 07:55:13
    Subject: PRO/AH/EDR> Ntwetwe virus - Uganda: (QZ) 2016
    Archive Number: 20180611.5849758
    NTWETWE VIRUS - UGANDA: (KYANKWANZI) 2016
    *****************************************
    A ProMED-mail post
    http://www.promedmail.org
    ProMED-mail is a program of the
    International Society for Infectious Diseases
    http://www.isid.org

    Date: Sat 9 Jun 2018
    Source: Clinical Infectious Diseases journal [edited]



    ref: Edridge AWD, Deijs M, Namazzi R, et al. Novel orthobunyavirus identified in the cerebrospinal fluid of a Ugandan child with severe encephalopathy. Clin Infect Dis. 2018; ciy486
    ----------------------------------------------------------------------
    Abstract
    --------
    A Ugandan child with unexplained encephalitis was investigated using viral metagenomics. Several sequences from all segments of a novel orthobunyavirus were found. The S-segment, used for typing, showed 41 percent amino acid diversity to its closest relative. The virus was named Ntwetwe virus, after the hometown of the patient.

    [Introduction]
    --------------
    In 2016, a Ugandan girl presented to the hospital with a suspected CNS infection for which no pathogen could be identified using conventional diagnostics. Viral metagenomic sequencing was performed to find the causative agent and a novel orthobunyavirus was identified. Orthobunyaviruses are negative-sense RNA viruses consisting of 3 segments: Large (L), Medium (M), and Small (S). They are commonly found in Uganda, often zoonotic and vector-borne, and known to cause human CNS infections.

    Discussion
    ----------
    Ntwetwe virus is an orthobunyavirus identified in the CSF of a Ugandan child with a suspected CNS infection for which, despite extensive conventional investigations, no known pathogen could be identified. Partial sequence information from all (S, M, and L) Ntwetwe virus segments was obtained and showed considerable genetic distance to currently known viruses. According to the ICTV, distinct orthobunyavirus species show more than 10 percent amino acid distance of the nucleocapsid protein. The Ntwetwe virus nucleocapsid protein, coded for by the S-segment, showed 41 percent protein distance to its closes relative, Tataguine virus.

    Thus far, the patient described here is the only patient identified with a Ntwetwe virus infection. The prevalence of Ntwetwe virus infection, therefore, currently remains unknown. Phylogenetically, Ntwetwe virus clusters with the Anopheles-Tataguine clade of which all viruses are transmitted by _Anopheles_ mosquitoes, making Ntwetwe virus a likely arbovirus. _Anopheles_ mosquitoes are highly prevalent in Uganda and may thus increase the likelihood of human infections. Additionally, many orthobunyaviruses have non-human mammalian reservoirs. Consequently, because of the potential human exposure and severe disease of the patient, we believe there is an urgent need to investigate the prevalence of Ntwetwe virus infection.

    --
    Communicated by:
    Greg Folkers


    [A serological survey of individuals living in Uganda may provide some clues about the prevalence of Ntwetwe virus in different parts of the country. That might help to focus on the areas where mosquitoes might be caught and tested for the virus. Studies in wild mammals and birds could follow. In a list abstracted from Gideon (Global Infectious Disease & Epidemiology Network) and the Gideon e-book series on arboviruses in Senegal, West Africa, antibody to Tataguine virus, the closest relative to Ntwetwe virus is found in 57 percent of the population (see ProMED-mail archive Undiagnosed illness - Senegal (02): comment 20150907.3628503). Clearly, additional studies are needed in order to assess the public health importance of this virus in Uganda. - Mod.TY
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