Abstract
BackgroundSindbis virus (SINV) is a mosquito-borne alphavirus that is widely distributed worldwide. Little is known about the febrile and neurological disease burden due to SINV in South Africa.Patients and MethodsClinical samples of patients with acute febrile disease of unknown cause (AFDUC) were collected through the African Network for Improved Diagnostics, Epidemiology and Management of Common Infectious Agents at three sentinel hospital surveillance sites in South Africa. In total, 639 patients were screened using a PCR-based macroarray that can simultaneously detect nucleic acids of 30 pathogens, including SINV, from January 2019 to December 2020. Serum samples were randomly selected from the arbovirus season (January–June) and also screened with a commercial indirect immunofluorescence assay for anti-SINV IgM. In addition, 31 paired cerebrospinal fluid (CSF) specimens from the same patients were screened for IgM. Micro-neutralization assays were performed on all IgM-positive samples.ResultsNone of the specimens tested positive for SINV by molecular screening; however, 38/197 (19.0%) samples were positive for SINV-specific IgM. A total of 25/38 (65.8%) IgM-positive samples tested positive for SINV-neutralizing antibodies, giving an overall incidence of 12.7%. Furthermore, 2/31 (6.5%) CSF specimens tested positive for IgM but were negative for neutralizing antibodies. There was a higher incidence of SINV-positive cases in Mpumalanga (26.0%) than Gauteng province (15.0%). The most significant months for IgM-positive cases were April 2019 (OR = 2.9, p < 0.05), and May 2020 (OR = 7.7, p < 0.05).ConclusionSINV or a closely related virus contributed to 12.7% of AFDUC cases in hospitalized patients during the late summer and autumn months in South Africa and was significantly associated with arthralgia, meningitis, and headaches.
Highlights
Sindbis virus (SINV) is an arthropod-borne virus within the Alphavirus genus in the family Togaviridae (Strauss and Strauss, 1994)
This study aimed to investigate if SINV contributed to acute febrile disease of unknown cause (AFDUC) with or without neurological signs in hospitalized patients of all age groups in the Highveld (Gauteng province) and the Lowveld (Mpumalanga province) of South Africa (SA) as well as the risk factors associated with SINV infections
For IgM antibody testing, a total of 197/378 (52.0%) specimens submitted from January to June in 2019 and 2020 were randomly selected and tested
Summary
Sindbis virus (SINV) is an arthropod-borne virus (arbovirus) within the Alphavirus genus in the family Togaviridae (Strauss and Strauss, 1994). Its transmission cycle is primarily enzootic circulating between birds and mosquitoes (Ling et al, 2019). Spillover from mosquitoes or birds into humans results in sporadic infections (Ling et al, 2019). SINV is considered an Old World alphavirus, and these are primarily arthritogenic (Adouchief et al, 2016). New World alphaviruses, such as Venezuelan, Eastern, and Western equine encephalitis virus, are considered more neuro-invasive (Go et al, 2014) for humans and horses neurological SINV and Middelburg virus (MIDV) infections have been reported in horses in South Africa (SA) (van Niekerk et al, 2015). Sindbis virus (SINV) is a mosquito-borne alphavirus that is widely distributed worldwide. Little is known about the febrile and neurological disease burden due to SINV in South Africa
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