RESUMO
The prevalence and distribution of African alphaviruses such as chikungunya have increased in recent years. Therefore, a better understanding of the local distribution of alphaviruses in vectors across the African continent is important. Here, entomological surveillance was performed from 2014 to 2018 at selected sites in north-eastern parts of South Africa where alphaviruses have been identified during outbreaks in humans and animals in the past. Mosquitoes were collected using a net, CDC-light, and BG-traps. An alphavirus genus-specific nested RT-PCR was used for screening, and positive pools were confirmed by sequencing and phylogenetic analysis. We collected 64,603 mosquitoes from 11 genera, of which 39,035 females were tested. Overall, 1462 mosquito pools were tested, of which 21 were positive for alphaviruses. Sindbis (61.9%, N = 13) and Middelburg (28.6%, N = 6) viruses were the most prevalent. Ndumu virus was detected in two pools (9.5%, N = 2). No chikungunya positive pools were identified. Arboviral activity was concentrated in peri-urban, rural, and conservation areas. A range of Culicidae species, including Culex univittatus, Cx. pipiens s.l., Aedes durbanensis, and the Ae. dentatus group, were identified as potential vectors. These findings confirm the active circulation and distribution of alphaviruses in regions where human or animal infections were identified in South Africa.
Assuntos
Aedes , Alphavirus , Febre de Chikungunya , Animais , Feminino , Humanos , Alphavirus/genética , Filogenia , África do Sul/epidemiologia , Mosquitos VetoresRESUMO
Although Old World alphaviruses, Middelburg- (MIDV) and Sindbis virus (SINV), have previously been detected in horses and wildlife with neurologic disease in South Africa, the pathogenesis and clinical presentation of MIDV and SINV infections in animals are not well documented. Clinical samples from horses across South Africa with acute or fatal neurologic and febrile infections submitted between 2014-2018 were investigated. In total, 69/1084 (6.36%) and 11/1084 (1.01%) horses tested positive for MIDV and SINV, respectively, by real-time reverse transcription (RT) PCR. Main signs/outcomes for MIDV (n = 69): 73.91% neurological, 75.36% fever, 28.99% icterus and anorexia, respectively, 8.70% fatalities; SINV (n = 11): 54.54% neurological, 72.73% fever, 36.36% anorexia and 18.18% fatalities. MIDV cases peaked in the late summer/autumn across most South African provinces while SINV cases did not show a clear seasonality and were detected in fewer South African provinces. MIDV could still be detected in blood samples via RT-PCR for up to 71,417 and 21 days after onset of signs in 4 horses respectively, suggesting prolonged replication relative to SINV which could only be detected in the initial sample. Phylogenetic analyses based on partial sequences of the nsP4 (MIDV n = 59 and SINV n = 7) and E1 (MIDV n = 45) genes, as well as full genome sequences (MIDV n = 6), clustered the MIDV and SINV strains from the present study with previously detected strains. MIDV infection appears to be more prevalent in horses than SINV infection based on RT-PCR results, however, prevalence estimates might be different when also considering serological surveillance data.
Assuntos
Infecções por Alphavirus , Infecções por Alphavirus/diagnóstico , Infecções por Alphavirus/epidemiologia , Infecções por Alphavirus/veterinária , Animais , Anorexia , Genômica , Cavalos , Filogenia , Sindbis virus/genética , África do Sul/epidemiologiaRESUMO
BACKGROUND: The Old world Alphavirus, Middelburg virus (MIDV), is not well known and although a few cases associated with animal illness have previously been described from Southern Africa, there has been no investigation into the association of the virus with human illness. The current study aimed to investigate possible association of MIDV infection with febrile or neurological manifestations in hospitalized or symptomatic patients fromGauteng, South Africa. METHODS: This study is a descriptive retrospective and prospective laboratory based study. Archived cerebrospinal fluid (CSF) samples submitted to the National Health Laboratory Service (NHLS), Tshwane Academic division for viral investigation from public sector hospitals in Gauteng as well as EDTA (ethylenediaminetetraacetic acid) whole blood samples from ad hoc cases of veterinary students, presenting with neurological and febrile illness, were selected and screened for the presence of alphaviruses using real-time reverse transcription(rtRT) PCR.Virus isolations from rtRT-PCR positive samples were conducted in Vero cell culture and used to obtain full genome sequences. Basic descriptive statistical analysis was conducted using EpiInfo. RESULTS: MIDV was detected by rtRT-PCR in 3/187 retrospective CSF specimens obtained from the NHLS from hospitalised patients in the Tshwane region of Gauteng and 1/2 EDTA samples submitted in the same year (2017) from ad hoc query arbovirus cases from veterinary students from the Faculty of Veterinary Science University of Pretoria.Full genome sequences were obtained for virus isolates from two cases; one from an EDTA whole blood sample (ad hoc case) and another from a CSF sample (NHLS sample).Two of the four Middelburg virus positive cases,for which clinical information was available, had other comorbidities or infections at the time of infection. CONCLUSION: Detection of MIDV in CSF of patients with neurological manifestations suggests that the virus should be investigated as a human pathogen with the potential of causing or contributing to neurological signs in children and adults.
Assuntos
Infecções por Alphavirus/líquido cefalorraquidiano , Infecções por Alphavirus/virologia , Alphavirus/genética , Infecções do Sistema Nervoso Central/líquido cefalorraquidiano , Infecções do Sistema Nervoso Central/virologia , Genoma Viral , Adolescente , Adulto , Alphavirus/isolamento & purificação , Infecções por Alphavirus/sangue , Infecções por Alphavirus/epidemiologia , Infecções do Sistema Nervoso Central/sangue , Infecções do Sistema Nervoso Central/epidemiologia , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Masculino , Pessoa de Meia-Idade , Filogenia , África do Sul/epidemiologia , Adulto JovemRESUMO
Alphaviruses from Africa, such as Middelburg virus (MIDV), and Sindbis virus (SINV), were detected in horses with neurologic disease in South Africa, but their host ranges remain unknown. We investigated the contribution of alphaviruses to neurologic infections and death in wildlife and domestic animals in this country. During 2010-2018, a total of 608 clinical samples from wildlife and nonequine domestic animals that had febrile, neurologic signs or unexplained deaths were tested for alphaviruses. We identified 32 (5.5%) of 608 alphavirus infections (9 SINV and 23 MIDV), mostly in neurotissue of wildlife, domestic animals, and birds. Phylogenetic analysis of the RNA-dependent RNA polymerase gene confirmed either SINV or MIDV. This study implicates MIDV and SINV as potential causes of neurologic disease in wildlife and nonequine domestic species in Africa and suggests a wide host range and pathogenic potential.