EPIDEMIOLOGY, DIAGNOSIS AND CONTROL OF VECTOR-BORNE AND ZOONOTIC VIRUSES IN ANIMALS AND HUMANS IN SOUTHERN AFRICA
The zoonosis research group in the Department of Medical Virology, Faculty of Health Sciences is in the unique position to conduct research on both human and animal zoonotic diseases. This enables the group to study a wide range of pathogens such as the vector-borne flaviviruses (e.g West Nile virus), alphaviruses (e.g Middelburg and Sindbis), and bunyaviruses (e.g Shuni, Rift Valley fever and Crimean Congo hemorrhagic fever) as well as viruses transmitted directly from animals to humans including Avian Influenza and certain hanta and arenaviruses. The group has a broad focus on disease surveillance; epidemiology, molecular biology; immunology and ecology of these viruses; development of novel diagnostics and vaccines; viral pathogenesis and discovery. A new state of the art BSL-3 lab was acquired specifically to expand this programme as part of the IRT and allow pathogenesis and ecology studies of known and emerging zoonotic viruses under BSL-3+ conditions. The group has strong links with the National Institute of Communicable Diseases (NICD) and several overseas collaborators including the Global disease detection Programme of the Centre for Disease Control and Prevention.
An important research focus area is on the surveillance of unexplained fevers, neurological, hemorrhagic syndromes and respiratory illness in animals such as horses, livestock, wildlife as well as in humans to identify zoonotic vector-borne, neuroinvasive as well as respiratory and hemorrhagic fevers viruses as causative agents. The ZRU has described West Nile virus as a cause of neurological disease in humans and animals in South Africa and provided the first description of the bunyavirus, Shuni and alphavirus Middelburg virus as a cause of up to 6-10% of neurological diseases in horses and as a pathogens of several wildlife species including rhinoceros, buffalo, warthogs and crocodiles. Pathogenesis, ecology and molecular characterisation studies of these viruses are underway. West Nile virus (WNV) and other arbovruses are being investigated for their role in unexplained aseptic meningitis in hospitalized patients in South Africa. Results suggest that the role of these viruses as the cause of neurological disease in South Africa may have been underestimated and so far several WNV cases have been identified in patients with neurological syndroms. Veterinarians and other humans with frequent exposure to livestock may also have an increased risk of infection with these viruses. Through the group’s association with the NICD, the risk of the ostrich Avian influenza outbreak to humans in frequent contact with these animals is also being investigated. The application of virus discovery tools at the human: animal interphase feed into the “One Health” approach of identification of emerging viruses. Sero-surveys in humans and animals have been undertaken for WNV and Avian Influenza already and will be used to identify occupational exposure and host range of newly described viruses and determine the importance of uncharacterized vector-borne zoonotic diseases in Southern Africa.
Several projects on the development of specialized molecular and serological diagnostic tools are underway as a key to pathogen discovery, epidemiological investigations and disease control. A 30 plex micro array for differential diagnosis of viral meningitis, aimed at identifying zoonotic causes of meningitis in South Africa, was developed and has been implemented for use in humans. This tool is currently used to define the causes of aseptic meningitis in a prospective hospital based study in humans. The group has also developed realtime PCR assays to detect flavi, orthobunya and alphaviruses and has thereby significantly strengthened their ability to detect zoonotic viruses that cause fatal infections in livestock and wildlife in South Africa. There diagnostic expertise is not limited to South Africa and the group has also shown that Crimean Congo Haemorrhagic Fever Virus show a 14% sero-prevalence in the pastoralists in a District of Kenya. Such epidemiological studies and the development of diagnostic tools and vaccines will facilitate the study and control of these previously neglected diseases.
Molecular epidemiology; genomic characterisation, pathogenesis and ecological investigations are underway to describe these viruses in more detail. Vaccinology related research has included evaluating cross lineage protection of a West Nile virus lineage 1 Pfizer vaccine for use against lineage 2 in horses in South Africa. Collaboration projects on locally development of subunit vaccines have been undertaken for WNV and are planned for other zoonotic viruses shown to be of significance in this programme.