What Insights Does the Surveillance of Viral Haemorrhagic Fevers in South Africa Offer?
Viral haemorrhagic fevers (VHFs) are a group of illnesses caused by RNA viruses that can lead to severe bleeding, organ failure, and even death. These viruses belong to different families and are associated with specific geographic regions, making them significant public health concerns, especially in Africa.
Some of the key RNA viruses causing VHFs in Africa include the Ebola virus (EBOV), Marburg virus (MARV), Crimean-Congo haemorrhagic fever virus (CCHFV), Lassa virus, Lujo virus, Rift Valley fever virus (RVFV), and yellow fever virus (YFV). Among these, CCHFV, RVFV, and MARV are considered endemic in South Africa.
One of the challenging aspects of VHFs is their zoonotic nature, meaning they can be transmitted from animals to humans. Bats, rodents, and primates are common reservoirs for these viruses, and transmission can occur directly from these animals or through arthropod vectors like ticks and mosquitoes. Human-to-human transmission is also possible, primarily through contact with infected bodily fluids, which is why healthcare settings can become hotspots for transmission if proper precautions are not taken.
The clinical presentation of VHFs can range from mild symptoms like fever, headaches, and malaise to severe manifestations such as haemorrhage, organ failure, and shock. The initial signs and symptoms are nonspecific, making early detection and management challenging. However, prompt recognition based on epidemiological factors and clinical suspicion is crucial for timely intervention.
In South Africa, the National Institute for Communicable Diseases (NICD) plays a vital role as the national reference laboratory for investigating VHFs, RVF, and YF in humans. Suspected cases of these diseases are immediately notified as category 1 notifiable medical conditions (NMCs), triggering swift laboratory investigations to confirm or rule out the diagnoses.
This report summarises surveillance for VHF, RVF and YF in humans in South Africa for the period 2019-2023.
Materials and Methods
The report is a retrospective record review using documents submitted to the Special Viral Pathogens Laboratory and the Arbovirus Reference Laboratory, Centre for Emerging Zoonotic and Parasitic Disease, NICD/NHLS, for suspected cases of VHF, RVF and YF. All requests for laboratory investigation for VHF, RVF and YF in humans in South Africa were referred to this laboratory during the reporting period.
Data extracted from the laboratories’ records were collected in a database prepared in Microsoft® Excel. Descriptive epidemiological analysis was performed for laboratory-confirmed cases considering age, reported sex, geographical distribution, source of exposure and outcome of disease. Geographic distribution of laboratory-confirmed CCHF cases was mapped using ArcGIS Pro 3.2
Results
A total of 232 cases (not the number of tests conducted) was investigated during the reporting period. The endemic diseases, CCHF and RVF, were most frequently investigated, i.e. 77 and 90 cases, respectively. A single case of Lassa fever (LF) was reported in 2022, and ten cases of CCHF were confirmed in South Africa during the reporting period. No cases of other VHF, RVF, YF or haemorrhagic fever associated with newly identified viruses were detected during the reporting period.
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