Genomic surveillance is widening Africa’s viral map without settling the threat question
Africa’s expanding genomics capacity is exposing a wider field of viruses in mosquitoes, wildlife and livestock, yet a sequence alone cannot tell clinicians, veterinarians or public health teams whether a discovery belongs in a routine database or a response plan. Two 2025 studies involving South African virologist Marietjie Venter illustrate the central problem: detection is faster than interpretation, and interpretation depends on clinical, laboratory and field evidence that often arrives piecemeal.
The work matters because genomic surveillance can reveal viral material that targeted assays miss. It can also identify unusual combinations of genetic segments, including reassortants, long before a virus is linked to a recognized outbreak in people. Even so, a new sequence does not automatically equal a new human threat. In practice, the difference between an interesting finding and a public health emergency rests on whether the virus infects people or animals, whether it spreads, whether disease follows, and whether the signal is growing in real time.
Archived mosquitoes showed diversity, not spillover
One study used metagenomic RNA sequencing on 10 archived mosquito pools, each containing up to 50 mosquitoes, collected in 2017 in Kruger National Park and around Jozini in KwaZulu-Natal. The samples had already undergone testing for major arbovirus groups, but metagenomic sequencing opened a wider window and identified partial and complete genomes of insect-specific viruses, including viruses not previously described in South Africa.
The result expanded the catalog of viral diversity in South African mosquitoes and suggested virus–mosquito interactions worth further study. It did not show imminent spillover into humans. Insect-specific viruses infect insects and are not known to cause disease in vertebrates, which sharply limits the bedside significance of the finding despite its scientific value.
The clinical lesson is narrow but important: broad sequencing can reveal what targeted testing leaves behind, yet discovery does not equal danger.
Bernard Bett of the International Livestock Research Institute framed the operational challenge directly, describing genomics, environmental monitoring and cross-disciplinary collaboration as the tools that convert scattered observations into an early-warning system. Michele Miller of Stellenbosch University pointed out that finding evidence of a pathogen in wildlife does not necessarily mean it will spill over into humans. Jinal Bhiman, chief research officer at the University of Cape Town and head of The Oracle Lab, went further, arguing that it is a mistake to equate the finding of a pathogen with a threat.
His point reaches to the heart of surveillance strategy. Genomic data can show that something has changed, but it cannot by itself answer whether transmissibility, disease severity, immune escape or population-level impact has changed with it. Those are clinical and epidemiologic questions, not sequencing outputs.
Reassortment in animals raises a sharper, but still incomplete, signal
The second study examined orthobunyaviruses circulating among animals and vectors in South Africa. Researchers detected Shuni virus in horses and in sheep foetuses, Shamonda virus in a goat foetus, and a Shuni/Shamonda virus reassortant in a horse with fatal neurological disease. Other reassortants were found in Culicoides biting midges.
Reassortment occurs when two related segmented viruses infect the same cell and exchange genome segments, creating progeny viruses with mixed ancestry. In principle, this can alter host range, virulence or transmission behavior. In this setting, however, the presence of a reassortant in a severely ill animal still falls short of proving causation. A fatal neurological case is a serious signal, but not a final verdict on pathogenicity, and certainly not evidence of human threat on its own.
Marvin Hsiao of the Network for Genomics Surveillance in South Africa described sequence change on its own as insufficient evidence of increased threat and characterized genomics as a generator of hypotheses. That is the right frame for bedside translation: a genome can raise suspicion, but clinical correlation must confirm whether the signal belongs to disease biology or background viral traffic.
Bhiman said scientists also need to know whether a virus is spreading or expanding into new areas, and whether laboratory findings on infectivity, replication and immune evasion line up with disease severity or mortality in the field. A comprehensive risk assessment, she said, must integrate genomic, epidemiologic, clinical and laboratory data. Anything less leaves decision-makers with a biological possibility rather than an actionable risk assessment.
SARS-CoV-2 still shows how incomplete evidence complicates origin work
The same problem can persist long after a pathogen has already reshaped the world. In a 2026 Nature Comment, Venter and 22 other scientists who served on the World Health Organization’s Scientific Advisory Group for the Origins of Novel Pathogens reviewed the evidence on how SARS-CoV-2 emerged. Most peer-reviewed evidence supported a zoonotic origin, but the precise timing, location and route of emergence in humans remained unresolved.
That unresolved origin is a reminder that even a global emergency can leave core questions unanswered when crucial evidence is missing. If detecting and documenting infections occurs earlier and more systematically, later reconstruction becomes more precise. Genomics infrastructure, in other words, is not only for variant tracking during crises; it is also for preserving the evidence base that allows future investigators to understand how crises began.
Sequencing capacity is growing faster than the systems around it
The COVID-19 pandemic accelerated genomic surveillance across Africa. By 2024, sequencing capacity had expanded from seven African countries in 2019 to 40, according to the Africa Pathogen Genomics Initiative. Expansion is impressive, but capacity alone does not equal readiness. Hsiao described Africa’s genomics capacity as fragile rather than consolidated, citing unstable funding, too few skilled personnel, geographical inequality and difficulty maintaining consistent sampling in under-resourced areas.
Those gaps matter because surveillance depends on continuity, not one-off sequencing runs. Dense human and animal populations, high biodiversity and rapid land-use change create ideal conditions for spillover, yet those same settings often have the weakest sampling infrastructure. In that environment, a missed cluster can be more consequential than an elegant genome assembly.
In August 2026, Africa CDC launched a three-year programme in Ethiopia, the Democratic Republic of the Congo and Kenya to link wastewater and environmental monitoring with pathogen genomic surveillance. The move points toward a more integrated model in which sampling, sequencing and response are connected rather than isolated.
Detection only matters when response capacity exists
Venter argued that collaboration networks must function across Africa and between the Global North and South so that One Health genomic surveillance can be paired with rapid diagnostic deployment and local capacity to produce vaccines and therapeutics. Wendy Burgers of the Institute of Infectious Disease and Molecular Medicine at the University of Cape Town made the same argument from another angle: detection is only one part of the problem. The larger question is whether local scientists can develop solutions, run clinical trials and manufacture the tools needed to control a pandemic.
That is the bedside consequence of surveillance policy. A virus detected early but left without diagnostic follow-up, veterinary investigation or public health coordination may still become an outbreak. A signal that triggers rapid field work, lab confirmation and clinical assessment has a better chance of being sorted into noise or threat before patients are affected.
Africa’s growing genomic network is producing more viral discoveries than ever before. The unresolved challenge is not sequencing itself, but deciding which findings deserve escalation, which need more field data, and which remain interesting pieces of viral ecology rather than warnings of impending disease.