A deadly cross over: In South Africa, rabies moves from land animals to seals

Along South Africa's Western Cape, Cape fur seals have been attacking humans with increasing frequency — 135 aggressive incidents since September 2021, 73 involving bites — and researchers now believe the cause is rabies, a disease never before confirmed to have established itself in a marine mammal population. Genetic sequencing traces the outbreak to a canid strain most closely linked to black-backed jackals in Namibia, likely introduced when a rabid jackal bit a seal, with a possible second introduction from a bat-eared fox strain.

South Africa's National Institute for Communicable Diseases and Department of Agriculture, Land Reform and Rural Development have documented dozens of confirmed cases since May 2024, with retrospective testing showing the virus was actually present in seals as far back as 2021. Scientists at a July 2025 workshop concluded the disease is now endemic in the densely packed, physically constant-contact seal colonies and is no longer eradicable.

Researchers are now watching for whether the virus could spread further to other marine mammal species or even reach Antarctica as seals travel and interact with other wildlife, though no cases have yet been found outside Cape fur seals.

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