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Researchers have discovered the first case of bird flu transferring from a cow to a human, marking a concerning development in the study of influenza viruses and their pandemic potential.

Worker gets bird flu from cow

A Texas dairy farm worker experienced redness and discomfort in his right eye in March 2024. Medical examination revealed subconjunctival hemorrhage, bleeding beneath the eye’s clear membrane. The worker showed normal vital signs, with no fever, respiratory issues, or vision changes noted.

The distinguishing factor in this case is the worker’s exposure to dairy cows rather than wild birds or poultry. Despite no direct contact with sick birds, the worker had close interaction with cows displaying symptoms consistent with avian influenza. Healthcare providers reacted promptly by conducting influenza tests on the worker, revealing positive results for influenza A and A(H5) virus in conjunctival and nasopharyngeal swab specimen.

The worker showing symptoms was quickly isolated at home and treated with oseltamivir. Their household contacts also received oseltamivir as a precaution. Fortunately, the worker’s condition improved, with conjunctivitis resolving and no respiratory symptoms appearing.

The Centers for Disease Control and Prevention (CDC) confirmed the presence of highly pathogenic avian influenza A(H5N1) virus in specimens from a worker. Genetic sequencing identified the virus as part of clade 2.3.4.4b, closely related to strains found in Texas dairy cattle and local wild birds.

H5N1 infection on the rise due to mutation in virus

The recent human case of H5N1 infection raises significant concerns due to the virus’s history of causing deadly infections in numerous countries. With a high fatality rate, it has demonstrated adaptability to various hosts, including birds, poultry, and now even domestic cattle. Genetic analysis revealed a mutation in the virus sample from the infected worker, indicating potential adaptation to mammalian hosts. Questions remain about the virus’s transmission among cattle, potential cow-to-human transmission, and human-to-human spread. To tackle these concerns, increased surveillance of animal and human populations is crucial. Research into cross-species transmission mechanisms and genetic factors aiding viral adaptation is necessary for targeted interventions.