A highly pathogenic strain of avian influenza has been spreading among American livestock for months, according to preliminary analysis of genomic data. The outbreak likely began when the virus jumped from an infected bird to a cow, probably in late December or early January. Conjunctivitis with hemorrhage in both eyes, without impaired vision, is the symptom presented by the first human case linked to the highly pathogenic H5N1 avian influenza virus epidemic circulating among dairy cattle in the USA. This is the worker of a Texan dairy company whose infection made headlines a month ago, bouncing around the international media. The description of the case is the subject of a letter to the editor published in the ‘New England Journal of Medicine’, signed by experts from the Centers for Disease Control and Prevention (Cdc) in Atlanta, the Texas Department of State Health Services and Texas Tech University Bioterrorism Response Laboratory in Lubbock, of the Texas Department of State Health Services in Austin. An image to accompany the correspondence: a photo of the patient’s eyes.
«Sporadic human infections with highly pathogenic avian influenza (Hpai) A(H5N1) viruses, with a broad spectrum of clinical severity and a cumulative mortality rate exceeding 50% – recall the authors of the letter – have been reported in 23 Countries in more than 20 years. Hpai A(H5N1) viruses belonging to clade 2.3.4.4b have spread extensively among wild birds worldwide since 2020-2021, causing outbreaks in poultry and other animals. Recently” the same viruses “were identified in dairy cows and in samples of unpasteurized milk in several US states”. In humans, “a case of Hpai A(H5N1) virus infection has been reported in a worker of a dairy company in Texas”, the signatories continue, going into the details concerning him. The patient “showed redness and discomfort in the right eye at the end of March 2024”. At the first medical examination, “subconjunctival hemorrhage and serous drainage were noted in the eye.” Normal breathing, saturation 97%, clean lungs, no fever or respiratory symptoms, no changes in vision or anything else, the experts specify.
«The worker did not report any contact with wild birds, poultry or other sick or dead animals», but spoke of «direct and close exposure with dairy cows that appeared to be well and with others that instead showed the same signs of disease of cows from other herds, in the same area of North Texas, with confirmed infection with Hpai A(H5N1) virus”. Again according to the man’s story, “when he worked with the animals he wore gloves, but no respiratory or eye protection”. The patient underwent a swab, with conjunctival and nasopharyngeal samples taken. The results of both were “presumptive for the influenza A and A(H5) virus”, therefore “home isolation was recommended and the antiviral drug” oral oseltamivir was administered (75 mg 2 times a day for 5 days)” both to the man and to his direct contacts. “The next day – the case description continues – the patient reported no symptoms, except discomfort in both eyes.” Upon re-evaluation, therefore, the doctors detected “subconjunctival hemorrhage in both eyes, without vision impairment. In the following days the worker reported resolution of the conjunctivitis, without respiratory symptoms, and family contacts remained in good health.”
