Antibodies to avian influenza viruses were detected in livestock in Egypt

During the serological study, specialists collected 444 blood sera from outwardly healthy adult livestock animals on 33 small farms and subsidiary holdings in three provinces of Northern Egypt. The samples were tested for antibodies against the Egyptian H5N1 virus clade 2.3.4.4b (strain A/duck/Egypt/BA20361C/2022) using hemagglutination inhibition (HI) and microneutralization (MN) assays, as well as against the H9N2 G1-like lineage virus (strain A/chicken/Egypt/RA20191OP/2022) using the HI assay.

The results showed that antibodies to the H9N2 virus were detected in 2.5% of the analyzed serum samples. Positive results for antibodies to H5N1 were 4.5% according to the HI assay and 2.9% according to the MN assay. At the same time, no samples with antibodies to both virus variants simultaneously were found. All sera with antibodies to H5N1 belonged to cattle. Antibodies to H9N2 were recorded in 1.6% of cattle samples, 3.2% of goat samples, and 10.3% of sheep samples.

The obtained data indicate that the transmission of avian influenza viruses to livestock in Egypt does occur; however, due to the serological nature of the evidence, the authors were unable to confirm the presence of a full infection or the manifestation of symptoms similar to those in animals in the USA. Further monitoring is required to clarify the transmission routes, frequency, and infection factors.