As Navapur in Maharashtra’s Nandurbar district battles its third major bird flu outbreak in two decades, authorities are ramping up surveillance, culling operations and hospital preparedness amid fears over the H5N1 virus’s potential to infect humans. While the disease primarily affects birds, health experts say certain strains of the virus, especially H5N1, can occasionally infect humans and cause severe illness. Though human-to-human transmission remains rare, the virus continues to worry scientists globally because of its ability to mutate. Bird flu, also called avian influenza, is a viral infection that mainly affects birds such as chickens, ducks and wild birds. Some strains, especially H5N1, can sometimes infect humans. How does bird flu infect humans? “Bird flu can infect humans through close contact with infected poultry, contaminated surfaces or during culling operations.…