The Centers for Disease Control and Prevention (CDC) announced Thursday that the H5N1 bird flu virus has not spread from person to person, following an extensive investigation into a patient in Missouri hospitalized for the infection.
The Missouri patient tested positive for bird flu in August but had no known exposure to poultry or dairy cows. H5N1 has primarily affected farm animals and wild birds, with 31 reported human cases in the U.S., mostly among farmworkers.
After the patient’s illness, several close contacts exhibited respiratory symptoms, prompting health officials to conduct blood tests. The results for five healthcare workers who cared for the patient were negative for the virus, according to Dr. Demetre Daskalakis, head of the CDC’s National Center for Immunization and Respiratory Diseases.
“We’ve reached a conclusion based on our investigation,” Daskalakis stated.
One blood test from a household member showed potential H5 antibodies, but subsequent testing could not confirm this finding. Further investigation indicated that the household member and the patient likely contracted the virus from the same source, probably an animal or animal product, as both developed gastrointestinal symptoms simultaneously.
Dr. Nirav Shah, the CDC’s principal deputy director, emphasized that the findings reaffirm the absence of human-to-human transmission. All individuals who fell ill have since recovered, suggesting that the virus has not mutated to enable easy human transmission.
Despite this reassuring news, the CDC noted an increase in bird flu cases linked to infected animals. While the general risk remains low, individuals working directly with wildlife and farm animals face higher exposure.
The outbreak has affected 333 dairy herds across 14 states, with most human cases linked to dairy workers. Recently, two workers at a poultry farm in Washington fell ill, prompting state officials to request CDC assistance in their investigation.
“This is a rapidly evolving situation,” Shah remarked, highlighting ongoing laboratory tests.
California, which has reported the highest number of bird flu cases at 15, is also seeking federal support. Dr. Erica Pan from the California Department of Public Health mentioned that health officials are proactively checking in with farm workers to monitor symptoms.
Overall, infections from H5N1 in humans have generally resulted in mild symptoms, such as eye irritation and some upper respiratory issues. Other states reporting human cases include Colorado, Michigan, and Texas.
