More than a month after a person in Missouri mysteriously fell ill with H5 bird flu, researchers in the state are still trying to identify people who became sick after contact with the patient, raising questions about the due diligence of the ongoing health research.
On September 6, the Missouri Health Department reported the first human case of H5 bird flu, a case that appears to be closely related to the H5N1 bird flu that is currently causing a nationwide outbreak among dairy cows. But the infected person had no known contact with infected animals – unlike all the other 13 human cases identified during this year's dairy outbreak. These previous cases have all occurred in workers on dairy farms or poultry farms. In fact, Missouri has not reported any bird flu in its dairy herd, nor any recent outbreaks in poultry.
Given the unexplained source of the infection, health researchers in the state have been working to track the virus both backward in time – to identify its source – and forward – to identify any further spread. The bird flu patient was initially hospitalized on August 22, but recovered and had been released by the time the state publicly reported the case.
In an update Friday, September 27, the Centers for Disease Control and Prevention reported that officials in Missouri have now identified four more health care workers who developed mild respiratory illness after caring for the person with bird flu. None of the four employees were tested for flu at the time of their illness and all have since recovered.
Test new cases for antibodies against H5N1
The four newly identified cases bring the total number of healthcare workers who became ill after contact to six. Missouri researchers had previously identified two other health care workers who developed mild respiratory symptoms. One of those employees was tested for the flu around the time of their illness – and tested negative. But the other, like the four newly identified cases, was not tested. That person has since submitted a blood sample to test for antibodies against bird flu, which would indicate a previous infection.
In addition, a home contact of the bird flu patient became ill at the same time as the patient, indicating a possible common source of the infection.
The illnesses are concerning given fears that H5N1 bird flu could spread from person to person and cause a widespread outbreak or even a pandemic. However, we should not overlook that there are a plethora of other respiratory viruses in circulation – and transmission of SARS-CoV-2 was relatively high in Missouri at the time – it is impossible to draw conclusions at this time as to whether the diseases were bird flu. infections.
But the illnesses clearly raise concerns about the health investigation, which is being conducted by Missouri officials. “The slow trickle of information is the most worrying part,” infectious disease expert Krutika Kuppalli wrote on social media on Friday. The CDC can intervene at the request of a state, but no such request has been made. For now, the CDC is only providing technical assistance from Atlanta.
In today's update, the CDC highlighted that “to date, only one case of influenza A(H5N1) has been detected in Missouri. No contact of that case has tested positive for influenza A(H5N1).” The agency added that blood test results for H5 antibodies are pending.
Currently, 239 dairy farms in 14 states are infected with H5N1.
