A third person in the United States has tested positive for bird flu, which is currently affecting dairy cows.
This is already the second human case of highly pathogenic avian influenza (HPAI) A(H5) identified in Michigan tied to the multistate outbreak in cattle. Another case was reported in Texas in April.
All infected individuals are dairy farm workers who are exposed to infected cows, making this another instance of probable cow-to-person spread, according to the Centers for Disease Control and Prevention (CDC). However, none of the three cases are associated with the others.
Unlike previous cases where patients reported conjunctivitis and fatigue as their only symptoms, the Michigan patient experienced a cough without fever, congestion, sore throat, and watery eyes, the symptoms more typical of acute respiratory illness.
"Risk depends on exposure, and in this case, the relevant exposure is to infected animals. The risk to members of the general public who do not have exposure to infected animals remains low," the agency said in a statement.
Is human-to-human transmission possible?
The Michigan patient has been treated with antiviral oseltamivir and is isolating at home, and their symptoms are resolving.
Neither the patient's household contacts nor other workers at the same farm have developed symptoms.
The presence of respiratory symptoms means that the exposure risk is higher, according to the CDC deputy director Nirav Shah.
Simply put, someone who's coughing may be more likely to transmit the virus than someone who has an eye infection like conjunctivitis.
Shah
Some epidemiologists worry that mild bird flu cases can be more difficult to recognize and isolate, increasing the risk of further spread.
Bird flu in humans is rare — only about 900 cases were reported globally in the last two decades. However, according to the World Health Organization, bird flu can cause severe disease and even death, as its mortality rate is 56%. The virus also has the potential to mutate and become more contagious.
The symptoms reported in previous human infections with A (H5N1) viruses include conjunctivitis, gastrointestinal symptoms, encephalitis, and encephalopathy, which can lead to coma. There have also been asymptomatic cases of bird flu infections.
Protecting yourself from bird flu
Bird flu has been confirmed in dairy cattle in nine states: Michigan, Texas, New Mexico, Idaho, Kansas, Colorado, South Dakota, Ohio, and North Carolina.
Investigation reveals that the currently circulating strain, which is the same that has been affecting wild birds and commercial poultry flocks and has caused sporadic infections in several species in the U.S.
The CDC recommends taking the following precautions to protect yourself from bird flu:
- Avoid close, long, or unprotected exposures to sick or dead animals, including wild birds, poultry, and cows.
- Avoid unprotected exposures to animal poop, bedding (litter), unpasteurized ("raw") milk, or materials that have been touched by, or close to, birds or other animals with suspected or confirmed bird flu virus.
- Wear recommended personal protective equipment when interacting with infected or potentially infected animals and monitor your health for 10 days after their most recent exposure.
While bird flu risk for the general population remains low, it is crucial to take recommended precautions in case of exposure to animals and animal foods.
3 resources
- CDC. CDC confirms second human H5 bird flu case in Michigan; third case tied to dairy outbreak.
- WHO. Avian influenza A(H5N1) - United States of America.
- American Veterinary Medical Association. Avian influenza virus type A (H5N1) in U.S. dairy cattle.
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