What avian influenza cases among U.S. farm workers tell us about infection tracing

CNN
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A U.S. farm worker who contracted bird flu after caring for dairy cows in Texas appears to be the first known case of mammal-to-human transmission of the virus, a new study shows.

The dairy worker sought treatment in late March after a blood vessel burst, causing painful symptoms that left his eyes red, swollen, and watery. However, a letter about the incident published in a magazine said he did not have a fever and his lungs were normal. New England Medical Journal on friday.

Although he reported no contact with sick or dead birds or other animals, he had repeated direct and close contact with dairy cows in the same area as other infected herds in the state.

Although the man did not become seriously ill, his case is important because it confirms that humans can become infected with H5N1 after coming into contact with cattle. At the same time, the study leaves important questions unanswered about the virus, which the study authors describe as having “pandemic potential,” and how this vulnerable population of workers who test positive for infectious diseases. This shows how difficult it is to track infections. Getting sick can mean missing days of work and pay.

“There's no question that farmworkers in particular are people who are in desperate economic situations. What they're not going to do is they're not going to get tested for anything unless they have paid sick leave. 'Because they can't be sent home and told to stay home and not work,' said Elizabeth Strater, United Farm Workers Strategic Campaigns Director. .

Strether said the UFW, like other organizations, has heard rumors that some dairy workers are sick but don't want to be tested, but he can't confirm anything.

Texas health officials said they tested the dairy workers for other illnesses, including one with bloodshot eyes, but found it was not bird flu but a different illness.

“Those who were tested volunteered to be tested,” said Lara Anton, a senior spokeswoman for the Texas Department of State Health Services.

“We cannot say for sure that there are no other H5N1 cases, as there were likely others who had symptoms and did not wish to be tested. “I can say with certainty that I have tested positive for other respiratory viruses,” Anton said.

In the case of the man who tested positive for bird flu, he took antiviral medication and recovered without any lasting problems, and his next of kin received the medication as a precaution, the letter said.

Swab tests of the patient's eyes and lungs also revealed interesting findings. His eyes were full of H5N1 virus, but his lungs had very little virus. That's because the worker didn't get it through his lungs, but from rubbing his eyes with contaminated hands, or through contaminated milk droplets, and the virus didn't travel there, and the virus didn't spread to him. This could mean that it was unable to establish a foothold in the body. That's because it is adapted to primarily infect birds, not cells in the human respiratory tract.

The letter about the incident was written by researchers from the U.S. Centers for Disease Control and Prevention, physicians from the Texas Department of State Health Services, and researchers from the Texas Tech University Bioterrorism Response Laboratory.

Health authorities said they could not further investigate how the man became infected because “an epidemiological investigation could not be carried out on the farm” where the man worked. Nor could they test other workers on the same farm.

This type of testing determines how the worker became infected, whether others have been infected, if so, how long they have been infected, and if they have symptoms. This is important for answering questions such as what symptoms you had.

The CDC is looking for farms that can conduct such detailed investigations.

“Understanding the current avian influenza epidemic among dairy cows is a critical priority to protect human health,” the agency said in a statement to CNN. “Consultations are underway with farms in multiple jurisdictions to participate in the CDC-led epidemiological investigation. In the meantime, states will continue to test symptomatic farm workers and monitor those who have been in contact with infected animals.” CDC also continues to closely monitor our robust national influenza surveillance system. To date, no unusual influenza activity has been detected.”

White House press secretary Karine Jean-Pierre said in a press briefing Friday that the administration is “monitoring the situation very closely and taking this very seriously.”