NEW YORK (AP) — Well being officers mentioned Thursday that there’s no proof chicken flu is spreading between folks after investigating a mysterious an infection in Missouri.

The sickness reported final month was completely different from the 30 different chicken flu infections in folks within the U.S. up to now this yr. These instances have been in farmworkers who had contact with contaminated dairy cows or chickens.

There was no identified contact with an contaminated animal within the Missouri case, however well being officers mentioned Thursday that’s the one remaining rationalization.

“There isn’t any proof of person-to-person transmission,” mentioned Dr. Demetre Daskalakis of the Facilities for Illness Management and Prevention.

The H5N1 chicken flu has been spreading broadly within the U.S. amongst wild birds, poultry, cows and quite a few different animals. Its rising presence will increase the probabilities that folks can be uncovered, and doubtlessly catch it, officers say.

The newest of the 31 confirmed human instances are two staff at a business egg farm in Franklin County, in southeast Washington state. The remainder: 15 in California, 10 in Colorado, two in Michigan, one in Texas and the bizarre one in Missouri. Signs have been principally gentle, together with eye redness.

Few particulars have been launched concerning the Missouri case. The individual had preexisting well being issues and was hospitalized in late August. The affected person was given a check for flu that was optimistic for influenza A, a broad virus class. Additional testing discovered partial genetic sequences much like chicken flu viruses from U.S. dairy cows.

As a result of the Missouri individual didn’t work at a farm and had no identified contact with an contaminated animal, well being officers have been trying into the chance it had come from one other individual with an undetected an infection. That form of unfold can be a worrisome signal the virus may be turning right into a extra frequent risk to people.

They did difficult blood testing of the affected person, 5 hospital staff, and an individual described as a “family contact” of the affected person — on the lookout for antibodies that will function proof of a previous an infection. The family contact received a abdomen sickness similtaneously the affected person, however was not initially examined.

On Thursday, CDC officers mentioned check outcomes have been destructive for the well being care staff. The affected person and the family contact confirmed indicators of previous an infection in a single spherical of testing, however not in others. Neither met the World Well being Group’s blood testing threshold for a chicken flu case. The family contact isn’t a part of the U.S. tally.

Since they each received sick on the similar time, officers consider the affected person and the contact have been uncovered collectively to some unknown animal or animal product — ruling out unfold of the virus from one in every of them to the opposite, Daskalakis mentioned.

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The Related Press Well being and Science Division receives help from the Howard Hughes Medical Institute’s Science and Instructional Media Group. The AP is solely chargeable for all content material.