PHOTO COLLECTION: AP Top Photos of the Day, Thursday, November 7, 2024

This is a collection of photos chosen by AP photo editors.

Telekom devices are surrounded by clouds on top of the Feldberg mountain near Frankfurt, Germany, Thursday, Nov. 7, 2024. (AP Photo/Michael Probst)

A man pushes his pig back home after taking it to higher ground after Hurricane Rafael passed through Batabano, Cuba, Thursday, Nov. 7, 2024. (AP Photo/Ramon Espinosa)

A Norway Spruce that will serve as this year's Rockefeller Center Christmas tree is cut down, Thursday, Nov. 7, 2024 in West Stockbridge, Mass. (AP Photo/Matthew Cavanaugh)

Denver Nuggets guard Christian Braun, left, fouls Oklahoma City Thunder guard Shai Gilgeous-Alexander as he drives the land in the second half of an NBA basketball game Wednesday, Nov. 6, 2024, in Denver. (AP Photo/David Zalubowski)

PSG's Bradley Barcola, left, and Atletico Madrid's Giuliano Simeone, right, fight for the ball during the Champions League opening phase soccer match between Paris Saint Germain and Atletico Madrid, at the Parc des Princes stadium, in Paris, Wednesday, Nov. 6, 2024. (AP Photo/Michel Euler)

Riders perform during a freestyle motocross show at the EICMA exhibition motorcycle fair in Rho, outskirt of Milan, Italy, Thursday, Nov. 7, 2024. (AP Photo/Luca Bruno)

Jennifer Lopez poses for photographers upon arrival at the photo call for the film 'Unstoppable' on Thursday, Nov. 7, 2024, in London. (Photo by Scott A Garfitt/Invision/AP)

A Nepalese woman offers prayers to the setting sun on the bank of Bagmati River during the Chhath Puja festival in Kathmandu, Nepal, Thursday, Nov. 7, 2024. (AP Photo/Niranjan Shrestha)

President Joe Biden walks to speak in the Rose Garden of the White House in Washington, Thursday, Nov. 7, 2024. (AP Photo/Mark Schiefelbein)

Britain's newspapers’ front pages reporting on U.S. President-elect Donald Trump in the U.S. presidential election, are seen in London, Thursday, Nov. 7, 2024. (AP Photo/Kirsty Wigglesworth)

Nayely Nunez, from Honduras, uses her luggage to carry a child as she walks along the highway with a migrant caravan in Huixtla, southern Mexico, heading toward the country's northern border and ultimately the United States, Thursday, Nov. 7, 2024. (AP Photo/Moises Castillo)

Dolores Merchan, 67, reacts in tears as she is assisted by volunteers clearing mud from her home, where she has lived all her life with her husband and three children, and which has been severely affected by the floods in Masanasa, Valencia, Spain, Thursday, Nov. 7, 2024. (AP Photo/Emilio Morenatti)

People drive along a road littered with fallen power lines after the passing of Hurricane Rafael in San Antonio de los Banos, Cuba, Thursday, Nov. 7, 2024. (AP Photo/Ramon Espinosa)

Firefighters and sheriff's deputies push a vintage car away from a burning home as the Mountain Fire burns in Camarillo, Calif., on Wednesday, Nov. 6, 2024. (AP Photo/Noah Berger)

German Chancellor Olaf Scholz leaves Bellevue Palace in Berlin Thursday, Nov. 7, 2024. (Kay Nietfeld/dpa via AP)

Federal health officials on Thursday called for more testing of employees on farms with bird flu after a new study showed that some dairy workers had signs of infection, even when they didn't report feeling sick.

Farmworkers in close contact with infected animals should be tested and offered treatment even if they show no symptoms, said Dr. Nirav Shah, principal director of the U.S. Centers for Disease Control and Prevention.

The new guidance comes after blood tests for 115 farmworkers in Michigan and Colorado showed that eight workers — or 7% — had antibodies that indicated previous infection with the virus known as Type A H5N1 influenza.

“The purpose of these actions is to keep workers safe, to limit the transmission of H5 to humans and to reduce the possibility of the virus changing,” Shah told reporters.

The CDC study provides the largest window to date into how the bird virus first detected in March in dairy cows may be spreading to people. It suggests that the virus has infected more humans than the 46 farmworkers identified in the U.S. as of Thursday. Nearly all were in contact with infected dairy cows or infected poultry.

Outside experts said it’s notable that the study prompted the CDC to take new action. Previous recommendations called for testing and treating workers only when they had symptoms.

“This is a significant move towards the assessment that these H5N1 viruses are a greater risk than the CDC estimated before,” said Dr. Gregory Gray, an infectious disease researcher at the University of Texas Medical Branch in Galveston.

Every additional infection in animals or humans gives the virus the chance to change in potentially dangerous ways, said Angela Rasmussen, a virus expert at the University of Saskatchewan in Canada.

“It shows yet again that we are not responding effectively to the H5N1 cattle outbreak in humans or animals and if we continue to let this virus spread and jump from species to species, our luck will eventually run out,” Rasmussen said in an email.

The CDC study included 45 workers in Michigan and 70 in Colorado tested between June and August. Of the eight workers with positive blood tests, four reported no symptoms. All eight cleaned milking parlors and none used respiratory protection such as face masks. Three said they used eye protection.

High levels of the virus have been found in the milk of infected cows, increasing the risk of exposure and infection, researchers said.

Researchers said that efforts to monitor dairy workers for illness have been hindered by several barriers including the reluctance of farm owners and farmworkers to allow testing.

Rasmussen and others have criticized the federal response to the outbreak as too slow and “lackluster.”

“These studies should have been performed months ago and should have been prioritized,” she said.

The virus has been confirmed in at least 446 cattle herds in 15 states. Last week, the Agriculture Department said a pig at an Oregon farm was confirmed to have bird flu, the first time the virus was detected in U.S. swine.

The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Science and Educational Media Group. The AP is solely responsible for all content.

This colorized electron microscope image released by the National Institute of Allergy and Infectious Diseases on March 26, 2024, shows avian influenza A H5N1 virus particles (yellow), grown in Madin-Darby Canine Kidney (MDCK) epithelial cells (blue). (CDC/NIAID via AP)