CUTLER, Calif. — As migrant workers from Mexico begin their journey north to take summer jobs in fields and construction sites across the U.S., public health officials and others are fanning out to intercept them at food lines and churches in hopes of stemming the spread of swine flu.

Industries such as agriculture and meatpacking rely on an influx of thousands of seasonal workers each year. Officials worry that some of those laborers may be ill and could infect co-workers and others in the U.S.

Mexican consular officials, social service organizations and health authorities are handing out Spanish-language fliers with information on swine-flu symptoms and prevention tips. They are sending out mobile health care crews in buses or vans. And they are urging workers who feel sick to go to the hospital or a free clinic.

The traveling population of poor farmworkers, day laborers and construction workers poses a challenge for authorities, who say it can be difficult for people to wash their hands or go to the hospital if they lack running water or fear deportation.

"People are constantly coming here from Mexico and migrating back and forth," said Dr. Edward Moreno, director of public health in Fresno County, some 440 miles north of the Mexican border. "That means that people may not have a land line, hot water or Internet access, and no regular doctor."

Alfredo Mendoza, 24, of the Mexican state of Oaxaca, crossed the border two weeks ago to work with his family pruning California's vineyards.

"I feel healthy, so I'm just washing my hands a lot and keeping my mouth covered, and not leaving the house other than to work," he said. "People aren't too freaked out about the flu here yet. I just feel lucky that I left Mexico before it got really bad down there."

At a California clinic, Nely Garcia, the 26-year-old wife of a farmworker, filled out forms for her 3-year-old daughter, who had a cough and runny nose. Her mother feared the girl might have the flu, but she turned out to have an eye infection.

Garcia, who was born in Mexico and moved to the U.S. as a child, said she was worried that her family could be exposed to the virus through relatives who recently traveled to the Mexican state of Colima, or through the local school system.

"We have to be really careful because of the children, especially since so many people are making their way back up here. And when we cough we cover our mouths, right?" Garcia instructed her toddler as they waited in Cutler, a farming town of about 4,500 people 40 miles from Fresno.

Down the street, health workers applied hand sanitizer as they passed out Spanish-language brochures about swine flu to 200 people waiting in line to pick up bags of free potatoes, onions and mushrooms.

The global outbreak apparently began in Mexico, where it is suspected of causing nearly 170 deaths and sickening about 2,500 people. The first flu death in the U.S. was confirmed Wednesday: a toddler from Mexico City who was visiting Texas with his family.

In Chicago, the Mexican consulate is sending mobile units to Hispanic neighborhoods to distribute fliers. Community organizations and churches are doing the same.

Pastor Jose Landaverde of Our Lady of Guadalupe Anglican Church in Chicago's Little Village neighborhood, which has one of the biggest Mexican communities in the Midwest, said so many people had stopped in to ask about the flu that he planned to address it during Mass.

If seasonal labor trends mirror last year's, the number of agricultural workers in the U.S. will grow to about 700,000 by June and peak at 828,000 by September, according to U.S. Department of Agriculture figures. It is unclear how many are from Mexico.

A farmworkers union plans to meet Mexican legal guest workers as they arrive in the U.S. with a medical van, where they can get screened for flu symptoms and learn prevention tactics. The workers will later pick vegetables on North Carolina farms.

Pastors and health care workers also are hoping to reach tomato pickers near the Florida town of Immokalee and field hands harvesting asparagus in Michigan.

The Mexican consulate and local health organizations in California are mounting a prevention campaign that will send buses to isolated communities where there is no doctor. Healthcare workers aboard the buses will talk to people about swine flu and where they can find medical care.