SEATTLE, Washington, (ENS) - Contrails spread by fleets of jet aircraft in elaborate cross-hatched patterns are sparking speculation and making people sick across the United States.

Washington state resident William Wallace became ill with severe diarrhea and fatigue after watching several multi-engine jets spend New Year's day laying cloud lines in an east to west grid pattern. A neighbor working outside came down with similar symptoms. But their wives, who remained indoors, suffered no ill effects from the inexplicable maneuvers which observers liken to high-altitude "crop-dusting" by unidentifed multi-engine aircraft.

Condensation trails, called contrails, are generated at altitudes high enough for water droplets to freeze in a matter of seconds and not quickly evaporate - typically where the temperatures are below -38 degrees Celcius.

Contrails can form through the addition of water vapor to the air from the jet engine exhaust. Even tiny nuclei released in the exhaust fumes may be sufficient to generate ice crystals, and hence, condensation trails.

Wallace wonders if ethylene dibromide, a highly toxic component of JP-8 jet fuel, is making people sick. Similar incidents over Las Vegas last year prompted a US Air Force spokesman to explain that the military aircraft were "dumping fuel" before landing.

But the strange spray patterns are being reported repeatedly over towns in at least 29 states.

Wallace has been watching formations of high-flying jets weave grid-like contrails above his home since last summer. Each time, "We get a taste in our mouth," he reports. He and his wife Ann get "kind of tired and sick," having "no energy to do anything."

After plants began dying around his mountain cabin, "I got real sick for about three weeks," Wallace relates. "My eyes watered. Fluid came out of my nose. I could hardly move my arm up above my head to comb my hair for about a week."

Wallace and his wife are not alone in their plight. In March, 1996, Dr. Greg Hanford bought an expensive camera and binoculars to keep an eye on jets spraying white bands above his Bakersfield, California home. Hanford has counted 40 or 60 jets on some "spray days."

"Everybody seems to be getting sick from it," Hanford told ENS. "Hackin' and coughin' when you really get nailed with this stuff." The dentist, many of his patients and two receptionists have repeatedly contracted severe respiratory infections. Hanford's illness lingered for five months despite courses of four different antibiotics.

"It's really weird," Hanford says. "You think two jets are going to hit each other - and then they make an X." The dentist says he has sometimes seen "furry globular balls" spread downwind in a long feather from the high-flying aircraft.

Unlike normal contrails, which dissipate soon after a lone jet's passage, video taken by Wallace and Hanford show eerily silent silver jets streaming fat contrails from their wingtips in multiple, criss-cross patterns. But instead of dissipating like normal contrails, these white jet-trails coalesce into broad cloud-bands that gradually occlude crystal clear skies.

"Passenger jets don't make contrails that stay and become clouds," Wallace observes.

Government officials deny that anything unusual is taking place. When Hanford called the local airport, tower personnel told him there was "nothing going on." The jets were "just commercial" undergoing "international flight training."

But a skeptical Hanford responded, "Is the FAA going to allow two jets to come at each other?"

Pseudo-color, multispectral images taken April 20, 1994 by a NOAA satellite, reveal a number of contrails over Oklahoma and Kansas. X'es, overlapping W's and the Roman numeral XII are among the patterns flown by the mystery aircraft. Last June, Hanford watched four aircraft spraying in circles to form a perfect bulls-eye.

Through his Swaroski binoculars, Hanford could see what "looked like a 737" painted all-white on top with an "orangish-red" underbody and red engine cowlings. Another 727-like aircraft was painted "all-white with a black stripe up the middle of fuselage." None of the planes carried identifying markings.

Pat Edgar has been watching the jets spraying over eastern Oklahoma since a sunny day in October, 1997 when as many as 30 contrails gradually occluded the sky. "They look like they're playing tic-tac-toe up there," he says. "You know darn well it's not passenger planes."

Edgar says he has watched "cobwebbing stuff coming down" from the zigzagging jets flying "all day long, line after line, back-and-forth, like furrows in a farm field."

Edgar adds that "There is a lot of Lupus in the area now. A lot of women have come down with it."

Edgar's father-in-law, a former judge, and three or four other close friends were hit hard in their immune systems. Symptoms include swollen hands and legs, night fever and shortness of breath.

Retired Oklahoma state judge Bill Ed Rogers now runs out of breath after walking 20 feet to the bathroom. Climbing stairs, he says, "is directly out of the question."

Rogers, does not attribute his strange malady to the mystery jets. But neither he nor his doctors can explain his breathing difficulty, which began shortly after spraying began in November, 1997, and is getting worse. The 57 year old former judge says he thought he was experiencing congenital heart failure when he was admitted into the Mayo clinic last January. But after being diagnosed with severe inflamation in his right lung, a team of top surgeons were unable to pump an unidentified "jello-like" fluid from his lung.

Edgar, Wallace, Hanford and other eye-witnesses are uneasy over the ongoing aerial "experiments and the secrecy surrounding them. "They're gettin' ready, practicing," Edgar believes, for some kind of mass population cull.

Before Edgar sold his restaurant, customers came in complaining of airplanes "flyin' around all night" over a remote area of Oklahoma. In the morning, they could see "stuff comin' out of their wings."

Edgar says he knows four-dozen witnesses who have "come down violently ill, coughin' up blood for two weeks - or [with] real bad nosebleeds." As far as he's concerned, "it had to be something in that doggone plane that was spillin' out in the middle of the night."

Edgar joins witnesses across the U.S. who worry that whoever is behind the mystery spraying just has to "come up with something a little stronger later on. It's just a guess," he says. "But it sure seems weird. They have a mission. They go back and forth all day. Hey man I'm talkin' hundreds of contrails in a day! It's unbelievable."