DENVER -- Colorado is dealing with one of its worst flu outbreaks in years.

The state has had nearly 3,400 confirmed cases of the flu this season. That includes more than 1,100 cases reported between Thursday and Monday. Four children have died of flu-related illnesses, three of those at Children's Hospital in Denver.

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A 15-year-old boy who had other medical conditions died from flu complications last week, becoming the first flu-related fatality in Colorado this year. A 2-year-old girl and a 21-month-old died in the past week. The fourth death was an 8-year-old boy in a northern Colorado town.

A Denver pediatrician called the outbreak "crazy" and said it's one of the most serious she's ever seen.

Colorado's outbreak is considered widespread, the most serious category. Texas and Nevada also have widespread outbreaks.

The parents of the 8-year-old flu victim are speaking out about what happened to their son in hopes that it will help other parents take action and take the illness seriously.

Scott and Carry Ann Williams, of Wellington, lost their son, Joseph, on Monday.

"It happened so quick and so sudden. He was fine. He wasn't even that sick," Scott Williams said.

The boy went to school last Friday and then went home, complaining of a stomachache later that evening.

"He didn't have the symptoms of the flu, so there was no alarm, no fever," Williams said.

Although Joseph never had a fever or a headache, the pain persisted. The Williamses called their doctor, who suggested fluids and rest. By early Monday morning, Joseph was still hurting, so his parents took him to a hospital.

Hours later, his veins collapsed. An autopsy confirmed he had died from respiratory failure with influenza type A infection. According to health officials, the child's illness was not typical of influenza symptoms, which are usually respiratory in nature with coughing and fever, and generally not what people often call the "stomach flu." The child's symptoms included nausea and abdominal pain.

The Williamses believe by sharing their story, they can convince other families to deal aggressively with the flu if it strikes their home.

Carry Ann Williams (pictured, left) said she hopes Joseph's death has a purpose.

"You know, he was purpose driven," she said tearfully.

Joseph's father said he doesn't want his son to have died in vain.

"Just have your kids checked, even if they act sick, there's meaning in it," Scott Williams said.

Joseph did not receive a flu shot this year, his parents said. His younger brother was taken to an emergency room later on Monday, also suffering from flu symptoms, but he's doing fine now.

Parents of children who attend Joseph's elementary school were notified by the principal about the student's death. There is no current flu outbreak in the school and no unusual numbers of students had been absent, health officials said.

Flu Symptoms

Influenza is a respiratory illness that affects the lungs and respiratory system. The most common symptoms of the flu include:

Fever, usually 102 degrees Fahrenheit, but can go up to 104 degrees Fahrenheit and usually lasts three to four days
Headache, sudden onset and can be severe
Sore throat
Muscle aches, often severe
Coughing, which can become severe
Tiredness and weakness, which can last two or more weeks
Sneezing
Runny nose
Young children may also have nausea and vomiting