More than 332,000 students nationwide are out of school due to closures in 21 states.
The CDC has confirmed a total of 144 cases in 21 states.
About 400 students had flu-like symptoms at the University of Delaware, state officials reported Thursday. Of them, at least four cases have been confirmed by local officials.
Georgia announced its first confirmation of swine flu Thursday in a 30-year-old Kentucky woman who fell ill on a trip to the western part of the state. State officials have said the CDC has confirmed this case.
Wednesday a small cluster of infections appeared to be emerging in Washington state, which if confirmed would mean the virus would have spread to 19 states.
South Carolina officials reported 10 confirmed cases of swine flu among students who recently took a trip to Mexico.
Arizona announced its first confirmed case of swine flu April 29, the same day that neighboring Nevada announced its first case.
New England gained its first cases of swine flu April 29, after two people were confirmed to have the virus in Massachusetts. Maine also confirmed three cases in the state April 29 -- all adults who were reportedly recovering in their homes, according to Gov. John Baldacci.
Michigan joined the list of states with confirmed cases April 29, and now has a total of two people diagnosed with swine flu.
California was the first state to confirm a case of swine flu on April 21. Since then, 14 of cases in ages ranging from grade school to adults have been confirmed in Sacramento and southern California.
On April 29, officials confirmed that a Marine at Twentynine Palms military base had come down with the swine flu. In response the base quarantined 30 marines. Gov. Arnold Schwarzenegger declared a state of emergency in California on April 28 to release funds to fight the outbreak.
Texas had the first death in the United States from the swine flu: a 22-month-old boy died April 27 in a Houston hospital. A total of 26 of people have been diagnosed with swine flu in Texas. The Fort Worth Independent School District decided to close all schools, likely until May 11th to stem further infections.
New York has seen the largest number of confirmed swine flu cases after the first few were detected in California and Texas. A cluster of swine flu cases confirmed at St. Francis Preparatory School has since spread to a total of 51 cases across New York City.
Neighboring Indiana announced its first case of swine flu just days later on April 29. Health officials confirmed that a student at Notre Dame fell ill.
A Kansas couple represented the first -- and only -- cases to be diagnosed in the state April, 25 apparently after the husband traveled to Mexico for professional conference. Officials described their case as mild and said the couple cooperated in quarantining themselves.
On April 27 the U.S. Department of State issued a travel advisory against unnecessary trips to Mexico, as did the top European Union health officials.
International Swine Flu Cases