The West Nile deaths are the first in the country this year and raise the national toll to 22 since 1999, when the mosquito-borne virus was first detected in the United States.
Louisiana was waiting for lab results in 34 more suspected cases.
Eight people in Texas and 22 in Mississippi are also sick with West Nile encephalitis. Since 1999, the virus has been found in more than 30 states and it is spreading south and west, reaching Texas, Nebraska, Oklahoma, North Dakota, South Dakota, Minnesota and West Virginia this year.
"It will eventually get to all the Western states over time," said Dr. Roy Campbell, an epidemiologist at the Centers for Disease Control and Prevention.
Overall, the number of human cases this year has already surpassed the 64 reported last year; 43 were reported in Louisiana and Mississippi on Friday alone.
The Louisiana victims were three men, ages 53 to 75, and an 83-year-old woman, all of whom died in the past few weeks, state health officials said. Twelve people remained hospitalized, four in intensive care.
"This is only the beginning," said Dr. Raoult Ratard, the state epidemiologist.
Gov. Mike Foster declared a statewide emergency, hoping to get $3 million to $5 million in federal money for parishes that are rapidly using up their mosquito spraying budgets.
"There ought to be some kind of relief. This is an emergency situation," Foster said Thursday.
AP
A laboratory researcher sorts mosquitos retrieved from a trap.
The virus is carried by mosquitoes that feed on infected birds and other animals. Most people bitten by the infected insects do not get sick, but the virus can cause flu-like symptoms and encephalitis, a potentially fatal swelling of the brain, in the weak and elderly.
Until June, Louisiana's only human West Nile case was last year, in a homeless man in suburban New Orleans. He survived.
Experts said the virus has now spread to virtually every part of watery Louisiana, where mosquitoes are jokingly called the state bird. The outbreak here is the deadliest since the virus killed seven people and hospitalized 55 others in the New York City area in 1999.
Across southeastern Louisiana, people have been putting fresh water in birdbaths and dumping water out of flowerpot saucers to deprive mosquitoes of the standing water they need to breed. St. Tammany Parish north of New Orleans has sprayed for mosquitoes every night for the past month, three to four times more often than typical during the summer.
Sales of mosquito traps and insect repellents have been brisk.
In Baton Rouge, where police are investigating a string of three slayings, Louisiana State University employee Patty Scuotto said: "The joke around here is, if the serial killer doesn't kill you, the mosquitoes will."
Dr. Campbell said Louisiana residents are not necessarily at greater risk because of the state's bayous and other mosquito-breeding terrain. The severity of the outbreak depends on the species of mosquito, the climate and other factors, he said.
Wayne Machado, owner of Mosquito Control Inc., said the species that carries the disease usually breeds near homes instead of in swamps.
Becky Hunt, the widow of one of Louisiana's victims, said her husband might still be alive if he'd used mosquito repellent and if he hadn't insisted on working when he had a raging fever. Hunt said if she hadn't demanded that doctors keep him on life support and continue blood tests, they might never have known what killed 72-year-old E.C. Hunt Jr.
Hunt said her husband, a lawyer, insisted on traveling to Lafayette to defend a client, even though he had a 103-degree fever and she begged him to stay home.
In Folsom, Edgar Theall said his 53-year-old son, Steven Wayne Theall, had emphysema, West Nile, and two strokes. Theall said his son had been in intensive care for five weeks when he died on July 26, after the second stroke.
Hunt and Theall, a former jockey, both put off seeing a doctor.
Theall said his son was determined to stay out of the hospital as long as possible, in spite of weakness and persistent headaches. Only the first stroke, about two months ago, convinced Steven Theall that it was time.
14 New Cases Reported in Mississippi
Mississippi state health officer Ed Thompson announced 14 new cases of the West Nile virus on Friday. West Nile encephalitis has infected 22 people in Mississippi and state health officials are scrambling to stop the spread of the virus through mosquito control workshops for municipal leaders.
Seven cases were announced last week. The first human case of West Nile virus in Mississippi was identified July 19.
Additional testing is needed to confirm some of the new cases, but Thompson said all 22 people have been or are being treated for West Nile virus symptoms. Eight people are hospitalized.
Thompson's announcement came at the first of three mosquito control workshops held by the Mississippi Department of Health in Jackson.
"West Nile appears to be producing an outbreak in Mississippi," Thompson said.
The new cases were reported in 11 counties. The patients range in age from 15 to 82, but most are over the age of 50.
The virus has caused no deaths in Mississippi.
Thompson said state health officials will test every case of encephalitis, or brain inflammation, that does not have an obvious cause.
"We're going to have more cases," Thompson said. "How many more depends on ... how well people protect their families and how well communities protect their citizens by reducing mosquito populations."
Louisiana Confirms Four West Nile Deaths; More Cases in Mississippi 
