( CNN ) -- The recent West Nile virus outbreak is the largest ever seen in the United States , according to new numbers from the Centers for Disease Control and Prevention . The number of cases so far this year is the highest recorded through August since the disease was first detected in the United States in 1999 . As of Tuesday , 38 states had reported human infections . The cases reported to the CDC as of Tuesday total 1,118 , including 41 deaths . Arkansas , Michigan and Mississippi have each reported an additional death . `` The peak of West Nile virus epidemics usually occurs in mid-August , but it takes a couple of weeks for people to get sick , go to the doctor and get reported , '' said Dr. Lyle Petersen , the director of the CDC 's Vector-Borne Infectious Disease Division . `` Thus we expect many more cases to occur . '' Fast facts on West Nile virus . Petersen said that the reason for the high number of cases this year is unclear , but that unusually warm weather could have fostered favorable conditions for the disease 's transfer to humans . About 75 % of the cases are in Texas , Mississippi , Louisiana , South Dakota and Oklahoma . Texas has been at the epicenter of the outbreak , with 586 confirmed cases and 21 deaths , according to the Texas Department of State Health Services . Here are five things you need to know about West Nile virus : . 1 . Most mosquitoes do not carry West Nile . In areas where mosquitoes carry the virus , only about one in 500 mosquitoes is infected , according to the Connecticut Mosquito Management Program . 2 . Most people bit by West Nile mosquitoes do not get sick . About 80 % of people bit by a mosquito infected with the West Nile virus do not get sick , according to the CDC . About 20 % will have relatively mild symptoms , such as fever , headache and vomiting . Symptoms can last for as short as a few days or as long as a few weeks . About one in 150 people infected with West Nile will develop a severe illness , which can include paralysis , coma or death . 3 . You can help prevent West Nile with the `` four Ds . '' • Use mosquito repellent with DEET . • Dress in long pants and long sleeves . • Be especially careful at dusk and dawn . • Drain any standing water , such as kiddie pools or bird fountains , where mosquitoes like to breed . 4 . People over 50 are most vulnerable . Those older than 50 are the most likely to become severely ill with West Nile and should take special care to avoid mosquitoes , according to the CDC . 5 . Seek medical care immediately if you have severe headaches or confusion . If you develop symptoms of severe West Nile virus illness , such as unusually severe headaches or confusion , seek medical attention immediately , according to the CDC . Severe illness usually requires hospitalization . Milder cases improve on their own and do not necessarily require medical attention . West Nile blamed in death of Illinois official as U.S. battles virus . ' I knew my husband was going to go , ' West Nile widow says . CNN 's Jacque Wilson contributed to this report .
More than 1,100 cases and at least 44 deaths have been reported . The numbers are the highest through August since the virus was first detected . Comment: Steps can be taken to prevent West Nile infection .