ATLANTA , Georgia -LRB- CNN -RRB- -- All Lyle Petersen wanted to do was get his mail . Lyle Petersen , a CDC expert who was infected with West Nile virus , says , `` it will ruin your summer . '' In the time it took him to walk down his driveway in Fort Collins , Colorado , chat briefly with a neighbor and return to his house , Petersen got infected with a potentially serious mosquito-borne illness called West Nile virus . Within hours of being bitten , he said , he began to feel symptoms he recognized . And how was he sure so quickly ? Petersen , as director of the division of vector borne diseases at the Centers for Disease Control and Prevention , is one of the foremost experts in the world on the condition . A blood test confirmed his suspicion . `` From my own experience , I can tell you it 's not a very mild illness , '' Petersen cautioned . `` It will ruin your summer . '' Experts are expecting another epidemic of the disease this summer . The incidence of West Nile virus has remained the same for the past four years , and Petersen says he does n't expect this year to be any different . It should reach its peak between mid-July and mid-September . Health Minute : More on West Nile virus risk '' `` People tend to discount this as a significant problem , '' Petersen said , `` but more than 1.5 million people have been infected so far in the United States , and about 300,000 have had West Nile fever . '' West Nile virus emerged in the U.S. nine years ago . The virus is spread by the bite of an infected mosquito . Mosquitoes contract the illness by feeding on infected birds . The CDC reported that in rare cases , West Nile virus has spread through blood transfusions , organ transplants and breastfeeding . The disease is not spread through casual contact . The symptoms range from mild to severe and typically develop between three and 14 days after a person is bitten . Explainer : West Nile 101 '' Debbie Koma , a 50-year old hairdresser from Atlanta , Georgia , developed West Nile virus two years ago . She described it as `` unlike anything that I ever had before . I was sick as a dog . '' She recalled being hospitalized for three days with a high fever , a horrible headache and body aches . After 14 days , she was strong enough to get out of bed , but she says her strength did n't fully return for three months . Petersen had a similar experience when he was stricken five years ago . `` I discovered I had West Nile virus because I am a long-distance runner , '' he said . `` About halfway through one of my runs , I felt terrible . Within a couple of hours , I was lying in bed with severe headaches , eye pain , muscle pain and fever , which lasted about a week . I basically could n't get out of bed for a week . '' It was n't just Petersen who became sick , but his daughter and the neighbor were complaining of West Nile virus symptoms hours after being swarmed by mosquitoes at the mailbox . A medical doctor , Petersen actually tested his own blood in the laboratory and diagnosed his own illness . Like Koma , he was sick for a couple of months . His chief symptom : severe fatigue . `` I could barely walk up the stairs , '' he said . `` This is not a mild illness , and people should try to avoid it . '' Petersen mentioned that some patients with West Nile virus can develop a severe neurological disease that can be fatal . There is no effective treatment for the virus . In more serious cases , the CDC recommends that patients be hospitalized so they can receive supportive care with intravenous fluids . Researchers are working to develop a vaccine , but Petersen notes that it will be years before it is available to humans . The best way to stop the spread of West Nile virus is through prevention , he said . `` Wear mosquito repellent , especially around dawn and dusk , which are peak mosquito biting times , '' Petersen suggests . He says bug sprays that contain concentrations of the chemical DEET up to 50 percent work the best . Be sure to read the label or check with a doctor regarding the acceptable concentrations for children . Spraying repellent that contains permethrin on clothing is another option . Experts caution not to put the chemical directly on exposed skin . Petersen added that a natural product such as oil of lemon eucalyptus CQ may also be effective . The CDC says vitamin B and ultrasonic devices do not work in preventing mosquito bites . Another way to reduce the risk of getting bitten by a mosquito is to get rid of standing bodies of water around the house , Petersen said . `` The mosquitoes that spread West Nile virus often breed around people 's homes in small containers like flower pots , rain barrels and bird baths , '' he explained . Even by taking precautions , Petersen concluded , the disease wo n't be eradicated in the U.S. anytime soon . `` I think West Nile virus is here to stay , and I ca n't tell you how many cases will occur this summer , but there will be epidemics . ''