However, international travel among US residents is increasing, and frequent travelers may be at risk http://www.selleckchem.com/products/pirfenidone.html of secondary dengue infection and thus, more severe dengue illness. The volume of US residents traveling abroad hit a record high of 64 million in 2007, reflecting an increase of roughly 15% since 1998.11 Moreover, increased travel to Central America, South America, Africa, and Asia, all regions with dengue-endemic countries, contributed to the new record for US outbound travel.11 There is potential for limited secondary

transmission of dengue upon return of an infected traveler to the United States as competent vectors exist throughout much of the southeastern region. With incubation and viremic periods of roughly 5 days each,4,5 travelers may be infectious for several days upon return to their state of residence. In 2001, Hawaii experienced its first dengue outbreak in over 50 years, an outbreak likely caused by importation of dengue virus from an infected traveler.29 Sporadic outbreaks of DF have occurred in the past two decades in southern Texas along the US-Mexico border.30–32 US healthcare providers are often unfamiliar with

DF, which can delay accurate diagnosis in symptomatic travelers, thereby increasing the risk of secondary transmission. Despite the risk of secondary Apoptosis inhibitor dengue transmission in the southeastern United States, infrastructural factors such as the widespread usage of air-conditioning in homes in the United States may prevent the establishment of autochthonous transmission.30,32 Lastly, asymptomatic dengue infections may also potentially pose a risk to others via blood donations,33–36 as current screening practices do not defer persons from donating blood solely on the basis

of recent travel to the tropics. Future work is needed to more accurately determine the burden of dengue infection and the risk of infection among US travelers. Mathematical modeling techniques may be employed to determine this risk.37 Data captured by the PDSS could be supplemented by reports of suspected and confirmed dengue cases from the major commercial reference laboratories throughout the United States those which perform dengue diagnostic testing. We recommend making dengue a nationally reportable disease and strongly encourage reporting from all state and local health departments to the CDC. A timely and sensitive surveillance system with more complete data is essential for detecting introductions of dengue virus, preventing secondary transmission within the households and communities of returning travelers, and guiding prevention efforts. Persons traveling from the United States should be given pre-travel advice on lowering their risk of dengue infection while overseas.