Two years ago it was Chikungunya. There are hundreds of thousands of cases now WW. Chikungunya is a virus that can cause rather severe musculoskeletal pain and, uncommonly, neurologic and longer-term arthritic sequelae. Local transmission has even been documented in Florida, Puerto Rico, and the Virgin Islands.
Beyond chikungunya is the more serious virus, dengue, which has been on the radar of many public health officials for years. Dengue also causes fever, headache, and muscle and joint pain, and it is often hard to distinguish between the two viruses. The dengue virus is known to be endemic in the Virgin Islands and Puerto Rico, but cases have been seen in Texas and South Florida. Of interest, Hawaii is currently experiencing a small outbreak on the Big Island (probably from an imported case), where more than 181 cases have been reported since September of 2015.
Now a third virus, the Zika virus, has been a cause for concern. This virus, first described in Africa and Southeast Asia, appears to now be epidemic in Brazil. It’s a flavivirus, much like dengue or yellow fever. It can cause fever, rash, joint pain, and conjunctivitis, but generally has not resulted in death or severe illness. There has also been concern about an increased rate of birth defects in Brazil, specifically microcephaly, which might be caused by the Zika virus. The link isn’t clear, but the possibility has created a lot of concern among pregnant women in that country.
Takeaway: mosquito avoidance is the only practical measure to prevent these three virus.