What with all the coverage of Ebola virus infection taking first place in news outlets, you may have missed another viral infection that's likely to be much more impactful here in the US, also originally an African import: Chikungunya. As Rick and I discuss on PodMed this week and featured in an online first release in JAMA, the first two cases of local transmission of Chikungunya have occurred here in Florida, so it's official: Chikungunya has arrived on mainland USA. And it's not cause for celebration.
As the report notes, since late last year the number of cases of Chikungunya has been increasing worldwide, with some 400,000 or so cases reported by the Pan American Health Organization. The virus has been wreaking havoc in the Caribbean this summer, with tens of thousands of infections spread over much of the region. Until now, most cases in the United States have been the result of people traveling to the Caribbean islands and becoming infected there, then returning home.
Now, however, the typical pattern of infection has taken place in Florida, where an infected mosquito bites someone who is infected, then transmits that infection to the next person it bites. The mosquito is merely the vector for the virus to pass from one person to another. The virus has mutated such that it can now infect two species of mosquito: Aedes aegypti and Aedes albopictus. Aedes aegypti is the preferred and longstanding host, but acquisition of a single point mutation by the virus now allows it to be transmitted by A.albopictus as well.
So what about these mosquitos? A.aegypti makes its home in the southeastern US and parts of the southwest, while A.albopictus also forays further north to the mid-Atlantic and lower Midwest regions. It's worth pointing out that in contrast to many of their peers, these two species of mosquito feed during daytime hours so wisdom regarding bite avoidance at twilight is sketchy at best. In view of the fact that the infection mimics the flu except for joint pain many describe as 'excruciating' and 'disabling,' and can last as long as six months post-acutely, we all would like to avoid infection, so what should we do? Rick emphasizes that mosquito control is the best strategy, primarily by eliminating areas of standing water, such as flower pots, kiddie pools and the like. Use of insect repellants and clothing is also helpful. He points out to healthcare providers that Chikungunya is a reportable disease, so samples should be sent to local health authority or CDC labs for confirmation.
Good news has emerged also with release of data from a very early study on a vaccine candidate for Chikungunya reported in the Lancet. In this small trial using a virus-like particle approach, volunteers did mount neutralizing antibodies to the virus and few side effects of vaccination. Stay tuned.
Other topics this week include a number of studies examining the role of salt with hypertension and cardiovascular disease in NEJM, flexible sigmoidoscopy benefits in JAMA, and BMI and cancer in the Lancet. Until next week, y'all live well.