You can blame climate change for lots of things besides bad weather, and one of them is deadly mosquito-borne diseases. New England has recently been fighting an outbreak of equine encephalitis and now California, already home to the West Nile virus, is grappling with dengue ('den-gay), yet another viral infection that can have dire consequences.
Until last year, all the dengue cases in California were traced to people who had recently traveled to a country where the disease is common.
But now, Los Angeles County health officials say, the disease is being transmitted locally, something they say is "unprecedented." Four locally-acquired cases were found in September.
While saying no one should be too concerned, LA officials are urging residents to use insect repellent to prevent mosquito bites.
Person to person via mosquitos
If it's any comfort, it's worth noting that the mosquitos themselves don't have dengue, they merely pick it up from one person and transmit it to the next.
That's fine but obviously, if enough mosquitos bite enough people and then go on to bite other people, the disease could spread exponentially.
What to do
Besides wearing insect repellent and long sleeves, there's not too much individuals can do. Staying indoors is another obvious solution, though no one moved to California just to stay inside.
However, everyone can help eliminate mosquito breeding sites -- basically any container that holds water. Buckets, empty cans, old tires are all examples of prime mosquito breeding sites.
It's not just dengue, mosquitos also spread West Nile virus and yellow fever, so it's worth taking a few minutes to help eradicate them.
More about dengue
Also known as breakbone fever, dengue is a mosquito-borne tropical disease caused by the dengue virus.
The Dengue virus, transmitted by certain species of mosquitoes, infects about 400 million people annually in the warmer regions of the planet, causing more than 3 million deaths. Climate change is also expanding the habitat of the mosquitoes that carry the virus, leading to new Dengue outbreaks in an increasing number of countries.
Symptoms typically begin three to fourteen days after infection, which can include a high fever, headache, vomiting, muscle and joint pains, and a characteristic skin rash, according to the CDC.
In a small proportion of cases, the disease develops into severe dengue, also known as dengue hemorrhagic fever, resulting in bleeding, low levels of blood platelets and blood plasma leakage, or into dengue shock syndrome, where dangerously low blood pressure occurs.
Dengue is spread by several species of female mosquitoes of the Aedes type, principally A. aegypti. The virus has five different types; infection with one type usually gives lifelong immunity to that type, but only short-term immunity to the others.
Subsequent infection with a different type increases the risk of severe complications. Several tests are available to confirm the diagnosis including detecting antibodies to the virus or its RNA.
There is no specific treatment for dengue fever. Management of severe dengue requires careful attention to fluid management. Prevention of dengue fever is targeted at reducing the habitat and the number of mosquitoes and limiting exposure to bites.
Vaccine available
One type of dengue vaccine -- Dengvaxia -- is available for use in areas with risk of dengue in the United States.
CDC recommends dengue vaccination for children 9 through 16 years old, but only when they have been previously infected with dengue and living in areas where dengue is common.
This vaccine is different from other vaccines in that it is only recommended for people who have already been infected with dengue virus.
The reason is that children without previous dengue infection are at increased risk for severe dengue disease and hospitalization if they get dengue after they are vaccinated with Dengvaxia.
There is another Dengue vaccine available in some European countries which researchers say has an efficacy rate of over 50% in reducing disease cases, with lasting effects and a very good safety profile.
This is confirmed by the first global meta-analysis on the efficacy of TAK-003, better known as Qdenga: the only vaccine approved to date in Italy and many European countries for fighting Dengue. Published in the journalVaccines, the study was conducted by scholars from the University of Bologna and the University of Ferrara.
"This is the first comprehensive global analysis and we are very pleased with the data," says Lamberto Manzoli, director of the School of Specialization in Hygiene and Preventive Medicine at the University of Bologna, who coordinated the study. "It was not a foregone conclusion: it took many years to develop a vaccine with such good results."