By John J. Hidore
September 14, 2013--Global warming and climate change are having a significant affect
on human health in a variety of ways. Changes in temperature and rainfall affect the life
cycles of disease carrying insects such as mosquitoes and ticks. As the planet warms it
also increases the range and frequency of tropical diseases. Tropical diseases have
become more prevalent in their traditional zones and have broken out in areas where they
were unknown previously. Diseases that have increased in frequency or severity include
malaria, cholera, yellow fever, the plague, dengue fever, meningococcal meningitis,
influenza, diarrhea disease, Hantavirus, West Nile encephalitis virus, and chikungunya.
Rising temperatures may lead to increased frequency of some of these diseases n the
Dengue fever is a mosquito-borne disease that is found throughout the tropics and
sub-tropics. It is a viral infection carried by day biting mosquitoes. The symptoms are
excruciating pain in the bones, fever, muscle aches, and rash. Most cases are not serious,
and only last a few weeks. A more severe form known as severe dengue (dengue
hemorrhagic fever) has similar symptoms but also causes internal bleeding and bleeding
through the nose and gums. This form of the disease can lead to shock and death. The
world health organization reported that this fever is now the fastest spreading vector-
borne virus on Earth. There have been 50 to 100 million new cases reported each year in
the last decade. The range in which it occurs is expanding horizontally and is increasing
its range upward in mountain areas as warm temperatures move to higher altitudes. Most
cases are found in urban areas. Mosquitoes that carry the fever are increasing in numbers
in urban areas where stagnant pools of water form in unused containers and puddles.
There currently exist no vaccines or medications specifically for the disease.
There is currently a worldwide pandemic and it is most common in India, Viet
Nam and the Caribbean. It appeared in South America in the last decade of the 20th
century and it existed on the Pacific side of Costa Rica for some time. There were
epidemics there in 1993 and 1994. In 1995 unusually warm weather allowed the
mosquitoes to cross the mountains into the rest of the country. Outbreaks of the disease
occurred in other areas of South America also. Thousands died of the epidemic and
nearly 150,000 were infected.
In the fall of 2007, dengue fever spread across the Caribbean in one of the worst
outbreaks in decades. Health agencies declared the disease was at near record levels in
2007. It affected hundreds of thousands of individuals and killed more than 200. Puerto
Rico reported some 5000 cases in 2012.
An epidemic of the fever ravaged Charleston, S.C as early as 1828. The fever was
endemic in the south of the United States prior to World War II. Following the war a
nationwide program to eliminate flies and mosquitoes was begun. This attempt included
ridding the country of malaria. The program largely eliminated dengue fever in this
country. However, cases are now diagnosed in the United States nearly every year in
persons that have traveled to regions where the disease is endemic. The Center for
Disease Control reported that 1167 of these cases were reported between 1996 and 2005.
There were 25 cases reported in Brownsville, Texas in 2005. Blood tests were conducted
by the CDC on residents of Brownsville. Thirty-eight percent showed signs of past
dengue infection. Eleven percent of these had not been outside the country and so had to
be infected in the local area. Two and one-half percent of those tested showed signs of
In 2009 the first case in 40 years was reported in Florida. In 2010 an outbreak
occurred that reported 63 cases among people that had not traveled in tropical regions. A
strain of the Aedes mosquito had established itself in Key West. The last case there was
reported in November of that year. This summer the fever appeared in Martin County
Florida. As of August 27, 2013 four cases had been confirmed
Chikungunya (Chicken Guinea) is a disease similar in symptoms to dengue fever.
The disease is a relatively new mosquito borne viral fever. The symptoms are sudden
high fever reaching 39ºC (102ºF), a variety of skin rashes and other skin irregularities,
arthritis of the joints, and headache. Severe joint pain may last for weeks or months. In
the recent epidemic in India, high fever and joint pain were the most common symptoms.
Fever normally lasts about 48 hours before breaking. The mosquitoes carrying the virus
are found in the United States, especially in the South. The Center for Disease Control
reported that cases have developed in the United States in persons who have traveled to
the areas where outbreaks were occurring. An unknown number of Canadian and
Europeans have also contracted the disease. None are known to have developed in
individuals that have not traveled to regions where the disease is endemic.
Several factors have led to the increased numbers of persons contracting these
diseases. The higher temperatures associated with global warming increases mosquito
activity, the human population is increasing in the areas where the mosquitoes are found,
and more people traveling into and out of the affected areas.
World Health Organization
Center for Disease Control