Hawaii hit with outbreak of dengue fever, also known as 'breakbone fever'

Hawaii has been hit by an outbreak of dengue fever, a mosquito-borne illness also known as "breakbone fever" because of the debilitating joint pain it causes.

At least 157 people on the island  — known as the Big Island — have been diagnosed with dengue, which causes fever, a rash, intense headaches, severe muscle aches and serious joint pain, according to the Hawaii state health department.

It's Hawaii's largest outbreak of dengue in 60 years, said physician Harold Margolis, the dengue branch chief for the Centers for Disease Control and Prevention.

"Americans should definitely be concerned about diseases such as dengue," said Amesh Adalja, a senior associate at the Center for Health Security at the University of Pittsburgh Medical Center.

Dengue can be extremely painful, but it's rarely fatal. Although some people never develop symptoms, up to 15% of dengue patients can develop a serious complication, Margolis said.

Dengue doesn't spread from person to person like the flu. Mosquitoes pick up the virus when they bite infected people, then spread the disease when they bite someone new.

People can reduce their risk of dengue or other mosquito-borne illnesses by using bug spray, wearing long sleeves and pants and staying in places that have secure window screens and air conditioning, according to the CDC. Communities can reduce the risk of dengue by eliminating places where mosquitoes breed, such as the standing water that collects in flower pots, dog bowls, rubber tires or elsewhere.

Dengue is one of 17 illnesses listed as "neglected tropical diseases" by the World Health Organization. These diseases afflict millions of people a year, most of whom are poor and live in developing nations, said Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston.

Although dengue hits 390 million people a year, it makes headlines in the U.S. only when the disease flares up here.  Doctors consider the tropical diseases neglected because drug companies have shown little interest in developing medications to treat them or vaccines to prevent them.

In an encouraging sign, Mexico approved the world's first vaccine against dengue, made by Sanofi Pasteur, earlier this month.

In addition to dengue, two other mosquito-borne diseases are spreading rapidly in the Western Hemisphere: chikungunya virus,which first arrived in the Americas in 2013; and Zika​  virus, first diagnosed in Brazil in May. Both have symptoms similar to those of dengue.

In recent years, tropical diseases have spread beyond their usual neighborhoods, fueled by global travel and commerce, human migration and even international events such as the World Cup, Hotez said.

Scientists say that many tropical diseases could spread north as the climate warms.

Diseases on the move because of climate change

Dengue was widespread in the U.S. until the middle of the 20th century. Although mosquito-control efforts beat the disease back in most of the continental U.S., dengue was never eliminated in Puerto Rico, the U.S. Virgin Islands or the Texas-Mexico border, Adalja said.

Dengue previously hit Hawaii in 2001 and 2011. The virus also caused outbreaks in the Florida Keys in 2009-2011 and Brownsville, Texas, in 2005. The current dengue outbreak in Hawaii is the largest in 60 years.

The California Department of Public Health last week warned residents to protect themselves from mosquitoes if traveling to Mexico or Latin America because of the dangers of dengue and chikungunya. The name chikungunya comes from the Kimakonde language of Tanzania, and translates roughly as "bent in half," referring to the stooped posture of those with debilitating joint pain, which can last months or years.

Dengue, chikungunya and Zika are all spread by the Aedes mosquito, which is found in much of the U.S., Adalja said.

There have been more than 1.7 million cases of chikungunya in the Western Hemisphere in the past two years, according to the Pan American Health Organization. The disease is now entrenched in the U.S. Virgin Islands and Puerto Rico, with 202 cases reported this year, according to the CDC.

Many infectious disease specialists worried that chikungunya would spread north from Mexico to the U.S. via the Rio Grande Valley this year. A severe drought dried up the mosquitoes' breeding places, however, and has slowed its northward march, said Nikos Vasilakis, an assistant professor in the department of pathology at the University of Texas Medical Branch and a member of the Center for Biodefense and Emerging Infectious Diseases.

Scientists are especially concerned about the spread of the Zika virus, because it's been linked to an epidemic of birth defects in Brazil, said Robert Tesh, a  professor in the pathology, microbiology and immunology departments at the University of Texas Medical Branch and director of the World Reference Center for Emerging Viruses and Arboviruses.

Zika virus — which was originally identified in Uganda in 1947 — was first diagnosed in Brazil in May. In October, Brazil's Ministry of Health began receiving reports of an unusually high number of cases of microcephaly, in which babies are born with small heads and incomplete brain development.

By early December, Brazil had reported 1,761 cases of microcephaly, a rate more than 20 times higher than usual, according to the Pan American Health Organization. Nineteen of the affected infants died. Brazil also has reported dozens of cases of Guillain-Barre syndrome, a rare immune system disorder that can cause temporary paralysis, that appear related to Zika virus.

Scientists have been taken aback by how quickly Zika is moving through the Americas.

"Chikungunya took two years to spread through Latin America," Vasilakis said. "It took Zika just a few months to spread through Latin America and be at our doorstep in Mexico."

In addition to Mexico and Brazil, Zika cases have been reported in Panama, Venezuela, El Salvador, Suriname, Colombia, Guatemala and Paraguay.

In a study published in Memórias do Instituto Oswaldo Cruz, researchers noted that Zika could have spread to Brazil during the 2014 World Cup games, given that there were Zika outbreaks in some Pacific island nations at the same time.

According to the CDC, "because the Aedes species mosquitoes that spread Zika virus are found throughout the world, it is likely that outbreaks will spread to new countries."