Homegrown Strain of Dengue Fever Virus Pinpointed in Florida

Some 2009-2010 cases originated in Key West mosquitoes, not from travelers, CDC says

By Alan Mozes

HealthDay Reporter

THURSDAY, March 14 (HealthDay News) -- Some people who fell prey to a 2009-2010 outbreak of dengue fever in Florida carried a particular viral strain that they did not bring into the country from a recent trip abroad, according to a fresh genetic analysis conducted by the U.S. Centers for Disease Control and Prevention.

To date, most cases of dengue fever on American soil have typically involved travelers who "import" the painful mosquito-borne disease after having been bitten elsewhere. But though the disease cannot move from person to person, mosquitoes are able to pick up dengue from infected patients and, in turn, spread the disease among a local populace.

The CDC's viral fingerprinting of Key West, Fla., dengue patients therefore raises the specter that a disease more commonly found in parts of Africa, the Caribbean, South America and Asia might be gaining traction among North American mosquito populations.

"Florida has the mosquitoes that transmit dengue and the climate to sustain these mosquitoes all year around," cautioned study lead author Jorge Munoz-Jordan. "So, there is potential for the dengue virus to be transmitted locally, and cause dengue outbreaks like the ones we saw in Key West in 2009 and 2010," he said.

"Every year more countries add another one of the dengue virus subtypes to their lists of locally transmitted viruses, and this could be the case with Florida," said Munoz-Jordan, chief of CDC's molecular diagnostics activity in the dengue branch of the division of vector-borne disease.

He and his colleagues report their findings in the April issue of CDC's Emerging Infectious Diseases.

Dengue fever is the most widespread mosquito-borne viral disease in the world, now found in roughly 100 countries, the study authors noted.

That said, until the 2009-2010 southern Florida outbreak, the United States had remained basically dengue-free for more than half a century.

Ultimately, 93 patients in the Key West area alone were diagnosed with the disease during the outbreak, which seemingly ended in 2010, with no new cases reported in 2011.

But the lack of later cases does not give experts much comfort. The reason: 75 percent of infected patients show no symptoms, and the large "house mosquito" population in the region remains a disease-transmitting disaster waiting to happen.

To try and get a handle on just how serious that risk might be, the CDC team looked at blood samples from 16 of Florida's 67 counties, collected from dengue patients by the Florida Department of Health.

Rigorous genetic testing revealed what researchers feared: the identification of a local Key West strain among dengue patients who had not recently traveled outside the United States.

The team was able to trace the new Key West strain back to its original imported source: a Central American viral strain initially brought into Florida by patients infected in that region. But they stressed that as the local mosquito population acquired the virus from this first round of patients, it developed into a distinct strain of its own. In turn, the new strain was passed on to local residents who had not recently visited Central America.

View the original article here

New Strain of Norovirus Spreading Quickly in U.S.

Jan. 24, 2013 -- The flu is not the only highly contagious disease raging this winter.

A new strain of norovirus is causing intestinal illness outbreaks across the country, the CDC confirmed today.  

Norovirus is often to blame when large numbers of people get sick on cruise ships or in schools, nursing homes, and other places where people live, work, or play in close quarters.

CDC officials also reported a rise in outbreaks of sickness caused by drinking raw milk.

The findings appear in the Jan. 25 issue of the Morbidity and Mortality Weekly Report.

The new norovirus strain was first identified in Australia in March of last year, and it had spread across the United States by year’s end.

Of the 266 norovirus outbreaks reported during the last four months of 2012, 141 involved the Australian strain. During this time, outbreaks caused by it rose from 19% to 58%.

Sickness from norovirus is often called "food poisoning," but the highly contagious virus can also be spread by water, person-to-person contact, or simply by touching an infected object.

Outbreaks can happen anytime, but they are most common in the winter months.

A norovirus outbreak late last week that involved 300 children at an Arkansas middle school was not caused by the newer strain. But one that happened during a Christmas sailing of the luxury cruise ship Queen Mary 2 was, says Jan Vinje, PhD, who heads the National Calicivirus Laboratory at the CDC.

CDC epidemiologist Aron Hall says it may not be clear for several months if more people are getting sick or more outbreaks are occurring as a result of the new strain.

“We see new strains emerge every few years and sometimes they are associated with increased disease activity,” he says. “We certainly want people to be aware that this potential exists, but the mainstays of norovirus prevention are still the most important things people can do to protect themselves.”

He suggests these strategies to prevent infection:

Wash your hands often.Disinfect surfaces.Avoid preparing food or caring for others when you're sick.Keep your hands away from your face as much as possible.

View the original article here