CDC Report: Chikungunya Fever Outbreak in Southern U.S. Probable
The U.S. Center for Disease Control and Prevention in Atlanta (CDC) is reporting that the mosquito borne illness, Chikungunya Fever, has the potential to be imported to the southern United States, areas with temperate climates and large mosquito vectors.
Chikungunya Fever is a viral disease, a mosquito-borne pathogen, similar to Dengue Fever.
The disease is transmitted by mosquitoes of the Aedes genus, the same type of mosquitoes that transmit the Dengue Fever Virus.
Chikungunya Fever is endemic to Asia, Africa and the Indian Subcontinent. A large outbreak was reported in 2006-2007 in India, and several other countries in southeast Asia. Italy experienced an outbreak of the disease in the northeastern portion of the country in 2007 as well.
There is no known cure for the disease.
The virus is transmitted from human to human by the bites of infected female mosquitoes of the Aedes aegypti and Aedes albopictus genus, two species which can also transmit the dengue fever virus. These mosquitoes can be found biting throughout daylight hours, although there may be peaks of activity in the early morning and late afternoon.
Once bitten symptoms usually appear between four and eight days but can range from two to 12 days.
Signs and symptoms include acute onset high fever, joint and muscle pain, joint swelling, headache, nausea, fatigue and rash. Most patients generally make a full recovery, and in rare cases death occurs. Debilitating joint pain may last a few days or even weeks, and persist joint pain may last for several months, or even years.
Neurological and heart related issues have been reported, as well as gastrointestinal complaints along with ocular problems. The disease can contribute to the death of the elderly, those with compromised immune systems and the very young. Symptoms often go unrecognized in infected individuals, or be misdiagnosed in areas where dengue fever is endemic.
Treatment options are non-existent, and symptom relief for joint pain is recommended.
There is no known vaccine for Chikungunya Fever.
A study conducted under the auspices of the U.S. National Institute for Food and Agriculture and Cornell University’s Atkinson Center for Climate Change and Disease Program, indicates that the Chikungunya Fever pathogen could become epidemic in the deep south and in the Caribbean basin due to the regions warm temperature and vector for mosquitoes.
Cases of Chikungunya Fever have been reported in the U.S. from travelers returning from areas with tropical climates.
The study, published on November 29, 2012 in the journal PLoS Neglected Tropical Diseases, creates a model for the dynamic introduction of the Chikungunya Fever virus to the United States.
The study models examined 3 U.S. cities, and the possibility of outbreak in these cities because two factors. Their warm, humid temperatures in the summer months, and the available mosquito population.
The cities are, NYC, Atlanta, Ga and Miami, Fl.
New York City had an available temperature window from late July through September, this being the time of the season with the highest risk factors for an outbreak of Chikungunya Fever.
Atlanta’s temperate weather last a bit longer, from June through September, putting it at a higher risk than New York City.
Miami, Florida has the highest risk factor for an outbreak of Chikungunya Fever because of its year round warm, tropical climate, and large mosquito vector.
The study used 1 infected person as the model, and indicated that if the normal chain of events that occur with an outbreak were not interrupted, a pandemic would be a likely scenario.
The probability of a disease outbreak, when paralleled with temperature, indicated that warmer weather allows the Asian tiger mosquito, which transmits the virus, to breed faster and grow in larger numbers, according to the study published in the November issue of PLOS Neglected Tropical Diseases.
Asian tiger mosquitoes were introduced to the United States in Texas in the 1980s, and have taken hold up and down the East Coast and into New York and New Jersey and the numbers are rising fast in the New York City area. The aggressive mosquito outcompetes local varieties and transmits more than 20 pathogens, including Chikungunya and Dengue.
“The probability of an outbreak refers to the chance of the occurrence of a human to mosquito to human transmission event,” said Diego Ruiz-Moreno, a postdoctoral associate in the ecology and evolutionary biology department and the paper’s lead author. “When this number is over 30 percent, it could be said that such a probability is high.”
“The model estimates that with typical regional temperatures, a Chikungunya outbreak in New York would infect about one in 5,000 people,” he said. “However, this number would increase drastically as temperatures rise due to climate change,” he added.
The possibility of an outbreak of Dengue Fever is also a distinct possibility, given the study’s findings, related to the computer models.
The computer simulation could also be applied to such diseases as Dengue Fever that hold similar risks in the United States.
Dengue Fever is an infectious tropical disease, similar to and often mistaken for Chikungunya Fever, caused by a virus of the same name. In 80 percent of cases, the affected patient encounters only a minor fever and flu-like symptoms, muscle and joint pain, and a skin rash akin to Measles, generally dismissing these symptoms, and recovering in about 10 days to 2 weeks.
The other 20 percent are not so lucky. These patients develop Dengue Hemorrhagic Fever, which can result in bleeding, blood plasma discharge, and dangerously low blood platelet levels. And stage 2 puts the patient into shock, were a major blood pressure drop occurs, and is usually fatal.
“The global dengue problem is far worse than most people know, and it keeps getting worse,” said Dr. Raman Velayudhan, the World Health Organization’s Dengue Director.
Dengue Fever is endemic in similar areas as Chikungunya Fever, and is epidemic in India.
Recent outbreaks of Dengue Fever on the Isle of Madeira, Portugal have European Health Officials worried. A similar outbreak has taken hold in India, with Government Health Ministers trying to ignore the findings.
In Europe, travelers returning from holiday are reportedly seeking medical attention for the Dengue Fever virus.
The European Centre for Disease Prevention and Control (ECDC) issued a statement on Tuesday, saying that The Portuguese Health Ministry had reported over 1,300 confirmed cases of the disease, with 600 more probable cases additionally.
Portugal, France, Britain, Sweden and Germany reported that vacationers had been diagnosed with the virus upon returning from the Portuguese Island of Madeira.
Similar outbreaks have been reported in the Canary Islands and on the Island of Cape Verde, all archipelago’s off the western African coast.
The news is even worse for the population of India.
Indian Government Officials have reported that 30,000 people in India have been diagnosed with Dengue Fever through October of this year. This is a 60 percent rise from calendar year 2011, when a total of 18,860 cases were reported. Hundreds of thousands of cases go unreported each year, and this underreporting policy has its roots at the highest levels of the Indian government.
The problem with that policy, said Dr. Manish Kakkar, an official from the Public Health Foundation of India, is that the “massive underreporting of cases” is the major factor contributing to the disease’s spread.
“There is no denying that the actual number of cases would be much, much higher,” adding, “Our interest has not been to arrive at an exact figure.”
Dr. Scott Halstead, Adjunct Professor in the Department of Preventive Medicine and Biometrics, Uniformed Services University of the Health Sciences, Bethesda, MD said, “I’d conservatively estimate that there are 37 million dengue infections occurring every year in India, and maybe 227,500 hospitalizations.”
“When you look at the number of reported cases India has, it’s a joke,” said Dr. Harold S. Margolis, chief of the dengue branch at the Centers for Disease Control and Prevention in Atlanta.
Article by Jim Donahue