Posts Tagged ‘Dengue fever’

Fight Against Dengue Enlists Genetic Engineers

Wednesday, September 21st, 2011 by

Recent bulletins carry news of dengue fever on the rise in Panama, Pakistan and the Bahamas. Add these destinations to those mapped by the Centers for Disease Control, including Brazil, Paraguay, Bolivia, Vietnam, Australia, Thailand, the Caribbean and the Philippines, and it’s clear dengue is spreading at an alarming pace throughout the tropics and subtropics. How are we fighting back?

Controlling dengue is largely an exercise in combating the mosquito species Aedes aegypti, which transmits the viral disease to over 50 million people per year and is becoming resistant to pesticides. Now New Scientist magazine is reporting that Oxford, England-based Oxitec, Ltd. is applying its genetic engineering expertise in field trials in the Caribbean, Malaysia and Brazil to reduce mosquito populations. Oxitec has created a disruptive strain of A. aegypti by modifying the genome to include genes that kick in after reproduction to kill the mosquito in the pupa stage. Genetically modified insects have been released into wild, and trials have been encouraging. Now the company has also engineered flightless females among the modified population, which are released to maximize the odds that the “killer males” will mate only with unmodified females and thereby cut an even wider swath.

Critics point out that genetic modification can lead to both intended and unintended consequences. It will pay to keep an eye on this experiment both as a weapon against a growing scourge and as an index of whether these tactics will prove to be safe over the long-term. 

Photo by Curtis Palmer.

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Travel Bulletin Cambodia: Country Braces for Nightmare Dengue Season

Tuesday, May 24th, 2011 by

Dengue season—June and July—is approaching in Cambodia where the National Dengue Control Program (NDCP) is warning of an impending outbreak at least as severe as the 2007 epidemic when 40,000 people were hospitalized, 10,000 in one week. A spokesman for the NDCP says the number of cases in recent months has been unusually high, which has been a reliable predictor of large scale outbreaks in the past. Adding to the anxiety are the detection of a new serotype as well as Dengue hemorrhagic fever, which may make cases more deadly or difficult to treat. Prevention programs have been woefully underfunded. Ironically, Cambodia is home to a demonstration project costing $1 per household that has been effective in preventing local outbreaks by introducing guppy fish into water storage containers to eat the larvae of the mosquito that transmits Dengue.

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Travel Bulletin Philippines: Dengue Cases Double in Manila

Wednesday, April 20th, 2011 by

The Philippine Department of Health reports that the incidence of dengue fever doubled in metro Manila during the first quarter of 2011. The Philippines have been a dengue fever hotspot for several years, but the latest statistics are alarming: 4,399 cases in 2011 versus 1,984 in 2010. This outbreak comes despite the distribution of over 700,000 mosquito trap kits in recent months. The Department of Health cited Manila’s Barangay San Miguel in Pasig City and Barangay Hen. T. de Leon in Valenzuela as particularly high risk areas.

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Dengue Fever Takes Hold in Thailand

Thursday, September 16th, 2010 by

More evidence that the incidence of dengue fever is swelling significantly around the world:  since January, Thailand has recorded almost 71,000 cases–more than double the amount this time last year.

The World Health Organization has spoken out, asking the Thai government to increase its efforts to minimize the spread of the disease. According to the Bangkok Post, efforts to eradicate “breeding grounds for mosquito larvae like unsanitary pools, stagnant water, abandoned potted plants and automobile tires around the home, still need to be strengthened in communities, particularly urban areas prone to the disease.”

We continue to track the wave of dengue across Africa, the South Pacific, Central and South America, the Caribbean, the Middle East, and now Asia. If you are traveling to any of these areas, be vigilant: protect yourself from the bites of mosquitoes.

Photo by wise_kwai.

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Hemorrhagic Version of Dengue Fever Now Spreading in Mexico

Friday, July 30th, 2010 by

Mosquito BiteLast week, Mexico’s top epidemiological official reported a rise in the number of cases of dengue hemorrhagic fever (DHF) throughout the Gulf coast state of Veracruz.  The disease is moving towards Tamaulipas state and is getting closer to the United States border.  The recent flooding in Mexico has been a factor in the increased number of cases, with some 1,900 cases and 16 deaths being reported so far this year.

DHF was first recognized in the 1950’s and is a more dangerous version of dengue fever.  DHF frequently requires those infected to be hospitalized, and if not treated properly, the fatality rate for DHF can exceed 20%.  The CDC cites symptoms of DHF as similar to dengue fever, but ratcheted up to include persistent vomiting, severe abdominal pain, and difficulty breathing.  Bleeding from the nose, mouth, and gums can also occur.  As with dengue fever, there are a variety of medications used in the treatment of DHF.  If detected early, it can be treated with fluid replacement therapy.

As we reported in an earlier post, dengue fever is also on the rise in dozens of countries.  Since our last post, we’ve discovered that Thailand, French Polynesia, Indonesia, Cambodia, Nicaragua and Venezuela all belong on the list.  Dengue fever and DHF are both spread by mosquitoes, so travelers should do their best to protect themselves from mosquito bites.  Symptoms begin about 5-7 days after an infected bite.  DHF can be deadly, so it is important that travelers who suspect that they may have DHF see a doctor immediately. We will be keeping a close eye on this growing epidemic.

Photo by James Jordan

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Dengue Fever in the United States

Wednesday, July 7th, 2010 by

Last month we addressed dengue fever’s reappearance in the United States.  Since last summer 28 cases have been reported.  Though this disease is a little known entity in the United States, it is the most common vector-borne viral disease in the world, causing an estimated 50–100 million infections and 25,000 deaths each year.  Dengue is now the leading cause of acute febrile illness in U.S. travelers returning from the Caribbean, South America, and Asia.  However, those who have not travelled abroad or do not reside close to the Mexican border have historically not been at risk.

Dengue fever often exhibits only mild symptoms, so there is an excellent chance that hundreds of other infections have gone undetected.  The virus is transmitted primarily by the Ae. Aegypti mosquito, and results in fever, chills, headache, muscle aches, nausea with vomiting, eye pain, and occasionally a spotty red rash on the trunk or legs.  The disease may be suspected when there is a drop in the body’s platelet count- the small cells responsible for blood clotting, but can only be confirmed with the detection of antibodies in the blood. There is no treatment for dengue fever, and symptoms will usually resolve spontaneously within days.  However, in a small percentage of cases, the disease may progress to cause internal bleeding with organ failure and death. 

A vaccine for dengue fever is in development, and may ultimately join vaccines for hepatitis and yellow fever as recommended inoculations for U.S. citizens travelling to tropical areas.  In the meantime, visitors returning from areas where dengue is endemic should be suspicious of possible dengue infection if experiencing flu like symptoms, and seek medical attention if a spotty red rash develops.

Photo by Koala:Bear

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CDC Updates Dengue and Polio Outbreaks

Friday, June 4th, 2010 by

Key West, FL has reported 28 cases of dengue fever since July 2009 – prior to July 2009 dengue was absent from the continental U.S. since 1945 and from Florida since 1934. Why dengue has returned to Florida is still being investigated but some contributing factors might be an increase in mosquitoes capable of delivering the disease, an increase in international travel to areas where dengue fever is more common (Key West is, after all, a Caribbean destination — see below), and the popularity of south Florida as a vacation destination.

Travelers headed to Africa, the South Pacific, Central and South America, the Caribbean and Middle East are reminded to take precautions to guard against the mosquito while traveling.  According to the Centers for Disease Control (CDC), a high number of cases of dengue fever, are being reported from the following areas:
Africa
Cape Verde, Senegal, and the Indian Ocean islands of Mayotte and Reunion

South Pacific
Malaysia, Philippines, Singapore, Sri Lanka, Vietnam and the northern parts of Queensland, Australia

Central and South America and the Caribbean
Argentina, Brazil, Colombia, Costa Rica, Dominican Republic, El Salvador, French Guiana, Guadeloupe, Honduras, Peru and Puerto Rico

Middle East
Jeddah (Saudi Arabia)

Meanwhile,the polio outbreak in Tajikistan seems to be spreading to the borders it shares with Uzbekistan.   An additional 261 cases have been reported since our post in early May.  The CDC is reminding travelers headed to these areas to talk to their doctors regarding the necessary vaccinations for children and those previously vaccinated. 

When traveling into any area affected by an outbreak, be smart, protect yourself however you can, and practice good hygiene.

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Malaria Strikes in Haiti; Dengue in Puerto Rico

Friday, March 5th, 2010 by

The US military announced on February 27 that 6 soldiers involved in the Haiti earthquake relief have been diagnosed with malaria. One day later, health authorities declared a dengue fever epidemic in Puerto Rico, which reported 210 cases in January. These news stories are a reminder that relief workers and tourists in the Caribbean face dangerous threats.

Serving in Haiti can be very rewarding, but there are significant health and security risks which must be considered before jumping on the volunteer bandwagon. An increase in the incidence of malaria and other infectious diseases already endemic in Haiti has been widely expected since relief efforts began almost seven weeks ago.  Although the greatest risk is among the weak and those in poor health living in the streets or in severely cramped quarters, healthy volunteers are also susceptible.

Even before the earthquake hit, Haiti was considered by the World Health Organization as a “high risk” country for becoming infected with the malaria parasite and was ranked 34th in the Maplecroft Malaria Risk Index.  ”Overcrowding in the camps for the displaced, inadequate shelter and sanitation, overburdened medical facilities, ruptured sewer systems — all these factors provide favorable conditions for the breeding of malaria vectors,” said Fiona Place, a British researcher specializing in disease risk analysis.

The CDC has published “Guidance for Relief Workers and Others Traveling to Haiti for Earthquake Response” for anyone intending to assist in the relief effort.  Take the proper precautions or risk becoming a victim yourself

Dengue fever, a viral illness with symptoms of fever, muscle aches, headache and occasionally a faint rash on the trunk and back, is relatively new to Puerto Rico but common in Haiti.  There is no vaccination or treatment. Since the disease is transmitted by mosquitoes, the same precautions taken to prevent malaria will help to avoid infection with the Dengue virus. Bug sprays that contain DEET, picaridin or oil of lemon eucalyptus are effective.

Photo info: http://www.flickr.com/photos/teutoburg/ / CC BY-NC-SA 2.0
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The Long Arms of El Nino

Thursday, February 25th, 2010 by

Weather is enjoying celebrity-like status in the news this year.  The unusually warm weather in Vancouver has caused all kinds of problems with the outdoor Olympic events, but these abnormal conditions are not unique to British Columbia.  Many areas of Canada and the U.S. are experiencing unseasonable warmth and rain, or equally unusual cold and snow.  These strange patterns extend beyond North America as evidenced by floods and mud slides in Machu Picchu and Portugal.  The blame for this weather can be squarely attributed to El Nino once again.

El Nino emerges every 2 – 7 years and is caused by irregular warming and cooling of the Pacific Ocean west of South America.  This disturbance kicks up atmospheric conditions that give rise to unusual patterns of deluge and drought.  When El Nino delivers a large amount of rainfall to a desert area,   problems occur.  Likewise, El Nino can indirectly unleash freezing temperatures and precipitation that harm crops cultivated in areas used to a warm dry climate.

In addition to the immediate havoc caused by these weather patterns — floods, mudslides and crop failures, there are long-tem implications for public health.  As the World Health Organization (WHO) reports, flooding can cause pollution leading to food-borne illnesses that attack one’s digestive system.  Flooding also creates a moisture-rich environment ideal for mosquitoes to breed. More mosquitoes mean more carriers for vector-based diseases such as malaria, dengue fever and chikungunya. 

Recent reports from Environmental Research show how scientists are analyzing El Nino to predict some of these outbreaks.  Their insights can help determine which vaccines travelers will need to stay healthy.  As you plan your trip, don’t just look at the weather forecast.  Do some digging into recent weather trends to uncover any problems El Nino might be drumming up, whether it’s disease, digestion or the dislodging of entire mountainsides.

This map from Wikipedia (click to enlarge) shows the weather patterns created by El Nino. (http://upload.wikimedia.org/wikipedia/commons/5/53/El_Nino_regional_impacts.gif).

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