DENGUE FEVER IN SOUTHEAST ASIA

DENGUE FEVER

A dengue fever pandemic swept across the Western Pacific in 1991 and 2004, peaking with 350,000 cases in 1998, according to the WHO. In the early 2000s, tens of thousands of people were infected with dengue fever in Thailand. More than a hundred people died in 2001. Particularly hard hit were Bangkok and the central provinces of Chonburi and Nakhon Sawan. In some places outbreaks occur every two or three years as immunity after not getting the disease only lasts a year. The disease has also made its presence known in Southeast Asia in the late 2000s and early 2010s. In 2007, the number of cases of dengue fever in Thailand rose 36 percent . As of mid-2007 the disease had killed 17 people and affected more than 21,000 people. The increases was blamed on the early arrival of the rainy season.

Dengue fever is a nasty, viral disease transmitted by the Aedes mosquito, usually the Aedes aegypti , the same mosquito that often carries yellow fever. Sometimes called "breakbone fever" or "break-heart" because of the intense pain it can produce, the disease is characterized by sudden onset of fever; intense pounding, frontal headaches; aching bones and joints; nausea and vomiting; and a feeling of being too sick to eat anything. Other symptoms include severe sweats, symptoms: eye pain, rash, chills, and excruciating chest pains. Tests foe dengue rely on the presence of antibodies, which can take up to a week to develop.”

Dengue fever is found in 100 countries and kills about 20,000 people annually. Nine out of 10 people who get dengue fever don’t even feel it or get a mild case in which they feel something akin to a slight flu. People who get full-blown dengue fever are sick for a week or more. Many patients have a rash, which appears 3 to 5 days after the onset of the disease, and experience severe emotional and mental depression during the recovery period. Most cases of the disease are benign and self-limiting although convalescence may take a long time.

A few people with dengue fever suffer gastrointestinal bleeding. Fewer still suffer brain hemorrhages. In about 1 percent of cases dengue fever can cause a severe and often fatal hemorrhagic disease called dengue hemorrhagic fever (DHF) that occurs when capillaries leak and the circulatory system collapses.. Those that die of dengue fever often get DHF hemorrhaging in the final stage of the sickness. Failing to realize they are infected, they go don’t get treatment soon enough and lose blood plasma and go into shock after the initial fever passes. Some victims die within 10 hours of developing serious symptoms if they don’t get appropriate treatment.

There are several strains of dengue fever (the four main one are immunologically related). Those who get the disease develop an immunity to the strain they were infected by but are more likely to get DHF and get seriously sick if they get infected with a second, different strain. Scientists are not sure why this happens but think it may be because the immune system reacts the second time as if the invader were the first strain, wasting precious energy and leaving the body vulnerable to an attack by the second strain. Many doctors believe that since so few people show symptoms the when get dengue those that do display symptoms probably have gotten the disease a second time from a second strain. Getting the disease twice for two different strains seems to provide immunity for life from all strains of dengue fever.

History of Dengue Fever

Dengue fever and yellow fever are so closely related they are regarded as sister diseases. Dengue was first identified about 300 years ago but remained an isolated problems until it was spread around Asia and Pacific by troops during World War II. Both dengue and yellow fever were thought to have been close to eradication in the 1940s but have since made comebacks. The disease took off in crowded conditions in Asia. By 1975 it was a leading cause of hospitalization and death among children in the region.

From Southeast Asia dengue fever made its way to India, Africa, the eastern Mediterranean and finally to the Americas where it emerged as a threat in the 1970s just as campaigns to stamp out yellow fever in Latin America were declared a success.

Several new strains of the dengue virus have emerged in Asia and Latin America since the mid-1970s. The disease was a problem in Latin America and the Caribbean in the 1980s and 90s. It first took hold in Central and South America and progressed into Caribbean and the southern United States. There were 116,000 infections in Latin America alone in 1990. Cases have been reported in Florida and Hawaii.

In recent years there have been severe outbreaks of nasty forms of dengue fever and of DHF in Southeast Asia. See Thailand, Indonesia and Southeast Asia.

One Person’s Experience with Dengue Fever

Dengue fever often begins with a headache and an achy feeling. The headaches seems to migrate towards the eyes behind the sockets as fever takes hold rises. If full-blown symptoms take hold the pain spreads throughout the entire body.

One suffer who was struck by dengue fever in Singapore wrote in the New York Times, “Not for nothing is dengue also known as breakbone fever...I, for one, felt as though someone had tied a Brink’s truck to my lower back. My skin was flushed, I could not eat, and I slept 12 to 14 hours at stretch. When I went to my doctor two days later, I could hardly open my blood-stained eyes...The doctor had little choice but to send me home with the painkiller Panadal and some muscle relaxants.”

“A week after my first feverish night, a doctor looked at the tiny pinpricks of blood under the skin on my shoulders, and sent me for a blood test, which confirmed that I had dengue...My first blood tests also revealed that my platelets---the cells that allow blood to clot and prevent hemorrhaging---had dropped to almost half of what doctors consider normal. They weren’t low enough for me to be hospitalized for transfusions, fortunately, but they were low enough to earn me daily blood tests to make sure.”

“The virus had inflamed my liver, as well, sending liver enzymes into my bloodstream, another mysterious symptom. For weeks after my fever subsided and my platelets returned to normal, I was still laid out, lethargic and giddy. My appetite returned slightly, but food and even water tasted strangely unpleasant...A month of afternoon naps later I was completely recovered.”

Dengue Fever Mosquitos

Where dengue fever is found in Africa, Asia and Oceania Aedes aegypti is a small, dark mosquito with white markings and banded legs. It originated in Africa and made its way around the globe centuries ago when it hitchhiked on transoceanic voyages.

Aedes aegypti mosquitos prefer to feed on humans during the daytime and are most frequently found in or near human habitations. They are most likely to bite during a period of several hours in the late afternoon before dark and for several hours after day break.

In 2007, scientists published the genome---a map of all the DNA---of the Aedes aegypti, the mosquito that carries yellow fever and dengue fever. It turns out the genetic make up of this mosquito is more complex than the one that carries malaria. Both Aedes aegypti and the mosquito that carries malaria have about 16,000 genes but the genome for Aedes aegypti is about five times larger.

Dengue Fever Treatment and Prevention

Dengue fever has no vaccine and no cure. Most victims that show symptoms recover on their own with rest and hospital care. Dengue fever can be avoided by staying out of endemic areas (the Center of Disease Control can tell you where they are) and protecting oneself against mosquitos.

Dengue outbreaks often have followed unusually hot, rainy and humid conditions. The danger of dengue fever rises when there is a lot of stagnant water for mosquitos to breed in. In some places where it rains a lot people get infected every two or three years as their immunity from the previous illness lasts only a year and they get infected again..

Developing a vaccine against dengue fever is difficult because one a vaccine has to be developed that can work on all the strains.. Scientists are tinkering with the genetic material of 17D to come with a vaccination for dengue fever. See Yellow Fever.

Scientist were able to wipe out mosquitos that carry Dengue fever in a village in northern Vietnam by using a one-eyed crustaceans that lives in ponds where mosquitos breed and has a large appetite for the larvae mosquitos that carry Dengue fever.

There are concerns dengue fever could spread northwards, even becoming common place in the United States, as result of global warming. Already species capable of carrying the disease have been found in 28 states in the U.S. and as far north as the Netherlands in Europe. Cases of dengue fever have been reported in all 50 U.S. states but people who had it contacted the disease abroad and brought it home.

Dengue Ravages Laos in 2012

In September 2012, Radio Free Asia reported: “Dengue fever cases have flooded hospitals in northwestern Laos. The disease is striking Laos and Cambodia in particular at a time when the two countries are contending with seasonal outbreaks of malaria and other infectious tropical illnesses, and as they struggle with weak health care infrastructure systems. Dengue fever is caused by a virus transmitted by mosquitoes and mostly affects younger children. Symptoms include fever, headache, muscle and joint pains, and a characteristic skin rash that is similar to measles. The infection occasionally develops potentially lethal complications. [Source: Radio Free Asia, September 20, 2012]

In Laos, cases have more than tripled up to late August this year from the same period last year to 3,758 from 1,173, according to the World Health Organization (WHO). Nine deaths have been reported so far this year. In northwestern Laos, the country’s worst-hit Oudomxay province has seen hospitals flooded with patients as officials bring in dozens of additional beds to cope with the rising demand for treatment. But they say that the buildings are now overcrowded and that many people have been forced to sleep outside in tents. “The hospitals are packed. We set up 30 additional beds and tents outside of the building and along the hallways to accommodate the patients,” said one provincial hospital official, who asked to remain anonymous. “The number of cases keeps increasing.”

According to an official report, the number of patients in Oudomxay province suffering from dengue fever reached 1,124 on Sept. 9. The report said that all provincial and military hospitals had been filled and that the provincial health department has been forced to hire more health workers and volunteers to handle the recent increase in patients. The Oudomxay health official said that resources are strained in the impoverished province and called for assistance to meet the growing needs of health care workers trying to treat patients. “We are asking individuals and private businesses to donate money, water, and other materials to help health workers who are working hard, day and night. They are exhausted,” he said. “The most badly needed supplies are coffee and drinking water. We also ask that the public lend their support by helping to destroy the mosquito population and their habitat.”

Dengue Fever in Vietnam

Dengue fever infects between 50,000 and 100,000 people in Vietnam every year, killing nearly 100, according to figures from Vietnam’s Health Ministry cited in a report on the government website. Large outbreaks of the virus, which first appeared in Vietnam in 1969, tend to occur every three or five years, according to health experts, and this year is within the circle of heavy infection. Dengue fever strikes mostly in the rainy season in the summer. September marks the peak of the annual dengue fever season.

In 1998 there were 235,000 cases in Vietnam, with 383 deaths. In 2005 Vietnam reported 49,400 cases of dengue fever infections, including 51 fatalities, 32.7 percent and 49.5 percent from the previous year, respectively, according to the country's General Statistics Office. In 2004 Vietnam reported 73,300 cases of dengue fever infections, including 101 fatalities, up 108 percent and 74 percent against the year earlier, respectively. To minimize the number of new infections, local health workers have encouraged residents to kill mosquitoes and their larvae more actively. More chemicals used to kill the insect are given to the residents.

Vietnam has responded to the increase in cases in the Mekong Delta by spraying for mosquitoes in urban areas and urging rural families to kill mosquitoes and try to avoid their bites. Most of the sufferers are from the provinces of Hau Giang, An Giang and Dong Thap, where weather conditions and local people's habit of storing water in containers at their houses favored the development of mosquitoes -- the disease's transmitter.

In Vietnam, the WHO said some 29,010 dengue cases with 20 deaths were reported in 2012 up to the end of July 2012 with 22,853 cases and 22 deaths in all of 2011. [Source: Radio Free Asia, September 20, 2012]

Dengue Fever Outbreak in Cambodia in 2007

A total of 407 people died of dengue fever and nearly 40,000 were infected with it in 2007, most them children, according to the Cambodian Health Ministry . This was the highest toll in nearly a decade. Major outbreaks began in May. In 1998, 424 people died from it and 16,000 were infected.

Ek Madra of Reuters wrote: “Dawn has not yet broken but already more than 1,000 sick children queue outside a hospital in Phnom Penh in a desperate wait to get treatment for dengue. Dengue has killed 389 people in Cambodia, nearly all of them children. "Please help my grandson. He has had a fever for three days now," pleads 50-year-old Loung Neang, tears rolling down her cheeks as she cradles the listless body of an 18-month-old child outside the hospital before dawn. She traveled 80 kilometers the previous day from the eastern province of Kampong Cham, where medical facilities are nearly non-existent. But she arrived at the overcrowded hospital too late to have the child admitted and must wait another 24 hours for a bed to open up when patients are discharged. Whether her grandson will live that long is another question. Outside the hospital, waiting children lie on reed mats on the ground, their arms hooked up to saline drips hanging from the trees. [Source: Ek Madra, Reuters, October 17 2007 )(]

“Dengue has infected more than 38,000 people in Cambodia so far this year, government figures show. "Every day, every ten minutes, a child is arriving in shock, without a pulse and with no blood pressure," said Beat Richner, a Swiss doctor and founder of four donor-funded hospitals in the war-scarred Southeast Asian nation. In all, his clinics can treat 900 infants, but it is not enough. "More will die as the dengue continues to spread," he said. )(

"I am poor and can't afford a private clinic. Where should I go now?" 43-year-old Pov Sokhom shouted at the policemen keeping order at the hospital gates as she covered her 7-month-old granddaughter with a wet cloth to keep her cool. The child's mother is working in one of the many garment factories around Phnom Penh, leaving parental duties to grandparents. )(

“Even though dengue has always been a rainy season threat in the tropical Southeast Asian nation, Richner said this year appeared to be the worst yet despite government and World Health Organization (WHO) campaigns. He blamed the domestic and international authorities, which are responding to higher-than-normal levels of dengue across the region, for being slow to act even when it became clear in May that 2007 was going to be a bad year. "That is very sad. It's a huge suffering for the children," he said. )(

“The WHO, United Nations Development Program, Asian Development Bank and International Red Cross have all chipped in to help provide pesticides to kill mosquito larvae. Richner's Kantha Bopha hospitals, which offer advanced medical facilities to Cambodians for free, need $7 million a year to keep themselves afloat, but the size of the dengue outbreak is already causing them to eat into next year's budget. Furthermore, raising cash is becoming harder because of Western preoccupation with diseases like bird flu, he said. "Bird flu is a threat to the Western world, so they pour money and commitment into that," he said. "But dengue? There's no threat to the United States or Europe so nobody's interested." )(

Dengue Fever Ravages Cambodia in 2012

In September 2012, Radio Free Asia reported: “Dengue fever cases in Cambodia have reached an “alarming level” with deaths rising rapidly. The disease is striking Cambodia at a time when the two countries are contending with seasonal outbreaks of malaria and other infectious tropical illnesses, and as they struggle with weak health care infrastructure systems. Dengue fever is caused by a virus transmitted by mosquitoes and mostly affects younger children. Symptoms include fever, headache, muscle and joint pains, and a characteristic skin rash that is similar to measles. The infection occasionally develops potentially lethal complications. [Source: Radio Free Asia, September 20, 2012]

In Cambodia, the Ministry of Health announced that an epidemic in the country had reached an “alarming level,” with Banteay Meanchey, Siem Reap, Oddor Meanchey, and Kandal provinces most severely affected. Senior health officials reported that in the first eight months of the year, the disease had killed 134 children, up from only 48 deaths last year, and sickened 32,000 others, compared to only 11,020 cases a year ago. Among the fatal cases, 70 percent died of gastrointestinal bleeding They said that the outbreak is the worst since 2007, when at least 400 children died and more than 36,000 children were sickened.

Director of the National Center for Parasitology, Entomology and Malaria Control Chor Meng Chour said the Ministry of Health is focusing on the provinces that have been affected by heavy rainfall, which creates conditions for mosquito breeding. “This year … the outbreak has lasted longer,” he said. “Right now, the epidemic has surpassed the national red line.”

In Cambodia, the outbreak of dengue fever usually begins at the onset of the rainy season in May and lasts until October. Meas Ly, a 70-year-old villager from Kompong Cham province, said the residents of his district don’t have enough larvicide to prevent mosquitoes from breeding in swamp areas and local waterways. “We don’t have Abate yet,” he said, referring to a larvicide product. “We want the government to distribute Abate to us.” Ministry of Health officials said they have reserved about 320 tons of Abate for distribution but so far have released only half of that. They said the ministry spends around U.S. $2.5 million annually to fight the disease.

In October 2012, Xinhua reported: “At least 34,483 dengue fever cases were reported in Cambodia in the first nine months of this year, a 166 percent increase compared with 12,972 cases in the same period in 2011, a report of the National Center for Parasitology, Entomology and Malaria Control showed. From January to September 2012, the disease had killed 146 Cambodian children, up 147 percent compared with 59 deaths during the same period in 2011. "The disease continues to kill between 3 and 5 children a week," said Dr. Char Meng Chuor, director of the center. He explained that there were more deaths this year because parents had sent their ill children to private clinics first, and when the treatment was ineffective and the disease became more severe, they would send them to public hospitals, but it was too late for them to be cured. Char Meng Chuor said to prevent the outbreak, the center has distributed some 270 tones of Abate (a chemical substance used to kill larvae in water pots) to households this year.[Source: Xinhua, October 3, 2012]

Ek Madra of Reuters wrote: “There is no vaccine for dengue but even if a treatment existed, the Health Ministry, which has an annual budget of $3 for each of Cambodia's 13 million people, would struggle to afford it. Instead, the Health Ministry focuses its efforts on prevention, telling people in towns and villages to use mosquito nets, keep an eye on their children, burn rubbish and not allow pools of stagnant water, where the insects breed, to collect. "We can change lots of things, but changing people's behavior is hardest of all," said Ngan Chantha, head of the ministry's anti-dengue program. "We tell them what to do, but as soon as we go away, they revert to their old habits." Many people disagree, saying it is impossible to keep an eye on children when so many mothers and fathers have to work to provide for their families in what remains one of the poorest countries in Asia. [Source: Ek Madra, Reuters, October 17 2007]

Dengue Fever and Flooding in the Mekong Delta

In December 2001, Associated Press reported: “Dengue fever is renewing its grip in Vietnam as devastating flood waters help to provide an ideal breeding ground for disease-carrying insects, official media said Friday. Eighty-one people died from the disease this year, marking a 59 percent increase on the previous 12 months, Tuoi Tre (The Youth) newspaper said. An epidemic of the mosquito-borne ailment, which has coincided with disastrous flooding in parts of the country, has also left more than 39,563 people sick, The outbreak is particularly rife in the Mekong Delta region in the south, where moist and humid conditions provide perfect conditions for mosquitoes, the paper added. Dengue fever, an infectious disease of African origin which first appeared in Vietnam in 1969, killed 380 Vietnamese in 1998 but only about 50 people in each of the subsequent two years. [Source: The Associated Press, December 28, 2001]

In 2004, AFP reported: “Eighty-seven people have died in Vietnam from mosquito-borne dengue fever since the beginning of the year, an increase of 64 percent over the same period in 2003, officials said on Thursday. The deaths were among nearly 60,000 reported infections, an 83 percent rise year-on-year, said Tran Hung, head of the health ministry's epidemiology department. The worst affected provinces were in the southern Mekong Delta region where moist and humid conditions provide ideal breeding grounds for mosquitoes. The region accounted for more than 95 percent of cases, Hung said. Experts have also blamed an unusually lengthy spell of hot and humid weather for the increased infection rate. Health authorities have launched clean-up campaigns to eliminate stagnant water to prevent mosquitoes from breeding. They have also set up mobile emergency teams to treat victims. [Source: Agence France Presse, October 21, 2004]

in 2007, Deutsche Presse Agentur reported: “Mosquito-borne dengue fever has killed at least 60 people in Vietnam so far this year with a nearly 50-per-cent rise in reported cases, an official said Tuesday. At least 68,000 people have come down with dengue fever in Vietnam so far this year, up 48 percent from the same time last year, said Nguyen Huy Nga, director of the Preventative Medicine Department under the Ministry of Health. "Most of the victims are people under 15 years old in the Mekong Delta region, which is exposed to rainfall and a long period of sunshine," Nga said. "Those are perfect conditions for the proliferation of mosquitoes." However, speedy treatment and public awareness has meant that the number of deaths have not risen significantly in Vietnam, where 55 people died of dengue during all of last year. [Source: Deutsche Presse Agentur - September 25, 2007]

Dengue Fever in Vietnam in 2013

In the first six months of 2013 dengue fever infected more than 13,900 people, killing ten, Vietnam health ministry said.“Thang Noen reported: “Dengue fever is raging again in many central Vietnam provinces. Tran Nhu Son, 41, was confirmed the first casualty of dengue fever in Phu Yen Province this year. He died on July 3 of stomach hemorrhage two days after admitted to hospital, news website VnExpress reported. Nine people in his neighborhood were later found to have the same fever. The Phu Yen Health Department has counted around 1,140 cases of dengue fever so far this year, up nearly four times year-on-year. Its neighbor Binh Dinh Province has reported nearly 1,300 infections including one death during the first half, and although specific figures have not been given, officials say the number is many times more than during the same period last year. [Source: Thanh Nien, July 12, 2013 \=/]

“Bui Ngoc Lan, director of the Binh Dinh Preventive Health Center, said he is worried about a sharp increase in the number of cases during the remaining months of the year, especially with the onset of the rainy reason. He said local authorities need to work with the residents to destroy larvae at each house. “That is the only way we can hope to prevent dengue fever.” \=/

“A Lao Dong report cited authorities in Khanh Hoa, south of Phu Yen, as saying the province has recorded the highest number of dengue fever infections in the country this year at 3,180 as of the end of last month, 3.5 times more than the same period last year, including two deaths. It cited an unnamed source from the provincial health department as saying the disease has not reached its peak, but all medical facilities are already filled up with patients. \=/

“The provincial government has allocated an additional VND1 billion (US$47,090) from its budget towards urgent preventive measures. Khanh Hoa was also the hardest hit in the central region last year with 5,300 infections including five fatalities. Vien Quang Mai, deputy head of the Pasteur Institute for the central region, located in Nha Trang, said people in the coastal provinces have unwittingly turned the lack of tap water supply into an advantage for mosquitoes to breed. He said locals would store rainwater in jars which are “very convenient environments” for the mosquitoes. \=/

“Furthermore, the situation in the area has become complicated due to the existence of four different strains of the virus, possibly a result of climate change, Mai said. Health authorities in the region have been sending out teams to kill mosquitoes and their larvae using chemicals and by cleaning water containers. Officials from Khanh Hoa Health Department and experts from the National Institute of Hygiene and Epidemiology as well as the Nha Trang Pasteur Institute are also working on a scientific project that seeks to erase dengue fever from the country by replacing the current species of mosquito with new ones that carry Wolbachi, a bacteria genus that has been linked to viral resistance in mosquito species. The project, which follows similar ones in China, Brazil, Singapore and Thailand, started with the release of around 200,000 Wolbachi-carrying larvae into local water containers in early April. Family Health International, a US-based non-governmental organization specializing in public health issues, is the project sponsor. \=/

Vietnam Releases Mosquito with Bacteria That Blocks Dengue Fever

In November 2013, Associated Press reported from Tri Nguyen Island: “Nguyen Thi Yen rolls up the sleeves of her white lab coat and delicately slips her arms into a box covered by a sheath of mesh netting. Immediately, the feeding frenzy begins. Hundreds of mosquitoes light on her thin forearms and swarm her manicured fingers. They spit, bite and suck until becoming drunk with blood, their bulging bellies glowing red. Yen laughs in delight while her so-called "pets" enjoy their lunch and prepare to mate. [Source: Associated Press, November 15, 2013 |:|]

“The petite, grandmotherly entomologist -- nicknamed Dr. Dracula -- knows how crazy she must look to outsiders. But this is science, and these are very special bloodsuckers. She smiles and nods at her red-hot arms, swollen and itchy after 10 minutes of feeding. She knows those nasty bites could reveal a way to greatly reduce one of the world's most menacing infectious diseases. All her mosquitoes have been intentionally infected with bacteria called Wolbachia, which essentially blocks them from getting dengue. And if they can't get it, they can't spread it to people. |:|

“So how can simple bacteria break this cycle? Wolbachia is commonly found in many insects, including fruit flies. But for reasons not fully understood, it is not carried naturally by certain mosquitoes, including the most common one that transmits dengue, the Aedes aegypti. The germ has fascinated scientist Scott O'Neill his entire career. He started working with it about two decades ago at Yale University. But it wasn't until 2008, after returning to his native Australia, that he had his eureka moment. |:|

“One of his research students figured out how to implant the bacteria into a mosquito so it could be passed on to future generations. The initial hope was that it would shorten the insect's life. But soon, a hidden benefit was discovered: Wolbachia-infected mosquitoes not only died quicker but they also blocked dengue partially or entirely, sort of like a natural vaccine. "The dengue virus couldn't grow in the mosquito as well if the Wolbachia was present," says O'Neill, dean of science at Monash University in Melbourne. "And if it can't grow in the mosquito, it can't be transmitted." The Australians tapped 58-year-old Yen at Vietnam's National Institute of Hygiene and Epidemiology, where she's worked for the past 35 years. Their plan was to test the Wolbachia mosquitoes on a small island off the country's central coast this year, with another release expected next year in Indonesia. |:|

“Just getting the mosquitoes to Tri Nguyen Island was an adventure. Thousands of tiny black eggs laid on strips of paper inside feeding boxes had to be hand-carried inside coolers on weekly flights from Hanoi, where Yen normally works, to Nha Trang, a resort city near the island. The eggs had to be kept at just the right temperature and moisture. The mosquitoes were hatched in another lab before finally being transported by boat. Yen insisted on medical checks for all volunteer feeders to ensure they weren't sickening her mosquitoes. She deemed vegetarian blood too weak and banned anyone recently on antibiotics, which could kill the Wolbachia. "When I'm sleeping, I'm always thinking about them," Yen says, hunkered over a petri dish filled with dozens of squiggling mosquito pupae. "I'm always worried about temperature and food. I take care of them same-same like baby. If they are healthy, we are happy. If they are not, we are sad." |:|

“Vietnam has logged lower numbers this year overall, but the country's highest dengue rate is in the province where Yen is conducting her work. At the area's main hospital in Nha Trang, Dr. Nguyen Dong, director of infectious diseases, says 75 of the 86 patients crammed into the open-air ward are infected with the virus. Before jabbing his fingers into the stomach of one seriously ill patient to check for pain, he talks about how the dengue season has become much longer in recent years. And despite the government's increased education campaigns and resources, the disease continues to overwhelm the hospital. |:|

“If the experiment going on just a short boat ride away from the hospital is successful, it eventually will be expanded across the city and the entire province. The 3,500 people on Tri Nguyen island grew accustomed to what would be a bizarre scene almost anywhere else: For five months, community workers went house-to-house in the raging heat, releasing cups of newborn mosquitoes. And the residents were happy to have them. "We do not kill the mosquitoes. We let them bite," says fisherman Tran To. "The Wolbachia living in the house is like a doctor in the house. They may bite, but they stop dengue." |:|

“Specimens collected from traps are taken back to the lab for analysis to determine how well Wolbachia mosquitoes are infiltrating the native population. The strain of bacteria used on the island blocks dengue 100 percent, but it's also the hardest to sustain. At one point, 90 percent of the mosquitoes were infected, but the rate dropped to about 65 percent after the last batch was released in early September. A similar decrease occurred in Australia as well, and scientists switched to other Wolbachia strains that thrive better in the wild but have lesser dengue-blocking abilities. The job is sure to keep Yen busy in her little mosquito lab, complete with doors covered by long overlapping netting. And while she professes to adore these pests nurtured by her own blood, she has a much stronger motivation for working with them: Dengue nearly claimed her own life many years ago, and her career has been devoted to sparing others the same fate. "I love them," she says, "when I need them." |:|

Tiny a One-eyed Crustaceans Conquers Dengue in Vietnam Village

Scientist were able to wipe put mosquitos that carry dengue fever in a village in northern Vietnam by using a one-eyed crustaceans that lives in ponds where mosquitos breed and has a large appetite for the larvae mosquitos that carry Dengue fever. Reuters reported from Nam Dinh: “Scientists have wiped out mosquitoes that carry the potentially fatal dengue fever in a village in northern Vietnam, a feat believed to be a world first.Pivotal to their success is a microscopic, one-eyed crustacean, which is eating its way into medical history with a voracious appetite for the larvae of dengue-carrying mosquitoes. The experiment was pioneered by Australian and Vietnamese scientists, who say the results could have global implications for combating a disease for which there is still no vaccine nor specific cure. [Source: Reuters, July 30, 1999 ^^]

"Dengue-carrying mosquitoes were wiped out in the village of Phan Boi within 18 months,'' said Ahmet Bektas, country director for the Australian Foundation for Peoples of Asia and the Pacific, which oversees the scientific project. The American Society of Tropical Medicine and Hygiene recently hailed the project as the first anywhere in the world to eradicate the dengue-carrying Aedes mosquitoes. "The great fear is that it's spreading,'' Jeremy Farrar, a dengue fever expert at Britain's Oxford University, said after observing the project in Nam Dinh, south of Hanoi. But in Vietnam, which has one of the highest regional rates of dengue infection, the shrimp-like crustacean mesocyclops -- named partly after the one-eyed maneaters of Greek mythology -- is making inroads by preventing the spread of the disease. ^^

It has enabled scientists in Vietnam to reduce dengue-carrying mosquitoes by 96 percent across 45 villages, completely wiping them out in at least one, Phan Boi. But the tiny creature does not act alone. Villagers ensure the mesocyclops, which occurs naturally in Vietnam and other countries, are put into household water supplies where mosquitoes commonly breed. It is too early to predict the global implications of the experiment's success, but long-time project participant John Aaskov, who works with the WHO in Australia, is optimistic. "This program is going to be of benefit wherever people want to try it, certainly throughout the region,'' said Aaskov, adding it could also be used in Africa and South America. ^^

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© 2008 Jeffrey Hays

Last updated April 2014

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