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Dengue Fever
What is Dengue?Dengue fever is a disease spread by the vector called Aedes mosquito, which breeds on still water that gets collected especially after the end of the summer. It is primarily transmitted by the bite of an infected mosquito but it is non-contagious i.E. It never transmits from one person to another.
When a mosquito bites a person already infected with dengue, the virus transfers to the salivary gland of the mosquito—when this infected mosquito bites a human, the virus gets transmitted to the person. The mosquito usually bites in the daylight. Dengue is also known as the break-bone fever and typically occurs in tropical regions.
Fast Facts about DengueThe dengue virus affects the platelet production in dengue patients. The general lifespan of platelets is about 4 days and the normal count is between 1.5 and 4.5 lakhs. Dengue virus affects the body's ability to form new platelets and decrease the number of platelets already present; the decrease in the platelet count is known as thrombocytopenia. The disability of the body to form new platelets also affects the body's ability to form blood clots. A reduction in the platelet count ups the risk of a brain haemorrhage or bleeding. If the count becomes lower than 20,000-25,000/mm3, then your doctor may recommend platelet transfusion.
Symptoms of DengueThe symptoms can be seen only after 3-7 days after a person is bitten by the mosquito. The symptoms of dengue include:
The symptoms may disappear after a couple of days and these symptoms only occur at the earliest stage of the fever. More symptoms are seen when the dengue progresses into one of its severe forms: Dengue Shock Syndrome and Dengue Hemorrhagic Fever. These two are rare complications of dengue and they can be life-threatening.
Complications of Dengue Dengue is mainly characterized by sudden fever accompanied by severe headaches, joint and muscle pains, nausea, vomiting, skin rash and nose or gum bleeding. But lack of treatment could lead to complicated forms of dengue fever, which are: Dengue Hemorrhagic Fever -This is a severe complication of dengue fever. It can be fatal if left untreated. The symptoms of hemorrhagic fever are similar to dengue fever but the former is more severe. If the disease is not severe, the signs and symptoms decrease after the fever resolves.
A person suffering from dengue hemorrhagic fever may experience:
This bleeding may lead to purplish bruises. But in some cases, symptoms of dengue fever resolve and signs of circulatory failure develop which can rapidly progress to severe shock, which can then lead to death within 12-24 hours.
Dengue Shock Syndrome -This is the most severe condition of dengue and the patient should be taken to the hospital immediately if there is:
Dengue shock syndrome could also lead to an organ dysfunction because of low blood pressure. It occurs in only about 5% of the dengue patients but if it is detected, the patient should immediately be taken to the hospital.
Dengue and PregnancyThe signs and symptoms of Dengue fever and DHF in Pregnancy is similar to that in the non-pregnant patient. In pregnancy infections with dengue virus is not more severe as compared to a non-pregnant patient as in the case, for instance, of malaria. Infection with dengue virus does not increase the risk of foetal malformation or deformity.
Dengue fever can affect the unborn baby. The risks in the unborn child include:
People of all age group suffer from dengue fever. Clinical diagnosis of dengue fever can be difficult as the signs and symptoms of dengue fever are similar to that of a viral fever, malaria or typhoid fever. To confirm the diagnosis your doctor will test your blood for the presence of dengue virus.
Tests done to confirm a diagnosis of dengue fever include a serum or autopsy tissue sample, which is taken to identify the virus. Reverse transcriptase-polymerase chain reaction (RT-PCR) test is also used to identify the virus. The Dengue ELISA test is done to test for IgG and IgM antibodies to dengue virus.
Serological TestsAcute dengue virus infection is most frequently confirmed by the use of serological tests. Dengue viral antigen can be detected for early diagnosis of the disease. The tests are carried out to detect dengue and also to ascertain the acuteness of the infection. When there is an increase in the dengue antibodies between initial and later samples, the infection is confirmed as acute.
MAC-ELISAThe MAC-ELISA test is used for rapid confirmation of dengue fever. It needs to be repeated every 10 to 14 days in case the initial test was negative. The samples collected initially and later can be analyzed through what is called hemagglutination inhibition (HI) or made to undergo enzyme immunoassays for definite confirmation or denial of acute dengue infection.
Complex TestsThere are some complex tests called complement fixation and neutralizing antibody which are not possible in every medical centre. Since these assays are very technically demanding, they are possible only in specialized laboratories.
Dengue Virus IsolationSeparation of dengue virus or detecting dengue viral RNA in a patient's sample of serum or tissue gives a confirmation of the infection. But these assays have limited application because of their complex techniques. They are generally performed for the purposes of different types of medical research.
Treatment of Dengue FeverPeople with uncomplicated dengue fever improve within two weeks. Treatment offered to people suffering from the mild dengue fever includes:
The treatment offered to people suffering from the severe form of the disease includes:
Prompt and judicious administration of fluids (oral and intravenous), supportive care and good monitoring (blood pressure, heart rate, and fluid status) in patients with DHF or DSS can prevent complications and even death.
Prevention from DengueThe bite of the Aedes mosquito can be prevented by:
To Combat Dengue, Brazil's Health Agents Scour Junkyards, Roofs For Mosquitos
RIO DE JANEIRO -- The small team of state public health workers slalomed between auto parts strewn across a Rio de Janeiro junkyard, looking for standing water where mosquitoes might have laid their eggs.
They were part of nationwide efforts to curtail a surge in Brazil of the mosquito-borne illness of dengue fever during the country's key tourist season that runs through the end of February.
Paulo Cesar Gomes, a 56-year-old entomologist, found some mosquito larvae swimming in shallow rainwater inside a car bumper.
"We call this type of location a strategic point" because of the high turnover in items converging from all over, he said. "It's difficult not to have mosquitoes here."
Earlier in the month, just days before Rio kicked off its world-famous Carnival festivities, the city joined several states and the country's capital in declaring a public health epidemic over this year's greater-than-normal number of cases of dengue.
"We had more cases in January than any other January," Ethel Maciel, PhD, head of health surveillance at Brazil's Health Ministry, said in an interview with the Associated Press.
So far this year, Brazil has recorded 512,000 cases nationwide, including both confirmed and likely cases -- nearly four times more than those registered in the same period a year ago.
There have been 425 deaths under investigation for dengue so far this year, with 75 confirmed, as compared with just over 1,000 for all of 2023.
Dengue is a viral infection transmitted to humans through the bite of infected mosquitoes. Frequent rains and high temperatures, which accelerate the hatching of mosquito eggs and the development of larvae, make the famously hot city of Rio especially susceptible to outbreaks.
Many who are infected never develop symptoms, but dengue can cause high fever, headache, body aches, nausea, and a rash, according to the World Health Organization. While most get better after a week or so, some develop a severe form that requires hospitalization and can be fatal.
Health workers like Gomes, equipped with masks and plastic gloves, meticulously combed the junkyard on a hot morning, gently kicking and shaking piled up auto parts looking for any trace of the Aedes aegypti mosquito that can spread dengue.
Whenever he saw standing water Gomes grabbed a hand pipette out of his bag and looked for larvae, which he collected in a white plastic container. Captured mosquitoes and larvae are kept alive and brought to a city laboratory to be tested for dengue.
At locations with positive tests, health agents spray the walls with a product that kills mosquitoes and then monitor the location for weeks.
Maciel, from the Health Ministry, said the first warning about a possible epidemic came in September.
Brazil's leading research institute, the state-funded Oswaldo Cruz Foundation, or Fiocruz, came up with several scenarios indicating that Brazil could have as many as 4.2 million cases this year, up from 1.6 million in 2023.
Maciel said the surge is due to excessive heat and intense rain, both possible effects of climate change or El Niño, a natural, temporary and occasional warming of part of the Pacific that shifts weather patterns across the globe.
Maciel also cited the circulation of four dengue virus serotypes at the same time, one of which authorities had not seen in 15 years.
In Rio, more than 80% of mosquito breeding sites are located in residential properties, health officials say. So, efforts to combat dengue must start in homes, and raising awareness is key, said Mário Sérgio Ribeiro, a health surveillance official for Rio de Janeiro state.
State officials launched a "10 minutes that save lives" initiative to encourage residents to inspect their homes, offices, and places of worship for any standing water.
Health workers and volunteers went door to door, pacing up and down the narrow streets of Rio's Tabajara working-class neighborhood, or favela, to spread the word. They distributed leaflets and climbed on rooftops, looking for containers with rainwater.
One elderly woman, Vilza da Costa, told the AP she believes she contracted the disease.
"It started with a fever, then my body was itching all over, weakness, and a lot of pain. I was in a very bad way," she said. "There are a lot of mosquitoes here."
During Carnival, which ended Wednesday, health employees welcomed visitors with free repellent. A van with a giant crossed off mosquito and the words "Against Dengue Everyday" opened and closed the parades several nights, for millions of TV viewers to see.
Maciel said the effect of Carnival will not be known for another week. Even though dengue is not transmissible from person to person, increased tourism can boost the spread of the disease to locations that had not been affected.
It's not clear if the cases have reached a peak and now "are going to start going down, or if the worst-case scenario is indeed happening," Maciel said.
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Dengue Fever: What You Need To Know About The Mosquito-Borne Threat Surging Worldwide
ToplineBrazilian health officials are working to contain a growing outbreak of dengue fever as crowds prepare to pack city streets to celebrate Carnival, amid a global surge in cases as experts warn climate change could allow the mosquitoes carrying the disease to expand their range into previously inhospitable areas.
Female Aedes aegypti mosquitoes are carriers of the Dengue fever, which was found in Arizona.
Getty Images Key FactsDengue, often called "breakbone fever" for the severe muscle pain it causes, is caused by viruses spread through the bites of infected female mosquitoes, normally the highly invasive Aedes aegypti.
Dengue infects an estimated 400 million people each year and around half of the world's population live in areas at risk of dengue outbreaks, including parts of the continental US, where the mosquito carrying the disease is common.
The vast majority of dengue infections are asymptomatic or mild—around a quarter (25%) of people infected with dengue will get sick, though its flu-like symptoms including fever, rash, headache, nausea and vomiting often mean it is confused with other illnesses.
Around 1 in 20 of the people getting sick will develop severe dengue, a serious and potentially fatal medical emergency that often requires hospitalization and can cause severe muscle pain, shock, internal bleeding and organ damage.
There is no specific medicine to treat dengue and for most people the disease will go away on its own after a week or two and can be managed with rest, staying hydrated and the use of fever reducers and painkillers, though blood thinning drugs like aspirin and ibuprofen should be avoided.
Without proper medical treatment, the mortality rate of severe dengue can be as high as 20%, 1 in 5, though access to care can lower the fatality rate to below 1% and experts say maintaining the patient's body fluid volume is critical.
News PegBrazil has launched a mass vaccination campaign in an effort to control a dramatic uptick in dengue. Several states have declared emergencies and troops have reportedly been deployed to eliminate breeding hotspots for mosquitoes spreading the disease. The country's health ministry said nearly 365,000 cases were reported in the first five weeks of 2024, four times the number from the same period last year. The outbreak has already caused 40 confirmed deaths, with 265 more under investigation. Cities like Rio de Janeiro have taken steps to prevent the outbreak from spiraling as they prepare for crowds celebrating Carnival in coming weeks. The outbreak in Brazil comes as part of a noted upsurge in dengue globally that has alarmed health officials. There were over 6 million dengue cases and over 6,000 dengue-related deaths in 2023, according to the European Centre for Disease Prevention and Control. Infections were reported from 92 different countries and territories, the agency said, and most cases were reported in the Americas. Infection hotspots included Brazil, Bangladesh, Mexico, Peru and Burkina Faso. The agency also warned of an uptick in diseases carried by the same mosquitoes like Zika and chikungunya.
Big Number2,556. That's how many dengue cases were reported in the U.S. In 2023, according to the CDC. Cases in the US are relatively rare and many are linked to travel—1,104 of overall cases were acquired locally and reported in people with no history of travel to a dengue-endemic region—though experts warn climate change could make the US more hospitable to the virus' mosquito vectors.
Key BackgroundDengue is a leading cause of illness and death in many parts of the world, particularly in some Asian and Latin American countries, the World Health Organization says. Cases have risen sharply in recent decades—eightfold over the past 20 years—though part of the alarming rise can be explained by improved reporting practices. Global dengue cases appear to have fallen during the Covid-19 pandemic and research suggests pandemic curbs prevented some 750,000 cases in 2020, though the WHO notes the pandemic may have hampered reporting efforts in some countries. The issue of dengue's prevalence is of renewed importance as world leaders struggle to address the growing climate crisis, which could help the mosquitos carrying the disease make inroads into new parts of the world. Changes to weather and flooding, such as in the aftermath of hurricanes, also pose challenges for preventing the spread of disease. The mosquitos that can carry dengue—as well as a host of other pathogens like West Nile—can multiply rapidly in floodwater and debris left behind after major storms and pose a major public health threat to those recovering from disaster.
Surprising FactThere are four distinct, though closely related, types of virus that cause dengue. Infection with one type of dengue virus does not confer immunity against the others, though recovery is thought to provide lifelong immunity against that particular variant. Counter to what happens with many infections, where a pathogen can generate some form of immune response against a related one, prior dengue infection actually increases the risk of developing severe disease if infected with another variant. Until recently, the issue was a contentious topic among scientists, though many now believe the usually protective antibodies developed after infection can actually help the new dengue variant virus gain ground in the body, worsening the infection.
What To Watch ForThis increased risk of severe disease when exposed to dengue a second time complicated efforts to develop a vaccine for decades and for many years the only available vaccine against dengue has been for people who have already been infected before. In the US, the CDC's United States Advisory Committee of Immunization Practices recommends children and adolescents with a laboratory confirmed infection in the past who are living in dengue endemic regions to get vaccinated with Sanofi Pasteur's shot, Dengvaxia. A vaccine for those who haven't been infected previously—Takeda's Qdenga—is now available, although not universally and has been recommended by many health agencies in areas including Europe, Brazil, Indonesia and Thailand as a means of tackling the disease. The vaccine is an option regardless of previous infection. The company voluntarily withdrew its application to be authorized in the US last year citing data collection issues.
Further Reading MORE FROM FORBESAs Dengue Fever Fears Grow In U.S., First Prevention Pill Has Promising TrialBy Robert HartMORE FROM FORBESFirst Vaccine For Chikungunya-An Emerging Mosquito-Borne Threat-Nears After Promising Trial ResultsBy Robert HartMORE FROM FORBESBrazil Places Millions Under Public Health Emergency On Eve Of Carnival-As Dengue Outbreak GrowsBy Zachary FolkScientists solve a dengue mystery: Why second infection is worse than first (STAT News)
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