Dengue Fever Essay Example

Dengue Fever Essay In subtropical and tropical regions, the dengue virus represents a major threat to human health. The microorganisms natural hosts include mosquitoes, lower primates, and humans. Infection of the human host results in a biphasic fever with the potential to evolve into severe hemorrhagic disease. Over the past few decades, the virus genome structure, viral proteins, and viral antigens have been well characterized. Unfortunately though, the precise mechanisms by which the dengue virus causes disease remain unknown. Throughout history, major dengue fever epidemics have generally occurred at irregular intervals within the range of the mosquito vector. For instance, in 1922, one such epidemic may have affected between 1 and 2 million people in the southern United States. At present, dengue fever may cause more human morbidity and mortality than any other arthropod-borne viral disease (Henchal Putnak, 1990, pp. 376-396). The dengue viruses are currently endemic in most tropical areas of the world (Lanciotti, Lewis, Gubler, Trent, 1994, p. 65). It has been estimated that there could be as many as 100 million cases of dengue infection every year (Halstead, 1988, p. 476). The only natural hosts for dengue virus infections are mosquitoes, lower primates (e. g. , chimpanzees, rhesus monkeys, and macaques), and humans. Dengue Fever Dengue fever is a flu-like viral disease common throughout the tropical and sub-tropical regions around the world, mainly in urban and peri-urban areas. Today, it afflicts an estimated 50 million to 100 million in the tropics (Epstein, 2000). The virus has four antigenically related serotypes, which are named DEN-1, DEN-2, DEN-3, and DEN-4. We will write a custom essay sample on Dengue Fever specifically for you for only $16.38 $13.9/page Order now We will write a custom essay sample on Dengue Fever specifically for you FOR ONLY $16.38 $13.9/page Hire Writer We will write a custom essay sample on Dengue Fever specifically for you FOR ONLY $16.38 $13.9/page Hire Writer Each dengue serotype is a variation of the flavivrus genus. Dengue is spread by the aedes aegypti, a domestic, day-biting mosquito that prefers to bite humans. Currently, there is no vaccine available to prevent dengue. Each type of the dengue virus is re-emerging worldwide, especially in the Western Hemisphere. Research has shown that several factors are contributing to the resurgence of dengue fever such as uncontrolled urbanization, increased international travel, substandard socio-economical conditions, and finally global warming. Global warming has shown to be a major contributor o the spread of dengue fever. On a molecular level, dengue fever is classified as a flavivirus and appears as a spherical particle, about 40 to 50 nanometers in diameter Dengue fever Dengue fever, also known as break bone fever, is an acute febrile infectious disease caused by the dengue virus. Typical symptoms include headache, a petechial rash, and muscle and joint pains; in a small proportion the dis ease progresses to life-threatening complications such as dengue hemorrhagic fever or dengue shock syndrome. Dengue is usually transmitted by the mosquito Aedes aegypti, and rarely Aedes albopictus. The virus has four different serotypes, and an infection with one usually gives lifelong immunity to it but only short-term immunity to the others. There is currently no available vaccine, but outbreaks can be prevented by reducing the habitat and number of mosquitoes, and limiting exposure to bites. Treatment of acute dengue is supportive, using either oral or intravenous rehydration for mild or moderate disease and blood transfusions for more severe cases. Rates of infection have increased dramatically over the last 50 years with approximate 50–100  million people being infected yearly. The disease has become global and is currently endemic in more than 110  countries with 2. 5  billion people living in areas where it is prevalent. Classification The World Health Organizations 2009 classification divides dengue fever into two groups: uncomplicated and severe. [1][2] This replaces the 1997 WHO classification, which was simplified as it was found to be too restrictive, but the older classification is still widely used. [2] The 1997 classification divided dengue into undifferentiated fever, dengue fever, and dengue hemorrhagic fever. 3] Dengue hemorrhagic fever was subdivided further into four grades (grade I–IV), with the two most severe being classified as dengue shock syndrome. [2] Signs and symptoms Infections from dengue virus range from asymptomatic, to a simple fever, to life threatening. [1] The incubation period (time between exposure and onset of symptoms) is 4–10 days. Most infections are very mild, and many probably experience no symptoms at all. [1][4] Most commonly symptoms include: sudden onset fever, headache (typically behind the eyes), muscle and joint pains, and a rash; the nickname break-bone fever comes from the associated muscle and joints pains. 1] If fever or other symptoms developed more than 14  days after returning from an endemic area, dengue is very unlikely. [3] The course of infection may be divided into three phases: febrile, critical, and recovery. [5] The febrile phase involves high fevers, frequently over 40  Ã‚ °C (104  Ã‚ °F) and associated with generalized pain and a headache; this usually lasts 2–7  days. [5] Flushed skin and some petechia (point-like hemorrhages in the skin) may occur at this point. [5] The critical phase follows the resolution of the high fevers and typically lasts one to two days. 5] During this phase there may be significant fluid accumulation into the thoracic cavity and abdominal cavity due to increased capillary permeability and leakage. This leads to depletion of fluid from the circulation and decreased blood supply to vital organs. [5] During this phase, organ dysfunction and severe bleeding (typically from the gastrointestinal tract) may occur. [3][5] Shock and hemorrhage occurs in less than 5% of all cases of dengue. [3] Those who have previously been infected with other serotypes of dengue (secondary infection) have an increased risk of developing severe complications. 3][6] The recovery phase occurs next if the person survives with resorption of the edematous fluids. [5] The improvement is often striking, but there may be striking itching and a slow heart rate. [3][5] It is during this stage that a fluid overload state may present with symptoms of cerebral edema such as an altered level of consciousness or seizures. [3] Prevention There are currently no approved vaccines for the dengue virus. [1] Prevention thus depends on control of and protection from the bites of the mosquito that transmits it. [7][17] The primary method of controlling Ae. aegypti is by eliminating its habitats. 7] This may be done by emptying containers of water or by adding insecticides or biological control agents to these areas. [7] Reducing open collections of water through environmental modification is the preferred method of control, given the concerns of negative health effect from insecticides and greater logistical difficulties with control agents. [7] People may prevent mosquito bites by wearing clothing that fully covers the skin and/or the application of insect repellent (DEET being the most effective). [8] There are ongoing programs working on a dengue vaccine to cover all four serotypes. 17] One of the concerns is, that a vaccine may increase the risk of severe disease through antibody-dependent enhancement. [18] The ideal vaccine is safe, effective after one or two injections, covers all serotypes, does not contribute to ADE, is easily transported and stored, and is both affordable and cost-effective. [18] A number of vaccines are currently undergoing testing. [13][18][19] It is hoped that the first products will be commercially available as early as 2015. Warning signs[2] Abdominal pain Ongoing vomiting Liver enlargement Mucosal bleeding High hematocrit with low platelets Lethargic Flood In Pakistan 2010 Flood In Pakistan The devastating flood in Pakistan had destroyed more than half of the economy of the country. The country which was already facing several other crises including terrorism,poverty,corruption,illiteracy    has now hit by another challenge in the form of flood. At this crucial time ,the world has pledge to help Pakistan in any form . U. N. Secretary-General Ban Ki-moon arrived in Pakistan on Sunday August 16 2010    to boost relief efforts as concerns grew about the 20 million people made homeless in one of the worst disasters to hit the country. Authorities said more flood surges were coursing down the River Indus and other waterways in southern Sindh province and were expected to peak later Sunday, causing fresh deluges. The river, which in better times irrigates the crops of millions of farmers, is 15 miles (25 kilometers) wide at some points— 25 times wider than during normal monsoon seasons. The United Nations said the rate of diarrheal disease continued to increase among survivors. Cholera, which can spread rapidly after floods and other disasters, had also been detected in the northwest, where the floods first hit more than two weeks ago. About 1,500 people have died in the disaster and more than 7. 9 million acres (3. 2 million hectares) of cotton, sugar cane and wheat crops destroyed. The International Monetary Fund has warned of dire economic consequences in a country already reliant on foreign aid to keep its economy afloat and one key to the U. S. -led war against al-Qaida and the Taliban. People are hesitating to give fund to Government    because of the corruption allegations against government as it was also seen at the time of Earth Quake disaster five years back.