Dengue Advisory
Dengue Advisory
Dengue Fever: Dengue fever is a
self-limiting flu-like illness, which is transmitted by the bite of an
infected female Aedes aegypti mosquito. The mosquito transmits the
disease by biting an infected person and then biting someone else.
The mosquitoes that transmit dengue live among
humans and breed in discarded tires, flower pots, old oil drums, and
water storage containers close to human dwellings. Unlike the
mosquitoes that cause malaria, dengue mosquitoes bite during the day.
These mosquitoes gather around stagnant water. Hence, it is common for
a surge in reports of dengue infections just after the monsoon.
Dengue is also known as Break Bone Fever. If the
infection is treated on time, the mortality rate is less then 15%. The
fever comes within eight days of the mosquito bite.
Types of Dengue:
There are two types of dengue:
1) Classical Dengue Fever: Infected person
complains of high fever, intense headache, muscle and joint pain,
bitter taste, insomnia, anorexia, retro orbital pain and photophobia.
Instances of it proving fatal are extremely low.
2) Dengue Haemorrhagic Fever or Dengue Shock Syndrome: Dengue hemorrhagic fever is a severe, often fatal, complication of dengue fever. The infected person complains of high fever, bleeding from nose, gums, ears, skin. The patient may go into shock due to blood loss.
2) Dengue Haemorrhagic Fever or Dengue Shock Syndrome: Dengue hemorrhagic fever is a severe, often fatal, complication of dengue fever. The infected person complains of high fever, bleeding from nose, gums, ears, skin. The patient may go into shock due to blood loss.
Detection: How to detect if you are infected:
1) Serological test to detect IgM, IgG antibodies: IgM antibodies appear in blood at the end of eight days and persist for 1-3 months. It indicates acute infection. This is the test that most people undergo. It has an accuracy of 80-90% and is referred to as the preliminary test.
2) Isolation of virus in blood: This is a sophisticated test, conducted only by selected agencies for example, the Pune-based National Institute of Virology. This test can be undertaken 10 days after the first blood test. The test itself is quite expensive, but it can confirm if the person is infected by dengue.
3) Polymerized Chain Reaction: This test involves amplification of the DNA (Deoxyribo Nucleic Acid). Very expensive and hence, undertaken only in rare cases. Dengue is diagnosed primarily by a blood test. The last two are undertaken to confirm infection.
1) Serological test to detect IgM, IgG antibodies: IgM antibodies appear in blood at the end of eight days and persist for 1-3 months. It indicates acute infection. This is the test that most people undergo. It has an accuracy of 80-90% and is referred to as the preliminary test.
2) Isolation of virus in blood: This is a sophisticated test, conducted only by selected agencies for example, the Pune-based National Institute of Virology. This test can be undertaken 10 days after the first blood test. The test itself is quite expensive, but it can confirm if the person is infected by dengue.
3) Polymerized Chain Reaction: This test involves amplification of the DNA (Deoxyribo Nucleic Acid). Very expensive and hence, undertaken only in rare cases. Dengue is diagnosed primarily by a blood test. The last two are undertaken to confirm infection.
Prevention: How to avoid it:
1. Water from flower pots should be changed at least once a week
2. All containers storing water should be covered with a tight lid
3. Water stored in barrels, drums etc should be replaced by fresh stock (at least) once a week
4. All large water tanks, like those in buildings, should have single piece cast iron, tight fitting cover. The overflow pipe should be protected by a net that can keep away mosquitoes.
5. Discarded container-like objects like tyres, coconut shells, bottles, etc should be disposed off or destroyed.
6. Water fountains should be kept dry once a week
7. Surface wells should be well-maintained so that mosquitoes do not breed in the vicinity
8. Rain water collected on terraces/roofs should be cleared (at least) once a week
No vaccine is available. Travelers should be advised that they can reduce their risk of acquiring dengue by remaining in well-screened or air-conditioned areas when possible, wearing clothing that adequately covers the arms and legs, and applying insect repellent to both skin and clothing. The most effective repellents are those containing N,N-diethylmetatoluamide (DEET). (See Protection against Insect Bites)
2. All containers storing water should be covered with a tight lid
3. Water stored in barrels, drums etc should be replaced by fresh stock (at least) once a week
4. All large water tanks, like those in buildings, should have single piece cast iron, tight fitting cover. The overflow pipe should be protected by a net that can keep away mosquitoes.
5. Discarded container-like objects like tyres, coconut shells, bottles, etc should be disposed off or destroyed.
6. Water fountains should be kept dry once a week
7. Surface wells should be well-maintained so that mosquitoes do not breed in the vicinity
8. Rain water collected on terraces/roofs should be cleared (at least) once a week
No vaccine is available. Travelers should be advised that they can reduce their risk of acquiring dengue by remaining in well-screened or air-conditioned areas when possible, wearing clothing that adequately covers the arms and legs, and applying insect repellent to both skin and clothing. The most effective repellents are those containing N,N-diethylmetatoluamide (DEET). (See Protection against Insect Bites)
Prevention of Insect Bites:
Insects, especially mosquitos, carry diseases such as Malaria, Dengue fever, Yellow fever, and Japanese encephalitis are commonly encountered while travelling overseas.
The following is the basic advice to avoid insect bites, and thus the diseases:
• Most insect borne diseases are seasonal. Change the itinerary if possible may reduce the risk.
• Avoid outdoor activities during twilight periods at dawn and dusk as the mosquitoes and insects are most active at these times.
• Wear long-sleeved shirts, long pants and hats to minimize exposed skin.
• Avoid dark clothes, perfume and after shave as these attract mosquitoes and insects.
• Use insect replants containing DEET.
• Use mosquito nets when staying in accommodations that are not air-conditioned or adequately screened.
• Use premethrin containing repellents to treat the mosquito net, clothing and shoes.
Symptoms:
• Dengue fever usually starts suddenly with a high fever, rash, severe headache, pain behind the eyes, and muscle and joint pain. The severity of the joint pain has given dengue the name 'breakbone fever.' Nausea, vomiting, and loss of appetite are common. A rash usually appears 3 to 4 days after the start of the fever. The illness can last up to 10 days, but complete recovery can take as long as a month. Older children and adults are usually sicker than young children.
• Most dengue infections result in relatively mild illness, but some can progress to dengue hemorrhagic fever. With dengue hemorrhagic fever, the blood vessels start to leak and cause bleeding from the nose, mouth, and gums. Bruising can be a sign of bleeding inside the body. Without prompt treatment, the blood vessels can collapse, causing shock (dengue shock syndrome). Dengue hemorrhagic fever is fatal in about 5 percent of cases, mostly among children and young adults.
• The time between the bite of a mosquito carrying dengue virus and the start of symptoms averages 4 to 6 days, with a range of 3 to 14 days. An infected person cannot spread the infection to other persons but can be a source of dengue virus for mosquitoes for about 6 days.
Treatment:
Acetaminophen products are recommended for managing fever. Acetylsalicyclic acid (aspirin) and nonsteroidal anti-inflammatory agents (such as ibuprofen) should be avoided because of their anticoagulant properties. Patients with dengue fever should be encouraged to rest and take abundant fluids. In severe cases, the prompt infusion of intravenous fluids is necessary to maintain adequate blood pressure. Because shock may develop suddenly, vital signs must be monitored frequently. Hypotension is a more frequent complication of DHF than severe hemorrhage.
There is no specific treatment for dengue. Patients should be kept away from mosquitoes for the protection of others. Dengue hemorrhagic fever is treated by replacing lost fluids. Some patients need transfusions to control bleeding.
Acetaminophen products are recommended for managing fever. Acetylsalicyclic acid (aspirin) and nonsteroidal anti-inflammatory agents (such as ibuprofen) should be avoided because of their anticoagulant properties. Patients with dengue fever should be encouraged to rest and take abundant fluids. In severe cases, the prompt infusion of intravenous fluids is necessary to maintain adequate blood pressure. Because shock may develop suddenly, vital signs must be monitored frequently. Hypotension is a more frequent complication of DHF than severe hemorrhage.
There is no specific treatment for dengue. Patients should be kept away from mosquitoes for the protection of others. Dengue hemorrhagic fever is treated by replacing lost fluids. Some patients need transfusions to control bleeding.
Occurrence: Distribution of dengue, Western Hemisphere Distribution of dengue, Eastern Hemisphere
Travel Advisory:
The principal vector mosquito, Ae. aegypti, is most frequently found in or near human habitations and prefers to feed on humans during the daytime. It has two peak periods of biting activity: in the morning for several hours after daybreak and in the late afternoon for several hours before dark. The mosquito may feed at any time during the day, however, especially indoors, in shady areas, or when it is overcast. Mosquito breeding sites include artificial water containers such as discarded tires, uncovered barrels, buckets, flower vases or pots, cans, and cisterns.
Estimates derived from studies of military and
relief workers allow for an estimate of risk near one illness per
thousand travelers. This estimate may overstate the danger for tourists
who will have less contact with the vector, who stay only a few days in
air-conditioned hotels with well-kept grounds, and who participate in
outdoor recreational activities where the vector mosquito may be absent
(such as sunbathing or playing golf in the middle of the day).
Travelers who stay at other types of accommodations or with friends and
relatives in locations with intense disease transmission may have a
higher risk of illness. Cases of dengue are confirmed every year in
travelers returning to the United States after visits to tropical and
subtropical areas. Travelers to endemic and epidemic areas, therefore,
should take precautions to avoid mosquito bites.
Current data suggest that virus strain, the immune
status (i.e., having had a previous dengue infection), age, and genetic
background of the human host are the most important risk factors for
developing DHF. In Asia, where a high proportion of the population has
experienced a dengue infection early in life, DHF is observed most
commonly in infants and children <15 years of age who are
experiencing a second dengue infection. In the Americas and the
Pacific, where herd immunity is lower, DHF is more commonly observed in
older children and adults. International travelers from non-endemic
areas (such as the United States) are generally at low risk for DHF.
There is little information in published reports
about the consequences of dengue infection for pregnant women. In spite
of many epidemics, no increase in congenital malformations has been
noted after dengue epidemics. A small number of recently reported cases
suggests that if the mother is ill with dengue at the time of delivery,
the child can be born with dengue infection or can acquire dengue
through the delivery process itself, and then develop the
manifestations of dengue fever or DHF.
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