Feb-march-2016

DENGUE FEVER – A MOSQUITO FEAR!

Authors: Dr. Usha Rani Chadalawada, Prof. M. Habeeb Ghatala

Dengue is a disease caused by any one of four closely related dengue viruses or serotypes, and they are DENV 1, DENV 2, DENV 3, or DENV 4. Infection with one serotype does not protect against the otherand sequential infections put people at greater risk for dengue hemorrhagic fever (DHF) and dengue shock syndrome (DSS).

The viruses are transmitted to humans by the bite of an infected mosquito. In the Western Hemisphere, the Aedesaegypti mosquito is the most important transmitter or vector of dengue viruses.

Today about 2.5 billion people, or 40% of the world’s population, live in areas where there is a risk of dengue transmission is It is estimated that there are over 100 million cases of dengue worldwide each year.

Dengue is endemic in at least 100 countries in Asia, the Pacific, the Americas, Africa, and the Caribbean. The World Health Organization (WHO) estimates that 50 to 100 million infections occur yearly, including 500,000 DHF cases and 22,000 deaths, mostly among children.

The official reports of dengue in India suggest only some 20,500 cases a year, in a population of more than 1.2 billion people. The gap is worryingly large between the official data—which present dengue as a negligible problem—and the common perception that the disease is a widespread threat. A tamilnadu study projecting over 5000 deaths due to the disease in 2012. The numbers are over 3200/deaths as per current statistics.

Dengue hemorrhagic fever (DHF)

It is a more severe form of dengue infection. It can be fatal if unrecognized and not properly treated in a timely manner. DHF is caused by infection with the same viruses that cause dengue fever. With good medical management, death due to DHF can be less than 1%.

Spread of Dengue and dengue hemorrhagic fever (DHF)

Dengue is transmitted to people by the bite of an Aedes mosquito that is infected with a dengue virus. The mosquito becomes infected with dengue virus when it bites a person who has dengue virus in their blood. The person can either have symptoms of dengue fever or DHF, or they may have no symptoms. After about one week, the mosquito can then transmit the virus while biting a healthy person. Dengue cannot be spread directly from person to person.

Symptoms of the disease

The principal symptoms of dengue fever are high fever, severe headache, severe pain behind the eyes, joint pain, muscle and bone pain, rash, and mild bleeding (e.g., nose or gums bleed, easy bruising). Generally, younger children and those with their first dengue infection have a milder illness than older children and adults.






Dengue hemorrhagic fever is characterized by a fever that lasts from 2 to 7 days, with general signs and symptoms consistent with dengue fever.

Once the fever reduces,symptoms like persistent vomiting, severe abdominal pain, and difficulty breathing, may develop. This marks the beginning of a 24- to 48hour period when the smallest blood vessels (capillaries) become excessively permeable (“leaky”), allowing the fluid component to escape from the blood vessels into the peritoneum leading to ascites and pleural cavity leading to pleural effusions. This may lead to failure of the circulatory system and shock, followed by death, if circulatory failure is not corrected. In addition, the patient with DHF has a low platelet count and hemorrhagic manifestations, tendency to bruise easily or other types of skin hemorrhages, bleeding nose or gums, and possibly internal bleeding.

Treatment for dengue:

There is no specific medication for treatment of a dengue infection. Persons who think they have dengue should use analgesics to relieve pain with acetaminophen and avoid those containing aspirin. They should also rest, drink plenty of fluids, and consult a physician. If they feel worse like develop vomiting and severe abdominal pain in the first 24 hours after the fever declines, they should go immediately to the hospital for evaluation.



Effective treatment for dengue hemorrhagic fever (DHF)

As with dengue fever, there is no specific medication for DHF. It can however be effectively treated by fluid replacement therapy if an early clinical diagnosis is made. DHF management frequently requires hospitalization. Physicians who suspect that a patient has DHF may want to consult the Dengue – vector control disease division.

Outbreaks of dengue occur:

Outbreaks of dengue occur primarily in areas where Ae. aegypti (sometimes also Ae. albopictus) mosquitoes live. This includes most tropical urban areas of the world. Dengue viruses may be introduced into areas by travelers who become infected while visiting other areas of the tropics where dengue commonly exists.

Preventing the risk of acquiring dengue:

There is no vaccine for preventing dengue. The best preventive measure for residents living in areas infested with Ae. aegypti is to eliminate the places where the mosquito lays her eggs, primarily artificial containers that hold water.

 


Items that collect rainwater or containers used to store water like plastic containers, buckets or used automobile tires.They should be covered or properly discarded. Pet and animal watering containers and vases with fresh flowers should be emptied and cleaned at least once a week to remove eggs. This will eliminate the mosquito eggs and larvae and reduce the number of mosquitoes present in these areas.

Using air conditioning or window and door screens reduces the risk of mosquitoes coming indoors. Proper application of mosquito repellents containing 20% to 30% DEET as the active ingredient on exposed skin and fully covered clothing decreases the risk of being bitten by mosquitoes. The risk of dengue infection for international travelers appears to be small. There is increased risk if an epidemic is in progress or visitors are in housing without air conditioning or screened windows and doors.

Prevention of epidemics of dengue hemorrhagic fever:

The emphasis for dengue prevention is on sustainable, community-based, integrated mosquito control, with limited reliance on insecticides (chemical larvicides, and adulticides). Preventing epidemic disease requires a coordinated community effort to increase awareness about dengue fever/DHF, how to recognize it, and how to control the mosquito that transmits it. Residents are responsible for keeping their surrounding balconies and courtyards free of standing water where mosquitoes can be produced.

References:
  1. Burden-of-dengue-chikungunya-in-india-far-worse-than-understood
  2. http://www.cdc.gov/dengue/fAQFacts/index.html
  3. http://www.economist.com/blogs/banyan/2014/10/dengue-india
  4. http://www.thehindu.com/sci-tech/health/dengue-outbreak-in-india/article4
  5. http://www.jhsph.edu/news/news-releases/2015/.html
  6. http://www.cdc.gov/dengue/clinicalLab/clinical.html
  7. The survivor story
  8. http://yucalandia.com/science-health-issues/dengue-what-to-do/