Suspected Dengue Fever Cases In Tamilnadu Is Coming Down

Dr. M.A.Aleem M.D., D.M. (Neuro)

HOD & Professor of Neurology

KAPV Govt. Medical Collage & MGM Govt. Hospital

Trichy – 620017.

Introduction

Dengue virus is primarily spread to people by the mosquito Aedes aegypti. Over 2.5 billion people live in areas where dengue fever ( DF ) is endemic. The World Health Organization estimates that there are between 50 million and 100 million dengue infections each year.
Dengue is the most important arthropod-borne viral disease of public health significance, the global prevalence of which has grown dramatically in recent decades with estimated 2.5 billion people at a risk of acquiring dengue viral infection and more than 50 million new infections being projected annually. Dengue and its severe manifestations: DHF and dengue shock syndrome (DSS), are recognized as important emerging public health problems in tropics and subtropics.

Dengue fever and DHF/DSS are caused by the four viral serotypes transmitted from viraemic to susceptible humans mainly by bites of Aedes aegypti and Aedes albopictus mosquito species. Recovery from infection by one serotype provides lifelong immunity against that particular serotype but imparts only partial immunity against subsequent infection by other three serotypes. Dengue is one of the notable viral infections, the global epidemiology of which has changed dramatically in recent years and the Indian encounter with this disease is intriguing. Dengue infection has been known to be endemic in many parts of India for over two centuries as a benign and self limited disease and outbreaks have been reported at regular intervals from almost all parts of India. Epidemiology of dengue infection is rapidly changing with increasing frequency of outbreaks. All the four serotypes have been reported to be circulating in India with changes occurring in the leading serotypes. Since there is no vaccine available for the DF, the prevention and control of the disease mainly depends upon the epidemiological surveillance that provides reliable estimate of the disease and thereby helping to implement effective vector control measures. It is of utmost importance to characterize the circulating serotypes of dengue virus in our community and understand the evolutionary processes influencing the dengue virus.
There has been a considerable increase in the geographic spread, number of cases and severity of the disease in the past four decades, since there is a drastic change in the environment due to rapid urbanization and increase in transportation facilities in several parts of India..
DF has been known to be endemic in India for more than 20 years as a benign and self-limited disease; however, during recent years, the severe form as DHF is manifesting more frequently. Outbreaks of dengue fever are reported almost every year in India. The first serotype isolated in India was Den-1 in the year 1945 from Kolkata. However, large and severe outbreaks in India have been mostly caused by dengue virus type-2.
Den-3 was the major circulating serotype in children, while Den-2 was the predominant one in adults. Den-2 was found to be the major causative type amongst DHF group.

Dengue virus and mosquitos

Scientists have shown for the first time that infection with dengue virus turns on mosquito genes that makes them hungrier and better feeders, and therefore possibly more likely to spread the disease to humans.

Dengue virus infection of the mosquito's salivary gland triggered a response that involved genes of the insect's immune system, feeding behaviour and the mosquito's ability to sense odours.

"The virus may, therefore, facilitate the mosquito's host-seeking ability, and could-at least theoretically-increase transmission efficiency, although we don't fully understand the relationships between feeding efficiency and virus transmission.
"In other words, a hungrier mosquito with a better ability to sense food is more likely to spread dengue virus,"
For the study, the researchers performed a genome-wide microarray gene expression analysis of dengue-infected mosquitoes.
Further analysis of infected mosquitoes showed that silencing, or "switching off", two odorant-binding protein genes resulted in an overall reduction in the mosquito's blood-acquisition capacity from a single host by increasing the time it took the for mosquito to probe for a meal.

What is dengue fever?

Dengue fever is a disease caused by a family of viruses that are transmitted by mosquitoes. It is an acute illness of sudden onset that usually follows a benign course with symptoms such as headache, fever, exhaustion, severe muscle and joint pain, swollen glands (lymphadenopathy), and rash. The presence (the "dengue triad") of fever, rash, and headache (and other pains) is particularly characteristic of dengue. Other signs of dengue fever include bleeding gums, severe pain behind the eyes, and red palms and soles.
Dengue (pronounced DENG-gay) can affect anyone but tends to be more severe in people with compromised immune systems. Because it is caused by one of four serotypes of virus, it is possible to get dengue fever multiple times. However, an attack of dengue produces immunity for a lifetime to that particular serotype to which the patient was exposed.
Dengue goes by other names, including "breakbone" or "dandy fever." Victims of dengue often have contortions due to the intense joint and muscle pain, hence the name breakbone fever. Slaves in the West Indies who contracted dengue were said to have dandy fever because of their postures and gait.
Dengue hemorrhagic fever is a more severe form of the viral illness. Symptoms include headache, fever, rash, and evidence of hemorrhage in the body. Petechiae (small red or purple splotches or blisters under the skin), bleeding in the nose or gums, black stools, or easy bruising are all possible signs of hemorrhage. This form of dengue fever can be life-threatening and can progress to the most severe form of the illness, dengue shock syndrome.

What geographic areas are at high risk for contracting dengue fever?

Dengue is prevalent throughout the tropics and subtropics. Dengue fever is common, in at least 100 countries in Asia, the Pacific, the Americas, Africa, and the Caribbean. Thailand, Vietnam,india, Singapore, and Malaysia have all reported an increase in cases.
Nearly 40% of the world's population lives in an area endemic with dengue. The World Health Organization (WHO) estimates that 22,000 deaths occur yearly, mostly among children.

How is dengue fever diagnosed?

The diagnosis of dengue fever is usually made when a patient exhibits the typical clinical symptoms of headache, fever, eye pain, severe muscle aches and petechial rash and has a history of being in an area where dengue fever is endemic. Dengue fever can be difficult to diagnose because its symptoms overlap with those of many other viral illnesses, such as West Nile virus and chikungunya fever.
In 2011, the U.S. Food and Drug Administration (FDA) approved a blood test to diagnose people with dengue fever, called the DENV Detect IgM Capture ELISA. The FDA notes that the new test may also give a positive result when a person has a closely related virus, such West Nile disease.

What is the treatment for dengue fever?

Because dengue fever is caused by a virus, there is no specific medicine or antibiotic to treat it. For typical dengue, the treatment is purely concerned with relief of the symptoms. Rest and fluid intake for adequate hydration is important. Aspirin and nonsteroidal anti-inflammatory drugs should only be taken under a doctor's supervision because of the possibility of worsening bleeding complications. Acetaminophen and codeine may be given for severe headache and for joint and muscle pain (myalgia).

What is the prognosis for typical dengue fever?

Typical dengue is fatal in less than 1% of cases. The acute phase of the illness with fever and myalgias lasts about one to two weeks. Convalescence is accompanied by a feeling of weakness (asthenia), and full recovery often takes several weeks.

Dengue fever facts

• Dengue fever is a disease caused by a family of viruses that are transmitted by mosquitoes.
• Symptoms such as headache, fever, exhaustion, severe joint and muscle pain, swollen glands (lymphadenopathy), and rash. The presence (the "dengue triad") of fever, rash, and headache (and other pains) is particularly characteristic of dengue fever.
• Because dengue fever is caused by a virus, there is no specific medicine or antibiotic to treat it. For typical dengue fever, the treatment is purely concerned with relief of the symptoms (symptomatic).
• The acute phase of the illness with fever and myalgias lasts about one to two weeks.
• Dengue hemorrhagic fever (DHF) is a specific syndrome that tends to affect children under 10 years of age. It causes abdominal pain, hemorrhage (bleeding), and circulatory collapse (shock).
• The prevention of dengue fever requires control or eradication of the mosquitoes carrying the virus that causes dengue.
• There is currently no vaccine available for dengue fever.

Preventive Measures to control Dengue Fever

Dengue fever is a disease caused by a family of viruses that are transmitted by mosquitoes However the affected person is treated with Paracetamol to bring down the fever. The person is usually recommended to drink lots of fluids.

• The prevention of dengue requires control or eradication of the mosquitoes carrying the virus that causes dengue.

• To prevent mosquito bites, wear long-sleeved shirts, long pants, socks and shoes when outdoors.

• For personal protection, use mosquito repellant sprays that contain DEET when visiting places where dengue is endemic.

• “Aedes” mosquitoes usually bite during the day. Therefore, special precautions should be taken during early morning hours before day break and in the late afternoon before dark.

• Eliminate stagnant water that serve as mosquito breeding sites at home, workplaces and their vicinity.

• Using mosquito nets at home and patients need to be kept under mosquito netting until the second bout of fever is over and they are no longer contagious.

• Cover overhead tank to prevent access to mosquitoes.

• Eliminate breeding ground by removing unused plastic pools, old tires, or buckets and clearing clogged gutters.

• Conducts dengue awareness programs in your apartment complex and neighborhood.

• Advise people showing symptoms of dengue to immediately go for a check-up and get treatment.

• The most effective way to reduce the number of mosquitoes around homes or neighborhoods is to find and eliminate their breeding sites.

Conclusion
At present, dengue control and prevention require awareness of factors beyond those commonly seen in tropical countries. Many of the affected countries are poor and developing. Realistic approaches for their infrastructure are required to be urgently developed.  Detailed serological and virological studies of dengue outbreaks in endemic areas are required to pinpoint the nature of the outbreaks to help to develop effective control measures. Well-targeted population-based epidemiological studies with clear operational objectives are urgently required to control high morbidity and mortality due to dengue.
In Tamilnadu
Recently In Tamilnadu suspected dengue fever cases are reported in a few districts. Our tamilnadu chief minister Jayalalitha has ordered various measures to prevent the spread of suspected dengue fever in the state. Miss.Jayalalitha’s warfooting measures is started giving results by reduction of new cases of suspected dengue fever  reported in Tamilnadu from third week of October 2012.