The diseased realm

Dengue fever is ranked by WHO as the most critical and the most rapidly spreading mosquito-borne viral disease in the world. Lahari Basu finds out the probable causes leading to the wide prevalence of the disease and the possible measures to curb it.

 Lahari Basu |  2017-11-25 16:43:14.0

The row over Gurugram's Fortis Hospital overcharging a seven-year-old patient's family for 15-day treatment of dengue fever has forced the nation to ask for some control over the situation as the mosquito-borne disease is spreading like a wildfire. With an ever-increasing number of dengue cases, the country is brimming over with dengue patients of all age groups, starting from infants to the elderly. But how deadly is the virus?

By now, citizens are aware of the cause of the disease and certain symptoms. Dengue is a human virus transmitted primarily by the mosquito Aedes aegypti, which is commonly found in homes and workplaces. Dengue fever is a severe, flu-like illness that affects all age groups, but seldom causes death. In the past few years, the capital alone had witnessed innumerable cases of dengue, 2015 being the worst affected year with 15652 cases and 60 deaths. Until November 18 this year, Delhi had 4375 cases with 4 resultant deaths, as per the South Delhi Municipal Corporation Anti Malaria Operations (HQ). Endemic to tropical and subtropical areas Dengue fever is estimated by the World Health Organization (WHO) to cause about 50-100 million infections per year globally. Dengue fever is ranked by WHO as the most critical and the most rapidly spreading mosquito-borne viral disease in the world.
As per experts, dengue will become more prevalent with the rising global temperature. More than 40 per cent of the world's population, in more than 100 countries is at risk of dengue infection. The most significant dengue epidemics in recent years have occurred in Southeast Asia, the Americas and the Western Pacific. Each year, an estimated 390 million dengue infections occur around the world.
Why is the virus affecting some people more severely, even resulting in death? "It is a matter of chance for someone to get affected, if the transmission is not 100 per cent effective then one might be affected by the virus. When a patient is admitted to the hospital, first we look into the symptoms and always conduct the ELISA test, to determine dengue," says Dr Kuldeep Kumar, Asst Professor, University College of Medical Sciences.
Says Dr Rajesh Kumar, Sr Consultant, General Physician Paras Hospitals Gurgaon, "The four types of Dengue virus include DEN-1, DEN-2, DEN-3, and DEN-4, among which DEN-2 and DEN-4 are more dangerous. Dengue fever starts in the month of June-July. But patients coming later in the month of Oct-November are more likely to have this infection. The government has to take care of the policies regarding health and hygiene. Individuals are also equally responsible for the rise of dengue fever as maintenance of good health is largely dependent upon individual behaviour."
Transmission
The transmission cycle for dengue is human-mosquito-human. The virus is transmitted to humans through the bites of infected female mosquitoes. After virus incubation for 4–10 days, an infected mosquito is capable of transmitting the virus for the rest of its life. Infected symptomatic or asymptomatic humans are the main carriers and multipliers of the virus, serving as a source of the virus for uninfected mosquitoes. Patients who are already infected with the dengue virus can transmit the infection through Aedes mosquitoes after their first symptoms appear. Being a day-time feeder, the Aedes aegypti's peak biting periods are early in the morning and during the evening before dusk.
Dengue test kit:
A team of scientists led by Dr Navin Khanna, from The International Centre for Genetic Engineering and Biotechnology, New Delhi, had developed a kit, 'Dengue Day 1' which can detect dengue within 15 minutes after an individual is bitten by Aedes Aegypti, whereas the standard procedures for attaining results can take between four to 15 days' time. "I have heard about the kit, but doctors usually stick to the old-school methods of conducting tests to detect dengue, it is probably due to lack of publicity. Every doctor would not have the kit and neither can an individual take the test on their own," said Dr Priya Upadhyaya.
Possible treatments:
There is no specific medical treatment for dengue, medical care by doctors experienced with the effects and progression of the disease can save lives in case of severe dengue fever. Also, maintenance of the patient's body fluid volume is critical in this case.
"It is better to go to private doctors or hospitals initially, because one gets more personal attention there, then follow the instructions of the doctor and approach a particular hospital. Symptoms of dengue often overlap with other diseases, therefore at one go, it is not easy to diagnose it," suggests Dr Upadhyaya. "Many patients approach the doctor too late, which leads to severity. A dengue patient must be well hydrated, which is often overlooked by many, eventually causing death," she added. "In Homeopathy, we have Dengue preventives for a year. It develops antigens in the body and prevents the individual from getting infected further over a year," informed Dr Upadhyaya.
The research of World Mosquito Program from Monash University in Melbourne, Australia, has shown that when Wolbachia is introduced into the mosquito it reduces its ability to transmit dengue among people, as well as other Aedes aegypti-borne diseases such as Zika and Chikungunya.
"Wolbachia is a natural bacteria present in up to 60 per cent insect species and is almost exclusively transmitted from mother to offspring via infected eggs. Males can be infected with Wolbachia but males do not transmit Wolbachia to offspring or any other hosts," informed Dr Rajesh Kumar. The World Mosquito Program is working in partnership with the Indian Council of Medical Research (ICMR) to investigate the use of self-sustaining Wolbachia bacteria to combat dengue and other mosquito-borne diseases in India.

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