Climate change-induced temperatures causing erratic precipitation patterns, severe rainfall events, and seasonal changes are all known to boost mosquito populations. This means, that once isolated to a few areas in the tropics, a higher number of mosquitos are available for transmission of infection. In addition, higher temperatures also lead to a shortening of the time of maturing of mosquito larvae and also shorten the time taken for female mosquitos to mature. The HEALTH PIONEER brings a report on this most rapidly spreading mosquito-borne disease in the world.
There are an estimated 100-400 million yearly dengue infections, with cases quickly on the rise, according to the World Health Organisation (WHO).
Rajeev Vaidyanathan, Ph.D., an entomologist at Oxitec, a US-owned biotech company developing genetically modified insects to assist in insect control, however, points out that reported numbers largely underestimate the global prevalence of mosquito-borne illnesses.
Many cases are underreported and, in the case of dengue fever, more than 80 per cent of cases are asymptomatic, a report quotes him. The situation is no good in India. Several parts of the States have reported an uptick in dengue cases.
Across the country, 10,172 persons have tested positive for dengue from January 1 to May 31, 2022 as per the website of the National Vector-Borne Disease Control Programme.
Last year, during the same period, the country reported only 6,837 dengue cases. Health experts say that since India is witnessing erratic environmental impacts induced by climate change, numbers are likely to be increased. Climate change has created warmer cities and increased reliance on artificial water storage, which makes them more hospitable to mosquitoes, say experts.
And since, they say, the DENV-2, or the strain D2 of the four serotypes of dengue virus, is what is causing the sudden rise in the number of cases and also leading to severity, deaths will also surge.
Apart from being more virulent, experts believe that the new strain can trigger a high-grade fever, vomiting, joint pains, and altered sensorium and may even lead to lethal complications resulting in dengue hemorrhagic fever and dengue shock syndrome.
According to the WHO, between 2030 and 2050, climate change will cause 250,000 additional deaths per year from heat stress, malnutrition, dengue, and malaria alone. In fact, Dengue cases have increased by 85 per cent in 30 years. Rising temperatures have led to increased survival and reproduction of the mosquitoes which carry the disease. The number of people at risk of dengue is predicted to reach 60% of the world's population by 2080.
The modeling of vector transmission rates due to climate change has shown that Aedes species are likely to be more abundant and expand in the current circulating geographical locations. It is likely to result in the more intense transmission of many Aedes transmitted viruses in the dengue endemic countries.
Studies have shown that climatic changes leading to higher temperatures and differences in rainfall, result in higher mosquito abundance. Due to the increase in mosquito populations, there would be a higher number of mosquitos available for transmission of infection. In addition, higher temperatures also lead to a shortening of the time of maturing of mosquito larvae and also shorten the time taken for female mosquitos to mature.
For instance, the time for mosquito larvae to mature at 15 C was 39.5 days, while at 35 C, it only took 7.5 days. This in turn leads to a longer duration of time available for female mosquitos to transmit infection. Therefore, climate change would lead to an exponential increase in the current burden of dengue, as per reports.
Clearly, as climate change is likely to make the existing dengue burden much worse, it is crucial that all efforts are concentrated to develop drugs, and upgrade health infrastructure besides taking measures to curb Green House Gas (GHG) emissions that will reduce the burden of dengue and its severity and hospitalizations.
Save Your Kid From That Bite
According to the National Library of Medicine, dengue presents more aggressively among younger age groups as compared to adults. The incubation period may range from 4 days-2 weeks and the duration of the disease could be between 2-7 days, say doctors.
The vast majority of dengue cases are kids under 15 years of age. Infants and kids with secondary heterologous dengue infections are most at risk for severe dengue disease. Mosquitoes are highly active early in the morning or evening, so ensure your kid wears long pants and shirts to cover his/her skin surfaces to reduce the chances of bites.
If diagnosed with dengue, doctors recommend a couple of ways in which you can help your child reduce the discomfort and speed up recovery from this illness.
*Make sure your child is drinking enough fluids and water along with healthy meals.
*Ensure that your child sleeps well.
*A healthy diet Including generous amounts of immunity-building foods in your child’s diet, like citrus fruits, almonds, turmeric, garlic, etc will help in strengthening your little ones' immunity and aid in quick recovery.
*Pain relievers like acetaminophen may be prescribed if your child is experiencing unbearable muscle and joint aches associated with dengue fever.
*Also, pain relievers like aspirin or ibuprofen should be avoided, as they can make bleeding happen, say doctors.
*To treat severe cases of dengue fever, doctors will give intravenous fluids and electrolytes to replace fluids lost through vomiting or diarrhea. If administered on time, this is sufficient to treat the disease in severe cases of dengue fever.
*However, in some advanced cases, a blood transfusion may be needed.
*Lastly, efforts must be made to keep the infected child from being bitten by any mosquitoes as this will help in preventing the spread of dengue fever to others.
Q&A WITH DR JUGAL KISHORE
*What is dengue fever?
Dengue fever is a viral disease caused by a virus called DENV which could be of four types namely DENV1 to DENV4. It is transmitted by the bite of the infected female Aedes mosquitoes.
*What are the symptoms of dengue fever?
Dengue fever symptoms are fever which can go up to 104 degrees F. Severe headache, pain behind the eyes, muscle and joint pains, nausea vomiting, and sometimes rashes.
*How is dengue fever caused and spread?
Bite of the infected mosquitoes mainly female Aedes aegypti and in some cases, albopictus transmit the dengue virus to new non-infected persons and cause disease. One such infected mosquito can transmit the infection to many persons and further transmit the dengue virus to new mosquitoes in a propagated manner. In a short period, a large number of persons get the infection which may cause an epidemic.
*What are the complications of dengue fever?
The majority of the time dengue is mild in nature but a small number of cases may be affected by complications and less than 1 percent may turn into deaths. Complications start 3-7 days after the onset of symptoms mainly after the fever subsides. Platelet counts start decreasing which resulted in plasma leakage, fluid accumulation, and bleeding. Therefore, bleeding from the nose or gum, blood in stool or vomitus, severe abdominal pain, respiratory distress, or subcutaneous bleeding appearing as petechiae are warning signs of fatality and should be managed at the hospital.
*How do you diagnose dengue fever?
Although clinical presentation is commonly picked up by doctors the diagnosis should always be made by the blood test to detect the virus, NS1 protein, or antibodies. When the Aedes mosquito population is high, particularly in the rainy season any fever should be suspected and a blood test for dengue should be done.
*How do you treat dengue fever?
As we don't have any drugs against dengue viruses, symptomatic treatment is the only solution. For fever, cold sponging and paracetamol are advised. Aspirin or its derivative drugs are contraindicated as they cause inhibition of platelet functions. It is better to get the advice of your family doctor in case of suspicion of dengue. The first dengue vaccine, Dengvaxia( CYD-TDV) has been approved for human use and is commercially available in India. It can be used in those who have previously been infected with dengue fever at least once.
*How do you prevent dengue fever?
As we know that prevention is better than cure, preventive measures, particularly against mosquitoes are best. Breeding of mosquitoes occurs in water accumulated in any storage anywhere extending from large water bodies to a small bucket, mud pot, discarded containers, used tyres, rooftop water tank, container, flower pot, leave, plastics, cistern, tree, etc. Once a female has laid her eggs, these eggs can remain viable for several months in dry conditions and will hatch when they are in contact with water. All such breeding sites need to be eliminated by physical and engineering methods. Larva, pupas, and mosquitoes can be killed by various environment-friendly insecticides. This mosquito is usually a day-biter. Bites of mosquito can be prevented by covering body parts with appropriate cloths, using repellents and mosquito bed nets. Housing windows should be covered with wire mesh.
*Which type of doctor should one consult for dengue fever?
General physicians may be consulted for dengue fever. However, specialists are required when complications set in.
*Can I be infected with dengue a second or more times?
Yes, dengue can occur a minimum of 4 times due to the presence of 4 types of dengue viruses.
*What kind of mosquito repellents are safe?
Picaridin is a good alternative to DEET because it is just as effective at repelling mosquitoes but is not harmful to the environment. Oil of lemon eucalyptus is also effective, but it is not as long-lasting.
*Is dengue becoming resistant to household repellents?
There are few results on resistance to household repellents. However, all living organisms try to protect their survival by changing their genetic makeup. There are many natural repellents such as citronella, lemongrass, and marigold plants that have mosquito repellent activities if they are kept in and around the house but it should be remembered that they should not be holding water which can be a potential site of breeding.
*Is the number of dengue cases on the increase?
Dengue fever has increased in recent decades due to unregulated urbanization, population mobilization, and climatic changes.
(Dr Jugal Kishore is Director Professor and Head of Community Medicine Department at Safdarjung Hospital, New Delhi)
Ayurveda Remedy
In the Ayurveda, various upchar or remedies are defined for the management of dengue fever, says Dr Zankhana Buch, MD(Ay) Medical Superintendent, Sr Physician at AyurVAID, Domlur, Bangalore Karnataka
*Can one seek Ayurveda medicines to prevent Dengue and its complications?
Ayurveda has a clear-cut understanding of preventing and managing Dengue fever. Dandaka Jwara is found in Ayurveda textbook named Madhava Nidana It has been described that a particular species of mosquito is the basic cause of the spread of fever called Dandaka jvara.
*What can we expect from Ayurveda Approach to the Management of Dengue?
Ayurveda has an elaborate description of JWARA (Fever)- with its natural history, clinical manifestation, types, diagnosis, differential diagnosis, management with ahara (diet), vihara (lifestyle measures), Aushadha (medicines), and kriyas (Panchakarma therapies). Various types of Jwara that are caused by external agents like dengue with insect/repellent bites are called AgantukaJwara
An effective vector control method- Dhoopana (fumigation) with Rakshoghnaganadravyas (antimicrobial drugs) is very effective to control mosquito infestation.
Although infection with the dengue virus (DENV) causes severe dengue, it causes a mild self-limiting illness in the majority of individuals. There is emerging evidence that an aberrant immune response in the initial stages of infection leads to severe disease. Many inflammatory biomarkers are significantly higher in patients with severe dengue compared to those who develop a mild infection, during the febrile phase of illness.
Ayurveda system of medicine helps to identify the level of inflammation and the risk of developing dengue complications.
The larger objective is to alter the extra-cellular or host environment so that the rate of multiplication of the viral load, i.e., increase in # of copies of the virus in one's body, is reduced and eventually made sub-viable. i.e., there will not be enough viral growth to sustain the infection, and in turn, the disease progression itself is slowed down/arrested/reversed.
Ayurveda first determines which key sub-systems (Srotas) of the body have deviated from its normal constitutional functional state, the status of your metabolism, and the presence of mild or severe inflammation in the body. The change in the host environment is achieved through a multi-mode approach of diet-lifestyle-medicine-
*Scope of Ayurveda Management
Early management: Prevention/ Prophylaxis- Vector Control Methods,
Institutional management: This means that patient diagnosed with Dengue fever is admitted in Ayurveda inpatient facility and monitored closely on clinical signs and observation of platelet counts and other necessary blood parameters. These patients are then provided whole-person care with a comprehensive prescription that entails Ayurveda diet, medicines, and panchakarma therapies as appropriate. Recovery- follow-up with privileged physicians at accredited Ayurveda institutions
Diet:
nIt is advised to have freshly prepared easily digestible vegetarian food like rice gruel(Kanji)/Khichdi, moong water, etc to keep digestion easy. In the case of non-vegetarian food, ensure that it is well cooked, and not too spicy.
Dinner should be the lightest meal.
l Avoid curds, oily and deep-fried items, maida, leftover meals, processed and packaged food items, oats and millets, cheese, and cold and aerated drinks as far as possible. Avoid Bengal Gram/Beans and difficult-to-digest Vata/gas-causing food items.
l Include: warm water, broken wheat, green and yellow moong/green gram, ghee, rice
l Eat vegetables like all gourd vegetable bottle/bitter/ridge/ash/snake gourd that reduces pitta.
l Minimize use of gas-causing items like cabbage and cauliflower while including fruits like amla, pomegranate, dry raisins, and cardamom
l Include bitter and pungent and astringent taste while choosing your food items as these items are light and easy and pacify pitta
l Maintain Adequate Hydration with around 6 to 8 glasses of water daily and avoid coffee, cocoa, tea, caffeinated, alcoholic and carbonated beverages.
Lifestyle
Avoid day sleep to prevent Kapha accumulation/to reduce further impairment of metabolism
Having sips of hot water to aid minimize the signs of bloating, belching, and flatulence. Avoid cold water baths. Ensure good hygiene with good air and sunlight.
What does Ayurveda not cover?
Dengue patients who are younger than 5 years or older and frail, pregnant women, patients with serious comorbidities (cardiac, renal, for e.g.) and patients in or near hemorrhagic emergencies, with deviated vital parameters should be advised to seek conventional Dengue managemen