From Dengue to Nipah virus, vector-borne diseases are a major concern for India

The death of a 12-year-old boy in Kerala owing to Nipah virus has put the state on high alert against the contagious disease that jumps from animals to humans. So far, 251 contacts of the boy have been traced of which 11 are symptomatic. Meanwhile, Uttar Pradesh and the National Capital are battling a dengue outbreak. At least 50 people, mostly children, have died of a 'mysterious' fever , which doctors believe is dengue. Delhi has had an uptick in dengue cases with 124 infections reported so far this year, the highest since 2018 when the city saw 137 cases. Mumbai too has seen a rise in dengue cases and in August alone the financial capital recorded 132 cases. At a time when the medical authorities are already burdened with the coronavirus, the rise in these kinds of illnesses is bringing back the focus on vector-borne diseases. What are vector-borne diseases? According to World Health Organisation, vectors are living organisms that can transmit infectious pathogens between humans, or from animals to humans. Many of these vectors are bloodsucking insects, which ingest disease-producing microorganisms during a blood meal from an infected host (human or animal) and later transmit it into a new host, after the pathogen has replicated. The WHO describes vector-borne diseases as “human illnesses caused by parasites, viruses and bacteria that are transmitted by vectors”. In lay man’s terms, vectors are mosquitoes, ticks, and fleas that spread pathogens. Prevalence in India In India, there are primarily five vector-borne diseases that are prevalent. Dengue fever Dengue fever is an extremely common vector-borne disease in India, spread through the mosquito bite of the daytime feeder, Aedes aegypti. Thousands of people are affected every year in India, especially during the monsoons. Currently, there is no direct cure or vaccination for dengue fever but one’s condition can be improved and cured through a combination of medical and home treatment. Nipah Virus The Nipah Virus is transmitted to humans through animals like infected pigs and bats. In India, the Nipah Virus is said to most commonly spread through date palm saps that are contaminated with either urine or saliva of fruit bats. Like most viruses, the symptoms of the Nipah Virus infection too are flu-like symptoms that can occur up to 5 to 14 days from being affected. As the infection spreads further in the body, it can lead to respiratory illnesses and encephalitis (inflammation of one or more parts of the brain). In 2018, the state of Kerala saw 19 cases. Malaria Malaria has a long history in India. In fact, it is still pretty much an epidemic in India. Malaria is spread through the bite of the female anopheles’ mosquito, which in turn is a carrier for a parasite called Plasmodium. The World Health Organisation data shows that 219 million people were infected with malaria and 435,000 died worldwide from the disease just in 2017. Although India hopes to be malaria-free by 2030, currently almost 87 percent of malaria cases in South-East Asia are from India itself. Zika Virus infection The Union Ministry of Health and Family Welfare reported India’s first case of Zika virus infection on 21 September, 2018, when a 78-year-old woman from Jaipur, Rajasthan, tested positive. Following this, the state government and Central health authorities started extensive programmes for testing. On 2 November, 2018, 157 people were found to be positive, of these, 63 were pregnant women. Aedes aegypti, the same mosquito that causes dengue, chikungunya and yellow fever, is the vector here. It usually bites during day time. In normal cases, the disease isn’t life-threatening. However, in pregnant women, Zika virus infection can lead to severe defects in the unborn child. Japanese encephalitis The disease mostly affects kids between three to six years old. Japanese encephalitis affects both humans and animals, and is spread through vectors like mosquitoes, pigs and water birds. It is the major cause of encephalitis (inflammation of one or more parts of the brain) all over Asia. Just last year, more than 150 infants and children died due to this viral disease in Muzaffarpur, Bihar after eating contaminated litchis. In India, still around 1,500 to 4,000 cases are reported every year. Threat to India Vector-borne diseases like malaria, dengue and chikungunya aren’t cheap for India. They carry a socio-economic burden of $3 billion to $4 billion every year for India, according to a study by the World Health Organisation. Experts believe that climate change is altering the geographical and seasonal distribution of vector-borne diseases. For instance, the number of mosquitoes would increase between March and April and then with the summers, it would drop. However, that is not the case anymore with the country experiencing early rains. Waterlogging in the monsoons is a perfect breeding condition for mosquitos, thus increasing the risk of its spread that becomes even higher in areas with hygiene issues. Prevention of these diseases Prevention can be done by maintaining neat and clean surroundings, by cleaning blocked drains, avoiding waterlogging, emptying stagnant water bodies (water accumulated in old tyres, pots and pans, coolers, small puddles at construction sites), keeping water tanks and containers tightly covered, pouring oil over the water sources, the introduction of larva eating fish into the water bodies to reduce mosquito breeding. Inputs from agencies