New Delhi: The monsoon covered the whole country in record time this year, but spread of vector-borne diseases such as dengue, chikungunya and malaria has been faster.

Till 24 June, over 9,143 cases of dengue were reported across the country, with 19 deaths, according to National Vector Borne Disease Control Programme (NVBDCP). Also, there have been around 1,632 cases of chikungunya and 76,238 malaria cases till April. Scientific studies have shown an epidemiological shift in dengue viruses, which means changes in the virus’s geographical incidence and distribution, and have indicated that climate change might be a reason for increase in dengue cases.

The Aedes aegypti mosquito is the main vector that transmits viruses causing dengue and chikungunya. Malaria is spread by anopheles mosquitoes. Special focus has helped bring down malaria by 47% in the past five years, according to Union health ministry data but dengue and chikungunya continue to be a major public health problem.

“Earlier, dengue cases used to surface only around monsoon, but with climate change and other environmental factors, dengue cases occurrence is also changing. Now, we see dengue cases round the year. We need to develop a climate-based model to address this problem," said A.C. Dhariwal, adviser at NVBDCP.

A joint study by the biology division at Council of Scientific and Industrial Research-Indian Institute of Chemical Technology, National Institute of Pharmaceutical Education and Research and Liverpool University explained how higher temperatures over the years helped the dengue virus develop faster in the mosquito.

The study stated that India’s mean temperature rose by more than 0.5 degree Celsius between 1960 and 2009 due to several environmental factors, including climate change. The researchers studied the temperatures in different seasons and found that an increase in temperature led to a shorter incubation period for the dengue virus.

A study published by The Lancet in July 2017 identified climate change as a potential factor for the rise in dengue cases. Between 2010 and 2016, India has recorded a 356% increase in the number of dengue cases, according to NVBDCP.

In May, Union health minister J.P. Nadda held a meeting with 20 endemic (where dengue is common and regularly found) states to discuss vector-borne diseases. The meeting was conducted to review the preparedness of various agencies to prevent and manage vector-borne diseases.

The health ministry has already made notification of dengue cases mandatory. All government health institutions, and private hospitals and clinics are required to inform the district health authority about suspected dengue cases every week or daily during transmission season. Dengue is endemic to Andhra Pradesh, Assam, Bihar, Goa, Gujarat, Haryana, Jharkhand, Karnataka, Kashmir, Kerala, Maharashtra, Odisha, Puducherry, Punjab, Rajasthan, Tamil Nadu, Telangana, Uttarakhand, Uttar Pradesh and West Bengal.

Delhi, the national capital, is also affected by vector-borne diseases, especially dengue. Nadda advised the agencies to create a separate registry for cases originating and being treated in Delhi. He emphasized on the need for adequate early preparedness for management of vector-borne diseases focusing on active case finding for source identification, and reduction of vectors and transmission.

“There should be no shortage of diagnostic kits, drugs, testing labs, manpower and funds. There should be focused and intensive Information Education and Communication campaigns and sustaining them through the monsoon season, especially at the time of onset of monsoon," Nadda had said.

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