Heavy rainfall triggering rise in dengue cases in Karnataka

As Covid-19 dies down, the state is facing the rise of another epidemic - dengue - which has come with a reckoning for a state beset by abnormal amounts of rainfall this year.

According to the official data, the state has already recorded 3,681 cases of dengue among 51,151 people tested this year. In comparison, last year, from January to December 2020, the state had recorded 3,685 cases.

Experts noted that the increasing numbers are a direct consequence of the larger amounts of rainfall the state has received this year, resulting in more pools of stagnant freshwater - an ideal breeding ground for the larvae of the Aedes aegypti mosquito. According to the Indian Meteorological Department (IMD), the state has been witness to a 60 per cent increase in rainfall in the last week alone.

State Health Commissioner D Randeep said that heavy rainfall usually has the end result of disrupting the life cycle of the aedes by displacing stagnant water. However, the copious water collection could herald more cases in November. The dengue season normally transpires between August to October, he said.

Data from the Bruhat Bengaluru Mahanagara Palike (BBMP) and the Department of Health and Family Welfare shows that while the city recorded 941 positive cases among 6,837 people tested in September, that October’s numbers are a fraction of this: 260 positive cases up to October 17, with 1,832 people having been tested.

“Dengue cases usually come down amid heavy rains, such as the situation we are currently in. But they will increase once the rains stop,” added Special Commissioner (Health), Dr Thrilok Chandra of BBMP.

He and Randeep added that larval surveillance teams are at work mitigating stagnant water sources.

Nevertheless, an increase has been already noted at one city hospital. “There have been day-by-day increases of people turning up with the severity of the disease,” said Dr Dinesh V Kamath, an internal medicine specialist at Manipal Hospital (Malleswaram).

“Four to five out of every 10 dengue cases that we see, have the moderate disease. While we cannot predict what the dengue incidence rate will be like in future, evidence shows that the numbers will increase over the course of the next two weeks. It is headed towards a peak.”

Experts fear that the annual totals could exceed 2020’s figures by a margin of 15 to 25 per cent, commensurate with increased rain.

“Our weather prediction shows that the heavy rains will not let up for the next five days at least. Furthermore, historically, the northeast monsoon onset date is October 20 - which means a further bout of heavy rain,” explained Dr Geeta Aghnihotri of IMD’s Bengaluru office.

“We are predicting a further bout of heavy rain on October 21 and 22 along with south belt districts of the state,” she added.

According to the IMD, Bengaluru, for example, receives an average of 98 cm of rain a year (between January and December). This year, the city has already received 115 cm.

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