Lesser vector density behind no dengue cases in Noida, say officials

No case of dengue has been reported from Noida this year, officials said. Attributing this phenomenon to lesser vector- or mosquito-density, doctors said normally the first few cases are reported in July every year.

While officials maintained the presence of lesser than usual number of mosquitoes has led to fewer cases of malaria and no case of dengue being reported so far, doctors said generally the arrival of the monsoon leads to a spike in the number of dengue cases, since fresh water accumulates in various parts of the city. However, they said, of the 26 suspected cases reported this year, none have been confirmed yet.

District malaria officer Rajesh Sharma said, “Usually there are more cases due to water accumulation in corners that people don’t notice. However, we have been testing samples of suspected cases, but none have been confirmed so far. This is a good sign as people are reporting that the number of mosquitoes is also less.”

He added that the number of mosquitoes is checked through a vector density test, where the per man hour density of mosquitoes is calculated physically. However, since the required staff is not available in the district, the report is based on crowdsourcing and the number of positive cases from the total samples collected.

“We speak to residents across the city and get an idea of whether there are fewer mosquitoes this year. One can usually get an idea depending on mosquitoes outdoors,” Sharma said.

The reduction in the number of dengue cases can also be seen from the ratio of samples collected and the positive cases of malaria in Gautam Budh Nagar. This year, 26,521 samples have been collected for malaria, over 12,000 more than last year. Of these, 65 confirmed cases have been reported this year, compared to 80 last year. In 2013, the malaria test was conducted on just 13,651 samples, of which 111 cases were found positive .

However, health officials suggest that the people need to continue to be cautious and not let water accumulate. Chief medical officer Dr Anurag Bhargava said, “People should remain careful so that fresh water does not collect and remain stagnant. Regular cleaning of coolers, rooftops, open areas around homes and open pits must be ensured. There may not be cases so far but the threat is still there.”

Meanwhile, the government has also issued a notification banning use of antibody-based tests for malaria, to ensure better accuracy. According to the notification, there are fewer false positives and more accurate results when an antigen-based diagnostic test is performed.

First Published: Aug 20, 2018 04:43 IST

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