The Brihanmumbai Municipal Corporation-run hospitals in Mumbai have treated more than 2,000 patients for dengue between October 1 and October 15 this year. Doctors have said the number of dengue cases could be much higher, as many people suffering from dengue may not undergo tests that are required to confirm the diagnosis.

The National Vector Borne Disease Control Programme records only those cases of dengue which are confirmed using the enzyme-linked immunosorbent assay or Elisa test which detects the antibodies in the blood against the dengue infection.

“Majority of the patients treated at the BMC hospitals are suspected of suffering from dengue,” said Dr Mini Khetrapal, in-charge of the epidemiology department of BMC.

According to the municipal corporation, only 124 people in Mumbai were confirmed to have been suffering from dengue between October 1 and October 15. In October 2016, Mumbai had recorded 228 cases of dengue from different parts of the city.

The intermittent rains in October in the city have led to an increase in the breeding of Aedes Aegypti, the dengue-spreading mosquito, officials of the insecticide department of BMC said. “If it rains continuously, there is little chance of water accumulation,” an officer told Scroll.in. “But when it rains intermittently, the chances of breeding is more.”

Another challenge is that the eggs laid by Aedes Aegypti mosquitoes can survive in dry form for very long periods. The eggs can become viable again once it rains.

Over the last month, several doctors from civic-run KEM Hospital in Mumbai also contracted dengue infection. “About 20 doctors had got dengue, but everyone has recovered now,” a doctor from the hospital said on the condition of anonymity.

Dr Om Shrivastav, an infectious disease consultant at Mumbai’s Saifee Hospital, said dengue patients this year are exhibiting symptoms which were not commonly reported in dengue cases. “We had patients who developed lung, stool infection along with dengue,” said Shrivastav. “It is difficult to point out the reason leading to such co-infections, but there is probably a need to conduct a detailed study to understand it better.”