Delhi: With the second-highest dengue infections in 2021, the gaps and lapses

Some reasons for the surge: Erratic monsoons, a more virulent strain, legal changes that have made it mandatory to report all cases and lethargy in the official response

New Delhi: Delhi has recorded 9545 dengue cases and 23 fatalities due to dengue during 2021, the vector-borne disease reports issued by the three municipal corporations of Delhi show. This is the second-highest caseload and death due to dengue on record. The dengue outbreak in 2015 had led to 60 deaths and 15867 infections. The caseload data between 2010 and 2021 shows that this is only the fourth time when the number of dengue cases has crossed the 5000 mark. In comparison, the city recorded 1072 dengue cases with 1 death in 2020, 2036 cases with 2 deaths in 2019 and 2798 cases with 4 deaths in 2018.

Early during the dengue outbreak, Delhi confirmed the presence of the more dangerous Type II strain being in circulation in the city(Ravi Kumar/HT Photo/Representative Photo)

Public health experts and senior doctors in the city attribute the high caseload and deaths to various factors including delayed and erratic monsoons, a more virulent strain of dengue in circulation, legal changes that have made it mandatory to report all dengue cases as well as lethargy in the official response to the outbreak.

Late and erratic monsoons

Senior municipal functionaries have argued that Delhi witnessed erratic and delayed monsoon rains during 2021 which led to the ideal breeding conditions for mosquitoes. This year Delhi has recorded the second-highest annual rainfall in 121 years. The city had brief but intense spells of rains leading to the overwhelming of the drainage system and large scale waterlogging. Delhi's four-decade-old drainage system can only cater to daily rainfall up to 50mm. In July alone, Delhi received 69.6 mm rainfall on 19th July, 100 mm rainfall on 26 July and 72 mm rainfall on 29th July leading to an overwhelmed drainage system. The normal rainfall in the month of July is 210.6 mm while 506 mm rain was received in July this year despite the monsoon arriving very late.

Leader of the house in south MCD Inderjeet Sehrawat said that the record monsoon and slow arrival of winter led to an increase in dengue cases this year and the cases dipped as soon as the temperature went below the 10 degree Celsius mark. A senior SDMC public health official explained that both the Anopheles and Aedes Aegypti mosquitoes prefer warmer environments above 30 °C. "Once the temperature lowers to about 20 °C, they become less active in the open environment and do not function below 10 °C. People still need to be careful as adult mosquitoes have a life of one month," the official said.

A more dangerous strain of dengue

Early during the dengue outbreak, Delhi confirmed the presence of the more dangerous Type II strain being in circulation in the city. Dr Rommel Tickoo, director, internal medicine at Max Saket said, “Moreover, the second strain of dengue was circulating in Delhi as well as Uttar Pradesh which is much more virulent," he added. Dengue has four types of strains. Type I can cause classic symptoms of fever along with chills and headaches while Type II can lead to haemorrhagic fever with shock and chills. Type III dengue causes fever without shock while Type IV causes fever without shock or profound shock.

Out of the 23 dengue deaths cleared by the death audit committee, 15 were minors less than 18 years old. A senior official, who is a member of the committee, said that the high number of deaths among children shows that the patients had not developed anti-bodies in previous infections. "In countries like India where dengue is endemic, adults develop resistance to disease due to earlier encounters with it," the official remarked.

Notifiable disease: Better reporting

A proposal which was several years in making, Dengue along with other vector-borne diseases — chikungunya and malaria — was declared a "notifiable disease" under the Epidemic Diseases Act, according to an official notification issued by the government of Delhi on 14th October 2021. The notification now makes it compulsory for all private hospitals and clinics to provide information to the government about any such case that they receive. It states that legal action will be taken against individuals or institutions found not following adequate measures or not informing cases to authorities. A senior official from SDMC, the nodal agency of data collection on dengue, said that the notification has vastly improved the reporting of cases. "Earlier several dengue cases were going unreported and people were being treated in small clinics and hospitals which were not under the sentinel scheme of civic bodies. Before the notification, 36 hospitals under the ‘sentinel surveillance system’ used to share weekly data with the malaria headquarters. But now, corporations are getting data from 180 healthcare facilities," the official said.

Lapses, negligence and vacant posts

Despite the climatic conditions being ideal for the spread of mosquito-borne diseases, enough steps were not taken by the authorities in Delhi to combat them. The Delhi High Court has come down heavily on the civic authorities in the last three months. The court remarked that there was complete paralysis of administration, rapping civic bodies for failing to tackle the dengue situation this season and questioning whether responsibility has been fixed for the increase in cases. In late October when the number of dengue cases was rising alarmingly, HT had reported how the North Delhi Municipal Corporation was running abysmally low on larvicide and insecticides needed to control vector populations. The civic body had run out of the stocks of diflubenzuron, BTI, mosquito larvicidal oil (MLO), alpha-cypermethrin. Moreover, all three civic bodies have large-scale vacancies at senior levels of the officialdom designated to implement public health measures in the city. For instance, data from East MCD shows that two sanctioned posts of anti-malaria officers are lying vacant, all 6 posts of senior malaria officers are vacant, 56 out of 65 posts of malaria inspectors and vacant while 94 out of 153 assistant malaria inspectors posts are lying vacant. Similar, largescale vacancies exist at the supervisory level in the other two corporations as well but no corrective steps have been undertaken.

A senior public health official said that mosquito breeding was also facilitated by the negligence of people. The anti-malaria operations headquarter conducted an analysis of breeding site data in 32 hotspot wards in November to chalk out the distribution of these sites. The analysis reported that 58.5% Aedes Aegyti larvae were found in water storage units such as drums, buckets, Jeri cans; 30.2% in peri-domestic units like money plant vases, flower pots, bird-pots etc with smaller contributions from over-head tanks (5.4%), pumps (2.1%) and desert coolers (3.8%). Dr SP Byotra, senior consultant at Sir Gangaram Hospital and chairman of the department of medicine said that there have been lapses on the part of people as well as authorities. "Why do we wake up so late when the infection has already crossed a limit? The dengue control program should be run all around the year. We should start the drives from March in next year," he said.

Structural changes needed

Delhi has made several structural changes that will help it to encounter future outbreaks. Besides making dengue and malaria notifiable diseases, the notification also makes it mandatory for new building projects to include anti-mosquito measures. Civic bodies are expected to issue guidelines that need to be followed to make them mosquito-proof. The city is also about to steeply increase fines issued for negligence leading to favourable breeding conditions from the existing ₹500. A senior MCD official said that the incidence of mosquito-borne diseases also indirectly indicated the gaps in infrastructural development like water supply lines, sanitation and drainage and that Delhi will have to find permanent solutions to the needs of neglected areas. "Areas that do not have piped water supply have a higher incidence of dengue as people are forced to store water in containers. The structural improvement of infrastructure is the only permanent solution. The problems related to climate are likely to increase in the coming year as well," the official remarked.