An ailing European who arrived in Delhi from Shimla was among the first cases recorded as influenza began spreading in the city in 1918. Within months, the disease had claimed 7,044 lives in Delhi city, according to archival records.
Two years later, in September 1920, the British India administration formally declared ordinary influenza an infectious disease in Delhi, according to documents accessed by PTI from the Delhi Archives.
The notification brought influenza under the infectious-disease provisions of the Punjab Municipal Act, which governed municipal administration in Delhi at the time, and gave the Delhi Municipality powers to control its spread.
Today, H1N1 is covered under Delhi's infection-control guidelines as a reportable infection, but not every seasonal influenza case is individually reportable, said Dr Sanchayan Roy, Senior Consultant, Internal Medicine, Apollo Spectra Hospital, Delhi.
A medical report preserved in the Delhi Archives from 1918 said the first case to come to the immediate notice of the province's chief medical officer was a European who had recently arrived from Simla (now Shimla), where members of his family were suffering from the same illness.
A week later, another European living in the same house was "evidently infected from the first case".
Through September, there was little to cause "anxiety or alarm", the report said. Patients suffered from fever, sore throat and cough. But by October, cases had become more frequent, severe and fatal.
At Delhi's Civil Hospital, cases rose from ones and twos in the first week of October to more than 100 a day by the third week. On October 14 alone, 181 influenza cases were recorded, the report said.
Severe cases developed pneumonia, bronchitis, pleurisy and empyema, while some patients suffered violent delirium and others died suddenly from heart failure. Doctors across the province worked "almost to a standstill", the report said.
An official communication from the Chief Medical Officer, Delhi, in 1918 recorded 23,175 influenza deaths across Delhi Province in October and November. Of these, 7,044 were reported in Delhi city and 16,131 in rural areas, according to documents accessed by PTI from the Delhi Archives.
The 1918-19 influenza pandemic was one of the worst public-health disasters in India's modern history.
The first outbreak in June 1918 was mild, but the disease spread rapidly across the country through the railway network before a much deadlier second wave emerged in September.
Patients developed acute fever, weakness, pain in the body and limbs, headache, soreness of the eyes, cough and bronchitis, while severe cases developed pneumonia within days, said Dr Arvind Aggarwal, Director, Internal Medicine, Sri Balaji Action Medical Institute, Delhi.
Roy further added that this influenza virus was called the Bombay influenza virus. It couldn't be differentiated further. Possibly, it was H1N1, but could have been a mix of Influenza A and B also.
The scale of the epidemic prompted Delhi officials to consider whether influenza should be brought under the city's infectious-disease law.
A July 1920 file from the Delhi Archives shows the Sanitation Sub-committee considering whether influenza, influenza pneumonia or acute pneumonia should be included among infectious diseases under the Punjab Municipal Act.
The committee examined arrangements in Bombay, Madras and England, where different forms of influenza and pneumonia were already subject to notification.
Delhi officials recommended that ordinary influenza should also be notified, saying it would help detect influenza and influenza pneumonia, protect the public and give the municipality powers to control the disease.
"Although the difficulties of diagnosing ordinary Influenza are considerable," the committee said notification was "on the whole desirable". It also noted there would be "no inconvenience to the general public and no considerable additional work to the medical practitioner".
The Delhi Municipality then sought a draft notification for publication in the Gazette, following which the Chief Commissioner issued the final notification in September 1920, formally declaring ordinary influenza an infectious disease.
The 1921 Census estimated 8.5 million deaths in India from the pandemic in 1918 and 1919, while historical research has put the figure at 12 million or more, Aggarwal said.
More than a century later, the reporting system makes a sharper distinction between different influenza infections.
"The reportable nature of swine flu or Influenza A (H1N1) disease is already included in the infection control guidelines formulated officially by the state of Delhi," Roy told PTI.
He said suspected or confirmed reportable infections have to be reported through appropriate public-health and hospital surveillance mechanisms. However, this does not mean all patients suffering from seasonal flu have to be individually reported.
"Influenza A includes H1N1 and H3N2, while Influenza B also circulates," Roy said.
H1N1 receives specific public-health attention, while H3N2, Influenza B and other influenza infections are monitored through laboratory reporting and the Integrated Disease Surveillance Programme.
"National Centre for Disease Control laboratory reporting formats contain Influenza A, pandemic H1N1, H3N2, Influenza B and others among their laboratory tests," he said.
Roy also said testing is not required for every patient. Those in mild Category A and many Category B patients may not be tested for H1N1 under national guidelines, while Category C patients require testing, hospitalisation and treatment.
"Public health reporting in this case will be done through clinical surveillance for suspected infection and laboratory testing where appropriate, as opposed to laboratory confirmation only," Roy said.
