Bengaluru: Karnataka has witnessed an alarming increase in H1N1 cases this year, with the number of reported cases up nearly sevenfold compared to last year, according to data from the state health department. As of July 31, 2023, the state has recorded 855 H1N1 cases, a stark contrast to the 118 cases reported during the entirety of 2022. This surge in cases has been particularly prominent in Bengaluru, under the Bruhat Bengaluru Mahanagara Palike (BBMP) limits.
Deaths and Severity of Cases
The rise in H1N1 cases has also resulted in fatalities, with a 15-year-old boy in Mysuru and a 48-year-old woman in Doddaballapur succumbing to the virus this year. Additionally, three other individuals who tested positive for H1N1 died due to comorbidities and advanced age, as noted by a senior official from the health department.
Increased Awareness and Testing
Dr Ansar Ahmed, Project Director of the Integrated Disease Surveillance Programme, pointed out that while active surveillance for H1N1 is not conducted, greater public awareness and increased lab testing have led to better reporting of cases, especially those related to seasonal changes. “We are closely monitoring the cases and improving our recording efforts,” he said.
Surge in Bengaluru Hospitals
Doctors in Bengaluru have observed an “atypical” surge in H1N1 cases, with outpatient department visits for flu-like symptoms rising from single digits per week to double digits daily. This has led to more severe cases requiring hospitalisation. Dr Majeed Pasha, Consultant-Pulmonology at a private hospital in Nagarabhavi, Bengaluru, reported that over the past month, more than 25 out of 70 patients who tested positive for H1N1 required oxygen support, and seven to 10 were put on ventilators.
Symptoms and Vulnerable Populations
H1N1, a viral respiratory infection diagnosed using the RT-PCR test, presents symptoms such as high fever, cough, sore throat, body ache, fatigue, and headache. Severe cases may also involve nausea, vomiting, diarrhoea, and pneumonia with breathlessness, especially in older adults. While the infection is particularly severe in those aged 50 and above, cases have been reported across all age groups, with schoolchildren and those with recent travel histories being more susceptible.
Possible Causes of the Surge
Several factors may contribute to this spike in cases, according to Dr Manjunath P H, Consultant – Interventional Pulmonologist. These include seasonal changes, increased transmission due to social interactions, evolving flu virus strains, and possibly reduced immunity in the population. Lower vaccination rates among certain groups may also be a factor.
This month has seen sudden fluctuations in temperature, further contributing to the spread of the infection. Dr Ravi K, head of Karnataka’s State Technical Advisory Committee for Communicable Diseases, recommended that high-risk individuals, including children, those above 60 years of age, and people with comorbidities, should take the influenza vaccine before the onset of flu season each year.
Historical Context
Karnataka’s H1N1 cases have fluctuated significantly over the years:
- 2018: 1,733 cases, 87 deaths
- 2019: 2,030 cases, 96 deaths
- 2020: 458 cases, 3 deaths
- 2021: 13 cases, 0 deaths
- 2022: 517 cases, 14 deaths
- 2023: 181 cases, 0 deaths (until earlier this year)
The sudden rise in 2023 underscores the importance of continued vigilance, vaccination, and timely medical intervention to mitigate the impact of H1N1 in Karnataka.