Three-year-old Aakriti Sharma’s parents brought her to PGIMER, Chandigarh with symptoms of a persistent cough for more than a week, with the child vomiting during severe bouts. Ten days ago, she had a runny nose, mild fever, sneezing and a slight cough, which her mother passed off as a seasonal viral infection. “I got concerned when she began coughing uncontrollably throughout the day, with the severity increasing at night. She would make a strange sound when she tried to take a breath. She had no asthma or allergies, and none of us had any symptoms, though there were some children in the kindergarten who had cough and cold,” shares her mother.
A nasal swab for Bordetella pertussis was positive by PCR, and a complete blood count also showed elevated white blood count, though the chest X-ray showed no pneumonia. Aakriti was put on antibiotics, with advice for plenty of fluids, small, frequent meals, avoiding pollution, and a follow-up after the course of antibiotics. Timely medical attention and antibiotics helped Aakriti improve in three weeks, and also prevented the spread of infection.
Cases like hers got researchers at the Postgraduate Institute of Medical Education & Research (PGIMER), Chandigarh, to probe deeper. They reported a significant rise in infections caused by a lesser-known bacterium that mimics whooping cough (pertussis) across Northern India.
The present study from PGI, published in the Emerging Infectious Diseases journal (Centers for Disease Control and Prevention, USA), has analysed 935 suspected pertussis cases between 2019 and 2023. This long-term research initiative was spearheaded by Prof Vikas Gautam, Department of Medical Microbiology, PGI, in collaboration with Dr. Prabhu Patil of CSIR–IMTECH, Chandigarh.
What is Whooping Cough?
Pertussis, commonly known as whooping cough, is a highly contagious respiratory illness that has historically been a major cause of childhood mortality, with fatality rates reaching 10 per cent in the early 20th century, explains Prof Gautam. In Asia, pertussis continues to pose a significant public health burden, particularly in India and China primarily affecting infants and children. After a brief decline during the COVID-19 pandemic, cases have sharply rebounded: India recently reported approximately 13.6 million cases, while China’s incidence rose from 0.13 per 100,000 in 2013 to 2.15 per 100,000 in 2019, exceeding 58,990 reported cases by early 2024.
“Nearly 37 per cent of infections were caused by Bordetella holmesii, surpassing the number of conventional infections from Bordetella pertussis. The most significant increase was recorded in 2023, predominantly among children aged 5–10 years in northern India. As per the data obtained under the ongoing surveillance programme at PGI since 2015, the prevalence of B. pertussis has declined from 15–20% to just 2–5%, while infections from B. holmesii have risen markedly. This shift signals an evolving pattern in the etiology of pertussis-like respiratory illness in the region. It is important to connect the dots, though the decline has come, a new species has come up causing the infection, and there will be some change in both the bacterium, so a lab diagnosis is paramount to make an early diagnosis,” adds Prof Gautam.
Why Early Diagnosis is Important
The main age group affected is between five and ten years of age, and after infection, it usually takes about five days to a week for symptoms to appear. At first, it may seem like a usual cold with a runny or stuffy nose, light cough, low-grade fever, says Prof Gautam, but after a week, in the second stage, the cough is stronger and more persistent. A thick mucus starts to build up in the airways, leading to long coughing fits, tiredness, and even vomiting. “You can hear a loud whooping sound when the child catches the breath, and in babies, they may have trouble breathing and may gag due to mucus in the lungs. We urge parents not to ignore any symptoms and visit a specialist, so that lab tests can be recommended and treatment can start immediately to kill the organism, avoid serious complications and check the spread of infection,” explains Prof Gautam.
Vaccination is the best prevention
Earlier called a childhood disease, Prof Gautam says that the trend is now changing, with rare cases of teenagers and adults also being affected, particularly when vaccine protection wanes. Therefore, testing after taking a sample is important.
“The best way to prevent this is vaccination and a regular course of antibiotics, as prescribed by the doctor. The course of medicines must be finished or else one runs the risk of antibiotic resistance and develops a higher chance of a relapse,” warns the doctor, adding that these findings reinforce PGI’s pivotal role in identifying emerging pathogens and strengthening infectious-disease surveillance in India.
The present study from PGI, published in the Emerging Infectious Diseases journal (Centers for Disease Control and Prevention, USA), has analysed 935 suspected pertussis cases between 2019 and 2023. (File photo) 
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