Disease surveillance involves systematically collecting, analysing, and interpreting health data to identify, monitor, and control diseases. Photograph used for representational purposes only
| Photo Credit: Getty Images
The recent focus on Human Metapneumovirus (HMPV) infections has stirred significant public interest, not only in the disease itself but also in the mechanisms that enable its detection. Social media was rife with speculation, branding HMPV as a “new disease,” only for experts to clarify that HMPV is far from novel. The larger question, however, is how we can distinguish such claims from reality and what enables us to identify these infections today. The answer lies in understanding India’s disease surveillance system.
What is disease surveillance?
Disease surveillance involves systematically collecting, analysing, and interpreting health data to identify, monitor, and control diseases. It enables health systems to detect outbreaks early, respond effectively, and mitigate public health threats by flattening the curve. Surveillance mechanisms can be broadly categorised into passive surveillance, where healthcare providers report cases as they occur; active surveillance, where public health authorities actively search for cases, particularly during outbreaks; and sentinel surveillance, which focuses on monitoring specific diseases in institutions across India over years, to identify trends.
Surveillance has been the cornerstone of military strategy for centuries. While military surveillance dates back millennia, disease surveillance has been no less prevalent. Global trade and commerce facilitated the spread of diseases, prompting early societies to develop measures such as quarantine and isolation. These rudimentary practices laid the groundwork for modern surveillance systems. Surveillance involves six essential steps: detection and reporting of health events, data collection and analysis, investigation and confirmation, response, and feedback dissemination.
India’s unique burden
India faces a unique triple burden of infectious diseases. The first includes novel diseases like COVID-19 that emerge unexpectedly. The second comprises diseases like malaria and dengue, which have ceased to be public health threats in many Western countries but remain endemic in India. The third includes diseases uniquely prevalent in India, such as Kyasanur Forest Disease. This diverse burden underscores the need for a robust surveillance system. Disease surveillance under programmes like the Integrated Disease Surveillance Programme (IDSP) /Integrated Health Information Platform (IHIP) is a form of passive surveillance. Notifiable diseases require mandatory legal reporting by healthcare providers, whereas disease surveillance, like IDSP/IHIP, relies on systematic passive monitoring. Both aim to protect public health and fulfil global commitments. Sustainable Development Goal 3 (target 3.d) calls for strengthening capacities for early warning, risk reduction, and management of health emergencies, emphasising the need for robust surveillance systems. The World Health Oranization publishes Disease Outbreak News and weekly epidemiological reports, leveraging its extensive intelligence network to monitor outbreaks and provide timely updates on global public health threats.
The evolution of surveillance in India
In India, organised disease surveillance began with the establishment of the National Centre for Disease Control (NCDC) in 1909. The NCDC acts as a nodal agency to control infectious disease outbreaks. The IDSP, envisioned in the 2002 National Health Policy, began as a World Bank-funded project in 2004 and was launched in three phases, achieving nationwide coverage by 2008. Initially, the system relied on paper-based reporting forms: Suspected case (S) forms, submitted by health workers to report syndromic cases; Presumptive case (P) forms, submitted by doctors to report probable cases; and Laboratory (L) forms, submitted by laboratories for lab-confirmed cases. These forms were consolidated weekly, but delays in reporting often hampered timely responses. This gap was addressed by IHIP in 2021, a digital platform enabling real-time disease reporting. IHIP now monitors 20 symptoms in S form, 34 presumptive cases in P forms and 28 diseases in L form daily, with weekly epidemiological reports published for policymakers and shared with the Prime Minister’s Office (PMO) and Chief Ministers’ Offices (CMOs) as part of intelligence briefings. The list of diseases for surveillance is selected based on their burden in the community, availability of public health responses, and special considerations like international commitments. The system categorises outbreaks into five triggers, ranging from suspected limited outbreaks to those requiring international responses.
The surveillance landscape
Disease surveillance in India extends beyond IHIP to other successful initiatives. The Health Management Information System (HMIS) in India collects data from State-run hospitals. Health workers enter data on patient admissions, diseases, immunisation, maternal and child health, and facility performance. This data from districts is sent to the State Bureau of Health Intelligence for consolidation and analysis at the State level, forming part of the State Surveillance Unit. The Central Bureau of Health Intelligence processes national-level data, aiding the Central Surveillance Unit in strengthening the disease surveillance network and guiding public health responses. The IHIP integrates data from the State Bureau of Health Intelligence & the Central Bureau of Health Intelligence.
National programmes for Polio/HIV/TB/Malaria exemplify sentinel surveillance using Geographic Information System (GIS) mapping to track cases and guide interventions. Advances in technology have transformed disease surveillance. IHIP’s GIS-enabled systems and geotagging capabilities allow for precise tracking of disease trends. Data is entered in real-time, ensuring timely detection and response. Tools like GIS enable accurate mapping of outbreaks.
Effective surveillance requires collaboration across multiple sectors. The IHIP has facilitated the establishment of district public health laboratories nationwide to strengthen diagnostic capabilities. At the district level, surveillance units bring together representatives from various sectors, including the Indian Medical Association (IMA), NGOs, Panchayat Raj institutions, Pollution Control Boards, Water Boards, and law enforcement, chaired by the District Magistrate.
The expansion of IHIP
Disease surveillance also borrows from non-formal systems by enabling media and responsible citizens to alert the system. A media scanning cell at the national level monitors reports from print, visual and social media, identifying potential outbreaks early. Disease surveillance is expanding to include non-communicable diseases (NCDs). While NCDs do not spread between individuals, tracking their prevalence is important for planning public health programmes and allocating resources. The existing IHIP network is being utilised to monitor the burden of NCDs. Recently, dog bites that lead to suspected rabies and snakebite envenomation have also been added to surveillance frameworks.
The detection of HMPV is not a sign of a growing threat but rather, a reflection of India’s strengthened surveillance and diagnostic capabilities. Before systems like IDSP/HIP, the country lacked comprehensive disease data and had limited capacity to respond to outbreaks. Today, India has a decent mechanism to recognise, report, and respond to health threats. But, integrating inputs from the private sector needs better coordination. A disease anywhere remains a threat everywhere, and India’s evolving surveillance infrastructure needs to ensure it stands ready to meet this challenge.
Published – March 03, 2025 04:13 pm IST