IDSP’s Surveillance Activities: Tracking Public Health in India

India’s public health system relies on vigilant disease tracking to identify outbreaks before they spiral into epidemics. The Integrated Disease Surveillance Programme operates across all states and union territories with a clear mission: detect threats early and respond rapidly. Through a multi-layered approach that combines notification systems, active field monitoring, and laboratory networks, IDSP tracks everything from tuberculosis and HIV to vector-borne diseases and antimicrobial resistance.

Notification and sentinel surveillance: Mandatory reporting systems 🔗

Notification surveillance requires health facilities to report specific diseases to public health authorities. This system captures critical data on conditions that pose immediate threats to communities. Two major examples demonstrate how notification and sentinel surveillance function in India’s disease monitoring landscape.

Tuberculosis notification through Nikshay 🔗

Nikshay serves as India’s real-time TB surveillance platform. The digital system registers patients at tuberculosis units nationwide and tracks pre-treatment tests, follow-up examinations, treatment progress, and contact tracing details. Health workers use SMS technology to communicate with patients and providers, sending registration confirmations and daily updates to monitoring authorities. India reported a peak of 2.4 million TB cases in 2019, and when notifications dropped 25% during the COVID lockdown, Nikshay’s real-time data allowed authorities to recognize the decline early and mount targeted recovery efforts through bi-directional TB and COVID screening.

The system establishes case-based web recording and reporting, monitors patient treatment, and improves care quality by health service providers. Both public and private sector facilities participate in TB notification, creating a comprehensive database used at district, state, and national levels for monitoring purposes.

HIV sentinel surveillance across risk groups 🔗

HIV surveillance monitors the epidemic through systematic sampling of specific populations. Initiated in 1985 and formalized into an annual system in 1998, sentinel surveillance evolved into a biennial system called HIV Sentinel Surveillance Plus. The 17th round in 2021 collected bio-behavioral data from eight population groups: pregnant women, single male migrants, long-distance truckers, central prison inmates, female sex workers, men who have sex with men, hijra/transgender people, and injecting drug users.

National estimates for 2019 showed approximately 23.49 lakh people living with HIV, with an adult prevalence of 0.22%. The surveillance data revealed 69,220 new HIV infections in 2019, representing a 37% decline since 2010 and an 86% reduction since the peak in 1997. This systematic approach allows health authorities to track epidemic trends and allocate resources effectively.

Active and passive surveillance: Complementary detection methods 🔗

Disease surveillance operates through two distinct but complementary approaches. Passive surveillance collects data from patients who voluntarily seek care at health facilities, while active surveillance involves health workers proactively searching for cases in communities.

Malaria tracking through dual surveillance 🔗

Malaria surveillance demonstrates how both methods work together. Passive surveillance occurs at Primary Health Centers, Malaria Clinics, Community Health Centers, and secondary and tertiary healthcare institutions where patients visit for treatment. Village-level workers provide diagnostic and treatment services through rapid diagnostic tests and blood smear examination.

Active surveillance takes a different approach. Health workers visit households every fortnight, asking if anyone currently suffers from fever or has experienced it since the last visit. If yes, they collect blood smears and provide presumptive chloroquine treatment. Research in Central India’s tribal belt found that active case detection in villages identified substantially more malaria positive cases compared to passive detection at health centers, with an odds ratio of 12.03. This difference proves especially important in reaching populations who don’t regularly access healthcare facilities.

Understanding the Annual Parasite Incidence 🔗

API measures malaria burden per 1,000 population. India’s National Framework for malaria elimination uses API as the primary criterion for classifying states and districts into different categories: intensified control, pre-elimination, elimination, and prevention of re-establishment. For sub-centers with API greater than 1, vector control measures include universal coverage with insecticide-treated bed nets and indoor residual spray rounds. Sub-centers with API below 1 receive foci-based interventions.

The indicator depends on the Annual Blood Examination Rate, which represents the number of people receiving parasitological tests per unit population per year. Blood smears are examined microscopically to identify Plasmodium parasites, determining both slide positivity rates and species distribution between P. falciparum and P. vivax.

Vector and laboratory surveillance: Monitoring disease carriers and resistance patterns 🔗

Beyond tracking human infections, IDSP monitors the vectors that transmit diseases and the laboratory patterns that reveal emerging threats like antimicrobial resistance.

Tracking mosquito breeding for dengue and chikungunya 🔗

Vector surveillance focuses on Aedes mosquitoes that transmit dengue and chikungunya. Both diseases share the same vector and often occur together, creating what researchers call a syndemic interaction. Analysis of IDSP data from 2014 to 2023 revealed significant geographic variability, with districts like Pune, Tumkur, and Kamrup experiencing high burdens of both diseases simultaneously.

Surveillance teams conduct immature vector surveys, identifying breeding sites in urban environments. Common breeding habitats include overhead tanks, ground water storage containers, discarded tyres, broken utensils, and plastic waste. Public health departments coordinate with local bodies to undertake anti-larval measures through source reduction and regular inspection of artificial containers. The Friday Dry-Day campaign encourages community participation in weekly removal of unnecessary breeding sites.

Entomological indices measure Aedes breeding potential through surveys of pupae and larvae in human habitations. High indices indicate elevated mosquito density and increased risk for dengue and chikungunya outbreaks, warranting intensive surveillance and vector control measures.

Laboratory surveillance and antimicrobial resistance detection 🔗

Laboratory networks detect antimicrobial resistance patterns across India. The National Centre for Disease Control coordinates a surveillance network strengthening State Government medical college hospitals and laboratories for AMR surveillance. The network uses WHONET software for data management and conducts regular training on specialized laboratory testing procedures.

District Public Health Laboratories perform diagnostic tests according to IDSP standards, with 138 labs equipped with trained manpower, essential equipment, and annual grants for reagents and consumables. State Referral Laboratories in medical colleges provide advanced diagnostic services for epidemic-prone diseases during outbreaks, creating a network functional in 23 States and Union Territories involving 108 laboratories.

Apex referral laboratories perform specialized testing for arboviral diseases including dengue, chikungunya, and Japanese encephalitis. India has established referral laboratory networks for AMR and tuberculosis, with the ICMR Antimicrobial Resistance Surveillance System capturing standardized data from laboratories nationwide. The system monitors resistance patterns in priority bacterial pathogens, helping authorities detect emerging threats and guide treatment protocols.

Laboratory surveillance extends beyond identifying pathogens to characterizing resistance mechanisms. Facilities perform antimicrobial susceptibility testing using disk diffusion, broth microdilution, and automated systems according to standardized procedures. National Reference Laboratories conduct external quality assessment testing and phenotypic and genotypic characterization of AMR determinants, ensuring data quality across the network.

What do you think? How can India strengthen coordination between notification systems, field surveillance, and laboratory networks to respond even faster to emerging disease threats? What role should community participation play in vector surveillance and outbreak prevention efforts?

References

1. https://ncdc.mohfw.gov.in/integrated-disease-surveillance-programme/
2. https://tbassessment.stoptb.org/India.html
3. https://naco.gov.in/surveillance-epidemiology-0
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5. https://pmc.ncbi.nlm.nih.gov/articles/PMC5072121/
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8. https://www.nhm.tn.gov.in/en/nhm-programscommunicable-diseases/national-vector-borne-disease-control-programme-nvbdcp
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10. https://jogh.org/2023/jogh-13-04028