India has a long history of combating infectious diseases, with smallpox being one of the earliest documented viral illnesses. Ancient Indian texts, such as the Sushruta Samhita (circa 6th century BCE), describe a disease resembling smallpox, indicating its presence in the region for millennia. These texts show that India was aware of infectious diseases long before modern medicine, utilizing various methods to manage outbreaks. Smallpox, one of the most devastating diseases, existed globally for thousands of years, affecting civilizations across the world. The historical context of smallpox in India reflects the country’s early awareness of public health issues.
Smallpox
Smallpox, highly infectious with no known cure at the time, has a documented history in India as far back as 1350 BCE. Archaeological studies have found evidence of smallpox in the study of Egyptian mummies, which suggests that the disease was widespread and known across ancient civilizations. In India, smallpox outbreaks caused widespread mortality and affected various regions, contributing to the development of early medical systems.
The Indian National Smallpox Eradication Programme (NSEP) was founded in 1962 with the ambitious goal of vaccinating the entire population within three years. However, this initiative initially failed due to lack of coverage and challenges in reaching remote areas. The policy was adjusted in 1964, focusing on regions with higher incidence rates, such as Bihar, Uttar Pradesh, Madhya Pradesh, and West Bengal. Despite early setbacks, the NSEP’s revised strategy proved effective. After years of sustained vaccination campaigns and public health awareness, India became one of the key players in the global smallpox eradication effort. The Indian program succeeded in eradicating smallpox by 1977, following the global initiative led by the World Health Organization (WHO).
Development of the Smallpox Vaccine
Dr. Edward Jenner, an English physician, is credited with developing the first smallpox vaccine in 1796. Jenner observed that milkmaids who had contracted cowpox—a milder disease—seemed immune to smallpox. This led him to hypothesize that exposure to cowpox protected against smallpox. His landmark experiment involved inoculating a young boy with cowpox material, demonstrating the protective effect of the vaccine. Jenner’s discovery laid the groundwork for modern immunology and the eventual global eradication of smallpox.
Prior to Jenner’s work, the practice of variolation—intentionally infecting individuals with smallpox to induce a mild form of the disease and grant immunity—was used in various cultures. Jenner’s use of cowpox represented a more scientific approach to inoculation and marked a critical turning point in the fight against infectious diseases.
Rabies
Rabies has been recognized in India since at least 3000 BCE. The god of death in ancient depictions was often shown accompanied by a dog, symbolizing the association between dogs and fatal outcomes, likely due to rabies. During British colonial rule, rabies became widespread in both humans and animals, posing significant health risks. The colonial government faced mounting financial pressure as the number of rabies cases soared, especially following dog bites.
The Pasteur Institute of India played a pivotal role in addressing rabies, developing an inactivated rabies vaccine in 1970, which improved the country’s ability to manage and prevent the disease. The establishment of the National Rabies Control Program (NRCP) further strengthened efforts to control rabies, focusing on training healthcare workers, raising awareness, and providing post-exposure prophylaxis. Despite these measures, India still faces a significant rabies burden, accounting for about 36% of the world’s rabies deaths.
Rabies Vaccine Development
Dr. Louis Pasteur, the French chemist and microbiologist, developed the first effective rabies vaccine in 1885. The first human patient treated with the vaccine, a nine-year-old boy named Joseph Meister, had been bitten multiple times by a rabid dog. After receiving 13 inoculations over 11 days, the boy survived without contracting rabies. Pasteur’s work revolutionized the treatment of rabies and paved the way for further breakthroughs in vaccine development.
Kyasanur Forest Disease (KFD)
Kyasanur Forest Disease (KFD), commonly known as “monkey fever,” is a tick-borne viral hemorrhagic fever endemic to South India, particularly the Western Ghats region. The disease was first identified in 1957 in the Kyasanur Forest of Karnataka. Since then, it has posed significant public health challenges. The causative agent, a virus from the Flaviviridae family, is primarily transmitted through the bite of infected hard ticks (Haemaphysalis spinigera). Over the years, KFD has spread beyond Karnataka, with cases also reported in Tamil Nadu and Kerala, expanding the geographic area of concern.
Public health efforts to combat KFD have included vaccination campaigns, tick control measures, and increased public awareness. The National Institute of Virology (NIV) has been instrumental in researching KFD, developing diagnostic tools, and formulating vaccines. The Indian Council of Medical Research (ICMR) initiated research into KFD in the 1960s, culminating in the development of an inactivated vaccine in 1985. This vaccine has been used to immunize individuals at risk, particularly those in endemic regions. Despite these efforts, KFD outbreaks are still reported regularly, and the disease remains a persistent public health threat.
Recent research has brought new hope for KFD control. In 2023, a study described the development of a single-dose vaccine using a genetically engineered vesicular stomatitis virus (VSV) platform. This vaccine has shown promising results in animal models, including mice and macaques, and is now set to enter clinical trials. These developments represent a significant step forward in combating KFD, offering hope for better control and prevention.
Chandipura Virus (CHPV)
Chandipura virus (CHPV), identified in 1965 in Maharashtra, India, is primarily transmitted through sandfly bites. Initially considered a low-pathogenic virus, CHPV has been associated with acute encephalitis syndrome (AES) outbreaks, particularly in children. The virus’s high case-fatality rate—up to 75% in some outbreaks—has made it a significant public health concern. Recent outbreaks, including one in 2024, have led to heightened awareness of the virus’s impact.
Preventive strategies for CHPV focus on vector control, early detection, and prompt medical intervention. Research into CHPV has contributed to the development of diagnostic assays and improved surveillance systems, with ongoing efforts to create effective vaccines. In 2011, researchers developed an inactivated vaccine candidate using Vero cells, which demonstrated immunogenicity in animal models. More recently, subunit vaccines targeting CHPV’s glycoprotein have shown promise, offering hope for a future vaccine.
Nipah Virus (NiV)
Nipah virus (NiV) is a zoonotic pathogen that can cause severe illness in both animals and humans. Since its emergence in Malaysia and Singapore in 1998, NiV has been responsible for several outbreaks in India, particularly in Kerala. The virus’s high fatality rate—often reaching 70%—and its ability to spread from animals (fruit bats) to humans have made it a critical focus of public health efforts in India. The state of Kerala has faced several outbreaks, with the most recent in 2018 resulting in 17 deaths. Surveillance, containment strategies, and strengthened healthcare infrastructure have been essential in managing outbreaks.
Ongoing research on NiV focuses on both vaccine development and therapeutic interventions. In 2024, the University of Oxford launched a clinical trial for a NiV vaccine, while the National Institutes of Health (NIH) in the United States is testing an mRNA-based vaccine, mRNA-1215, for its safety and efficacy. These efforts, along with therapeutic antibody development, are crucial steps in the fight against NiV.
Way forward
India’s battle against infectious diseases such as smallpox, rabies, KFD, CHPV, and Nipah virus has been a long and ongoing effort. From ancient remedies to modern medical breakthroughs, the country has made significant strides in managing these diseases. Public health initiatives, advancements in vaccine development, and continued research are central to reducing the burden of these diseases. However, challenges remain, and continued investment in surveillance, research, and healthcare infrastructure is critical to safeguarding the health of India’s population in the face of evolving infectious threats.
