by Merritt Clifton
DELHI, CHENNAI–Collecting current data about disease incidence in India since 2003, the Indian Central Bureau of Health Intelligence has known more than 10 years that the oft-claimed Indian human rabies death toll of 20,000 per year is high by a factor of nearly 100.
Often cited by politicians and media, the 20,000 figure has repeatedly inflamed rabies panics, including street dog massacres and mob attacks on humane societies that participate in the federally sponsored Animal Birth Control program. Funded by the Animal Welfare Board of India since 2003, the ABC program seeks to replace lethal dog population control with sterilization.
The purported 20,000 human rabies deaths per year have also been used to rationalize spending upward of $25 million U.S. ($1.1 billion rupees) to provide free post-exposure vaccination to dog bite victims, instead of funding a much less costly national dog vaccination program which could eradicate canine rabies from India.
Dogs sterilized under ABC auspices must be vaccinated, but the ABC program does not fund later revaccination or vaccination of dogs who are not sterilized. Many Indian humane societies nonetheless vaccinate or revaccinate all dogs presented to them as a public service, as resources permit.
According to the Central Bureau of Health Intelligence, rabies killed an average of 235 Indians per year from 2003 through 2012, within a range of 162 to 361. But apart from posting the data to a web site, the Central Bureau of Health Intelligence has done little to correct the 20,000 figure, which appears to have been projected from data collected more than 100 years ago, in 1911, but is claimed as current in publications of the World Health Organization, Alliance for Rabies Control, and other branches of the Indian government.
The 1911 data also forms the basis for inflated projections of rabies incidence in Pakistan and Bangladesh, which were part of India when the findings were first published.
Ironically, the Central Bureau of Health Intelligence findings reinforce the thus far little noted finding of the 2003 WHO-sponsored National Multicentric Rabies Survey, led by M.K. Sudarshan. This survey found that human rabies appeared to be “endemic and stable” at 235 human deaths per year, based on data collected from hospital isolation units. “From 1985, India reported every year about 25,000 to 30,000 human rabies deaths,” Sudarshan wrote in a 2005 summary of the survey. “However, these figures were an estimate based on the projected statistics of isolation hospitals,” which proved to be much too high, and which at that time had not been traced to source.
Sudarshan in a June 18, 2012 e-mail affirmed to me his belief that the high “official figures coming from the Government of India are erroneous,” and that “a scientific reassessment of the burden of rabies in India” is overdue.”
Providing the basis for such a scientific reassessment is what the Central Bureau of Health Intelligence has been quietly doing. The Central Bureau of Health Intelligence is an office within the Directorate General of Health Services, under the Ministry of Health & Family Welfare. Since 2005, the Central Bureau of Health Intelligence has included current rabies statistics in National Health Profile, an online annual report. From 2005 through 2012, the Central Bureau of Health Intelligence found, India had 274, 361, 221, 244, 260, 162, 223, and 212 human rabies deaths, respectively: an annual average of 246.
But the National Health Profile numbers won little notice until cited on April 29, 2012 in the Lok Sabha, the lower house of the Indian parliament, by Indian health minister Gulam Nabi Azad.
Unaware of the source of the information, longtime Blue Cross of India chief executive and Animal Welfare Board of India member Chinny Krishna summarized Gulam Nabi Azad’s remarks in an e-mail published as a letter-to-the-editor in the May 2012 edition of Animal People. Krishna’s summary was then further distributed to more than 40,000 public health professionals worldwide by the International Society for Infectious Diseases’ Program for Monitoring Emerging Diseases, and to more than 1,000 heads of Indian humane societies by the Federation of Indian Animal Welfare Organizations.
In June 2012 I examined the matter further in an article entitled “New Indian data cuts worldwide human rabies death toll by 40%.” Abstracted by ProMed, the article brought responses which helped me to find the Central Bureau of Health Intelligence information and publicize it to ProMed, FIAPO, and the Asian Animal Protection Network.
Human rabies deaths have at times been underreported in parts of India due to local political considerations and defects in public health data tracking systems. Both factors were involved when 15 rabies deaths were found to have gone unreported in Chennai suburbs during the first four months of 2011.
Rabies in humans is not “notifiable” in India, meaning that reporting deaths to the national epidemiological tracking system is not mandatory for all institutions. The National Health Profile “Health Status Indicators” tables open with a disclaimer acknowledging that “Since the reported data is by and large from government health facilities, it may have limitations in terms of its completeness as private medical and health care institutions still need to strengthen their reporting to their respective government health units.”
However, the possible omission of data from “private medical and health care institutions” means little as regards rabies, since the government clinics that provide free post-exposure rabies vaccination receive and treat most dogbite victims, and since active human rabies cases are handled almost exclusively by government hospitals.
Despite rare instances of officials suppressing awareness of rabies outbreaks, as exposed in Chennai in 2011, most rabies outbreaks in India receive intensive coverage from aggressively competing media. Speculation that the National Health Profile numbers might be low due to underreporting would appear to be negated by a search of 535 articles published by Indian mass media and medical journals, 2005-2012, which described 123, 73, 195, 29, 23, 103, and 69 human deaths for those years, respectively–an average of 65% fewer deaths than were recorded by the National Health Profile.
The articles reported rabies death totals for Andhra Pradesh, Goa, Manipur, Tamil Nadu, and Uttar Pradesh states. If these totals were projected to the whole of India by comparing deaths to the human population, the number of rabies deaths per year for all of India would be 415.
The National Health Profile, the media search totals of human rabies deaths, and projections from reported complete state data are all so low as to call into question how the figure of 20,000 originated, along with a figure of 35,000 often cited by Indian mass media before the 20,000 number gained currency.
These claimed death tolls, especially when cited by WHO, are more remarkable in view that WHO on June 15, 1975 distributed a media release asserting that “Rabies is on the rise throughout the world with ever increasing danger to human life,” as indicated by 430 total human rabies deaths worldwide in 1973, “most of them in Latin America and Asia, especially Brazil and India.”
A review of rabies data conducted at a 2002 Association for Prevention and Control of Rabies in India conference in Bhubanesh-war, a year before the National Multicentric Rabies Survey, lowered the then-Indian government estimate of human rabies deaths to 17,000 diagnosed cases plus 3,000 undiagnosed deaths per year, and projected the toll as 20,565 per year from 1992 through 2002.
The estimate of 20,565 rabies deaths per year has been attributed to British epidemiologist Katie Hampson, but Hampson herself has noted that “older published data was used,” expressing hope of obtaining “updated information.” Other reports based on the 2002 findings halved the projection of undiagnosed human deaths, to suggest a total of 18,500.
A 2005 WHO report appeared to reinforce the 2002 estimate with a projection of 19,700 human rabies deaths per year, based on the supposition that the human rabies death toll can be projected by estimating the dog population and making the rather shaky assumption that rabies occurs at a relatively constant rate among all free-roaming dogs.
The mysterious original source of the claims that there were ever either circa 35,000 or 20,000 human rabies deaths per year in India may have been revealed by The Statesman, a leading Indian newspaper, on July 11, 2011. According to an article reprinted on that date from 100 years earlier, in July 1911 a Major Harvey who was the director of the Pasteur Institute at Kasauli reported that through “personal inquiries” he had learned “that out of 3,289 Indians bitten by rabid dogs or dogs suspected of being rabid, only 1,636 came for treatment.”
Harvey also projected that only three out of every 17 bites by a rabid dog actually transmitted rabies to the human victim.
Founded in 1904 by Sir David Semple, inventor of the Semple nerve tissue culture anti-rabies vaccine, the Pasteur Institute at Kasauli is now called the Central Research Institute. Harvey was Semple’s colleague and successor, William F. Harvey. His findings, as reported by The Statesman, appear to have been in re-circulation ever since, in three different garbled forms.
Harvey’s estimate that only about half of rabid dog bite victims seek post-exposure treatment has become an oft-repeated claim that only about half of all victims of bites by any dogs seek post-exposure rabies vaccination–and that therefore any numbers reported for human rabies deaths are low.
Harvey’s estimate that three out of 17 bites from a rabid dog transmit rabies appears to have been mingled with a guesstimate that about one dog bite in 10 is inflicted by a rabid dog. Multiplied by two million dog bites per year, another long-circulating guesstimate, this produces the figure of about 35,000 human rabies deaths per year.
Harvey’s total of “3,289 Indians bitten by rabid dogs or dogs suspected of being rabid,” multiplied by the five-fold increase in Indian human population between 1911 and 2002, plus the 3,000 deaths that the Association for Prevention and Control of Rabies in India suggested occur without diagnosis, comes to very nearly 20,565.
There are other possible reasons for the discrepancy between the claims of 35,000 and 20,000 human rabies deaths in India per year, and the much lower Central Bureau of Health Intelligence figures. Chinny Krishna has suggested to me and to and FIAPO that the post-2000 turn away from use of the Semple vaccine, which required multiple painful injections into the abdomen, has encouraged more dog bite victims to seek post-exposure anti-rabies vaccination.
It is also likely that deaths from many other febrile diseases may have been misdiagnosed as rabies. Japanese encephalitis, for example, only recently recognized in India, can produce lookalike superficial symptoms, but according to the National Health Profile is now known to have killed between 600 and 1,600 Indians per year during the first decade of the 21st century.
A persistent belief among many Indians that some people and animals recover from rabies adds to the likelihood that some “rabies” cases are misdiagnosed, and are reported without being confirmed by post-mortem brain tissue examination.