A “One Health Vision” approach or a mix of veterinary public health is now being explored as one of the strategies to combat zoonotic diseases that are transmitted from animals to humans. While the National Centre for Disease Control (NCDC) has started networking with various sectors for effective surveillance, planning and control of these zoonotic diseases, this approach has helped improve the leptospirosis situation in Andaman and Nicobar islands.
Studies in the 1990s conducted at the Primary Health Care facilities in Andaman and Nicobar islands showed an incidence as high as 747 cases/100,000 population and case fatality ratio of 2.8% with disability adjusted life years (DALY) of 853.66/100,000.
“In the recent times, a drop has been observed in the incidence of leptospirosis as well as severe leptospirosis and specific mortality due to leptospirosis. The incidence at Primary Health Care facility dropped from 747/100,000 to 377/100,000 with DALY of 4.3/100,000,” Paluru Vijayachari of Regional Medical Research Centre, run by the Indian Council of Medical Research, Port Blair, told The Indian Express.
While direct transmission of leptospirosis occasionally occurs between animals and humans, majority of human infections are also acquired from the environment. Recent studies at the centre which is also the WHO collaborating centre for diagnosis, research, reference and training in leptospirosis have showed that leptospira is capable of forming biofilms by themselves or in combination with other environmental bacteria.
“These bacteria in biofilms are more resistant to physical stress such as temperature, pH, UV radiation and also to antibiotics. They are frequently seen on various surfaces such as walls of sewage canals, paddy fields and water bodies. They serve as perennial source of infection and perhaps can unravel the mystery of transmission dynamics of urban leptospirosis,” Vijaychari said.
The survival of leptospira is a crucial factor in the successful transmission of the infection. “This implies that environmental niches such as sewage canals and wet rice fields – once contaminated with pathogenic leptospira excreted by carrier animals – may remain infectious for prolonged period of time. This new paradigm in the environmental transmission model of leptospirosis has emerged and to reduce the risk requires multi-sectoral coordination,” he said.
Developing algorithms for clinical and laboratory diagnosis of the disease in humans and animals, tracking potential animal vectors that harbour virulent strains to predict future epidemics and monitoring antibiotic susceptibility pattern of circulating strains apart from promoting hygienic animal rearing practices for farm and working backyard animals coupled with personal protection while handling animal excreta are the key strategies that were also discussed at a recent capacity building workshop for leptospirosis programme held at ICAR-National Institute of Veterinary Epidemiology and Disease Informatics (NIVEDI), Bengaluru.
Experts from the department of health, animal husbandry and veterinary doctors from across the country were trained regarding the diagnostic tests. Specialists are being trained so that they improve the diagnostic capacities of various labs dealing in human and animal leptospirosis diagnosis, he said.
“We have developed laboratory network in India and several labs could do diagnosis at several parts of the country,” Vijayachari said. Meanwhile, the Centre is also setting up a national task force comprising medical, veterinary and environmental experts. “We are linking the integrated disease surveillance programme which tracks human cases with the animal disease programme,” Dr A C Dhariwal, director, NCDC, told The Indian Express.
AT NCDC every week, the Integrated Disease Surveillance Programme sends alerts regarding district-wise outbreaks. While food poisoning, chicken pox, measles, gastroenteritis feature regularly among these alerts, zoonotic diseases are also being reported. According to officials, surveillance has picked up cases of scrub typhus from Assam, anthrax from Jharkhand and Kyasanur Forest Disease from north Goa this year.
Diseases like scrub typhus, rabies, plague, avian influenza, leptospirosis and such diseases have become a major concern. “We are now training veterinary public health experts in diagnostics as part of the animal surveillance programme,” he said.
At least 68-70 per cent of people are in close contact with animals. However, the actual incidence of zoonotic diseases is not regularly reported, experts admitted. While rabies is predominant and as many as 30,000 rabies-related deaths occur annually, other diseases of increasing concern are also H1N1 virus (swine flu) and brucellosis (infection among cattle).
Dr Sunil Lahane, assistant commissioner, Regional Disease Investigation Laboratory, Department of Animal Husbandry, Maharashtra, told The Indian Express that the need has been felt for collaboration between various departments to control leptospirosis and bring both public health and veterinary sectors under one approach. “We have also called for blood and urine samples from affected and unaffected animals for further laboratory investigation,” Lahane said. This year, Maharashtra reported 193 cases and 10 deaths.
Health officials, however, said they were better prepared after Mumbai’s heavy flooding as against the deluge in 2005. Then, there had been an eight-fold rise in the cases of leptospirosis. Maharashtra surveillance officer Dr Pradip Awate said that they have been able to prevent a major outbreak due to prophylactic measures.
“Rapid response teams that include both public health experts and veterinary doctors are being set up at the district level to tackle emerging zoonotic diseases. In Mumbai itself, there are teams of night rat- catchers and this is being done in coordination with various departments, like health and veterinary experts,” Awate said. Animal husbandry departments of various states have issued district-level advisories to prevent access of rodents into cattle sheds and seek help from agriculture department officials to control the rodent population in the area.