- Explain what are zoonotic diseases.
- Give reasons for the increase in the frequency of such events.
- Suggest different ways in scientific, administrative, policy ways to deal with it.
Zoonotic diseases (transmitted from animals to humans), account for over 60% of infectious
outbreaks. In the past fortnight, spotlight has been on Nipah in India and the return of Ebola in
Africa. Both are viruses with high mortality rates and the fear of acquiring infection from
patients is terrifying communities around them, and causing concern in even those who are far
1. Research shows that changes in land use, including deforestation and forest fragmentation, urbanisation and intensification of agriculture, have contributed greatly to the rise in the incidence of infectious diseases.
2. A loss of biodiversity due to a change in the habitat often results in a simplification of the environment through elimination of specialist species and overpopulation of generalist species.
3. Migratory impacts on proliferation and adaptation of pathogens has been much more severe. Example avian influenza (bird flu) due to the advent of large-scale poultry farming.
4. Rapid urbanisation often bring people, especially migrant populations that are immunologically naïve, in close contact with pathogens. The spread and persistence of chikungunya serves as a classic example of how immunologically naïve populations can sustain an infectious disease.
5. Anthropogenic climate change creates conditions for vectors like mosquitoes and ticks to spread to new geographies. They transport the microbes to the human body.
6. Microbial genetics evolve far more rapidly than humans. Microbes which are confined to forest animals or small human communities follow the survival rules of evolution, and generally have low virulence, because the extinction of their host will lead to their own extinction.
1. Humans now crowd together in large numbers, travel fast and far in many modes of transport, and unknowingly transmit microbes to other humans through sputum, saliva, semen, blood, and other bodily fluids. This enables the virus to multiply rapidly and mutate to more virulent forms.
2. Vaccines are presently not available against many of these viruses, though some early success has been reported in candidate vaccines for Ebola and Zika.
3. Specific drug treatments too, are unavailable.
4. Laboratory diagnosis is possible in specialised labs but is mainly useful for identifying the nature of the outbreak, modelling its likely spread, and alerting the health system of the anticipated clinical severity of the cases that will arise.
5. India has one of the highest density of livestock population and poorly guarded animal-human interface makes it vulnerable to disease outbursts.
6. The Indian subcontinent has been identified as one of the four global hotspots at increased risks from emergence of new infectious diseases, particularly zoonoses according to various studies.
The case for control of zoonotic diseases (zoonoses) is compelling. The economic losses from six major outbreaks of highly fatal zoonoses between 1997 and 2009 amounted to at least US$80 billion.
The health infrastructure in India, already quite shabby, would bend it’s back in trying to deal with situations like these. India’s actions:-
India is now expanding its laboratory network but epidemiological surveillance systems need further strengthening.
In the absence of specific treatments, supportive care has been provided in the case of Nipah virus attack. Fluids for adequate hydration and electrolyte balance; medicines to control fever, and intensive care with respiratory and circulatory support are given when needed.
During any outbreak, isolation of the patient, avoidance of direct contact while providing care, tracing, examination of all contacts, and limiting their movement during the incubation period are helping to contain the spread.
Preventive measures include hand washing and avoiding contact with bodily fluids of a person known or suspected to be infected. Avoidance of direct or indirect contact with animals, who act as primary or reservoir hosts, is necessary and people are being made aware.
Effective risk communication to the public is especially necessary, to enable them to adopt preventive personal protection measures, seek timely medical care, and avoid mass panic. This requires clear and open information sharing by trusted experts who are adept in jargon-free messaging via mass media.
In Jaipur, India, dog vaccination and sterilization resulted in a decline of human rabies cases to zero.
How should India be ready:-
1. A rational response to such outbreaks requires an understanding of why these viruses cross species, how they are transmitted among humans, what preventive measures can be taken, which tests and treatments exist, and whether the health system is ready to contain the outbreak at an early stage.
2. Microbes must be vigilantly monitored during outbreaks to study if highly infective viruses are suddenly seized with mutation madness to develop higher virulence, especially in crowded populations where the virus has a free run.
3. Given the elevated risk to India from zoonotic diseases, it is important to have a policy framework in place to prevent an outbreak.
4. India needs to fund creation of data and evidence-base (data to support actions) on these infections so that they can be controlled in animals
5. The government has decided to form a national task force comprising medical, veterinary and environmental experts, and plans to make veterinary public health a part of the national health mission.
6. There is a requirement of multi-sectoral integrated response among medical, veterinary and other related departments. Under the 12th plan, a programme for strengthening mechanism of inter-sectoral coordination for prevention and control of zoonotic diseases has been approved and is being implemented.
7. The effectiveness of zoonotic disease control requires early detection at the source of the disease in animals, an early and accurate diagnosis, and rapid disease control measures.
8. Reporting by the media should exercise responsible restraint to avoid stoking mass hysteria.
9. More virology centres need to be established
10. Border screening has to be done strictly.
Coping with the unprecedented rise in the risk of pandemics and epidemics requires a holistic
approach to medicine that treats human health as part of environmental health. If we are to
address zoonotic outbreaks and emerging infectious diseases, there must be a proactive approach
to restore wildlife health. It will also require close monitoring of how the increasing ecological
footprint of humans is affecting health and disease dynamics.