While the public health discourse seems to shift to non-communicable diseases and their effects on the population, there still is great ground to be covered in prevention of infectious diseases. In Tamil Nadu, especially, there are infectious diseases that have been showing an upward trend over the years.
While the big bugbear malaria has been wrestled down to just over 14,000 cases a year in 2009 from over 43,000 in 2003, and the number of cholera and filariasis cases have been gently dropping, the State has not performed that well when it comes to other infectious diseases. Be it Acute Diahorreal Disease or those categorised as “emerging infectious diseases,” such as dengue, chikungunya or leptospirosis, the figures tell a sordid tale.
“We have managed to control vaccine-preventable diseases such as diphtheria and polio, thanks to our immunisation coverage,” explains S. Elango, Director of Public Health.
“However, the causative factors for vector-borne diseases are multiple and are constantly changing, which is one reason why we are grappling with control, though we have managed to bring down deaths due to such diseases,” he adds.
Multiple factors
According to him, the increase could be because of multiple factors, but three are key: the agent, host and environment. All these factors are constantly changing, including mutating bacterial and viral agents, and changing environments have an impact on the hosts (humans and, sometimes, vectors) themselves.
The changes in environment are primarily climatic factors, pollution, quality of water and increasing urbanisation, he says.
Urbanisation leads to stagnation of water at construction sites, increasing vehicles on the roads, crowded habitations in multiple housing complexes, deteriorating quality of water, air and soil. “All these are congenial for transmission of disease,” Dr. Elango says.
For instance, he says, a recent study from Mumbai established that there has been a manifold increase in the rat population compared to 20 years ago. This is responsible for the increasing number of leptospirosis cases. Again, with dengue, it is a question of peri-domestic breeding, or breeding of mosquitoes within the home.
Also, the indiscriminate use and disposal of plastic containers leads to collection of water in small quantities and this encourages rampant breeding of the aedes aegypti mosquito causing dengue and chikungunya.
However, the State has performed to the appreciation of many agencies, during the recent A (H1N1) epidemic, Dr. Elango said.
The number of cases and deaths had been minimised thanks to some intensive public health interventions.
Public health experts call for establishing scientific systems to monitor changes in the environment, including the effects of global warming on vector and disease patterns.
This is of great import as communities embrace modernisation — for instance, one needs to keep tabs on even something as simple as bottling of water, a Chennai-based public health expert says. Also, there is a need to establish a system to gauge microbial sensitivity against infectious diseases in the population and measure herd immunity and drug sensitivity, he adds.Some experts have also called for increased allocation of resources to battle infectious diseases.
While the overall expenditure on prevention and control of diseases has increased between 2008-2009 and 2009-2010, there has actually been a dip in the allocation for control of such infectious diseases
