Shantabai, a domestic worker in a number of buildings in Pune says, "See didi, nowadays you can find dengue-causing mosquitoes even in posh buildings but people there do not allow Corporation workers to come and spray inside. Even Bollywood actors are being told to take care". While it might be hard to believe, dengue fever has blurred the boundaries between the rich and the poor in India this year.
Residents of high rise buildings and posh areas of Mumbai--Bollywood actress Kareena Kapoor included--have been infected with dengue. Dengue has invaded Malabar Hills and Juhu causing actors like Juhi Chawla, Anil Kapoor and Jeetendra to be issued notices after mosquito breeding sites were found in their homes and gardens during a routine inspection. The disease is not new to India; however, there has been a drastic rise in the number of dengue cases over the last few years. This year too, dengue has been making headlines due to the rising number of cases and deaths in Delhi--the worst affected--along with other cities such as Mumbai, Pune, Bangalore, Kolkata.
Dengue at a global and national level
Dengue is a mosquito-borne viral disease that spreads through the bite of an infected Aedes mosquito, and as the fastest spreading tropical disease it is turning into a serious public health concern globally. Recognising the gravity of the situation, the World Health Organisation included dengue in its list of important Vector Borne Diseases that need to be controlled on a priority basis in 2014 [1].
Out of an estimated 96 million cases globally every year, 70% occur in Asia with India alone contributing to one third i.e. 34% of all cases [1]. A recent Oxford University study that used a map-based approach to find out the number of dengue cases occurring in various parts of the world found that India had the highest number, with around 33 million apparent and a 100 million asymptomatic infections occurring annually [2].
A comparison of year-wise data related to dengue and malaria in India shows that malarial deaths have been decreasing, while the number of deaths due to dengue have gone the other way [8].
State-wise occurence of dengue cases in the country shows that the cases have doubled this year as compared to last year. The most affected states (with dengue cases above 1500) according to the NVBDCP include Delhi--recording the highest number of dengue cases--followed by Karnataka, Kerala, Tamil Nadu, Andhra Pradesh, Gujarat, Maharashtra, Punjab and Arunachal Pradesh. Although studies have shown a high occurence of dengue in the Indian subcontinent, only a small fraction of clinically apparent cases are diagnosed and reported; the true burden of the disease remains uncertain [3]. Very few studies have attempted to measure the extent of transmission at the population level [4].
Changed dengue characteristics over the last two decades
- Both urban and rural areas exposed: Dengue is no more an urban area infection but it is extending to rural areas as well [5].The disease has recently spread to hilly regions such as the Nilgiris and Cardamom Hills, and larger and more frequent outbreaks have been reported throughout both urban and rural areas [5].
- Higher and middle income groups in urban areas affected: Recent examples from cities such as Pune show that the infection trend has changed and is now expanding into higher and middle income groups rather than slums [6].
- Not just hot and humid climates impacted: Not just tropical conditions but dengue outbreaks have also been reported from areas with sub-tropical and desert conditions as brought out by two recent studies [1].
- Rapid unplanned development and urbanisation is a trigger: Although unseasonal rains have been found to trigger the epidemic, other reasons that include rapid, unplanned development and urbanisation leading to poor housing conditions, increase in construction site activities, irregular water supply, poor environmental sanitation, inefficient garbage management practices, use of plastic bags and containers by people etc. are adding to the spread of the disease [1].
- Lack of awareness has further worsened the situation: Behavioural factors such as leaving small pots and pans filled with water in or near houses, storing large quantities of water due to the irregular availability of water etc., have also been found to trigger the spread of the disease as mosquitoes can breed in stored uncovered water [7]. In cities, people from high rise buildings and posh apartments prevent health workers from visiting their flats for preventive fogging, triggering an increase in mosquitoes [6].
- New strains of the dengue virus: The situation has worsened this year as although co-circulation of the four dengue serotypes was found earlier in Delhi, there are suspicions of the emergence of one more new serotype. Also, this year has seen a predominance of Type 2 and Type 4 serotypes that cause more severe symptoms leading to serious consequences if not treated in time.
- Ill-preparedness of the health care system: As the worst-hit city this year, Delhi's health services have been strained.
- Virus has been difficult to control: In addition to the rapid spread of mosquitoes, suspicions are being raised that the inherent characteristics of vector resistance might have also exacerbated the situation leading to the rapid spread of the disease. Genetic changes in the virus have also been suspected to influence infectivity, survival and the spread of dengue. All these factors have presented new challenges in the control of the virus and the vector i.e mosquitoes [1].
Are vaccines the answer?
It has been found that developing vaccines isn't practical due to the complicated nature of the epidemic [1]; blocking the channel of transmission by improved prevention measures against the Aedes mosquito as well as better community awareness measures is a more sensible option [1].
Health experts argue that very little has been learnt despite dengue epidemics happening every year with almost clockwork precision. Poor timely research, late start, lack of proper implementation, and a crucial shortage of specialists continues to hinder proper implementation of India's dengue control programme. Evidence shows that all efforts at controlling the epidemic continue to be handled in a haphazard manner without proper planning. Rather, addressing the gaps between knowledge, attitude and behavioral practices in the community can go a long way in the prevention of this epidemic.
The current epidemic at Delhi and other places has exposed the lack of preparedness of the health care systems. In response to this, the CAG has ordered an audit of Delhi's handling of the dengue epidemic while it also plans to conduct an audit of preparedness in the other states where dengue-related deaths have been high.
Perhaps it is time we learn from other countries such as Singapore, Thailand and Indonesia who have been successful in reducing the dengue epidemic through planned, systematic and concerted efforts at prevention by actively involving the community.
References
1. Editorial (2015) Dengue: A runaway epidemic and a bewildered public health worker. Medical Journal Armed Forces India, 71, (2015), 3-4
2. Gupta and Ballani (2014) Current perspectives on the spread of dengue in India. Infection and Drug Resistance 2014:7, 337–34
3. Shephard et al (2014) Economic and disease burden of dengue illness in India. American Journal of Tropical Medicine and Hygiene, 91 (6), 2014, pp 1235-1242.
4. Rodriguez-Barraquer et al (2014) The hidden burden of dengue and chikungunya in Chennai, India. PLOS Neglected Tropical Diseases, 9 (7)
5. Khan, Dutta, Topno, Soni and Mahanta (2014) Dengue Outbreak in a Hilly State of Arunachal Pradesh in Northeast India. The Scientific World Journal, Volume 2014
6. Isalkar (2015) More dengue cases in upmarket areas, healthier picture in slums. The Times of India, Pune, August 17, 2015
7. The Times of India (2015) Dengue spurt blame on water in urban containers. The Times of India, Pune, Friday, October 2, 2015
8. Central Bureau of Health Intelligence (2009, 2012, 2015) National Health Profile. Ministry of Health and Family Welfare, Government of India