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Indian Journal of Community Medicine

Chikungunya Fever Outbreak in Vellore, South India

Author(s): TS Selvavinayagam

Vol. 32, No. 4 (2007-10 - 2007-12)

ISSN No. 0970-0218

TS Selvavinayagam

Chikungunya is an arboviral infection, transmitted by the Aedes aegypti mosquito, caused by the chikungunya virus, which is a single-stranded RNA virus of family Togaviridae and genus Alphavirus; its ICD 10 code is A 92.0.

The chikungunya virus was first isolated in India in Calcutta in 1963.1 Subsequently, it seems that the virus has ‘disappeared’ from the subcontinent.2 However, outbreaks of fever caused by chikungunya virus infection in several parts of South India in 2006 have confirmed the re-emergence of this virus.

The usual incubation period is 2-4 days, and the illness is self-limiting with acute symptoms (abrupt onset of fever, headache, arthralgia, nausea, vomiting, abdominal pain, rash usually involving the limbs and trunk) and malaise lasting for 3-10 days.

Arthralgia or arthritis, affecting multiple joints, along with oedema can be debilitating, and may remain a problem for weeks to several months after the acute phase. Unlike dengue, haemorrhagic manifestations are relatively rare.

Materials and Methods

Following the reporting of first case on May 5, 2006 in Vellore town, an action plan3 was put up to contain chikungunya fever in the Vellore municipal area. Because of administrative reasons, only Vellore municipality area was chosen for the study.

Fever cases from the nearby rural areas under the administrative control of Public Health Department were confirmed as chikungunya fever through laboratory investigation from National Institute of Virology, Pune. It being an epidemic, we felt there was no need to confirm it again through laboratory tests; we have taken all the clinically diagnosed cases as chikungunya fever in our municipal limit.

The criteria we used for diagnosing chikungunya clinically were cases presenting with acute fever associated with arthralgia/myalgia without any other obvious cause of fever.

The following action plan was put up to control the epidemic.

Fever surveillance/enumeration teams were formed, which did the door-to-door survey to enlist fever cases and distribute paracetamol tablets to the needed as per the doses prescribed. Epidemiological investigation teams were formed with Medical Officer of the Urban Health Post to do case investigation. All the paramedical workers and Self Help Group women were trained and directed to distribute IEC materials and help the public in source reduction to control mosquito breeding. Health ambassador cards on chikungunya were printed and distributed through school children. We had formulated a ‘6-day block programme’ as per the directions from the Director of Public Health and Preventive Medicine, Chennai. In that, the entire town, which consists of 48 wards, was divided into ‘6-day blocks’, and abate application, fogging and source reduction work was carried out in cycles of 6 days. During fever surveillance, health workers were instructed to distribute paracetamol tablets. In addition, the public were advised to attend, if needed, municipal dispensaries or Urban Health Posts, where free treatment was available. Free medical camps were also conducted in this regard. Notices were issued to public buildings, lodging houses and marriage halls, etc, under Public Health Act 1939 to keep the environment clean and free from water stagnation and mosquito breeding.

Reports of suspected chikungunya cases were collected on daily basis from the Urban Health Posts, municipal dispensaries, government and private hospitals so as to take containment measures at the affected areas.

Results and Discussion

Out of the total 1094 cases reported during May 2006 to October 2006, 500 cases were selected for detailed analysis. Through stratified random selection, we ensured that cases from all the 48 wards of the municipality were given representation in detailed analysis.

Chikungunya commonly affects adults in the age group of 16-45 years (66.8%), and it is common in females (66.6%). Fever is mostly acute on onset (91.2%) and shorter in duration (1-5 days; 87.6%) but mostly regular (62%) The common symptoms are headache (94.8%), myalgia (95.2%), arthralgia (92.8%), neck stiffness (41.0%), oedema (24.2%) and rashes (2.6%). There was no associated case fatality in this outbreak. No significant association with history of travel was known. Within 6-8 weeks of implementation of the above action plan, there was drastic reduction in the incidence of cases, and it was brought down to zero within 20 weeks. We have monitored the impact through various indices like House Index, Container Index and Bruteu Index. The impact of our efforts is visible through Figures 1 and 2. Vaccine is not available at present. As there is no specific treatment for chikungunya, only supportive care with anti-pyretics and analgesics is given. The illness is usually self-limiting and resolved with time. However, the time taken for complete recovery varies from person to person. Movement and mild exercise improves stiffness and arthralgia.

The re-emergence of chikungunya may be due to a variety of social, environmental, behavioural and biological changes. Lack of herd immunity within the country may have probably lead to its rapid outbreak across several states.

Figure 1: Incidence of chikungunya cases

Incidence of chikungunya cases

Figure 2: Entomological indices chart showing the effect of ‘6-day block’ programme

Entomological indices chart showing the effect of '6-day block' programme

References

  1. Dandawate CN, Thiruvengadam KV, Kalyanasundaram V, Rajagopal J, Rao TR. Serological survey in Madras city with special reference to chikungunya. Indian J Med Res 1965;53:707-14.
  2. Khorshed P. Disappearance of chikungunya virus from India and south East Asia. Trans Royal Soc Trop Med Hyg 1986;80:491.
  3. Park K. Park’s Text book of preventive and social medicine. In; Bhanot BD, editor. 18th ed. Jabalpur; 2005. Municipal Health Officer, Vellore Municipality, Tamilnadu, India

Correspondence to:
Dr. T. S. Selvavinayagam,
Municipal Health Officer, Vellore Municipality, Vellore – 632 001, Tamilnadu, India.
E-mail: drselvavinayagam2005(at)yahoo.co.in
Received: 25.07.06

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