Indian Journal of Public Health

: 2011  |  Volume : 55  |  Issue : 4  |  Page : 313--316

A clinico-epidemiological study of chikungunya outbreak in Maharashtra state, India

Prakash Prabhakarrao Doke1, Deorao Satvaji Dakhure2, Archana Vasantrao Patil3,  
1 Ex.Executive Director SHSRC, Directorate of Health Services, Government of Maharashtra, Mumbai, India
2 Ex. Director, Directorate of Health Services, Government of Maharashtra, Mumbai, India
3 Joint Director, Directorate of Health Services, Government of Maharashtra, Mumbai, India

Correspondence Address:
Prakash Prabhakarrao Doke
Professor, Department of Community Medicine, MGM Medical College, Kamothe, Navi Mumbai - 410 209, Maharashtra


The year 2006 witnessed an extensive outbreak of Chikungunya fever in Maharashtra state. Out of 6467 sera of suspected patients sent to National Institute of Virology, Pune, 804 were serologically confirmed. This retrospective study was carried out by interrogating all those patients for their sickness experience. Adult females from rural area were more affected than males. In 68.2% families, there were multiple cases. Fever and multiple joint involvement were almost invariable. In 36.5% patients, there was history of recurrence. Along with pain, slight swelling was noticed in 55% patients. The commonest joints involved were wrist, inter-phalangeal, elbow, knee and ankle, in that order. The pain and swelling persisted for more than a month. After health education during outbreak, there was positive improvement in behavior pertaining to source reduction of vector. Inter-personal communication was best remembered. In health education, the role of paramedical workers and government doctors was prominent.

How to cite this article:
Doke PP, Dakhure DS, Patil AV. A clinico-epidemiological study of chikungunya outbreak in Maharashtra state, India.Indian J Public Health 2011;55:313-316

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Doke PP, Dakhure DS, Patil AV. A clinico-epidemiological study of chikungunya outbreak in Maharashtra state, India. Indian J Public Health [serial online] 2011 [cited 2020 Sep 24 ];55:313-316
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Maharashtra state is the second largest by area and the third largest by population in India. It has a population of 96.8 million (2001 census). The season is divided into three periods: Monsoon June-October, winter October-February, and summer February-June. The annual rainfall varies from 400 to 6000 mm. [1] The environment is most suitable for Aedes aegypti. The state experienced a large number of outbreaks of Chikungunya in the year 2006. Similar rise of cases of Chikungunya virus infection was also witnessed by the nearby states, i.e. Karnataka, Andhra Pradesh, and Tamil Nadu. [2]

In that year, totally 1,390,322 suspected cases were reported by 16 states in the country. [3] Out of these suspected cases, 15,961 samples were tested and 2001 were found to be positive. [2] From Maharashtra, 152,086 suspected cases were reported and 6467 samples were sent to National Institute of Virology, Pune, and 804 were diagnosed serologically as Chikungunya viral fever.

The disease occurred in epidemic form in the state of Maharashtra after a gap of about 32 years, that too, involving very extensive population in 26 districts out of total 35 districts. [3] For vector control, particularly larval control, the concept of "dry day," meaning weekly emptying of water containers, scrubbing and washing, drying, refilling and covering the containers on fixed day by all community members, was introduced.

This retrospective study was carried out during the period April to June 2007 by paying house visits. All the patients were interrogated. A structured format containing information of the patient and family members, details of treatment and recurrence for data collection, details of water supply and storage, preventive actions taken and knowledge and practice regarding Chikungunya was used after pretesting. Public health specialists supervised the survey and cross-checked about 5% forms. The investigators organized one day training for public health specialists and they in turn trained paramedical workers. Arthralgia was defined as painful joint without noticeable swelling. Arthritis was defined as painful and swollen joint. While answering, if the patient was not certain about the answer, then the response was excluded from the

The usual place of residence of 609 (75.75%) patients was rural area, indicating higher affection in rural area because only 58% population was rural as per 2001 census data of Maharashtra. A total of 740 patients could be contacted out of 804 (92.04%). Rest of them were not available in homes even after two visits. A total of 505 (68.20%) patients stated that there were other cases in the family. Median number of cases per family was 4. Only 557 patients responded to perceiving mosquito nuisance prior to onset of illness and 72.2% of them confirmed nuisance.

[Table 1] gives the number of patients having signs and symptoms. The duration of symptoms in the first episode ranged from 7.1 days for nausea to 28.8 days for CNS related symptoms like giddiness. The commonest symptom of fever had a mean duration of 11 days. The joint pain persisted (35.2-38.8 days) for about a week longer than swelling (26.8-35.5 days).{Table 1}

There were only 3.4% patients who did not have any painful joint. About 2% had two painful joints. Remaining patients had multiple painful joints. Arthritis was not observed in 31.2% patients. About 7% patients had single joint arthritis. About 8.5% had two joints involved. Rest of the patients had polyarthritis. The joints attaching appendicular skeleton to axial skeleton, i.e. shoulder and hip, were less involved. The commonest joints involved were wrist, inter-phalangeal, elbow, knee, and ankle, in that order.

In 270 (36.49%) patients, the symptoms recurred. Only 242 patients remembered the interval between episodes. The recurrence occurred after a median interval of 15 days in rural area and 9 days in urban area. The median frequency was 2 in 214 patients who reported with certainty.

Although many had some knowledge, data showed that 8.9% had correct knowledge about virus etiology, 5.2% knew about transmission by Aedes mosquito and only 38.1% knew the exact steps of dry day. The source of knowledge about Chickungunya, its transmission and control measures was also enquired. Paramedical workers and government doctors were the commonest source of information, in that order, in all the three aspects of knowledge. The findings are given in [Table 2].{Table 2}

The disease Chikungunya affects both sexes and all age groups. It was revealed that maximum cases were recorded in the reproductive age group. Children below 15 years were less affected; only 5% cases were seen in that age group. Less morbidity among children was also noticed in other Indian studies. [4],[5],[6],[7] Females were more affected (54.23%), which is again comparable to findings from South Indian studies. [4],[8] However, during outbreaks in 1965 at Chennai [5],[6] as well as at Nagpur city, [7] males were affected more than females. In fact, more morbidity in females was explained to be associated with daytime and indoor feeding habits of the mosquito vector in India. [8]

Perceiving mosquito nuisance before onset of illness was observed more frequently in rural area (76.70%) than in urban (23.30%) area (P < 0.001). Although high percentage of patients remembered mosquito nuisance prior to illness, monitoring of this attribute is difficult. There may be bias in the minds of patients as they are the suffered individuals. However, it is felt that simple news item or complaint register may serve the purpose of identifying villages at risk.

In 68% families, there were multiple patients. The transmitting vector prefers domestic and peri-domestic sundry articles for breeding. It has short range of flight. The short incubation period of the virus in vector as well as in host may be one factor for high morbidity in inmates of the house. This may also be due to the highly anthropophilic and day biting nature of the vector. During blood feeding, if the host disturbs vectors, then these mosquitoes tend to attempt biting any other person from nearby vicinity. [9] An earlier study also observed this phenomenon. [10]

The clinical pattern of the disease showed that fever (96.8%) and joint pain (96.4%) were almost invariably present. Usually, the fever was moderate to high and associated with rigors or chills. The fever was usually associated with body ache (90.10%) and headache (78.40%), in that order. Similar features were observed in other studies. [4],[5],[7],[10] Although most of these studies indicate that the fever was of shorter duration ranging from 1 to 7 days, [4],[5],[7],[10] in this study, the fever lasted for about 11 days. This may be due to subjective responses from patients. Nausea was present in 39.5% patients, which was more than that was observed earlier. [5] Maculopapular rash on extensor surfaces and trunk was seen in 15.4% cases and itching was present in 11.9% patients. The percentage of rash varied from 2.6 to 80%. [4],[5],[8],[10] The highest percentage (80%) was in Tanganyika in 1955. It indicates that in the recent outbreaks in India, rash was not a very common feature. Lymphadenitis was seen in 2.4% patients only. In other Indian studies, the observed range was 14-20%. [5],[7] Axillary, deep cervical, inguinal and post-auricular lymph glands are usually involved. In the Tanganyika study, lymph glands were not at all involved. [10] Bleeding tendency from mucosal sites was observed in only five patients (0.7%), which is far less than 5% range of other studies. [5] Slight giddiness was observed in 5.4% cases, which persisted for about 4 weeks. All other symptoms disappeared within 2 weeks.

Pain in joints was the most common presenting symptom. Pain was severe, incapacitating, intensified by movements and more severe in the morning. Non-involvement of joints is rare. [5] Slight swelling was noticed in about 67% patients, along with pain. Joints of vertebral column, particularly of neck and lumbar region, were affected in 11.8% cases in the present study, which slightly differs from other studies. [4],[5] Persistence of joint pains for weeks or even months is commonly observed. [5],[8] The recurrence of joint pains in more than one-third of the patients was in consonance with other studies. Recurrence of joint pains occurred intermittently in the majority of patients and in some up to 4 months. [10] In the present study, median frequency of recurrence was 2. Normally, recurrence of fever, joint pains was less severe/milder. [5],[7],[10] At the later stages of the epidemic, the onset becomes less sudden, the pain becomes less severe, and the duration shortens. [8]

People were aware about transmission by mosquito bites, emptying of domestic and peri-domestic water containers for source reduction of mosquitoes, and role of some infective agent in causation of Chikungunya, in that order. Only 8.9% patients knew correctly about viral origin of the disease; transmitting vector species was least remembered (4.2%). The role of behavior change communication is important in controlling vector density by source reduction. About 38% people certainly knew about how to carry out source reduction pertaining to domestic water containers. Although the role of mass communication is important, people remembered interpersonal communication with paramedical workers to the highest extent. The educational drive needs to be persistent or at least intermittently for longer duration to have real effect on Aedes transmitted diseases.

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