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An epidemic outbreak of Vibrio Cholerae El Tor 01 serotype ogawa biotype in a Lalpur town, Jamnagar, India HD Shah1, VP Shah2, AN Desai31 Department of Community Medicine, MP Shah Medical College, Jamnagar, Gujarat, India 2 Department of Microbiology, MP Shah Medical College, Jamnagar, Gujarat, India 3 Department of Medicine, MP Shah Medical College, Jamnagar, Gujarat, India
Correspondence Address: Source of Support: None, Conflict of Interest: None DOI: 10.4103/0022-3859.93247
Background: On December 19, 2010, 57 cases of gastroenteritis were reported in the community health center of Lalpur town. A rapid response team was sent to investigate the outbreak on December 21, 2010. Aim: To identify the source, to institute control and prevention measures. Materials and Methods: The outbreak was confirmed using the previous Integrated Integrated Disease Surveillance Project (IDSP) data. Detailed history was taken, line listing of patients and house-to-house investigations were done. Environmental investigation and laboratory investigation of stool samples were also done. As the study was conducted during emergency response to the outbreak and was designed to provide information to orient the public health response, ethical approval was not required. Remedial measures were implemented. Results: Three hundred and thirty cases were reported during December 19, 2010 to January 2, 2011 in Lalpur town of Jamnagar district. Nineteen patients were found to be positive for Vibrio Cholerae 01 serotype ogawa biotype out of 117 stool samples. The mean age of patients was 24.2319.01 years. The outbreak had 1.88% attack rate with no mortality and 59.1% cases had to be admitted. Investigations revealed that the epidemic was waterborne. Ten leakages were found in the pipelines of the affected areas of Lalpur town near two riverbanks. Conclusion: Among identified gaps, delays in the initiation of the investigation of the epidemic and repairing of leakages were most important. In India, waterborne epidemics are usual occurrences during the year. In this scenario, the village health and sanitation committee and water board should follow guidelines, and monitoring of water sources, proper sewage disposal and sanitation measures should be undertaken. Keywords: Cholera, Lalpur town, Jamnagar, outbreak investigation, waterborne outbreak
Cholera is an infection that leads to an acute diarrheal disease with a large cluster of cases. [1] Cholera remains a major public health problem since decades in developing countries like India, where six of the seven pandemics began. [1],[2],[3] Every year about 3-5 millions cases occur, from which about 120,000 to 100,000 patients die. [4] V. Cholerae is a curved Gram-negative bacillus that belongs to the family vibrionaceae and shares common characteristics with the family enterobacteriaceae. The species V. Cholerae includes both pathogenic and nonpathogenic strains, differing in their virulence gene contents and polysaccharide surface antigens. Only V. Cholerae O1 and O139 are responsible for the disease defined clinically and epidemiologically as cholera. [1] V. Cholerae O1 is divided into classical and El Tor biotypes, and into three sero-subtypes, Ogawa, Inaba and Hikojima. V. Cholerae O139 has characteristics in common with the El Tor biotype in India, but differs from O1 in its polysaccharide surface antigens. [5],[6],[7] Previous studies have shown that up to 80% cases of acute diarrhea can be treated successfully with timely intervention like oral rehydration salts. [4],[8] As cholera can spread both through fecal contamination of food and water by humans and through independent propagation of the pathogen in the environment, the environment plays a crucial role. [9],[10],[11] Cholera mostly happens with an outbreak, i.e. a large number of cases within a short time so there is need of timely identification, preparedness and response to outbreak control. [4] Widespread availability of Oral Rehydration Solution proper sanitation measures and adequate personal hygiene help the community to prevent cholera from becoming an epidemic outbreak. [8],[9] It is important to obtain epidemiological data on diarrheal outbreaks to formulate control and preparedness plans which suit a particular affected area with population-specific needs. This study aimed to find the reasons for the epidemic and focused on identification of gaps in the management of the epidemic with application of remedial measures in the V. Cholerae outbreak caused by V. Cholerae El Tor 01 biotype, Ogawa serotype in Lalpur block, Jamnagar.
Descriptive epidemiology After receipt of information about an outbreak of gastroenteritis by the surveillance team, a rapid response team from a tertiary teaching hospital, Jamnagar in Lalpur town having population of 17550, undertook the investigation and management of the epidemic on December 21, 2010. A case of diarrhea was defined as the occurrence of more than three watery stools a day among residents of the town. [12],[13] From the detailed history of indoor and outdoor patients at the community health center of Lalpur town and the tertiary hospital, which is a tertiary teaching hospital of Jamnagar district, the affected localities were identified [Figure 1]. All the diarrhea cases had high frequency of loose stools more than three times with or without rice water appearance. We reviewed the Integrated Disease Surveillance Project (IDSP) annual report to confirm the outbreak of diarrheal disease. [12] The case definition was consistent with cholera disease outbreak. The house-to-house survey was done with 12 teams of 24 health workers and line listing of all suspected cases of cholera was done. The cases that were admitted in Community health center and referred cases of the tertiary hospital were also included in the study. Information regarding age, sex, place of residence, date of onset and days of hospital admission, treatment and laboratory finding was collected. The hypotheses were generated based on the characteristics of the person, time and place of the outbreak. The epidemic curve was constructed to describe the development of the outbreak over time and cases were plotted on the geographical map of the town to plan action for control of the outbreak.
After reviewing the descriptive epidemiology and hypotheses-generating interviews, epidemic occurrence pointed to a contaminated water supply, and the investigation teams visited house to house and collected information regarding water quality, sources of water supply and drainage system. The information of mass gathering, exposure to mass food consumption was also included in the questionnaire. We also interviewed the water supply department and the local community members to enquire about the general water supply and sanitation situation. About 10 random water samples were taken from affected areas. Laboratory investigation Most of the patients had loose rice watery diarrhea. Stool samples were collected randomly and inoculated in alkaline peptone water from patients who had complains of diarrhea, admitted to two hospitals-community health center, Lalpur and tertiary hospital, Jamnagar. A total 117 stool samples during December 19, 2010 to January 2, 2011 were tested by standard bacteriological techniques. [14] Anti-microbiological susceptibility of isolated pathological organisms was done by disc diffusion technique. Ethical consideration This study was conducted during the emergency response to the cholera outbreak and was designed to provide information to orient the public health response, ethical approval was not sought prior to the survey. It was undertaken as a public health practice rather than a research. [15],[16] Privacy, confidentiality and rights of patients were ensured during and after the conduct of the study. Oral informed consent was obtained in each visited household after detailed explanation of the existence of an outbreak, the objective of the study and the planed use of the information. Moreover, health education was carried out in each household regarding cholera transmission and prevention. The information was entered and analyzed anonymously. The study was implemented in collaboration with the district health officials after obtaining authorization to carry out the survey.
Descriptive epidemiology The surveillance data of the past three months of the Jamnagar district and Lalpur town from the IDSP was analyzed which showed that on December 19, 2010, there was an unusual abrupt increase in case incidence of acute diarrheal diseases in the Community Health Center, Lalpur town which has a population of 17,550 and with 2700 households. The town is located between two rivers named Dhandhar and Roopavati. Most of the patients came with the complaints of increased frequency of loose watery diarrhea and a few had vomiting for the past two days. Further investigation ruled out population influx or any change in reporting system. This episode was declared as a cholera outbreak on December 24, 2010 after confirmation of the presence of Vibrio Cholerae in laboratory reports. It lasted up to January 2, 2011. The flow of indoor as well as outpatient department (OPD) cases was identified. A total of 330 patients reported with an attack rate of 1.88% in the outbreak, during the time period from 19 December 2010 to 2 January 2011. Out of 330 patients, 195 (59.1%) cases were kept on indoor treatment basis and out of them, 58 (29.74%) patients were referred to a tertiary care teaching hospital of Jamnagar district. No mortality occurred during the epidemic. Almost an equal number of males and females were affected during the outbreak. There was an initial increase in cases on December 19, followed by progressive decrease in cases. The second part of the epidemic curve [Figure 2] was stretched due to secondary person-to-person transmission, which is consistent with outbreaks of cholera.
The geographical map of the affected area was structured with the help of information gained from interviews of indoor and OPD patients [Figure 1]. The same has been plotted on the map to see the place distribution of the outbreak. [Table 1] shows the age distribution of the affected persons. Mean age of patients was 24.23±19.01 years. The majority of the patients had loose watery diarrhea more than three times, and vomiting on and off. The clinical features and stool macroscopy were also consistent with cholera findings.
Environmental investigation For house-to-house survey, a total of 12 teams of health workers were made and given the interview questionnaire. They collected information regarding age, sex, clinical features, water storage container, water supply of households and drinking water sources. They found ten leakages in the water pipelines from the affected areas. But super chlorination of water sources was done by local water board authorities before acquiring the samples, to prevent further transmission among the population. So the test result of water samples came negative and fit for drinking. Laboratory investigation Out of 330 cases, 117 stool samples were collected in alkaline peptone water, from which 19 samples were found positive for Vibrio Cholera El Tor Serotype, Ogawa [Table 2]. In addition, antibiotic susceptibility of isolated pathological organism was done by disc diffusion technique. For further investigation of phage typing, samples were sent to NICED, Kolkata.
Thus, a hypothesis was generated that contaminated drinking water could have been the reason of the cholera epidemic outbreak from leakages found in water supply pipelines and bore wells.
An outbreak of cholera occurred in the Lalpur, Jamnagar district in December 2010. After investigation, it was revealed that the outbreak occurred because of contaminated drinking water due to leakages found in the water pipes and bore-wells of localities near the rivers Dhandhar and Roopavati. These rivers are the prime drinking water sources of Lalpur town. The majority of the patients came from the areas near the riverbanks; Dhararnagar, Mazjid street, Husaini chowk, Madresa chowk, vagharivas [Figure 1]. Almost 90% of patients had complaints of diarrhea, vomiting and other signs of dehydration within hours on December 19, 2010. For the remaining cases, there was no specific explanation. A rapid response team was called on December 21, 2010 from local health authorities so there was two days of delay for initiation of epidemic investigation and management. During investigation, we found 10 leakages in water pipes and bore-wells of affected areas that contaminated the drinking water. The leakages were not repaired until five days of the outbreak because of technical difficulties. The second part of the peak of the epidemic curve had 22.47% patients who had contracted the disease due to secondary person-to-person transmission [Figure 2]. Contaminated water remains the prime vehicle for outbreaks of cholera in developing countries like India. Here at Lalpur, the affected areas near riverbanks are mostly slums. They have poor sanitation practices, lack sewerage and toilets at residence. So fecal contamination through leakages of water sources of households could be one of the possibilities. [9] The third target of the Seventh Millennium Development Goal of the United Nations proposes to halve the proportion of people who are unable to reach or afford safe drinking water between 1990 to 2015. [15] As per the United Nations' criteria, improved drinking water sources include household water connections, public water pipelines, bore-wells, and protected dug wells, springs and rainwater collection. In spite of political commitment and well-directed efforts, still in some parts of India, people do not have access to safe drinking water. [17] National surveys have shown that only 28% families in rural areas have access to pipe water. The majority of the households use water from bore-wells (53%). Still about one in eight families uses unsafe sources of drinking water like unprotected wells. Sixty-six percent households do not boil or treat their drinking water at home. [18] Indicator 7.8 of Goal seven is the proportion of population using an improved drinking water source. [19] It has increased from 66% in 1990 to 84% in 2008 in India. With this rate, it might be possible to reach this target by 2015 but occurrences of waterborne epidemics are also common in towns and cities. [20] The proportion of people using an improved sanitation facility though, remains a great challenge. Improper sanitary conditions lead to outbreaks of waterborne diseases. [9] From a dismal 7% in 1990 this figure has only improved up to 31% in 2008. [19] India should strengthen the implementation to obtain the targets with strong commitment and with dedicated efforts, because it is challenging task to achieve the seventh Millennium Development Goal that is "Ensure environmental sustainability" and its indicators 7.8 and 7.9 in this scenario. Our investigation revealed that the leakages in water pipes and bore-wells were the cause of this outbreak, which do not fall under improved water sources as per Millennium Development Goals criteria. This outbreak is a classical example of waterborne disease outbreak. There had been other reasons also, which could be the sources or agents during the outbreak. The second part of epidemic curve started on December 24, having a frequency of 22.72% of the total patients. During this period, transmission might have been person-to-person transmission. During outbreaks of cholera, it is commonly seen that more than one source are the cause. [21] Similar to past studies of diarrheal diseases outbreaks, there were certain limitations in the investigation: First, the initial cases of dehydration were not following the established hypothesis with a wide variation in the history of suspected diseases. [21] Subsequent house-to-house visits revealed contaminated drinking water as the main reason of the epidemic. Second, we could only obtain laboratory confirmation from the limited numbers of indoor patients. Thus, we could not exclude other causes, which may be acting together or on their own to cause this outbreak. However, 19 positive patients out of 117 tested patients confirmed the outbreak of V. Cholerae [Table 2]. So our suspicion of V. Cholerae was based on case definition compatible with V. Cholerae definition of IDSP and diagnosis of V. Cholerae. [12] Patients with complaints of diarrhea, vomiting and dehydration, irrespective of lab confirmation were also treated. Fourth, asymptomatic persons were not asked about history of similar episodes and not tested for stool examination. The above limitations could have had an impact on the association of the outbreak and Vibrio Cholerae, but either way our recommendation would be the same. Hence, it is proved that contamination of drinking water by sewage leads to possibilities of an epidemic outbreak. In Lalpur town, use of contaminated drinking water from the leaking water pipes and bore-wells near the riverbank areas lead to a cluster, and then possibly was followed by person-to-person transmission. With the confirmation of hypothesis and thorough investigation, we formulated a number of recommendations and advised certain interventions for both immediate action and prevention of future events. For immediate remedial action, the community was informed without making them panic, with proper education regarding safe drinking water, use of chlorine tablets and proper sanitation measures. Second, super chlorination of water sources was done during the outbreak and chlorine tablets were distributed by making house-to-house visits in the affected areas with Information Education and Communication materials. Third, on future preventive measures, the Village Health and Sanitation Committee and Taluka Panchayat authorities were advised to check the water sources for contamination on a monthly basis. Additionally, it is important that proper sewage treatment should be done before draining it into the river. The village health and sanitation committee can help in this regard for guidance and resources. Fourth, the district authorities should make sure that this type of leakages and contamination would not occur again and continuous monitoring should be done. Fifth, all residents of the town should be educated regarding proper household water storage, water disinfection by boiling and chlorination, healthy sanitation measures like clean sewage treatments, proper hand washing and oral rehydration therapy in case of dehydration. To summarize, not only drinking water but safe drinking water should be made available to succeed in achieving the seventh Millennium Development Goal. In addition, it will control the waterborne epidemics which are usual occurrences in India. Standardized indicators of the Millennium Development Goals will help to monitor the progress of the objectives in the long run.
[Figure 1], [Figure 2]
[Table 1], [Table 2]
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