Cholera Outbreak in Southeast of Iran: Routes of Transmission in The
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Jpn. J. Infect. Dis., 59, 174-178, 2006 Original Article Cholera Outbreak in Southeast of Iran: Routes of Transmission in the Situation of Good Primary Health Care Services and Poor Individual Hygienic Practices Shahrokh Izadi*, Hedayat Shakeri1, Pedram Roham1 and Khodadad Sheikhzadeh2 School of Public Health, Zahedan University of Medical Sciences; 2Sistan-va-Baluchestan Province Health Center, Zahedan; and 1Sarbaz District Health Center, Sarbaz, Iran (Received January 12, 2006. Accepted May 2, 2006) SUMMARY: Within the years 2001 to 2004, Sistan-va-Baluchestan was the only province with transmission of cholera in Iran. The objective of this study was to determine the epidemiological characteristics of the cholera outbreak that occurred in 2004 in the Sarbaz district in the southern parts of this province. The surveillance data were analyzed, and a matched case-control study was performed. From 22 October to 15 November 2004, from 2,242 diarrhea cases that were sampled for stool culture, 90 cases were positive for Vibrio cholerae O1 El-Tor biotype, serotype Ogawa. Multivariate analysis showed that risk factors for cholera were drinking beverages from street vendors (OR = 10.16, 95% CI: 2.55-40.50), illiteracy (OR = 5.76, 95% CI: 2.63-30.09), no hand washing with soap after toilet use (OR = 22.06, 95% CI: 2.91-167.11), no hand washing with soap before meals (OR = 3.64, 95% CI: 1.03-12.82), sex (OR = 3.73, 95% CI: 1.17-11.89) and eating food left over from previous meals without reheating (OR = 4.03, 95% CI: 1.23-13.18). The source of drinking water showed weak associa- tion with cholera only in univariate analysis (OR = 2.83, 95% CI: 1.12-7.19). The development of primary health care, even though it can improve the conditions that control the spread of an epidemic, is not enough of a control measure as long as the social hygienic standards are low and people do not follow the basic personal hygiene regulations. The outbreaks had a few common points. First, the focal INTRODUCTION points of all these outbreaks were located in rural areas. “Asiatic cholera,” as it is sometimes called, has been en- Second, the mean age of symptomatic confirmed cases usu- demic in south Asia, especially the Ganges delta region, from ally was below 20 years. Third, all these outbreaks occurred the time of recorded history. The current seventh pandemic in summer and early fall. The seasonality seems to be related began in 1961 when the Vibrio cholerae O1, biotype El Tor, to the ability of Vibrios to grow rapidly in warm environmen- first appeared as a cause of epidemic cholera in Celebes tal temperatures (7). (Sulawesi), Indonesia. The disease spread rapidly and reached In Iran, primary health care (PHC) coverage has been the USSR, Iran and Iraq in 1965-1966 (1). During the years increased markedly within the last decade, and some of 2001 to 2003, cholera showed a decreasing trend in Asia, the sanitary services such as safe drinking water are under but in 2004 officially reported cases of cholera from Asia strict supervision even in deprived rural areas of Sistan-va- increased by 66%. During these years the number of reported Baluchestan province. In this situation, cholera outbreaks cases from Iran has remained stable within the range of 90 to comprise special features. As mentioned previously, the last 110 cases annually (2-5), and all confirmed cholera cases from outbreak in Sarbaz began on October 22, 2004, when cholera Iran have been from Sistan-va-Baluchestan province, the was first reported in Jangal village, near the Pakistan border. largest province of Iran, with subtropical -- tropical climatic The disease crept rapidly up to the Ashar area. Within 2 weeks condition, located in the southeast part of the country, near of detection of the first case, the outbreak began to subside, Afghanistan and Pakistan. The territory of this province has and the last case was detected on November 15, 2004 in the divided into 8 districts. In 2001 and 2002, 105 and 118 con- Pishin region (Figure 1). The outbreak lasted about 25 days, firmed cases of cholera where reported, respectively, from and enforced surveillance activities continued for another 6 districts (Zahedan, Khash, Saravan, Iranshahr, Sarbaz and 30 days, during which time no additional cholera case was Chabahar) (2,3,6). In 2003, 96 confirmed cases were reported detected. from Iran, and of these 75 (78.12%) were from Zahedan Studies about cholera in these regions have mostly focused district (the capital of Sistan-va-Baluchestan province) and on descriptive epidemiology of cholera, and the risk fac- the remaining cases were from Khash district about 140 km tors and routes of transmission have mostly remained un- south of Zahedan (4,6). In 2004, 94 confirmed cases were recognized (8-10). The main objective of this study, therefore, reported from Iran, and of these 90 were from Sarbaz district, was to determine the epidemiological characteristics of located about 350 km south of Zahedan. The last mentioned the 2004 cholera outbreak in Sarbaz district in Sistan-va- outbreak that lasted about 25 days began in October 22. Baluchestan province. The study was conducted as an out- break investigation within 2 days of the report of an outbreak *Corresponding author: Mailing address: P.O. Box: 98156-759, at the province health center. We have tried to highlight Zahedan, Iran. Tel/Fax: +98-541-2449877, E-mail: izadish@ the risk factors for transmission identified by the results of yahoo.com a population-based case-control study, and discuss the new 174 Fig. 1. Map of the involved regions of the Sarbaz district in the cholera outbreak of October and November 2004, Sistan-va- Baluchestan province, Iran. The points show the main involved villages. aspects of cholera outbreaks in a rural society with good health sampled for stool culture. There was no age limitation for services and poor individual hygienic practice. Even though stool sampling. This policy was continued for 30 days after the routes of transmission of cholera are well defined in most isolation of V. cholerae from the last culture positive case references, each outbreak has its own characteristics and (i.e., until December 15, 2004). After November 15, 2004 deserves investigation. none of the stool specimens was positive for V. cholerae. As stated previously, we performed a case-control study at the involved villages in Sarbaz, enrolling nearly all culture MATERIALS AND METHODS positive cholera patients identified through surveillance Sarbaz is a rural region bordering Pakistan, with a popula- and matching controls by age (index case’s age ± 3 years). tion of approximately 132,000 people living in 541 villages. Controls were selected from the same villages of the resi- The residents are primarily subsistence farmers and traders. dence of patients within 2 days of presentation by the cases At the beginning of the outbreak, the district had 12 rural and were excluded if they described any diarrheal episode health clinics and 60 health houses. A general practitioner (more than 3 loose stools per 24 h) in the preceding 30 days. was in charge of every rural health clinic, and the coverage An identical 2-page questionnaire (especially designed for of PHC services was about 63%. Only 65% of houses in this study) was filled out for cases and controls during an the epidemic area had sanitary toilets, and 8 villages in the interview by two interviewers adept in local language to gather involved area did not have a water pipe network. information about demographics, food and water consump- The study design was a hybrid of a descriptive epidemio- tion, and hygienic practices of cases and controls in the 5 days logical study and a case-control study. For the descriptive preceding their clinic visit (or their interview for controls). part, we used the information gathered by the surveillance It was not possible to blind interviewers to the case-control system and for the case-control part, every cholera case who status of the subjects. Cases were interviewed within at most was positive in stool culture was compared with one healthy 24 h of confirmation of their disease by the laboratory (usu- control (see below for details). ally within 3 days after presentation). The surveillance for diarrheal diseases that is a routine ac- The following variables were checked: age, sex, nation, tivity and usually covers only the population under coverage education level, household density per room (household size of PHC was strengthened during the outbreak by organiza- divided by number of living spaces), the source of drinking tion of temporary mobile health care teams and a temporary water, whether there was a refrigerator in the house, preserva- field hospital. The population of the involved areas that was tion method of food left over from previous meals, preparation considered as the population at risk in this outbreak was about method of foods left over from previous meals, individual 41,000. hygiene after toilet use and before meals, eating and drinking The surveillance system gathers information about demo- from street vendors, getting ice from street vendors, chlorine graphic characteristics of all diarrheal cases including age, test of drinking water, history of traveling of the subject or sex, address, the date of appearance of clinical signs, the one of his or her relatives (e.g., father or brother) within date of stool sampling and the result of stool culture. For the the week before disease to one of the neighboring countries purpose of surveillance in Sarbaz, all patients after October (Afghanistan and Pakistan), presence of soap in the hand- 22, 2004 with a history of watery diarrhea for any duration washing place, sanitary condition of the house-toilet and were considered as suspected cases of cholera and were general knowledge about cholera (using multiple choice ques- 175 tions).