Public Health of Indonesia Tsheten et al.
Public Health of Indonesia.
2016 December.
: 165-171
http://stikbar.
org/ycabpublisher/index.
php/PHI/index ISSN: 2477-1570
Original Research
A NOVEL STRAIN OF SHIGELLA SPECIES OUTBREAK IN A RESIDENTIAL
SCHOOL IN PEMAGATSHEL.
BHUTAN, 2012
Tsheten1*.
Dorji Tshering1.
Kinley Gyem1.
Sangay Dorji1.
Sonam Wangchuk1.
Tri Hari Irfani2.
Letho3 Royal Center for Disease Control.
Ministry of Health.
Bhutan Faculty of Medicine.
Sriwijaya University.
South Sumatera.
Indonesia Nganglam BHU-1.
Pemagatshel distric.
Bhutan Accepted: 1 December 2016 *Correspondence:
Tsheten.
MPH Royal Center for Disease Control.
Ministry of Health.
Bhutan Tel: 975-17304883.
Fax- 975-02-332464 E-mail : tsheten@health.
Copyright: A the author.
YCAB publisher and Public Health of Indonesia.
This is an open-access article distributed under the terms of the Creative Commons Attribution Non-Commercial License, which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
ABSTRACT
Background: A cluster of suspected shigellosis was reported from health center in Pemagatshel district to Royal Center for Disease Control on 14th May 2012.
The investigation was done to determine the cause and risk factor for the outbreak so that appropriate control and prevention measures can be implemented.
Methods: A descriptive study was used for the outbreak investigation.
The food items and drinks served to boarding students were collected from the mess in-charge in order to assess their risk for the outbreak.
The kitchen and its premises were inspected to study the likely contamination by rodents and other animals.
The water and stool specimens were tested in the laboratory to identify all possible enteric pathogens.
Results: 82 boarding students were affected with an overall attack rate of 28% .
Diarrhea was the predominant symptom followed by abdominal pain and headache.
The onset date of the cases varied between 11th and 18th May, 2012.
Shigella species was isolated from stool specimens that showed resistant to amoxicillin, nalidixic acid, chloramphenicol and sulfamethoxazole.
Water specimen collected from source, distribution reservoir and tap water at school were found grossly contaminated.
Conclusion: The outbreak was caused by novel strain of Shigella species which was not detected earlier in Bhutan.
The promotion and provision of boiled water will greatly reduce the incidence of shigellosis especially in boarding facility.
Key words: Shigellosis.
MDR-Shigella.
Boarding school.
Bhutan
INTRODUCTION
Shigellosis or bacillary dysentery is an acute gastroenteritis which occurs in areas with crowding and poor sanitary 1 Shigella species are the major etiological agents of bacillary dysentery.
Globally, it is estimated that 164.
7 million people are infected annually by Shigella APublic Health of Indonesia Ae YCAB Publisher.
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often through contaminated food or Shigella considered to be highly infectious due to their low infectious dose .
Ae 100 Dysentery encompasses four serogroups namely Shigella dysenteriae.
Shigella flexneri.
Shigella boydii and Shigella sonnei.
Each of these is composed of different serotypes, which are identified based on the structure of lipopolysaccharide O-antigen repeats:
Shigella dysenteriae has 15 serotypes.
Shigella flexneri, 14 serotypes.
Shigella boydii, 20 serotypes and Shigella sonnei, a single serotype.
Shigellosis is a national notifiable disease that every health centers in the country has to notify to Public Health Laboratory, now renamed as Royal Center for Disease Control (RCDC) for verification and activating an outbreak 8 Annually, suspected shigellosis is reported sporadically from many of the health centers in Bhutan.
9,10 On 14th May, 2012, a cluster of suspected shigellosis among boarding students of Nganglam Higher Secondary School (NHSS) in Pemagatshel district was reported to RCDC by medical officer of Basic Health Unit 1 (BHU Ae .
A team from RCDC was sent to school on 16th May, 2012 to investigate an outbreak.
The investigation was conducted to determine the etiological agent of suspected shigellosis and their concomitant study of antimicrobial susceptibility pattern.
The investigation was also aimed to trace the source of outbreak so that appropriate control measures are implemented to prevent from further spread to general population in the METHODS Epidemiological investigation A descriptive study was used for the investigation of outbreak.
A suspected case was defined as any boarding students studying in Nganglam Higher Secondary School (NHSS) in Pemagatshel district.
Bhutan with clinical manifestation of diarrhea with or without abdominal pain, nausea, vomiting or fever from 10th to 18th May, 2012.
All school students and teachers were assembled in the dining hall with permission from the Principal to seek active case finding.
The food items and drinks served to boarding students in the past few days were collected from the mess in-charge.
The personal hygiene and stool specimens of the cooks were also examined.
Face to face interview was conducted among all cases to study the exposure of food items in the past few days.
Environmental investigation The hygiene of the kitchen and its premises was inspected by the team.
The store where vegetables and other culinary items were stacked was also inspected to study likely contamination by rodents and other possible sources.
The team visited school water source to inspect surrounding sanitation and collect water samples.
Water samples were collected from reservoir, distribution tank, and taps from kitchen, boys and girls hostel for testing indicator bacteria using fecal coliform medium .
FC brot.
Microbiological investigation A total 12 stool specimens from both hospitalized and outpatient unit were collected and subjected to standard microbiological test.
Both macroscopic and microscopic examination was done for all the collected specimens.
For microscopic examination, a wet mount was prepared 85% Normal Saline and observed using a light microscope for cells, ova and Furthermore, specimens were processed for culture and identification of bacterial pathogens.
Briefly, suspensions of stool specimens were made in 0.
85% Normal Saline.
The suspension was enriched in Buffered APublic Health of Indonesia Ae YCAB Publisher.
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Peptone Water (BPW).
Alkaline Peptone Water (APW) and Preston, and plated on Mac-Conkey Agar.
Hecton Enteric Agar and modified Charcoal Cefoperazone Deoxycholate Agar .
CCDA).
All media were incubated aerobically except for mCCDA which was incubated at microaerophilic atmosphere at 37AC.
The colonies from each media were identified biochemically using Kligler Iron Agar (KIA), indole, bile esculin, lysine decarboxylase, ornithine decarboxylase, arginine dihydrolase and also by using bioMerieux Analytical Profile Index (API) 20-E.
Identified organism was then subjected to antimicrobial susceptibility testing using Clinical Laboratory Standard Institute (CLSI) guideline.
Statistical analysis The demography of the cases and antimicrobial susceptibility pattern of bacterial pathogen were presented in terms of numbers and percentages.
The distributions of cases were presented graphically by using their date of onset of Ethical clearance from Research Ethics Board of Health (REBH).
Ministry of Health.
Bhutan was not required for the investigation conducted in response to disease outbreaks.
RESULTS
Epidemiological investigation The school had a total of 482 students out of which 294 are boarding students .
girls and 184 boy.
About 82 boarding students were affected in the outbreak with an overall attack rate of 28% .
Sex specific attack rate was observed high among girls .
%) than boys .
%).
The median age of affected students was 17 years which ranged from 15 - 21 years.
Diarrhea was the predominant symptom observed in all The other symptoms included abdominal pain, nausea, vomiting, fever and headache in this order (Table .
Table 1.
Symptoms of cases in an outbreak of suspected shigellosis in NHSS, 2012 .
= .
Percentage Symptoms Number
(%)
Diarrhea Abdominal pain Headache Fever Dysentery Nausea Vomiting The index case was detected on 13th May 2012 in health center.
However, on active case finding, the cases actually emerged on 11th May but they didnAot seek medical care and were not detected in the health center.
The onset date was between 11th May and 18th May 2012 with majority of the cases reporting their onset of symptoms on 13th May.
No case was detected on 15th May.
With one case on each 16th and 17th May, the case rose to five on 18th May and thereafter, no cases were reported (Figure None of the students were reported to have consumed food from nearby commercial shops or restaurants.
All boarding students had consumed same food items provided in the mess.
As per the information provided by the students, foods provided in the mess were cooked adequately and no hint was ever reported on the possibility of food contamination.
Even the personal hygiene of all four cooks was found satisfactory on screening their However they pointed out that the consumption of un-boiled water could be the risk for the outbreak as they are not provided with boiled water in the boarding facility .
tudent hoste.
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Number of cases Date of onset Figure 1.
Epidemic curve of shigellosis outbreak in NHSS, 2012, by date of onset Environmental investigation The kitchen and its premises were found Vegetables and other culinary items were also properly stacked in kitchen-store with no trace of rodents.
Water source was located around 20 - 30 minutesAo walk from the school.
Water source for the school was a running stream in the forest connected to reservoir.
During inspection, the surrounding of water source was found contaminated with cattle feces with few cattle grazing near it.
Water distribution reservoir and tap water at school were found grossly contaminated.
(Table .
Table 2.
Water quality test results at different water sources in NHSS, 2012 Sampling points Test results Interpretation School reservoir tank > 50 CFU/100 ml Grossly polluted Distribution tank > 50 CFU/100 ml Grossly polluted Boys hostel tap water 20 CFU/100 ml High health risk Girls hostel tap water 10 CFU/100 ml Intermediate health risk Kitchen tap water 26 CFU/100 ml High health risk Note: CFU = Colony forming unit.
ml = milliliter Microbiological Result Six stool specimens were collected from each of the hospitalized and nonhospitalized cases.
Mucus and blood were visible in nearly half of the collected stool Red blood cells and white blood cells were found in all the From culture and biochemical test.
Shigella was also isolated from five of 12 stool specimens.
The identification was further confirmed by Analytical Profile Index (API) 20 E as Auhighly pathogenic shigella speciesAy.
However on serotyping, none of the isolates were agglutinated with all available antisera (DENKA SEIKEN.
JAPAN) and additional antisera of S.
dysenteriae serotype 13, 14 and 15 (Reagensia AB.
Solna.
Swede.
The antibiotic susceptibility test showed that all APublic Health of Indonesia Ae YCAB Publisher.
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isolates were susceptible to cefazolin, ciprofloxacin, cephalexin, ceftriaxone and gentamycin, and resistant to amoxicillin and nalidixic acid.
Furthermore, except for one isolates, the four other isolates were DISCUSSIONS This is the first documented outbreak of shigellosis in the country caused by novel strain of Shigella species which could not be serotyped with the available antisera.
The past outbreaks in Bhutan are mostly caused by either Shigella sonnei or Shigella flexneri which were confirmed by serotyping with the The manifestation caused by serogroups of Shigella is similar with mucus and bloody However, the dysentery caused by S.
dyenteriae is severe as compared to other serogroups14.
The current outbreak is most likely caused by S.
dysenteriae based on non-fermentation of mannitol although isolates tested negative with all antisera.
Moreover, the current outbreak has caused hospitalization of the cases due to loss of body fluids and severe dehydration.
With timely intervention in the health center, no case fatality was reported in the outbreak.
Except for one pathogen, the remaining four pathogens were resistant to sulfamethoxazole and tetracycline.
Such Multi-Drug Resistant Shigella .
esistant to three or more antibiotic.
was also reported in Nepal.
Africa.
India and Zimbabwe15-19.
An emergence of MDR-Shigella might be associated with the irrational or overuse of antibiotics in the healthcare facilities.
All cases were residing in the boarding facility with preponderance of The exclusion of cases among dayscholar students suggests that they have more leverage than boarding students on their style of dietary habits.
Moreover, they also reported that they drink boiled or filtered water all the time, whereas, boarding students were not supplied with such facilities at the hostel.
A single isolation of nonserotyping Shigella species from the stool specimens suggest that all cases were exposed to same source.
Drinking water could possibly be the source of this outbreak because all water specimens tested at different sampling units were This finding was also supported by the number of cases detected on different dates which indicates that they might be exposed to contaminated water at different time periods.
The epidemic curve shows a difference of seven days between the first and the last case.
If it was a common point source outbreak, all cases would have their onset within 1-3 days after infection because the incubation period of Shigella is 1-3 days20.
The isolation of Shigella from water specimens would have confirmed the source of outbreak but RCDC do not have those sophisticated testing facility for water and other environmental specimens for isolating bacterial pathogens.
Interventions taken Water tanks that supplied water to school was cleaned thoroughly and provision of boiled water in boarding facility was suggested.
Health education was also given to all students and teachers on the transmission and prevention of CONCLUSIONS The outbreak is caused by novel strain of Shigella species which was not detected in any health centers of Bhutan.
Surveillance on bacillary dysentery has to be continued to monitor the distribution of serogroups and their antimicrobial susceptibility pattern to guide the treatment of patients.
School administration should APublic Health of Indonesia Ae YCAB Publisher.
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provide enough boiled water for drinking purpose in school including hostels.
ACKNOWLEDGMENT