Typhoid in traijiskitan
Typhoid fever in Tajikistan broke out after the civil war in the capital city, Dushanbe. The report is about the investigation done by the Sanitary Epidemiologic Service (SES). It will discuss the background, investigation and finally summarize the key findings and give recommendations to public health for interventions to control outbreak
Typhoid in Tajikistan was first noted in February 1997 when cases of typhoid fevers were reported on the capital city Tajikistan, Dushanbe, which had a population of about 600,000 citizens by then (Arnold et al 2007). Despite the fact, the fever was endemic at that time; initially about 2000 previous cases had been reported in a two week period between 29th January and 11th February. This was high when compared to the approximately 75 cases which used to be reported every week of the previous month. The hospitals and the polyclinics which served the city by then reported any cases of disease noted to the sanitary epidemiological service (SES), the health unit that tracked the infectious diseases every week (Clasen et al 2007).
The investigators suspected the foods and the public water for investigation. Given that previous outbreaks of typhoid were associated with beverages and foods sold by the street vendors, the government prohibited their sale. Therefore, the investigators narrowed down to the water where 3822 patients were investigated (Tarr Pe et al 1999). The investigator conducted epidemiological, microbial and environmental studies to explain the sudden increase in typhoid fever cases in two week period.
- Investigation of the outbreak
In a bid to get a clue to the typhoid outbreak, the investigators pursued various lines. The first step was to review available known information on the disease, the epidemiological risk factors and the previous outbreaks.
- Case definitions and confirmation of the outbreak
The SES investigators reviewed the cases of typhoid fever reported by the system of notifying disease surveillance and classified the cases by place, person and time. In identifying characteristics of the typhoid fever outbreak cases, the investigators came up with a definition of the typhoid fever as diagnosis by a physician or blood, stool or urine Salmonella Typhi isolation of a resident of Dushanbe.
The investigators did an analysis of the reported cases to the SES with the illness onset since 1st January. 3,822 cases was the number of patients that qualified the definition of the typhoid fever since 1st January. Out of those the number which had onset illness from 1st to 14th January was 127 and the number which had onset illness from 15th January to 18th February was 3,695 (Centre for Disease Control And Prevention 1998).
During the period between January 15th and February 18th, among the reported cases, the following symptoms and signs were reported according to Mermin et al (1999):
- 91% of the cases from sustained fever
- 81% from head ache
- 76% from weaknesses
- 73% from chills
- 67% from loss of appetite
- 51% from abdominal pain
- 39% from vomiting
- 30% from diarrhoea
- 6% from rose coloured spots
- 31% from the stool, blood and urine cultures (1,145 cases).
- Methods of data collection
During the data collection, hypothesis- generating detailed interviews were done to find out suspicious and common exposures among the typhoid fever sample patients. The interviews were conducted on 10 culture- confirmed illness patients who resided in the catchment areas of 5 different polyclinics and varied from the ages of 5-69 years. There were 6 female patients, and the patients showed symptoms of during the first two February weeks (Hamilton 1997).
- Hypothesis generation and the type of outbreak
From the interviews, it was revealed that all the patients had bought groceries from markets that are state approved. Moreover, four of the patients had bought food from the street vendors, however, no social event, street vendor, market and the restaurant was identified as common among all the interviewed patients.
Furthermore, the patient’s households who were included in the interviews were given public water, but only one of them reported occasional cloudiness and foul smell of the water. However, only one had gone out of the city during 6 weeks prior the outbreak, and seven had visitors from outside the Dushanbe city because of Ramadan. No patient knew the other, and two knew someone who had similar illness. The investigators hypothesized the supply of the public water as the typhoid fever source in city of Dushanbe. This is because of the wide spread city occurrence affecting all age groups and both sexes. The suspicion was heightened due to the interviewee’s complaints of the public water. This prompted the investigators to do environmental and epidemiological health studies to prove their hypothesis.
- Testing of the hypothesis by epidemiologic study
In testing their hypothesis of the system of public water as the source of the typhoid outbreak in the city, the SES investigators did a case- control study from March 24. All patients hospitalized in Dushanbe with typhoid fever were enrolled in the case-control study. A case in the study was defined as an illness that included the following:
- a) Clinical criteria
- I) Symptoms and Signs indicative of typhoid such as stomach pains, weakness, headache, rose coloured rash and appetite loss
- II) Sustained fever i.e. oral temperature >38.5c for more than 7 days
III) Culture for blood or stool positive for Salmonella Typhi
- b) Restriction on place, time and person
- I) Onset of the symptoms after 1st February
- II) Dushanbe resident
III) Person having earliest symptoms onset in household (Asia-Pacific Symposium On Typhoid Fever, Pang, Koh & Puthucheary 1992).
Case/control study including Odds ratio and how the controls were recruited
The interview was done to the case patients within five days of admission to the hospital, using a standardized questionnaire, by SES trained interviewer. The focus of the questions was on the one month exposure before the illness onset. The investigators then selected, within five days, neighbourhood control subjects in houses where no one had experienced fever for less than three consecutive days, during the 90 previous days.
Sarasombath et al (1995) observed that recruitment of the control subjects was done from door to door systemically, beginning at the house of the case patient; matching of the control subjects was then done with the age group of case patients. 2-3 control subjects identified were assigned one case patient.
According to Murdoch et al (1998), interview of the control subjects was conducted using same questionnaires as case patients, with a difference in information exposure was requested 30 days prior the interview. Between 24th march and 7th April, 127 control subjects and 45 case patients were recruited in the case-control study.0.05 was set as the p value as the statistical significant cut off (Taylor et al 1999). From the analysis case- patients and control subjects were similar with respect to sex, age and nationality. However, exposure to potential risk factors for Salmonella Typhi infection differed between the two groups.
From the matched case-control study, infection was associated with drinking of water not boiled 30 days prior symptoms onset. With the amount of water consumed daily, the odds ratio rose. Taking 1 glass of water not boiled had a matching odds ratio of 3; 2 glasses had a matching odds ratio of 12 (Roberts 2013). Furthermore, water from outside home taps, eating street vendor foods was also associated with the illness. The investigators applied multivariate logistic regression analysis.
- Other hypothesis confirming information
Environmental studies and investigation of the water supply
This was done concurrently with the case- control study to identify factors that might have introduced pathogens into drinking water. The SES investigators learned that the city uses in ground and surface water treated in four water treatment plants. Samotechnaya and Napornaya stations which formed the northern treatment used Varzob river surface water. The two southern treatment plants (South West and Kafefernigan stations) used ground water (Robbins 2007).
Water from the two southern treatment plants were directly pumped from wells to holding tanks and then to the distribution system of the public without treatment. The basins for sedimentation at the stations had algae and silt, and the machines for dredging were broken. Furthermore, the sand filters had mud balls and displayed fouling with iron oxide that compromises process of filtration. The water had also not been regularly regulated since December; with half of the pumps stalled .This limited the city with supply of water (Kiple 2008).
The turbidity and faecal coli forms test of the treated water from the treatment plants showed 150 nephelometric turbidity units, and 132 colony forming units per 100 millilitres at Napornaya station. Samotecnaya station had 70NTU and 118 CFU/100ml. Ground water plants were free. From the household investigations on water samples, 97% and community taps had contaminated water with faecal coli forms of 175CFU/100ml (Emmeluth 2004).
- Recommendations to prevent future out breaks
Rudenstine & Galea (2012) observed that to control and prevent future water borne diseases and typhoid fever in Dushanbe require many actions such as:
- Improved protection of river Varzob watershed.
- Replacement or repair of the water treatment plant equipments such as the sand filters, dredging machinery and pumps.
- Training of staff of the water treatments plant thoroughly.
- Change of processes of water treatment.
- Procurement of coagulant and chlorine in adequate amount.
- Replacement or treatment of old water distribution system
- Public education on water conservation to reduce wastage of water.
- Discussion and conclusion
The best approach to achieve healthy public supply of water is use of multiple barriers to prevent contaminants from entering water supply. Typhoid fever outbreak in Dushanbe was due to part of system failure. The contributing factors to Dushanbe water services include:
- Surface waters chronically contaminated due to untreated discharge of waste into rivers and flooding every spring.
- Inadequate processes of treatment.
- Water treatment plants disrepair.
- Frequent intermittent and low water pressure due to water pumps failure, line breakages and water wastage (Osler 1995).
- Lessons learned and recommendations
These problems that are attributed to reminiscent factors of the situation in Dushanbe include resources reduction devoted to water treatments plants maintenance, increasing repairs of the back log, loss of trained maintenance personnel, aging distribution pipes and treatment equipments. Therefore, steps should be taken to address and understand these problems.
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