Typhoid is an acute infectious disease caused by the bacterium Salmonella typhi, which infects people through consumption of contaminated food or water. The bacterium penetrates the intestinal wall and multiplies in lymphoid tissue;¹it may also enter the bloodstream and cause septicemia.² Early symptoms of typhoid appear between 10 and 14 days after infection. The symptoms include headache, general body weakness, generalized body pains, fever, and restlessness. Other notable prodromal signs include loss of appetite and diarrhea.³ High fever reaching a peak of 39 to 40°C is common after infection.³ Chronic typhoid infection sometimes leads to loss of weight.³ Typical complications of typhoid include acute inflammation of the gallbladder, heart failure, and pneumonia. Untreated typhoid has a case fatality rate of 25%.³ However, natural recovery is possible, and is usually characterized by a decline in body temperature of the infected patient.The laboratory culturing of venous blood and stool, as well as serological testing are used to diagnose typhoid. The Widal serological test is widely used in developing countries to confirm typhoid. Chloramphenicol and nalidixic acid represent first line treatment for typhoid.⁴

Use of contaminated food and water is the major cause of typhoid epidemics. Improperly prepared food, including inadequately pasteurized milk products are typical causes if typhoid. Houseflies are important vectors of the disease, which implies that improperly covered food may spread the disease.⁴Broken sewage systems in urban centers are major precipitating factors in the spread of typhoid. Practices such as water chlorination are important substitutes to municipal water treatment. The screening of food handlers who work in food industries and restaurants also plays a major role in preventing outbreaks of typhoid in urban settings.⁴ In Zimbabwe, typhoid continues to pose an important public health problem, particularly in urban settings. The disease is a notifiable under the country’s Public Health Act (Harare City Health report 2011, unpublished).⁵Notable outbreaks in the city of Harare include the Dzivaresekwa and Kuwadzana outbreaks, which occurred between October 2010 and January 2011.⁵ In total, 1078 cases were reported during the outbreaks (Harare City Health annual report 2011, unpublished).⁵ Another typhoid outbreak was recorded at Glenview Polyclinic on the 1^st of November 2012 involving a teenage school girl from Glenview High II. This study presents an epidemiological investigation of the Glenview typhoid outbreak. The paper also presents risk factors for contracting typhoid as identified by the Glenview investigation.

Study design This was a case control study based on quantitative and qualitative analyses in the investigation of the Glenview typhoid outbreak in Harare, Zimbabwe. These mixed methods of quantitative and qualitative analyses have been shown to address the research problem more reliably compared to limited approaches. Study setting and population Glenview suburb, particularly the Glenview Polyclinic was purposefully selected for this study because it was epicenter of the 2012- 2013 typhoid outbreak in Harare. Glenview is one of the high density suburbs located in the South-Western part of Harare. Glenview has an adult population, aged between 18 and 74 years, of approximately 58,782. Residents of Glenview are serviced by two primary healthcare clinics, including Glenview Polyclinic and one municipal infectious disease hospital known as Beatrice Infections Disease Hospital. Cases of notifiable disease such as typhoid are referred from the polyclinics to Beatrice Infections Disease Hospital. The target population included all eligible participants residing in Glenview who either received treatment for typhoid, were close contacts, or were neighbors of the cases. The key informants on treatment and emergency response to the typhoid were the senior staff at Glenview Polyclinic. Glenview typhoid case study On 1 November 2012, a teenage school girl from Glenview High II reported to Glenview Polyclinic with symptoms of diarrhea, a body temperature of 40°C, loss of appetite, abdominal pains, headache and general body pains. The symptoms had started two days before. A Widal test on a stool sample confirmed infection with Salmonella typhi. The patient was given nalidixic acid and discharged. A number of similar cases of typhoid were reported to the same health facility until June 2013. Water at the school borehole tested positive for above normal coliform count. Case definition The researchers defined a case as any patient aged above 18 years who presented at Glenview Polyclinic between 01 April and 30 June 2013 with symptoms of typhoid as defined in the case definition in the typhoid intensive
case finding and was diagnosed and treated for typhoid. Patient cases were selected from a line list, which was obtained at the Glenview Polyclinic for the identification of participants who had received typhoid treatment between 01 April and 30 June 2013. A total of 80 cases were selected using an intensified case finding strategy and also through hospital line list. Controls A control was defined as any person nonsymptomatic of typhoid, staying in a household with someone who had typhoid or the neighboring households during the same period as defined in the cases. The target ratio of controls to cases in this study was 2:1. Two controls were selected for each case, one in the case household and the other one in the neighboring households. Sample size calculation The Statistical function in Epi-info version 3 (CDC, Atlanta, USA) was used to calculate the sample size targeting 95% confidence level of the population mean and 80% power. Assuming an exposure rate of 10% in the control group
and a minimum odds ratio (OR) of 3, the minimum sample size required for the study was 240, which translates proportionally to:
control sample sizes of 160 controls to 80 cases. Clinical records of the 80 cases were therefore reviewed. This sampling approach was based on sampling recommendations for case control studies by Anand et al (2009).6 Data collection The study was based on intervieweradministered semi-structured questionnaires. In addition, patient history and case management were reviewed. Sanitation facilities of the affected households were assessed using a checklist prepared by the researchers. The quality of outbreak response as reported by the key informants at the Polyclinic was assessed using a semi-structured questionnaire adapted from the WHO Integrated Disease Surveillance and Response.7 Data analysis Quantitative data was captured using EpiInfo 3 statistical software and analyzed using the Stata 11 statistical package (Stata Corp LP, Texas, USA). Demographic and clinical data was summarized and compared between the cases and the controls using frequencies, proportions and medians. In addition, comparisons of means between cases and controls were performed using t-test. Stratified univariate analyses to assess for possible confounding and effect modification were performed using logistic regression to determine significant (p<0.05) risk factors for contracting typhoid. Qualitative data obtained from the key informants on the quality of emergence response and the sanitation facilities were analysed using the ENVIVO software (QSR International Pty Ltd, Victoria, Australia). Ethical considerations Permission to carry out the study was sought from and granted by the Director of Health Services at the City of Harare. Permission to conduct the study was obtained from the relevant hospital authority. The respondents signed informed consent forms and were provided with information on the background of the study. The respondents were also informed that their participation was voluntary and that they could decline to answer certain questions, including that they could withdraw their participation at any time. No information on respondents’ identities was collected. In addition, confidentiality of their information was also assured. Subsequently, each respondent signed a written consent form before data collection. 

The interval between the initial outbreak case seen at the health facility and its reporting to Provincial Health Office was timeous. It took the polyclinic 12 hours to report the case. This is in line with the outbreak detection, response and preparedness guidelines by the WHO.8-12 The interval between notification and field investigations conducted was 24 hours, also in accordance with the WHO guidelines for investigating an outbreak.7,11 This is in synchrony with another report by the embassy of the United States in Harare, dated January 9, 2012 where health experts from the United States Centers for Disease Control and Prevention (CDC) hailed Harare authorities’ response to the typhoid outbreak which was detected in October 2011, describing it as a model for other countries facing similar epidemics.3,5,11 Since the Glenview residence did not share common food, the water supply may have been the source of the Glenview typhoid outbreak. Most of the cases occurred around a borehole which was a major source of an outbreak in 2012. Water samples taken and tested from this source revealed excessive contamination with coliforms. Furthermore, the widespread occurrence of cases in this suburb may be indicative of a waterborne outbreak.12 An exploratory case-control study analysis did not yield any plausible results in terms of associated risk factors, which suggested that the epidemic was probably the result of a common source. Moreover, several typhoid outbreak investigations have shown that sources of drinking water appeared to be the most common reservoirs for Salmonella typhi. Knowledge amongst cases and controls with regard to typhoid was not similar. The emergency response included setting up a typhoid treatment camp, provision of oral rehydration services, conducting meetings to review progress on the outbreak, and typhoid health education in the community, and was appropriate and commendable. However the response team did not mount an adequate intensive case finding programme. The line list at the Polyclinic was notcomplete which suggests that there were gaps in information recording. In addition, interviews with the key informant revealed that the laboratory would not have coped had all stool samples been sent for laboratory testing. The laboratories at the Polyclinic had inadequate supplies of reagents and staff shortages. The major limitation in this study is that that typhoid cases were not confirmed by laboratory testing. 

Borehole water was associated with this typhoid outbreak. Environmental health officers should ensure that borehole water is regularly monitored for coliforms. The typhoid outbreak response team should ensure that all patients presenting with typhoid symptoms are line listed. Acknowledgement The researchers would like to thank the health authorities at the Harare City Council for approving this study. Authors’ contributions statement RM, SM, FMM designed and implemented the study. All authors participated in the analysis of the data and writing of the manuscript. All the authors read and approved the
final manuscript.

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