Descriptive Epidemiology of Typhoid Fever during an Epidemic in Harare, Zimbabwe, 2012

Abstract

BackgroundTyphoid fever remains a significant public health problem in developing countries. In October 2011, a typhoid fever epidemic was declared in Harare, Zimbabwe - the fourth enteric infection epidemic since 2008. To orient control activities, we described the epidemiology and spatiotemporal clustering of the epidemic in Dzivaresekwa and Kuwadzana, the two most affected suburbs of Harare.MethodsA typhoid fever case-patient register was analysed to describe the epidemic. To explore clustering, we constructed a dataset comprising GPS coordinates of case-patient residences and randomly sampled residential locations (spatial controls). The scale and significance of clustering was explored with Ripley K functions. Cluster locations were determined by a random labelling technique and confirmed using Kulldorff's spatial scan statistic.Principal FindingsWe analysed data from 2570 confirmed and suspected case-patients, and found significant spatiotemporal clustering of typhoid fever in two non-overlapping areas, which appeared to be linked to environmental sources. Peak relative risk was more than six times greater than in areas lying outside the cluster ranges. Clusters were identified in similar geographical ranges by both random labelling and Kulldorff's spatial scan statistic. The spatial scale at which typhoid fever clustered was highly localised, with significant clustering at distances up to 4.5 km and peak levels at approximately 3.5 km. The epicentre of infection transmission shifted from one cluster to the other during the course of the epidemic.ConclusionsThis study demonstrated highly localised clustering of typhoid fever during an epidemic in an urban African setting, and highlights the importance of spatiotemporal analysis for making timely decisions about targetting prevention and control activities and reinforcing treatment during epidemics. This approach should be integrated into existing surveillance systems to facilitate early detection of epidemics and identify their spatial range.

Typhoid fever outbreak investigation in Ofla Woreda, Southern Zone of Tigray Region, Ethiopia, 2016: An unmatched 1:2 case-control

“…Typhoid fever suspected cases were higher in females than males. This result is consistent with the result from a study in Zimbabwe (Muti et al, 2014;Imanishi et al, 2014;Polonsky et al, 2014) and in Mozambique (Sejvar, 2012). This may be due to females tending to be caregivers of those who are ill at home.…”

“…Therefore, the peak of an epidemic curve was seen on August 5, 2016 (WHO week 31) and the curve fell dawn within few days after getting its peak. This sharp increase and decrease of the epidemic curve typical characteristic of common source type of epidemic which is supported by the study in Zimbabwe at 2012 (Polonsky et al, 2014) and at 2014 years (Muti et al, 2014, Imanishi et al, 2014.…”

“…The infection is transmitted via contaminated food or water by fecal or urinary carriers excreting the bacterium. Contaminated water supply, food bought from street vendors, the consumption of raw fruit and vegetables, and a history of contact with other cases or chronic carriers, population density, rainfall, river level, and proximity to water sources were the associated factors of the illness (Parry, 2002;Polonsky et al, 2014;Tadesse, 2014).…”

Typhoid Fever in South Africa in an Endemic HIV Setting

“…Other literature series examining the association of HIV and typhoid fever have looked at populations where HIV is predominantly a male disease, in men who have sex with men [6,26], where sexual practices may constitute an additional risk factor, or the male-to-female ratio for typhoid fever was not reported [7]. Not all reports from African countries have highlighted a female predominance [4,27], although increased numbers of women were reported from large outbreaks of typhoid fever in Zimbabwe [28] and Malawi [29]: HIV status was not documented in these reports. In Zambia, male-to-female ratios were equal in a large outbreak from 2010 to 2012, but most cases were reported in children less than 15 years of age [12].…”

Detection of viable Salmonella Typhi by reverse transcription-multiplex polymerase chain reaction

“…enterica serovar Typhi (S. Typhi) is a gram negative bacillus belonging to the family Enterobacteriaceae. It is as a pathogen of human typhoid fever, one of the major health problems worldwide (Bhutta, 2006;Crump et al, 2004;Kothari et al, 2008;Polonsky et al, 2014). The transmission of S. Typhi is considered to be a direct contact transmission among human without any animal as an intermediate host.…”