High prevalence of Schistosoma mansoni infection and stunting among school age children in communities along the Albert-Nile, Northern Uganda: A cross sectional study

Abstract

Background: Knowing the prevalence of schistosomiasis is key to informing programmes to control and eliminate the disease as a public health problem. It is also important to understand the impact of infection on child growth and development in order to allocate appropriate resources and effort to the control of the disease.

Methods: We conducted a survey to estimate the prevalence of schistosomiasis among school aged children in villages along the Albert-Nile shore line in the district of Pakwach, North Western Uganda. A total of 914 children aged between 10-15 years were screened for Schistosoma mansoni using the POC-CCA and Kato Katz (KK) techniques. The infection intensities were assessed by POC-CCA and KK as well as CAA tests. The KK intensities were also correlated with POC-CCA and with CAA intensity. Anthropometric measurements were also taken and multivariate analysis was carried out to investigate their association with infection status.

Results: The prevalence of schistosomiasis using the POC-CCA diagnostic test was estimated at 85% (95% CI: 83-87), being highest amongst children living closer to the Albert-Nile shoreline. Visual scoring of the POC-CCA results was more sensitive than the Kato Katz test and was positively correlated with the quantified infection intensities by the CAA test. The majority of the children were underweight (BMI<18.5), and most notably, boys had significantly lower height for age (stunting) than girls in the same age range (p < 0.0001), but this was not directly associated with S. mansoni infection.

Conclusion: High prevalence of S. mansoni infection in the region calls for more frequent mass drug administration with praziquantel. We observed high levels of stunting which was not associated with schistosomiasis. There is a need for improved nutrition among the children in the area.

Fig 1. Map showing the study sampling sites within the sub-counties of Pakwach district, West Nile, Uganda.

The base map was obtained from Uganda Bureau of Statistics (2012), http://purl.stanford.edu/vg894mz3698, and is in public domain with no restrictions on use.

Fig 2. Flow chart showing the number of participants screened, recruited into the survey and which S. mansoni detection tests were done on them.

Fig 3. Prevalence of S. mansoni among children aged 10–15 years in the study sites as detected by POC-CCA test.

A. The overall prevalence as a percentage of infected individuals among the total screened individuals (N = 914).B. The number of POC-CCA S. mansoni (Sm) positive cases in the individuals screened per site.

Fig 4

The distribution of infection intensity among the cases in the different age groups of the study participants as scored by A. POC-CCA (N = 461) scored as band intensities of trace, 1+, 2+, 3+ and 4+ of increased concentration of the circulating cathodic antigen of the worm; and B. Kato Katz (N = 387) measured by the mean number of eggs/gram of stool with infection intensity classified as light (EPG < 100), moderate (EPG 100–399) and heavy (EPG ≥ 400). C. CAA test done on plasma samples from 600 individuals whose urine had been screened in the field by POC-CCA.

Fig 5

Relationship between POC-CCA and Kato Katz (A, C) and between POC-CCA and CAA (B, D). The original scale values for KK and CAA were used in panel A, B whereas the Log values were used in panel C, D.

Fig 6

Height for Age Z score distribution by A. Sex, B. POC-CCA screen, C. POC-CCA infection intensity.