Urogenital schistosomiasis among school children in northwestern Tanzania: Prevalence, intensity of infection, associated factors, and pattern of urinary tract morbidities

Abstract

Background: The planning and implementation of intervention measures against schistosomiasis, particularly mass administration, require knowledge of the current status of the infection. This is important for monitoring the impact of the intervention on disease indicators such as a decline in infection prevalence, intensity of infection, and urogenital morbidities. Following repeated rounds of mass treatment in northwestern Tanzania, the epidemiology of urogenital schistosomiasis has changed; thus, for the effective planning and allocation of resources, it is important to understand the current status of the disease in the targeted groups. Therefore, the objective of the current study was to determine the prevalence, intensity, and associated factors of Schistosoma haematobium infection and urinary tract morbidities in school-aged children from northwestern Tanzania.

Materials and methods: An analytical cross-sectional study was conducted among schoolchildren aged 5-17 years between November and December 2022. A single urine sample was collected from each child and examined for the presence of S. haematobium eggs and microhaematuria using a urine filtration technique and a urine reagent dipstick. Each child underwent an ultrasonographic examination of the urinary tract according to the World Health Organization standards (Niamey protocol) to detect S. haematobium-related morbidities.

Results: Of the 3225 participants, 54.2 % were female, and the mean age was 10.9 (±1.89) years. The overall prevalence of S. haematobium was 17.7 % (95 % CI: 16.4-19.1, 572/3225). Of the 572 infected children, 81.8 % (95 % CI: 78.4-84.9, 468/572) had light-intensity infections, and 18.2 % (95 % CI: 14.9-21.4, 104/572) had heavy-intensity infections. The prevalence of macro- and microhaematuria was 2.4 % (95 % CI: 1.9-3) and 18.5 % (95 % CI: 17.2-19.8), respectively. Age (aOR: 1.2, 95 % CI: 1.0-1.5), district of residence (aOR: 2.1, 95 % CI: 1.7-2.7) and history of schistosomiasis (aOR: 2.5, 95 % CI: 1.9-3.2) were significantly associated with urinary schistosomiasis infection. However, swallowing praziquantel during the last mass drug administration was protective (aOR 0.6, 95 % CI: 0.4-0.8). The overall prevalence of ultrasound-detectable urinary tract abnormalities was 9.9 % (95 % CI: 8.9-11.1, 299/2994) and included urinary bladder abnormalities in 9.9 % (95 % CI: 8.8-11, 297/2994), ureter abnormalities in 0.2 % (95 % CI: 0.07-0.4, 6/2994), and kidney abnormalities in 0.2 % (95 % CI: 0.09-0.4, 7/2994). Calcification of the urinary bladder was observed in 0.9 % (95 % CI: 0.6-1.3, 29/2994) of the examined children.

Conclusions: Schistosoma haematobium infection is still prevalent among schoolchildren in the study setting, and it causes substantial morbidity at an early age. Transmission is driven by the age of the child, district of residence, and history of schistosomiasis. However, swallowing praziquantel in rounds of mass drug administration reduces transmission. Urogenital schistosomiasis infection is associated with haematuria and ultrasound-detectable morbidities. In S. haematobium endemic areas, routine ultrasound screening for urinary tract morbidities could be considered in annual mass treatment programmes for early management. Special attention should be given to children with proteinuria, microhaematuria, and heavy infection intensities.

Keywords: Prevalence; Schistosoma haematobium; Schoolchildren; Tanzania; Ultrasound; Urinary tract morbidities.

Fig 1

A map of Tanzania showing the position of Simiyu region and administrative districts. (credit to https://gadm.org/maps/TZA/simiyu.html And https://commons.wikimedia.org/wiki/File:Simiyu-Region.svg)

Fig 2

Prevalence of S. haematobium infection by age group.

Fig 3

Prevalence of S. haematobium infection by sex.

Fig 4

Factors associated with Schistosoma haematobium infection among school children.

Fig 5

Factors associated with urinary tract morbidities among school children.

Fig. 6

Images showing A. Bladder calcification, thickening. B. Bladder wall irregularities, C. Mass, pseudo polyps D. Bladder shape (round/distorted) and E. Hydronephrosis.