Morbidity associated with Schistosoma mansoni infection in north-eastern Democratic Republic of the Congo
Authors: M Nigo Maurice , Odermatt Peter , Wully Nigo David , Salieb-Beugelaar Georgette B. , Battegay Manuel , R Hunziker Patrick 
Published: May 2020

Background

Controlling morbidity is the main target of schistosomiasis control. Yet only rarely do we assess morbidity linked to Schistosoma sp. infection. In the Democratic Republic of Congo (DRC), and particularly in the north-eastern Ituri province, morbidity associated with Schistosoma mansoni infection is unknown. For this reason, we aimed to assess intestinal and hepatosplenic morbidity associated with S. mansoni infection in Ituri province.

Methods / Principal Findings

In 2017, we conducted a cross-sectional study in 13 villages in Ituri province, DRC. S. mansoni infection was assessed with a Kato-Katz stool test (2 smears) and a point-of-care circulating cathodic antigen (POC-CCA) test in urine. A questionnaire was used to obtain demographic data and information about experienced intestinal morbidity. Each participant underwent an abdominal ultrasonography examination to diagnose hepatosplenic morbidity. Of the 586 study participants, 76.6% tested positive for S. mansoni. Intestinal morbidity, such as abdominal pain (52.7%), diarrhoea (23.4%) and blood in the stool (21.5%) in the previous two weeks, was very frequent. Hepatosplenic morbidity was demonstrated by abnormal liver parenchyma patterns (42.8%), hepatomegaly (26.5%), and splenomegaly (25.3%). Liver pathology (adjusted odds ratio [aOR] 1.20, 95% confidence interval [CI] 1.06–1.37, P=0.005) was positively and significantly associated with S. mansoni infection. Hepatomegaly (aOR 1.52, 95% confidence interval [CI] 0.99–2.32, P=0.053) and splenomegaly (aOR 1.12, 95% CI 0.73–1.72, P=0.619) were positively but not significantly associated with S. mansoni infection at the individual level. At the village level, S. mansoni prevalence was positively associated with the prevalence of hepatomegaly and splenomegaly. Higher S. mansoni infection intensities were associated with diarrhoea, blood in the stool, hepatomegaly, splenomegaly and with liver parenchyma, pathology patterns C, D, E and F. Four study participants were diagnosed with ascites and five reported hematemesis.

Conclusions/Significance

Our study documents a high burden of intestinal and hepatosplenic morbidity associated with S. mansoni infection status in Ituri province. The results call for targeted interventions to address both S. mansoni infection and related morbidity.

Author Summary

Schistosomiasis caused by Schistosoma mansoni is of great public health importance in sub-Saharan Africa. The World Health Organization (WHO) recommends that control efforts aim to reduce morbidity through large scale intervention programmes. However, intestinal and liver morbidity is rarely assessed in such control programmes. Hence, little is known about (i) the magnitude of the intestinal and liver morbidity burden in each community, or about (ii) the morbidity associated with S. mansoni infection, specifically. We conducted a (cross-sectional) study in which we assessed intestinal morbidity by questionnaire and liver morbidity by abdominal ultrasonography. Further, we determined the infection status of the study participants using standard diagnostic procedures (Kato-Katz technique and point-of-care cathodic circulating S. mansoni antigen [POC-CCA] test in urine). Among 586 study participants, six years and older, from 13 villages in Ituri province, DRC, we observed a high degree of intestinal (e.g. 23.4% with diarrhoea, 21.5% with blood in stool) and hepatosplenic morbidity (e.g. 42.8% with abnormal liver patterns C, D, E, and F, 26.5% with enlarged liver, 25.3% with enlarged spleen). S. mansoni infection was associated with liver and spleen enlargement. Likewise, S. mansoni infection intensity was linked to diarrhoea, to liver and spleen enlargement and to pathological changes in the liver parenchyma. At village level, we observed that the prevalence of enlarged liver and spleen among patients increased with the prevalence of S. mansoni infection. We conclude that the population of Ituri province carries an alarming burden of intestinal, liver and spleen morbidity associated with S. mansoni infection. Therefore, a comprehensive control programme to address this infection and disease burden is urgently required.