Schistosomiasis in Eastern Democratic Republic of the Congo: A major neglected healthcare concern

Nigo, Maurice Mutro. Schistosomiasis in Eastern Democratic Republic of the Congo: A major neglected healthcare concern. 2020, Doctoral Thesis, University of Basel, Faculty of Medicine.


Official URL: https://edoc.unibas.ch/78840/

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Among the neglected tropical diseases (NTDs), schistosomiasis remains a major public health issue in sub-Saharan Africa (SSA). Schistosomiasis is a blood fluke parasitic infection, caused by several species of trematodes of the genus Schistosoma. In sub-Saharan Africa, urinary schistosomiasis is caused by S. haematobium, whereas intestinal schistosomiasis is caused by S. mansoni. It is transmitted during contact with water contacts while fishing, washing, bathing or swimming. The infective larvae released by the freshwater snail as the intermediate host, penetrate through the skin, which are then transported by the blood, and become adults in the targeted blood vessels. Adult parasites lay eggs in the blood vessels, some of which are trapped in the tissues and are the root of the pathology. Recurrent and massive infections can primarily affect the liver and cause various chronic signs and symptoms. The resulting morbidity can be significant. Symptoms of schistosome infection vary from simple skin rashes to severe blood vomiting. Chronic schistosomiasis happens when diagnosis has not been performed quickly enough during disease progression. However, a large proportion of the infected population has no symptoms, and therefore a significant number of individuals may never be evaluated for infection burden, and so remains as a reservoir of the parasites and indirect infection source to others.
The current diagnosis is mainly based on clinical symptoms, which results in missing the identification of low level and asymptomatic/atypical or chronic infections. Undetected and untreated infections may be responsible for persistence of transmission. Rapid and accurate diagnosis is the key for treatment and control. Various diagnostic procedures are available; validated and include immunologic methods, direct parasitological techniques and molecular approaches. So far, parasitological detection methods remain the cornerstone of schistosoma infection diagnosis in endemic regions but conventional tests have limited sensitivity, in particular in low-grade infection. Recent advances contribute to improved detection in clinical and in field settings. The recent progress in micro- and nano- technologies opens a road by enabling the design of new miniaturized point-of-care devices and analytical platforms, which can be used for rapid detection of these infections. There is still a need for new diagnostic tests at the point-of-care (POC) in the endemic areas of low-income countries which would enable effective treatment and disease management.
In 2001, the World Health Assembly (WHA) resolution WHA 54.19 recommended the reduction of morbidity due to schistosomiasis. Since then, number of control programs in many countries have been established and started to treat more than 75% of school-age children in the endemic areas. Although these programs had obtained mixed successes, several countries in the region have implemented the recommendations of the resolution. Meanwhile, the Democratic Republic of Congo (DRC), one of the most affected countries, entangled in endless multiform conflicts and permanent instability, could not implement a viable control program to address schistosomiasis issue. In eastern DR Congo for the first time since decades, explored morbidity, examined demographic, geographic and socioeconomic factors, including 3 153 patients in 59 villages in an area of 65 658 km². Schistosomiasis prevalence was up to 90%, particularly in children, corresponding to millions of undiagnosed and untreated cases in this region alone, spreading far beyond historic hotspots. Predisposing factors included poverty, lack of good sanitation, limited access to clean water, vegetation characteristics, water contact activities, lack of knowledge on disease transmission and prevention. Significant morbidity was found. Profound poverty was contrasted with the richness in minerals exploited; proximity to mining sites was not associated with reduced poverty or reduced disease prevalence. Infrastructure was severely damaged and security was fragile. Past, national healthcare efforts had left little trace, and current Ebola containment activities nearby drain personnel away from basic healthcare.
In the DRC, the burden of NTDs in general, thus that of schistosomiasis, particularly, remains unknown. There is huge lack of surveys and publications. Most publications date from colonial time. For Ituri province, the most recent publication on schistosomiasis is from 1954. Despite these challenges, DRC started integrated control programs of NTDs including schistosomiasis in 2012, but the implementation did not take place until 2016 in Ituri province.
The main goal of this thesis is to enhance our understanding of the geographical distribution of intestinal schistosomiasis and the environmental, geographical, socioeconomic, and behavioural factors that underlie its transmission and its spread across Ituri province. This knowledge base will advocate for and facilitate the establishment of an effective and sustainable large-scale control and surveillance program for schistosomiasis in the Ituri province.
In this thesis, we have pursued five specific objectives. First, review of the current diagnostic tools available for endemic settings. Second, present the underlying context for the transmission and spread of intestinal schistosomiasis in the Ituri province, DRC. Third, assessthe distribution
of S. mansoni infection prevalence and intensity, and determine the main risk factors in the the province. Fourth, assess the associated intestinal and hepatosplenic morbidity. Fifth, describe some severe cases linked with S. mansoni infection. For this purpose, three different surveys were carried out, namely (i) a pilot survey among 435 schoolchildren from 7 primary schools for the appraisal of the situation ; (ii) a large community-based survey within 51 villages across the province with 2,131 participants of 1 year and older, both female and male ; and (iii) an in-depth and rigorous household-based survey within 13 villages and with 1,022 participants of 1 year and older, both female and male.
The field investigation activities related to this thesis were conducted in three field campaigns in Ituri province, eastern Democratic Republic of Congo. We first carried out in 2015, a cross-sectional pilot survey involving 435 schoolchildren in seven primary schools in three health districts across the province, in order to analyse the situation. Only one stool sample was requested and examined in accordance to the Kato-Katz (KK) technique. Demographic and anthropometric (weight and height) data were collected and completed in an appropriate form.
Based on the results and needs identified in 2015, we then conducted in 2016 a large, systematic, cross-sectional survey which covered 2,131 participants from 51 villages across the province. This survey aimed to assess the prevalence and intensity of infection within the different categories of the population aged 1 year or older. Once again, weight, height, and demographics were collected and only one stool sample was requested and obtained per participant and examined using KK technique. In addition, an abdominal ultrasound was performed on a limited number of participants. This field campaign resulted in a comprehensive map of schistosomiasis prevalence but also highlighted the need for improved diagnostic tools and in-depth understanding of morbidity.
To address this need, in 2017, we conducted a rigorous in-depth, cross-sectional survey among 1,022 individuals from 145 households in 13 randomly selected villages from the areas where the prevalence was found to be relatively high during the previous surveys. Household characteristics were collected. Household heads or representatives responded to an in-depth household questionnaire about house building material, household income, livestock, objects, access to water, sanitation, presence and quality of latrine, use of the latrine. Each participant responded to an individual questionnaire concerning matrimonial status, occupation, education, religion, drinking water, hand wash, body hygiene, hygiene care of clothes, where they are washing their clothes, where they are bathing, farming, fishing activities, owning shoes, wearing shoes habits, consumption of alcohol, smoking, length of stay in the village, knowledge of schistosomiasis, its transmission, its prevention, and its treatment, and what they think about the importance of schistosomiasis, whether it is a problem, and the overall attitudes towards it. Only permanent members of the household participated. Parents or household heads responded to some difficult questions of the behalf of their children under six years old. After this, every participant was weighed and its height measured. Participants were asked to provide one stool sample per day for five days in row. On the last day, a urine sample was requested from 75% of participants who had provided at least one stool sample in the period. All stool specimens were examined by the KK technique and the urine was tested by point-of-care circulating cathodic antigen (POC-CCA) test. Approximately, 85% of participants underwent clinical examinations, including abdominal palpation for large liver and large spleen research, observation of conjunctival staining for anaemia, and observation of the skin for rash and scabies, and abdominal percussion to detect ascites. Body temperature was measured in the very few participants who reported current perception of fever. Most participants who underwent clinical examinations also had abdominal ultrasound exams to estimate liver and spleen size, to detect both portal hypertension and fibrosis, to assess gallbladder size, thickness and contents, to detect and classify the types of ascites, and to look for any anomaly of the digestive organs.
All participants through the three successive surveys received 500 mg of mebendazole for general deworming. All individuals found positive for schistosomiasis by either the KK technique or the POC-CCA alone or combined received 60 mg/kg of praziquantel for treatment of the detected schistosoma infection.
In pursuit of the five objectives mentioned above, we structured our results as follows:
1 We provided an update of current relevant achievements in the field of schistosomiasis diagnosis.
2 We documented the challenging context of this disease, specifically wars and ongoing armed conflict, poverty and rush for precious minerals, also involving significant population displacements, that largely promoted the transmission and spread of schistosomiasis in previously unaffected areas of schistosomiasis in the Ituri province and prohibited efforts to detect or control disease. Today, the entire province of Ituri is plagued by the spread of the disease.
3 We described the distribution of S. mansoni infection and intensity among socio-demographic and geographic categories. The prevalence is high in the province: in some villages, it reaches 90% or more of those tested, highlighting the existence of relevant undiagnosed disease in a large segment of the population. The prevalence curve by age and sex is typical of high endemic areas where control programs are not yet implemented. The intensity of S. mansoni infection is immense. We identified that the main risk factors for schistosomiasis were poverty, the lack of latrine, of adequate sanitation, and of safe water; the surrounding environment that could favour the multiplication fresh-water intermediate host snails, activities in contact with the water such as fishing, washing clothing, dishwashing, farming and also the lack of knowledge about transmission and prevention of schistosomiasis. Other intestinal parasites including roundworms, hookworms, whipworm, tapeworms, and even some cases of S. intercalatum infection have also been diagnosed.
4 We provided for the first time since colonial time a comprehensive baseline data showing a high intestinal and hepatosplenic morbidity burden in Ituri province; a burden that is associated with S. mansoni infection at both the individual and community level.
5 We reported 8 severe cases from four villages with a very high S. mansoni prevalence up to 87.1%. Fifty-six percent of the population was underweight. Intestinal and hepatosplenic morbidity were highly frequent.
In conclusion, schistosomiasis is a major health issue in Ituri province. Prevalence and intensity of infection, and morbidity are high. Several factors including poverty, lack of both latrine, good sanitation, safe water, and education promotes the transmission and spread of schistosomiasis across the province. New diagnostic tools are urgently required to improve diagnosis, case management, mapping, development of control strategies, and monitoring of control programs.
These findings call for concerted efforts in implementation of effective control interventions that may quickly reach the most disadvantaged segments of population in the Ituri province. These interventions should include education of population, improved access to safe water, sanitation and hygiene facilities as well as snail control. The results of these investigations may contribute to the planning of efficient and sustainable control programs, based on revised strategies and can be used by decision-makers in the province of Ituri, eastern Democratic Republic of Congo.
Advisors:Hunziker, Patrick R. and Battegay, Manuel E. and Odermatt, Peter
Faculties and Departments:03 Faculty of Medicine > Departement Biomedizin > Associated Research Groups > Nanomedicine Research Group (Hunziker)
UniBasel Contributors:Hunziker, Patrick R. and Battegay, Manuel E. and Odermatt, Peter
Item Type:Thesis
Thesis Subtype:Doctoral Thesis
Thesis no:14074
Thesis status:Complete
Number of Pages:XVI, 252
Identification Number:
  • urn: urn:nbn:ch:bel-bau-diss140744
edoc DOI:
Last Modified:16 Apr 2021 04:30
Deposited On:15 Apr 2021 07:10

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