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Schistosomiasis in Malawi: a systematic review.

Makaula P, Sadalaki JR, Muula AS, Kayuni S, Jemu S, Bloch P - Parasit Vectors (2014)

Bottom Line: The main intermediate host species are Bulinus globosus and Bulinus nyassanus for urinary schistosomiasis and Biomphalaria pfeifferi for intestinal schistosomiasis.Seasonality of transmission tends to vary according to geographical, environmental, biological and behavioural factors.Functional infection risk assessment systems based on systematic investigations and surveillance are required for developing informed prevention and control strategies.

View Article: PubMed Central - PubMed

Affiliation: Research for Health Environment and Development, P.O. Box 345, Mangochi, Malawi. petmakau@yahoo.co.uk.

ABSTRACT

Introduction: Schistosomiasis remains an important public health problem that undermines social and economic development in tropical regions of the world, mainly Sub-Saharan Africa. We are not aware of any systematic review of the literature of the epidemiology and transmission of schistosomiasis in Malawi since 1985. Therefore, we reviewed the current state of knowledge of schistosomiasis epidemiology and transmission in this country and identified knowledge gaps and relevant areas for future research and research governance.

Methods: We conducted computer-aided literature searches of Medline, SCOPUS and Google Scholar using the keywords: "schistosomiasis", "Bilharzia", "Bulinus" and "Biomphalaria" in combination with "Malawi". These searches were supplemented by iterative reviews of reference lists for relevant publications in peer reviewed international scientific journals or other media. The recovered documents were reviewed for their year of publication, location of field or laboratory work, authorship characteristics, ethics review, funding sources as well as their findings regarding parasite and intermediate host species, environmental aspects, geographical distribution, seasonality of transmission, and infection prevalence and intensities.

Review: A total of 89 documents satisfied the inclusion criteria and were reviewed. Of these, 76 were published in international scientific journals, 68 were peer reviewed and 54 were original research studies. Most of the documents addressed urinary schistosomiasis and about two thirds of them dealt with the definitive host. Few documents addressed the parasites and the intermediate hosts. While urinary schistosomiasis occurs in most parts of Malawi, intestinal schistosomiasis mainly occurs in the central and southern highlands, Likoma Island and Lower Shire. Studies in selected communities estimated prevalence rates of up to 94.9% for Schistosoma haematobium and up to 67.0% for Schistosoma mansoni with considerable geographical variation. The main intermediate host species are Bulinus globosus and Bulinus nyassanus for urinary schistosomiasis and Biomphalaria pfeifferi for intestinal schistosomiasis. Seasonality of transmission tends to vary according to geographical, environmental, biological and behavioural factors.

Conclusion: Transmission of schistosomiasis in Malawi appears to be highly focal, with considerable variation in space and time. Many locations have not been covered by epidemiological investigations and, thus, information on the transmission of schistosomiasis in Malawi remains fragmented. Functional infection risk assessment systems based on systematic investigations and surveillance are required for developing informed prevention and control strategies.

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Related in: MedlinePlus

Decision tree showing the number of included and excluded documents identified from online literature searches. *Mixed = any document focusing on combination of (i) human, intermediate host and parasite; (ii) human and intermediate host; (iii) human and parasite or (iv) intermediate host and parasite.
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Fig1: Decision tree showing the number of included and excluded documents identified from online literature searches. *Mixed = any document focusing on combination of (i) human, intermediate host and parasite; (ii) human and intermediate host; (iii) human and parasite or (iv) intermediate host and parasite.

Mentions: As a third step, the documents were categorized into three groups according to the forms of schistosomiasis addressed (i.e. urinary schistosomiasis, intestinal schistosomiasis or a combination of the two). Each of these groups were further divided into four sub-groups according to the main focus of the study, namely: a) the definitive human host of the parasites, b) the intermediate host species of the parasites, c) the causative parasite species of the disease, e.g. studies that involved techniques for the detection of parasites in samples or specimens, or d) a mixture, i.e. any combination of two or all of the first focus areas of human, intermediate host and parasite. The decision tree for the inclusion or exclusion of documents and how they were assigned into these groups and sub-groups is shown in FigureĀ 1.Figure 1


Schistosomiasis in Malawi: a systematic review.

Makaula P, Sadalaki JR, Muula AS, Kayuni S, Jemu S, Bloch P - Parasit Vectors (2014)

Decision tree showing the number of included and excluded documents identified from online literature searches. *Mixed = any document focusing on combination of (i) human, intermediate host and parasite; (ii) human and intermediate host; (iii) human and parasite or (iv) intermediate host and parasite.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4288699&req=5

Fig1: Decision tree showing the number of included and excluded documents identified from online literature searches. *Mixed = any document focusing on combination of (i) human, intermediate host and parasite; (ii) human and intermediate host; (iii) human and parasite or (iv) intermediate host and parasite.
Mentions: As a third step, the documents were categorized into three groups according to the forms of schistosomiasis addressed (i.e. urinary schistosomiasis, intestinal schistosomiasis or a combination of the two). Each of these groups were further divided into four sub-groups according to the main focus of the study, namely: a) the definitive human host of the parasites, b) the intermediate host species of the parasites, c) the causative parasite species of the disease, e.g. studies that involved techniques for the detection of parasites in samples or specimens, or d) a mixture, i.e. any combination of two or all of the first focus areas of human, intermediate host and parasite. The decision tree for the inclusion or exclusion of documents and how they were assigned into these groups and sub-groups is shown in FigureĀ 1.Figure 1

Bottom Line: The main intermediate host species are Bulinus globosus and Bulinus nyassanus for urinary schistosomiasis and Biomphalaria pfeifferi for intestinal schistosomiasis.Seasonality of transmission tends to vary according to geographical, environmental, biological and behavioural factors.Functional infection risk assessment systems based on systematic investigations and surveillance are required for developing informed prevention and control strategies.

View Article: PubMed Central - PubMed

Affiliation: Research for Health Environment and Development, P.O. Box 345, Mangochi, Malawi. petmakau@yahoo.co.uk.

ABSTRACT

Introduction: Schistosomiasis remains an important public health problem that undermines social and economic development in tropical regions of the world, mainly Sub-Saharan Africa. We are not aware of any systematic review of the literature of the epidemiology and transmission of schistosomiasis in Malawi since 1985. Therefore, we reviewed the current state of knowledge of schistosomiasis epidemiology and transmission in this country and identified knowledge gaps and relevant areas for future research and research governance.

Methods: We conducted computer-aided literature searches of Medline, SCOPUS and Google Scholar using the keywords: "schistosomiasis", "Bilharzia", "Bulinus" and "Biomphalaria" in combination with "Malawi". These searches were supplemented by iterative reviews of reference lists for relevant publications in peer reviewed international scientific journals or other media. The recovered documents were reviewed for their year of publication, location of field or laboratory work, authorship characteristics, ethics review, funding sources as well as their findings regarding parasite and intermediate host species, environmental aspects, geographical distribution, seasonality of transmission, and infection prevalence and intensities.

Review: A total of 89 documents satisfied the inclusion criteria and were reviewed. Of these, 76 were published in international scientific journals, 68 were peer reviewed and 54 were original research studies. Most of the documents addressed urinary schistosomiasis and about two thirds of them dealt with the definitive host. Few documents addressed the parasites and the intermediate hosts. While urinary schistosomiasis occurs in most parts of Malawi, intestinal schistosomiasis mainly occurs in the central and southern highlands, Likoma Island and Lower Shire. Studies in selected communities estimated prevalence rates of up to 94.9% for Schistosoma haematobium and up to 67.0% for Schistosoma mansoni with considerable geographical variation. The main intermediate host species are Bulinus globosus and Bulinus nyassanus for urinary schistosomiasis and Biomphalaria pfeifferi for intestinal schistosomiasis. Seasonality of transmission tends to vary according to geographical, environmental, biological and behavioural factors.

Conclusion: Transmission of schistosomiasis in Malawi appears to be highly focal, with considerable variation in space and time. Many locations have not been covered by epidemiological investigations and, thus, information on the transmission of schistosomiasis in Malawi remains fragmented. Functional infection risk assessment systems based on systematic investigations and surveillance are required for developing informed prevention and control strategies.

Show MeSH
Related in: MedlinePlus