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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

Map of Malawi showing the geographical distribution of reviewed schistosomiasis studies. The numbers refer to the reference list as follows: red numbers relate to urinary schistosomiasis; blue numbers relate to intestinal schistosomiasis and black numbers relate to both urinary and intestinal schistosomiasis.
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Fig3: Map of Malawi showing the geographical distribution of reviewed schistosomiasis studies. The numbers refer to the reference list as follows: red numbers relate to urinary schistosomiasis; blue numbers relate to intestinal schistosomiasis and black numbers relate to both urinary and intestinal schistosomiasis.

Mentions: The prevalence of schistosomiasis varies according to the distribution of intermediate hosts and schistosome parasites in water bodies and according to the behavioural patterns of humans. In order to determine the distribution of schistosomiasis in Malawi, the reviewed articles were linked to districts where initial research was carried out. From the 89 articles reviewed, 63 (71%) mentioned at least one specific district linked to their field or laboratory work. FigureĀ 3 illustrates how these studies were distributed across Malawi. Mangochi was the most commonly mentioned district, with 40 references; 10 references each related to Lilongwe and Blantyre, 7 references related to Chikhwawa, 6 references related to Zomba, 4 references each related to Karonga, Mchinji, Salima and Mzimba, 3 references each related to Chiradzulu, Chitipa, Dowa, Kasungu, Machinga, Dedza, Balaka, Nsanje and Rumphi, 2 references each related to Mwanza, Phalombe, Thyolo, Mulanje, Ntcheu, Ntchisi and Nkhotakota, and one reference related to Likoma.Figure 3


Schistosomiasis in Malawi: a systematic review.

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

Map of Malawi showing the geographical distribution of reviewed schistosomiasis studies. The numbers refer to the reference list as follows: red numbers relate to urinary schistosomiasis; blue numbers relate to intestinal schistosomiasis and black numbers relate to both urinary and intestinal schistosomiasis.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig3: Map of Malawi showing the geographical distribution of reviewed schistosomiasis studies. The numbers refer to the reference list as follows: red numbers relate to urinary schistosomiasis; blue numbers relate to intestinal schistosomiasis and black numbers relate to both urinary and intestinal schistosomiasis.
Mentions: The prevalence of schistosomiasis varies according to the distribution of intermediate hosts and schistosome parasites in water bodies and according to the behavioural patterns of humans. In order to determine the distribution of schistosomiasis in Malawi, the reviewed articles were linked to districts where initial research was carried out. From the 89 articles reviewed, 63 (71%) mentioned at least one specific district linked to their field or laboratory work. FigureĀ 3 illustrates how these studies were distributed across Malawi. Mangochi was the most commonly mentioned district, with 40 references; 10 references each related to Lilongwe and Blantyre, 7 references related to Chikhwawa, 6 references related to Zomba, 4 references each related to Karonga, Mchinji, Salima and Mzimba, 3 references each related to Chiradzulu, Chitipa, Dowa, Kasungu, Machinga, Dedza, Balaka, Nsanje and Rumphi, 2 references each related to Mwanza, Phalombe, Thyolo, Mulanje, Ntcheu, Ntchisi and Nkhotakota, and one reference related to Likoma.Figure 3

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