WATER AND WATER BORN DISEASES

IN AFRICA AND ASIAIzabella Lecka

Faculty of Geography and Regional Studies University of Warsaw

XVth International Symposium in Medical/Health GeographyMichigan State UniversityJuly 7-12, 2013

In Africa and Asia…. where the highest indicator values in the world in terms of occurrence of the so called tropical disease;

The water engineering projects which are there implemented there serve muliple purposes such as flood control, water storage in man made lakes, ensuring its constant supply, even in dry months and years, development of irrigated agriculture, facilitated navigation as well as recreation and hydropower generation.

Group of diseases connected with implementation of water engineering projects

Short term appearence

Apper in later period

Connected with the construction per se

Linked with water resources by vector of diseases

Diseases

Schistosomiasis haematobium (blader variety) by snails

S. mansoni (intestinal)Malaria by mosquitosFilariasis Bancroft’s and Malayan by mosquitos

Onchocercosis - „river blinness” by Simulium fly

Vectors are linked with water because they are amphibious (like snals) or they spend in the water their larval stage of development (like mosquitos and Simulium gnat)

Ghana

Nigeria

Sierra Leone

Diama Senegal

Bandiagara Mali

Mayo-Danai Kamerun

Egypt

Gezira North Sudan

Kariba Zambia/Zimbabwe

Kisumu Kenia

Bakoloria Nigeria

RESULTS

The relation between the occurance of parasitic diseases of man and the construction as well as functioning of water engineering structures has a very complex nature. The analysis conducted on the bases numerous reports and field works allowed drawing the conclusions:

1

The emergence of water engineering projects is most often conducive to the spread of these parasitic diseases of man, whose appearance is linked with water. Not always, though, this dependence takes place automatically and numerous exceptions are observed.

1

After construction of new dam and artificial lake we can see :

Spread of schistosomiasis (ex. Egypt, Gezira in Sudan, Kisumu in Kenya, Bakoloria and Kainji in Nigeria)

But less frequently the increase of morbidity from malaria (ex. rice field of IADP in Sierra Leone; mayo-Danai in Cameroon)

1

There is now clear proof for a increase of filariasis (Bancroft’s and Malayan) by the emergens of water engineering projects in Africa and Asia (mainly due to a lack of adequate studies).

But actions oriented against malaria often succed in eliminating just the filariasis (ex. Kainji, Nigeria;Akosombo, Ghana;Mahaweli on Sri Lanka)

1

The influence of water engineering projects on the spread of onchocercosis is always distinct around of spillways on dams.

But formation of an artificial lake makes disadvantageus breeding conditions for a Simulium damnosum vector and the disease is eliminated from a vicinity.

Onchocercosis is relatively easily controlled outside of the edemic area in West Africa.

There are no cases of onchocercosis noted in Asia until now.

2

The increased intensity of spreading malaria and filariasis is observed in water engineering projects in South-Asia (Indonesia, Malaysia, Sri Lanka and India).

Such situation in Africa is observed less frequently (ex. Gambia, Burkina Faso, Cameroon, Mauritania)

But in some cases (Akosombo, Kariba) even before construction malaria was a problem for almost 100% local society.

2

Schistosomiasis and onchocercosis are the greatest threat in Africa (endemic areas).

In Asia just in small foci, although in many regions the conditions are perfect.

Most probably because in ex. in Indonesia, Philippines and Malaysia they decided not to built big surface irrigation systems exceed 16 th.

hectares.

3

It is quite exceptional that the parasitic diseases here considered be introduced for a first time into the areas where they have not been noted before. It happen with schistosomiasis in Gezira and Khashm-el Girba in Sudan, Diama in Senegal, Bakoloria in Nigeria, Kariba in Zambia/Zimbabwe or in some places in Ethiopia.

3

The sole confirmed cases concern the renewed appearance of malaria on some areas, which had been already clean of disease.

This phenomenon has been observed even without big engineering programs on such territories.

4

It was only in the case of malaria that we succeeded in demonstrating the relation between the spread of a disease and the type of climate where the engineering project is being realized.

5

The presence of vectors of parasitic diseases does not have to be necessarily linked with the spread of the diseases.

Snails capable of transmitting schistosomiasis or mosquito vectors of malaria or filariasis or Simulium are occupy much bigger area than those disease occur.

6

The realization of the large scale water engineering projects are connected with the risk of appearance of a number of parasitic diseases (Akosombo, Bakoloria, Kariba, Egypt).

Construction of smaller land improvement systems entails an increased hazard of spread of just one disease, ex. schistosomiasis in Malumfashi (Nigeria), Bandiagara (Mali)

7

The negative influence of more recent water engineering projects (constructed from 80. XX ) is definitely smaller than in the case of older ones. Especially in schistosomiasis and malaria cases.

In case of filariasis it seems that the time of construction of project has no essential significance.

8

The modifying influence of tradition and cultural habits is observed in cases of such diseases as schistosomiasis, malaria and two filariasis (Bancroft’s and Malayan).

No such influence was noted with respect to the process of spread of onchocercosis.

8

Hygienic habits play a much lesser role in the spread of parasitic diseases considered than it has been often supposed in the literature.

Hazard related to the hygienic routines are relatively easily removed:

1) By construction of modern latrines;

2) Elimination of simple sinks;3) Construction of modern

sanitary facilities.

8

A significant influence on the spread of parasitic diseases trasmitted by mosquitos is exerted by the nature and state of housing.

Where houses are built with clay and palm leaves, dust and mud floors prevail diseases vector may easily get in touch with humans.

In such conditions it is difficult to carry out chemical actions of elimination of mosquitos.

8

The traditional division of labor in the society exerts an influence on the spread of parasitic diseases over the areas affected by water engineering projects solely in the case of schistosomiasis and malaria on both continents: Africa and Asia.

No such correlation with the trasmission of filariasis and onchocerciasis.

9

Migration are an important factor modifying the dynamic of spread of schistosomiasis and malaria (Africa and Asia) .

Evidence on such influence on spread of filariasis and onchocerciasis is quite limited.

Thank you