Schistosomiasis: a water based disease By Mbaember J. David Wuam PUBH 6165-09  

Welcome The Director-General, Dr LEE Jong-Wook, of the World Health Organization stated, “Water and Sanitation is one of the primary drivers of public health. I often refer to it as “Health 101”, which means that once we can secure access to clean water and to adequate sanitation facilities for all people, irrespective of the difference in living conditions, a huge battle against all kinds of disease will be won” ( WHO Facts & figures, 2004). The Director-General, Dr LEE Jong-Wook ( WHO Facts & figures, 2004). This statement expresses how significant water is and its influence on health. Water is basically a determinant of health; it is the one natural resource that every nation relies on for disease prevention. Nations who have improved water supply and sanitation tend to have reduced incidences of morbidity or mortality. One of those diseases would be the prevention and control of schistosomiasis: a water contact disease. The parasitic disease is a public health problem that should be given priority at the international, national, local levels.

Prevalence of Schistosomiasis According to the world health organization, it is estimated that the morbidity and mortality from schistosomiasis vary a great deal. About 779 million people of which, 10% of the world’s population were in the mid-2003 at risk of being infected with schistosomiasis. An estimated 200 million people in the tropical and subtropical zones are infected with the parasite, but a recent estimate has the number at 207 by 2003. 120 million infected people are symptomatic while 20 million will develop severe disease. It is endemic in 76 countries. Active transmission is reported in 67 countries. Of these, 46 are in Africa. Of all cases more than half are in Nigeria, according to The Carter Center, Nigeria is the most endemic country in Africa. It is estimated that about 22 million Nigerians are infected of these parasites, 16 million are children (The Carter Center).

Types of Schistosomiasis Schistosoma mansoni, ( located in the intestinal tract of human host) and region most found are in Arabian Peninsula, Africa, Caribbean, and South America; Schistosoma haematobium, ( located in the genitourinary tract of human host) and region most found are in the Middle East, and Africa; Schistosoma Japonicum, ( located in the intestinal tract of human host) and region most found are in Japan, China, and the Philippines ( has a range of mammals as definitive host); Schistosoma mekongi, (located in intestinal tract of human host) region most found are West and Central Africa. Schistosoma intercalatum,( located in intestinal tract of human host) West and central Africa There are five different species of schistosomiasis and they are distributed according to specific geographic region.

Geographic distribution This is a map of the CDC showing as schistosomiasis prevalence increased in Sub-Saharan Africa. This is due to water resource projects such as dams and population movements. The shaded areas have eradicated the disease or the risk is minimal (CDC).

The life cycle of a blood fluke Image from: The University of Cape Town; Immunology Institute of Infectious Disease and Molecular Medicinehttp://www.iidmm.uct.ac.za/fbrombacher/images/schistosomiasis1.jpg The adult flukes (1-2 cm in length) inhabit the venous system of the mesentery or urinary bladder; here sexual reproduction takes place in the eggs that are excreted in the faces or urine in the case of urinary schistosomiasis; the eggs then hatch in fresh water releasing ciliated motile miracidia, which eventually penetrate the body of the snail that serves as the intermediate host ( specific to the geographic location); in the snail, the miracidia the multiplies asexually producing hundreds of fork tailed cercariae in about 4-6 weeks; the cercariae then penetrates human skin losing their tail, and becoming schistosomulae that will migrate into the lungs and liver where they mature; and in approximately 6 weeks, the adult fluke migrates to its final habitat in the venous system. The adult life span of a fluke is estimated to be about 5- 10 years in a human ( Wilson et al, 2001,p. 872)

Why should we care? First discovered by Dr. Theodor Bilharz in 1851 Also known as bilharz after the Dr. who discovered this disease It occurs in more than 200 million people world wide. Affects 22 million Nigerians. Of which 16 million are children( Cater foundation) http://www.cartercenter.org/news/documents/features/schistotx.html Schistosomiasis or blood fluke is a water contact disease. Each geographic distribution is specific to the presence of a specific snail intermediated host. Currently in Nigeria these are the most common: schistoma haematonium known to cause urinary schistomiasis, and schistosoma mansoni known to cause intestinal schistosomiasis are found in Nigeria

Who is affected? Carter center photo By: E. Staub Aside from the consequences of socioeconomic status, children infected with schistosomiasis are known to have poor growth, school age children experience impaired cognitive function, anemia, weakens the immune system, premature deaths and in adults bladder dysfunction that is known to have increase risk for bladder cancer.

Progression of the disease At the acute stage of infection individuals are invaded as the parasite penetrates the skin, and then migrates to within the circulatory system to where it matures to induce acute schistosomiasis. Urinary schistosomiasis induces fever, dysuria and haematouria (blood in the urine). Intestinal schistosomiasis it may induce fever and abdominal pain, bloody diarrhea and tender hepatosplenomegaly (enlarged liver & spleen). Aside from the symptoms the individual experiences, most of these reactions are dues to the host’s immune reaction to the eggs within the tissues. Because instead of passing through the host’s body, the eggs trigger an immune response which in turn causes the following pathologic symptoms: splenomegaly (enlarged spleen), hepatomegaly (enlarged liver). In the case of urinart schistosomiasi both acute and chronic stages the individual will experience dyuria and haematouria and finally calcification of the bladder wall, bladder stones, bladder carcinoma, hydronephrosis and renal failure may occur. Intestinal schistosomiasis may cause portal hypertention ( Bruun & Aagaard-Hansen, WHO,2008).

Progression of the disease cont' Carter center photo By: E. Staub http://ww w.cartercenter.org/resources/images/schistofebjs.jpg The individuals at risk are children who swim in infected fresh water or walk around parasitic snail infested areas with out shoes. And after being infected, if the parasite is residing in the urinary bladder then the symptoms will be Urinary schistosomiasis which induces fever, dysuria and haematouria (blood in the urine as seen here with some Nigerian children). Others at risk are women fetching water from the streams or rivers, also washing cloths in the streams or rivers and rice farm workers are all at risk or herding animals. This disease also further places young children at risk for other diseases such as malaria & TB.

Snail intermidiate Biomphalaria sp., the intermediate host for S. mansoni From:http://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/Schistosomiasis_il.htm This is one of the snail intermediates schistosoma mansoni known to reside in the intestinal of the host.

Snail intermidiate Bulinus sp., the intermediate host for S. haematobium and S. intercalatum. From:http://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/Schistosomiasis_il.htm This the second type of snail intermediate found in most of Nigeria, schistoma haematonium also known reside in the genitourinary to cause urinary schistosomiasis found in Nigeria.

How is it Diagnosed Urine and stool samples can used to make the diagnosis of Schistosomiasis. CDC schistosomiasis facts: from http://www.dhpe.org/infect/schisto.html According to the CDC, schistosomiasis can be diagnosed using sample from the infected individuals’ urine or stool. Currently there is a blood test that has been developed and is available through the CDC and can be made available through the organization, for the results to be accurate an individual will need to be tested with 6-8 weeks after they were exposed to contaminated water (CDC, 2009).

Treatment and prevention Praziquantal cost about $0.20 Carter center photo By: E. Staub According to WHO praziquantel is the drug of choice. It is effective for all forms of schistosomiasis infection and it is give according to body weight orally once a year. It cost about $0.20- $0.30 per average dose. Since 1999 the carter center has been working in Nigeria and has been able to provide about 800,000 treatment in three different states. Along with treatment, the carter center also provides health education to the people.

Treatment and prevention cont' Along with the Carter center, the Nigerian government is still only able to buy a fraction of the needed medication. Health Education of the general public with regards to the seriousness of this disease is also a measure that will help in reducing as well as minimizing the disease in the community. Other measures that can be taken would community involvement in awareness. The populations needs to be educated on better ways to dispose of fecal matter, and water treatment.

Treatment & prevention cont’ Control community contamination of rivers or streams with fecal matter be educations, providing latrines. No swimming in infected water Control snails by scooping According to the CDC & Wilson et al (2009,2005) the only effective measure of prevention is avoiding contact with fresh water in endemic areas.

Treatment & prevention cont’ Sanitation of the environment Control of community infections Education of individual in principles of personal hygiene Organization of medical and nursing services for the early diagnosis and preventive treatment of disease Development of social machinery that will ensure to every individual in the community a standard of living adequate for the maintenance of health. Schneider, M. J. (2006). Introduction to public health (2nd ed.). Sudbury, MA: Jones and Bartlett. As evidenced by Schneider (2006). The re-infection of this parasite is always possible but by taking preventive measure such as these would either minimize or eradicate the parasite all together.

Potential reduction for Schistosomiasis as a result of Improvements in water supply and sanitation   Will Increase quality and years of a healthy life Eliminate or minimize health disparities brought on by this parasite. School age children are said to be more alert in school and there is noticeable growth increase. Schneider, M. J. (2006). Introduction to public health (2nd ed.). Sudbury, MA: Jones and Bartlett. Shouldn’t a comfortable life, free of disease be the right of every human child?

Conclusion Schistosomiasis is one of many diseases of the developing nations that has been significantly ignored. It is a public health problem that affects people with limited access to healthcare and In information. There is a medication that is affordable and has been used successfully to treat this disease and should be given priority at the international, national and local levels. - Thank you all for your attention. I hope this was informative for some of you and at the same time , that those who can help would join the carter foundation currently working in Nigeria to help treat those infected and also educate people on sanitary measures. Schistosomiasis can not be eradicated but it can be treated and controlled.

References Brunn, B., Aagaard-Hansen,J.(2008) The social Context of Schistosomiasis and its control: An introduction and bibliography. World Health Organization on behalf of the Special Programme for Research and Training in Tropical Diseases. Schneider, M. J. (2006). Introduction to public health (2nd ed.). Sudbury, MA: Jones and Bartlett. Wilson et al (2001) Current Diagnosis & treatment in infectious diseases, Lange: McGraw-Hill World Health Organization: Water, sanitation and hygiene links to health Fact & figures update 2004. From http://www.who.int/water_sanitation_health/publications/facts2004/en/print/html World Health Organization: Division of Control of Tropical Diseases (2007) From http://www.microbiologybyes.com/introduction/Schisto.html Image references Center for disease control: dvision of parasitic disease http://www.dpd.cdc.gov/dpdx/HTML/ImageLibrary/Schistosomiasis_il.htm Carter center photo By: E. Staub  http://www.cartercenter.org/news/documents/features/schistotx.html Image from: The University of Cape Town; Immunology Institute of Infectious Disease and Molecular Medicinehttp://www.iidmm.uct.ac.za/fbrombacher/images/schistosomiasis1.jpg I want to thank the general public, public health professionals, all the target audiences and anyone who simply has an interest in public health for reading these slides. Please feel free to leave a comments or any questions below.