Facts About Waterborne/water Related Diseases

Definition 
Water borne diseases are viral, bacterial and parasitic diseases which use water as a common means of transmission. In this module we will discuss those water borne diseases in which the mode of entry of their etiologic agents into a susceptible host is oral...
Epidemiology 
Water borne diseases are major causes of morbidity and mortality world wide.
In Ethiopia, since a large majority of the rural population obtain their water supplies from unprotected sources such as streams, ponds wells, etc, water borne diseases are one of the most significant public health problems.
A person’s health may be affected by ingestion of contaminated water directly or through food. One’s health may also be affected by the use of contaminated water for the purposes of personal hygiene and recreation. The problem is especially acute where general hygiene and environmental sanitation are poor and where there is inadequate supply of safe water.
Developing countries carry a heavy burden of the water borne disease, the heaviest being the diarrheal diseases. Diarrheal episodes occur in all countries, but they are 5 to 6 times more common in developing countries (WHO, 1987a). The total number of diarrheal episodes each year worldwide may be as high as 4000 million (WHO, 1990a) and each year over 3 million deaths may occur due to diarrheal diseases.

• Diarrhoeal diseases are the leading cause of mortality and morbidity of children under five years of age. Estimated occurrence of diarrhea in developing countries accounts for 5 episodes per child each year in children under 5 years of age.  These young children are most at risk of water borne diseases because their immune systems are not fully developed. In addition their resistance may be further impaired by malnutrition.  In 1968 a shigella epidemic in Central America affected half a million people and killed 20,000. In India (West Bengal) some years ago shigella caused morbidity and mortality in 350,000 and 3800 people, respectively. Shigella, still causes endless human suffering in Bangladesh and other Asian, Latin American and African countries. Ethiopia, as a tropical and developing country, is frequently subjected to outbreaks of shigellosis. Outbreaks of shigellosis were recorded in Hararghe in 1978, Omo Region in 1979, Gondar in 1980 and Illubabor in 1981.  Diarrheal disease out breaks account for 30.1% of out patient visits and 27.2% of hospital admissions.
• Typhoid fever this occurs in all parts of the world where water supply and sanitation are sub-standard. It affects 17 million people world wide with more than 600,000 deaths. Almost 80% of these cases and deaths are in developing countries. Among 6 months to 12 year old children admitted to the children’s hospital in Addis Ababa between 1984 and 1996 with typhoid, 25% developed intestinal perforations and 37% of those died. 
• Giardiasis occurrence is world wide affecting more children than adults. According to surveys conducted in Ethiopia, it accounts for a prevalence of between 2 and 11 percent as recorded in some highland communities and nomadic pastoralists. Urban areas like Addis Ababa are equally affected with a prevalence of 9% recorded in some children.  In tropical and subtropical areas of the world, there are an estimated 400 million infections of amebiasis and 30,000 deaths annually. About 80,000 new cases of amebiasis were reported by the Ethiopian Ministry of Health in 1988 – 89, based on out patient reports. The highest prevalence of amebiasis in Ethiopia was found in hospital food handlers in a hospital in Addis Ababa (82%). 
• Dracunculosis (guinea worm infection) occurs in India, Africa and Middle East. About 20 million people are estimated to be victims of guinea worm infection world wide, but the global incidence is declining dramatically. In a single year 1994 – 1995, the incidence decreased 21%.  Active foci of the disease are now found only in Africa south of the Sahara and in Yemen. Ethiopia is listed among the endemic countries for the disease (8, 10). According to the Ethiopian 2002 Dracunculiasis Eradication Program (EDEP) guinea worm endemic areas are Gambella and South Omo. The number of cases reported were 1252 in 1994, but by 2002 the number of cases fell to only 46. 
• Cholera; it affects all age groups. It is more common among children less than 5 years of age and among adults 25 - 39 years old. Worldwide cholera causes 120,000 deaths a year. It is particularly deadly in Africa where epidemics have become more wide spread and more frequent since the 1970s. About 79 million people are estimated to be currently at risk of cholera infection in Africa.  
• Escherichia Coli is a common cause of diarrhea worldwide. In addition, the morbidity of E.Coli diarrhea is notable for its effects on childhood nutrition and development. In regard to poliomyelitis, a total of 150 countries reported zero cases. of poliomyelitis, 30 countries reported greater than ten cases, 27 countries from one to ten cases and 7 countries failed to report. [Editorial note: state the year this was reported] WHO estimated that approximately 80,000 cases of paralytic polio occurred in 1995. In 1996, 20,000 cases and about 7000 deaths were reported... Polio virus is still circulating widely in three specific areas: • Large densely populated areas such as Bangladish, India, Nepal, Pakistan, South Asia. • The Democratic Republic of Congo and Niger (Central and West Africa). • Ethiopia, Somalia and Sudan (Horn of Africa)
• Enteroviruses this have a worldwide distribution. They are most common in tropical climates and socio- economically disadvantaged areas, especially where there is poor hygiene and over-crowding. Rota virus occurs worldwide during infancy. It is most common in socioeconomically disadvantaged areas, especially in areas with poor hygiene and over-crowding as well as areas with tropical climates. It is the single most important cause of severe dehydrating diarrhea in infants and young children under the age of 3 in both developed and less developed countries. It accounts for 30 to 50% of all cases of diarrhea requiring hospitalization and intensive rehydration therapy.  
• Hepatitis A; is a viral disease transmitted via contaminated water or food. There is a high proportion of asymptomatic cases of Hepatitis A. Thus, it is difficult to estimate the incidence of Hepatitis A. According to WHO, about 10-50 persons per 100,000 are affected annually. It occurs as epidemic world wide with a tendency of cyclic recurrences. Hepatitis A infection is also common in Ethiopia. Infection is acquired early in childhood. Seropositivrty in regions surveyed was 34% at one year, 98% at 10 years and universal at about 15 years of age.
• The first case of Hepatitis E virus (HEV) was reported in Ethiopia in 1985. In 1988-1989 a water borne outbreak was detected in a military camp where 93% of icteric hospitalized patients were infected with HEV. Its case fatility rate is higher in pregnant women (23%) than in the general population (11%).(28).