8.3.1 Waterborne diseases
On average, every child in Ethiopia has diarrhoea five times before the age of five. What could be the cause of these illnesses in children? What other factors might have been involved in transmitting these illnesses?
Ingesting contaminated water and food is the cause of diarrhoea. Poor hand hygiene is also a significant factor in its transmission.
Diarrhoea (frequent loose stools) is a symptom of many waterborne diseases. They are caused by biological pollution from human bodily wastes from infected people. Faecal matter contains pathogenic organisms that cause waterborne diseases, mainly diarrhoeal diseases and parasitic worm infections. Some examples of diarrhoeal and other waterborne diseases and their causes are shown in Table 8.1.
| Group | Disease | Causative agent |
| Bacteria | typhoid fever | Salmonella |
| cholera | Vibrio cholerae | |
| Viruses | viral gastroenteritis | rotavirus and others |
| poliomyelitis | polio virus | |
| viral hepatitis | hepatitis A and E virus | |
| Protozoa | cryptosporidiosis | Cryptosporidium |
| giardiasis | Giardia | |
| Parasitic worms | ascariasis | Ascaris lumbricoides |
| schistosomiasis or bilharzia | Schistosoma |
With one exception, all the diseases in Table 8.1 are caused by people ingesting pathogens by drinking or eating contaminated water or food, or they result from poor hand hygiene. This is faecal–oral transmission which means people are infected with disease when pathogens from faeces enter their body through the mouth. The exception is schistosomiasis, which is caused by worms penetrating the skin when people are swimming or washing in water that has been contaminated with excreta from an infected person.
8.3 Effects of pollution on human health