January 2008 Updates Formatted to match other PowerPoint presentations. Altered definition of epidemiology slightly (incidence became determinants) Added slide 11 – childhood mortality differences by region Added more detailed notes to slides Added and changed pictures Rearranged order of slides - disease and pathogen classifications at beginning

Epidemiology & Microbiology

Presentation Outline Disease and pathogen Classifications Impacts of water and sanitation related diseases Water borne diseases Water washed diseases Water based diseases Water insect vector diseases

Epidemiology & Microbiology Epidemiology: the study of the determinants and distribution of diseases and of their control and prevention Microbiology: the study of microscopic organisms

Types of Water-Related Diseases 1.Water Borne: infections acquired by the ingestion of contaminated water 2.Water Washed: infections acquired due to insufficient water for bathing and hygiene 3.Water Based: infections transmitted by pathogens which have part of their life cycle in aquatic animals (snails, larvae, etc.) 4.Water Insect Vector: infections transmitted by vectors which live, breed or bite near water (often mosquitoes)

Disease Transmission Can be more useful to know the manner of transmission than the actual disease agent. Reservoir – serves as a continuing source of disease Host – target of an infectious agent/pathogen Vector – living organism that transmits disease Vehicle – inanimate object that transmits disease

Persons Animals Reservoir Water & Soil Vectors Direct Vehicles Transmission Persons Host Animals

Types of Pathogens 1.Viruses: (0.02 – 0.2 microns) smallest, most complex – requires a host cell to replicate 2.Bacteria: ( microns), most prevalent micro-organism 3.Protozoa: ( microns), may be able to form cysts that can stay alive without hosts and in harsh environments 4.Helminths: (40 – 100 microns), w orms & parasites which derive sustenance at the host’s expense

Size Comparison Virus (0.02 to 0.2 micron) Helminth 40 to 100 microns Pore size in a sand filter (1 micron) Smallest Largest Virus Bacteria Protozoa Helminth Bacteria (0.2 to 5 microns)

Viruses Many viruses cause disease in humans Viruses depend on the host cells that they infect to replicate When stimulated, new viruses are formed, and burst out of the host cell, killing it and going on to infect other cells Some viruses can remain viable outside of a host for long periods, also in dry conditions Viruses can survive but will not grow in food Source: Gems and Diseases, IFH, 2005 Hepatitis A Ebola

Bacteria Most dominant organism found in faeces Most diverse group of micro-organisms Simplest, wholly contained life system Abundant in faeces (1g = billions of bacteria) Most common pathogenic types are: cholera, salmonella, E. coli Cholera

Bacteria Total Coliforms – includes all bacteria in water Thermo-tolerant (Fecal Coliforms) – in intestines of mammals E. coli Heterotrophic Bacteria- Includes all bacteria in nature

Coliforms – E.Coli Healthy to have coliforms in intestines. Reproduce very quickly in our intestines. Each person discharges from 100 to 400 billion coliforms/day. Coliform bacteria are very numerous and easier to detect than pathogenic (disease-causing) micro organisms. Important in water testing - simple means to detect presence The presence of coliforms in water is used to indicate water contamination with human or animal waste. One in every thousand bacteria in adult intestines is E. coli.

Protozoa Single celled organisms Larger than bacteria and viruses Able to form cysts which are resistant to chlorine Some can stay alive outside of a host

Helminths Multi-cellular organisms Larger than bacteria, viruses and protozoa Can live for many years in the body Most do not multiply within the human host Derives sustenance at hosts expense Most helminths are passed in faeces Worm from a human intestine (20 feet in length)

Leading Causes of Death from Infectious Diseases

Childhood Mortality by Cause

Childhood Mortality by Region & Cause

Public Health Impact High morbidity and mortality Vicious cycle of poverty, disease, lowered potential for human development, poverty, disease,…and so on. Potential for large and explosive epidemics which can create panic in the affected community and beyond Increasingly difficult treatment of some diseases due to drug resistance, or no specific treatment available (super bugs)

Major Water Related Diseases Diarrhoeal Diseases Trachoma Schistosomiasis Malaria Dengue Fever

Diarrhoea What is Diarrhoea? Severe upsetting of the digestive system involving inflammation of the stomach and intestinal lining. Can cause rapid, life threatening dehydration. Chronic diarrhoea leads to malnutrition. What is the scope of the problem? 2.2 million deaths per year, 90% are children under 5 years of age 4 billion cases of diarrhoea worldwide.

Credit: meditek.co.za Cholera Bed

Factors in Diarrhoeal Disease

Diarrhoea is which type of water related disease? Water Borne Diarrhoea is caused by which type of pathogen? Most common pathogen is bacteria but may also be a virus. Diarrhoea may also be a symptom of other illnesses.

What Causes Diarrhoea? Ingestion of human faeces from contaminated hands, drinking water or food. Ingestion of animal faeces can also cause diarrhoea. Spreads from person to person, aggravated by poor sanitation and personal/domestic hygiene. Shortage of clean water for drinking and cooking, and basic personal/domestic hygiene.

How Can You Prevent Diarrhoea? Household water treatment Good personal hygiene (hand-washing) Safe excreta disposal Safe disposal of stools of young children Good food hygiene Health education, and promotion of good hygiene practices.

Trachoma What is trachoma? Bacterial infection of the eye. Progressive infection that scars the inside of the eyelids which causes the eyelashes to turn inwards The eyelashes rub and abrade the surface of the eyeball. This causes scarring of the cornea which leads to vision loss and eventual blindness.

What is the scope of the problem? At least six million people worldwide are blind and 150 million people are in need of treatment. Trachoma is which type of water related disease? Water Washed Trachoma is caused by which type of pathogen? Bacteria (chlamydia trachomitis)

How is trachoma transmitted? Through the contagious discharge from an infected person’s eyes. Trachoma is passed from person to person by the hands, on clothing, or by flies that land on the face of the infected person. How do you prevent trachoma? Improved sanitation, reduction of fly breeding sites and improved facial cleanliness The scarring of trachoma can be reversed by a simple surgical procedure performed at village level which reverses the in-turned eyelashes. SAFE – Surgery, Antibiotics, Facial cleanliness, Environmental improvements

Schistosomiasis What is schistosomiasis? Second most important parasitic infection after malaria in terms of public health and economic impact. Affects the liver, spleen, kidneys, bladder and nervous system and may lead to paralysis Affects the growth, nutrition, and cognitive development of children

What is the scope of the problem? 600 million people are at risk of infection and 200 million are infected. 80% of transmission takes place in sub- Saharan Africa. Schistosomiasis is which type of water related disease? Water Based Schistosomiasis is caused by which type of pathogen? Helminths – flat worms

What Causes Schistosomiasis?

How Do You Prevent Schistosomiasis? Improved sanitation reduces contamination of water bodies. Improved water supplies reduces the need to enter fresh water to collect water and/or to bathe, etc. Control of snails that act as the intermediate host Treatment of schistosomiasis is straightforward, so people working in higher risk professions such as fishing could be routinely treated.

Malaria Fever Transmitted by Anopheles mosquitoes 4 types of malaria –Falciparum, vivax, ovale, malariae Symptoms include fever, chills, headache, muscle ache, tiredness, nausea and vomiting, diarrhoea, anaemia, and jaundice. Convulsions, coma, severe anaemia and kidney failure can also occur. site.com What is Malaria?

What is the scope of the problem? million cases each year. More than one million deaths Malaria is classified as being which type of water related disease? Water Insect Vector Malaria is caused by which type of pathogen? Protozoa

Dengue Fever What is Dengue Fever? Transmitted by Aedes mosquitoes Four different types of dengue fever. Symptoms include a severe flu- like illness, severe headache, pain behind the eyes, muscle and joint pains, and rash The haemorrhagic form of dengue is a serious disease and can be fatal. sos-arsenic.netentm.purdue.edu

What is the scope of the problem? Dengue Fever: million cases of dengue fever each year. Dengue Fever is classified as being which type of water related disease? Water Insect Vector Dengue Fever is caused by which type of pathogen? Virus

What causes malaria and dengue fever? Infected mosquito. How do you prevent malaria and dengue fever? Health education on transmission and treatment Use of insecticide-treated bed nets - malaria Removal of mosquito breeding-sites Screens, protective clothing and insect repellents Indoor insecticide residual spraying

Other Common Water and Sanitation Related Diseases Cholera Shigellosis Salmonellosis Typhoid fever Giardia Hepatitis Roundworm Hookworm Guinea worm skin infections Scabies Cryptosporidiosis River blindness