Water Borne diseases

One fifth of the world’s population lacks access to safe drinking water. In most of the developing and developed nations, 60 to 90 per cent of untreated and harmful sewage water is directly dumped into fresh water sources like rivers and streams which are major source for drinking, washing and bathing. The untreated sewage water allows pathogenic organisms to spread water borne diseases. Diseases transmitted by vectors like mosquitoes which live in the water are responsible for about one third of all deaths in the world.

Growing pollution of the fresh water bodies constitutes a very big threat to public health. Polluted waters lead to various gastrointestinal problems, liver infection, cancer, etc. Large number of children die because of diarrhoea. Disease causing pathogens reach humans in various ways.

Through contact:

Some diseases can be transmitted by either direct physical contact with the infected person or the causative agent can be transmitted to the host indirectly by contact with the infected articles.

Through Vehicle:

• Pathogenic organisms are transmitted through water, food,etc. When the water is infected at the source, it spreads the infection to large populations.
• Pathogens causing Cholera, Typhoid and Hepatitis are transmitted from one person to another through their domestic water supply.
• Infection is also transmitted by organisms which live in water e.g. Helminthes (parasitic worms) which spend part of their lifecycle in water.
• Many chemical pollutants such as food additives, adulterants, poisonous industrialwaste, pesticides and metals get mixed with water including underground water and are consumed by humans and animals resulting in diseases.
• Inadequate water supply and lack of personal hygiene cause transmission of disease such as trachoma in theeye and skin infections.

Through Vector:

Vector is a carrier of pathogen. Mosquito spend a part of their life cycle in water. Vector for diseases such as malaria, yellow fever, encephalitis, filarial and dengue.

Water borne diseases, their spread and consequences

• It is estimated that 73 million work days are lost every year in India due to water related diseases.
• India is rich in rivers and surface flow represents 97 per cent of the available water. But rather than being a boon, these rivers are proving to be quite a disaster because of pollution.
• River Yamuna becomes highly polluted after entering Delhi due to the addition of untreated sewage, industrial waste and many other pollutants.
• It has been found that water sample staken in Delhi are about 20 times more polluted than the water samples taken before the river enters Delhi.
• Water borne diseases are spread by drinking water contaminated by faeces, by water used for personal hygiene, for washing food and other items.
• Diseasesare spread by poor quality water used for washing and include skin diseases like scabiesand eye disease such as trachoma and conjunctivitis.
• Water based diseases spread byparasites living in water include schistosomiasis transmitted by snails. Disease from pollutedwater include hook worm, round worm, etc.

Bacterial diseases:Typhoid

Typhoid is caused by Salmonella typhi. The bacteria can enter the body through contaminated food, unwashed raw vegetables, flies and milk. Symptoms include continuous fever, high temperature in the night than in the morning, body ache, headache and constipation. It also causes haemorrhage to the small intestine due to ulceration.

Cholera

Cholera is caused by Vibrio cholera, it is transmitted by flies, and water and food contaminated by bacteria. Symptoms include painless diarrhoea, vomiting, 30-40stools per day which soon becomes colourless with patient flakes of mucous floating in them.

Bacterial Shigella

It is caused by Shigella bacteria and is transmitted by contaminated food, water and direct contact. Symptoms include diarrhoea, with blood and dysentery, mucous in the stools along with severe gripping pain in the abdomen. Stools not too frequent (4-10 per day), faecal matter scanty. Patient looks ill.

Leptospirosis

It is caused by Leptospira and is transmitted through Rodents which are primary hosts and carry organisms in kidneys. Infection is caused by paddling or swimming in water contaminated with rodent urine. Symptoms include fever, pain in legs, nausea, vomiting are common, congestion of the conjunctival blood vessels around corneas of the eyes.

Viral diseases Infective Hepatitis

It is caused by Hepatitis Virus, transmitted through food and water contaminated with virus in stools. Symptoms include loss of appetite, nausea, vomitingand diarrhoea, accompanied withfever. Urine dark coloured. Eyeand skin appear yellow.

Protozoan diseases Bilharzia

It is caused by Schistosomaspp and is transmitted through Cercaria larvae of flukes in water penetrate skin of persons wading in water. Symptoms include- Allergy-like itch, rash, aches, fever, eosinophilia etc. When infection heavy eggs may block arterioles of lungs cardio-pulmonary water causing schistosomiasis and may lead to congestive heart failure.

Guinea worm

It is caused by Dracunculusmedinensis and is transmitted by unfiltered water. Symptoms include blister near the ankle, causingallergy and aches.

Vector borne diseases related with water:Malaria

Malaria s caused by plasmodium species. Vector is female anopheles mosquito and host is human. Plasmodium has two distinctive cycle’s one in mosquito and another in man. Symptoms include shivering, chills and sweating. As chills sub side body temperature rises as high as 106º F. When temperature comes downpatient sweats profusely and becomescomfortable until next attack which takesplace at regular intervals.

Filaria

This is notoriously also called as Elephantiasis which is caused due to Wuchereria and vector is Culexfatigans and host is man. Symptoms include enlargement of limbs and scrotum.

Dengue

Dengue is caused due to Barbo – virus and vector transmitting disease is Aedesaegypti. Final host is human. Symptoms include sudden onset of moderately high fever, excruciating joint pain, intense pain behind eyes, a second rise in temp following brief remission, reduction in neutrophilic white blood cells.