Water-borne Diseases - Viral Waterborne Diseases

Water-borne Diseases

These diseases are largely caused by pathogenic micro-organisms present in human or animal waste, which find their way into human body, through drinking from a contaminated water supply - faecal-oral route. It can also be spread through other routes, such as via hands, clothes, food, or materials used for cooking, eating or drinking. More rarely, some of these diseases may also enter the body through the eyes, nose or open wounds. These diseases are infectious, which means that they can spread from one person to another. So high standards of hygiene and sanitation are needed to stop the disease from spreading.

The causative agent can be:

 (i) Bacteria

(ii) Virus

(iii)Protozoa

(iv) Worms

            The diseases can be diarrhoeal or non-diarrhoeal.

Mortality from waterborne diseases exceeds the current mortality rates of all diseases combined. These diseases are extremely harmful not only to a person's health but to their productivity, and to the welfare of the community as a whole.

They:

(i) Lead to severe illness and may be fatal, in the case of a severe attack.

(ii) Lower the body's resistance to infection and disease.

(iii) Lower the body's intake of nourishment, and may lead to malnutrition (especially in children)

(iv) Decrease individual and social productivity.

(v) Hamper children's education.

(vi) Increase health expenditure.

 

Viral Waterborne Diseases

Main causative agents include

—  Hepatitis A

—  Hepatitis E

—  Rotavirus

—  Polio

 

Infectious hepatitis- Hepatitis A

·         Hepatitis A virus-  First documented viral disease spread through water

·         By ingesting contaminated food or water-usually in children and young adults

·         Incubation period is 15 to 50 days

·         A typical viral-type illness with variable fever, followed by Jaundice; enlarged liver, vomiting, abdominal pain

·         Virus excreted in faeces and urine during fever phase

·         Virus excretion ceases during jaundice phase - patient is no longer infectious. 

·         After a few days the appetite returns and the jaundice begins to resolve

·         Transmission- Faeco-oral route

Control:

·         Adequate treatment of sewage and water; viruses more resistant to chlorination- inadequate chlorination leads to outbreaks

·         Drinking boiled/safe water and food

Hepatitis E

·         Hepatitis E -infection with hepatitis E virus (HEV)- found worldwide

·         Transmission fecal-oral route

·         Infection is self-limiting and resolves within 2–6 weeks.

·         Occasionally a serious disease, known as fulminant hepatitis (acute liver failure) develops, can cause death.

·         Poor sanitation, ingestion of undercooked meat or meat products derived from infected animals (e.g. pork liver) and rarely, transfusion of infected blood products; vertical transmission from a pregnant woman to her baby.

·         Initial phase of mild fever, reduced appetite (anorexia), nausea and vomiting, lasting for a few days; some may also have abdominal pain, itching (without skin lesions), skin rash, or joint pain.

·         Jaundice, with dark urine and pale stools

·         a slightly enlarged, tender liver (hepatomegaly).

·         Pregnant women with hepatitis E, particularly those in the second or third trimester, are at increased risk of acute liver failure, fetal loss and mortality.

·         Control

·         Safe  public water supplies and proper disposal of human faeces.

·         Maintain hygienic practices;

·         Avoiding consumption of water and ice of unknown purity

·         A recombinant subunit vaccine registered in China- not yet been approved in other countries.

 

Viral Gasteroenteritis

 

·         intestinal infection with symptoms like watery diarrhea, abdominal cramps, nausea or vomiting, and fever.

·         often called stomach flu —caused by ingesting contaminated food or water/ contact with an infected person

·         Transmission- Faeco-oral route

·         common in infants and children

·         Rota viruses, Norwalk viruses, calici viruses, astroviruses and enteric adeno viruses

Control

·         Avoiding contaminated food and water

·         Practice self-hygiene- frequent hand-washings

 

Poliomyelitis

·         Poliovirus- an enterovirus

·         Infections occur primarily through the ingestion of contaminated food or drinking contaminated water

·         Transmission- Faeco-oral route

·         a highly infectious viral disease that generally affects children under 5 years of age

·         the virus is transmitted by person-to-person spread mainly through the faecal-oral route or, less frequently, by a common vehicle (e.g. contaminated water or food) and multiplies in the intestine, from where it can invade the nervous system and cause paralysis.

·         Asymptomatic/ mild influenza like illness

·         Mild infection involving central nervous system, with headache, neck stiffness and back pain

·         Acute illness in which the poliovirus selectively destroys the lower motor neurons of the spinal cord and brainstem, resulting in flaccid paralysis, most often affecting the lower limbs

·         Respiratory paralysis may also occur, following infection of the brain stem

Control

·         Vaccination – the only effective prevention

 

acute disease - A disease or disorder that comes on rapidly, lasts a short time, and is accompanied by distinct symptoms

Paralysis - loss of strength in and control over a muscle or group of muscles in a part of the body. Flaccid paralysis-when the muscles get soft and shrink.