Water-borne Diseases - Viral Waterborne Diseases

 

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.