Water-borne Diseases - Bacterial

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.

Etiology (causative agent) of the disease

The etiology/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.

Main Bacterial Pathogens

—  Vibrio cholerae

—  Escherichia coli

—  Salmonella typhi

—  Shigella flexneri

—  Campylobacter pylori

—  Legionella pneumophila

—  Leptospira

Diarrheal Diseases

Enteric fever/Gasteroenteritis/typhoid fever- Salmonella typhi

·         Characterized by fever and inflammation of intestine, ulcer formation, and other abdominal symptoms

·         Nonspecific symptoms - chills, sweats, headache, anorexia, weakness, sore throat, cough

·         The incubation period - 5 to 21 days.

·         Patients recover after 2-3 days; disease is limited to the GI tract in most cases

·         Organisms are excreted in urine and faeces in large numbers during the active phase of the disease

·         Max survival time 7 days; in natural waters above 15⁰C

·         Lack of adequate sanitation, major cause of the disease

·         Controlled by maintaining proper sanitation

Shigellosis (Bacillary dysentery)

·         Intestinal disease; most common among young children

·         Shigella species; S. dysenteriae, S. flexneri, S. boydii, and S. sonnei

·         S. sonnei (developed countries) S. flexneri (developing countries)

·         S. dysenteriae (most severe infections), S. boydii - not commonly isolated.

·         The organisms survive stomach acidity, pass through the small intestine, and adhere to the mucosal epithelium of the terminal ileum and colon

·         Destruction of the superficial mucosal layer - mucosal ulceration

·         Classic bacillary dysentery - characterized by diarrhea with blood, mucus, and painful abdominal cramping. Abundant neutrophils, erythrocytes, and mucus are found in the stool

·        An exotoxin (Shiga toxin) with enterotoxic and cytotoxic properties - isolated from S. dysenteriae; implicated in the development of intestinal lesions

·         Shigella species - remain viable in food and water for as long as 6 months

·         readily killed by chlorination of water, heat, and chemical agents

·         Infection - generally self-limited, spread through drinking water contaminated with human faeces

·         Shigella species carried primarily by humans and are not disseminated in nature

·     Most infections are passed by the faecal- oral route - Organisms excreted in faeces and urine; rarely survive more than 10 days outside

Cholera

·         Vibrio cholerae - ingested in contaminated food or water - multiply to large numbers on the mucosal surface and produce Cholera enterotoxin

·         The toxin causes hyper secretion of fluids and electrolytes into the intestinal lumen

·         After several hours to 3-days incubation, patients experience a sudden onset of severe watery diarrhea with vomiting and abdominal pain

·         The stool specimens are colorless and odorless, with mucuos flecks (rice-water stool)

·         Untreated, death from severe dehydration and loss of minerals. 

·     Cholera causes extreme fluid loss, so ORS-(Oral Rehydration Solution) replaces lost water and essential salts (like sodium, potassium, chloride) to maintain body function. Begin ORS as soon as symptoms (watery diarrhea, vomiting) appear and drink frequently, especially if vomiting.

(Cholera ORS is a mix of salts, sugar, and water used to rapidly replace fluids and electrolytes lost from severe diarrhea and vomiting caused by cholera, preventing fatal dehydration)

·         Large numbers of pathogens are excreted during the course of the disease - remain viable in natural waters till 7 days

·         Chlorination of water and standard disinfectants are able to destroy the organism easily

Campylobacter jejuni

·         Also causes diarrhea; transmitted through faeco-oral route

·      Campylobacter jejuni infection is one of the most commonly identified bacterial causes of acute gastroenteritis worldwide.

·         In developing countries, it is an important cause of childhood morbidity caused by diarrheal illness

·         among the most common causes of diarrhea in travelers from developed nations

·       Local complications of Campylobacter infections include cholecystitis (gall bladder infection), pancreatitis, peritonitis, and gastrointestinal hemorrhage

·   Extra intestinal manifestations of Campylobacter infection are quite rare and may include meningitis, endocarditis, arthritis, osteomyelitis, and neonatal sepsis.

·       Serious systemic illness caused by Campylobacter infection rarely occurs but can lead to sepsis and death. 

Other bacterial diseases - Non-Diarrheal

Legionnaires’ Disease (legionellosis)

·         Legionella pneumophila

·         Severe pneumonia; considerable morbidity, leading to death unless therapy is initiated promptly

·         commonly present in small numbers in natural bodies of water, such as lakes and streams

·         Multiply profusely in artificial  aquatic habitats like air conditioning, cooling towers and in water systems (e.g., showers, hot tubs)

·         Survive in moist environments for a long time, at relatively high temperatures, and in the presence of disinfectants such as chlorine

·         can parasitize amoebae in the water and replicate in this protected environment

·         Respiratory tract disease  in susceptible people who inhale infectious aerosols

·         Incubation period of 2 to 10 days;  fever, and chills, a dry non-productive cough,  headache

·         Can develop into multi-organ disease involving the gastrointestinal tract, central nervous system, liver, and kidneys

·         Maintain free residual chlorine in cold water supplies

·         Control the temperature of water (cold water below 20⁰C and hot water above 50⁰C)

Leptospirosis

·       Leptospira species; inhabit the kidneys of pet dogs and domestic livestock, excreted into natural waters in urine

·         enter through the abraded skin, oral or nasal mucosa, or conjunctiva following contact with urine-contaminated water by drinking, immersion of hands, or swimming  and infected wild life and domestic animals especially rodents

·         Leptospira icterhaemorrhagiae - associated with human disease; Weil’s disease

·         Fever, chills, headache, GI disturbance, and conjunctival redness

·         In 2 – 7 days, the patient becomes afebrile

·         After 1 – 3 day, a recurrence of fever, which persists for only couple of days

·         Jaundice, rash, hepatosplenomegaly, meningitis, and/or renal damage