Water-borne Diseases - Bacterial

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

·         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