Waterborne Diseases: Transmission, Prevention, and Control, Lecture notes of Community Health

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DIARRHEAL

DISEASES NOTES BY

ELIASPARAMEDIC.

The common feature with these diseases is that the

causative organisms are excreted in the stools of

infected persons.

The portal of entry for these diseases is the mouth

• The causative organisms have to pass through the

environment from the feces of an infected person to the

gastro-intestinal tract of a susceptible person

Food takes a central position;

• it can be directly or indirectly contaminated via polluted water,

dirty hands, contaminated soil, or flies.

Basic definitions related to Diarrheal

diseases

Contamination: The presence of an infectious

agent on a body surface, on or in clothes,

beddings, surgical instruments or dressings, or

other articles or substances including water and

food

Host: A person or an animal that affords

subsistence or lodgement to an infectious agent

under natural conditions.

An animal or an organism,or human being that

harbours an infectious agent or disease

Vector: An insect or any living carrier that

transports an infectious agent from an infected

Epidemic: The unusual occurrence in a community

of disease, specific health related behavior, or

other health related events clearly in excess of

expected occurrence

Endemic:It refers to the constant presence of a

disease or infectious agent within a given

geographic area or population group. It is the

usual or expected frequency of disease within a

population.

The word sporadic means “ scattered about ”. The

cases occur irregularly, from time to time, and

generally infrequently. The cases are few and

separated widely in time and place that they

show no or little connection with each other, nor a

recognizable common source of infection e.g.

polio, meningococcal meningitis, tetanus ….

However, a sporadic disease could be the starting

point of an epidemic when the conditions are

favorable for its spread

Eradication is the Termination of all transmission

of infection by the extermination of the infectious

agent through surveillance and containment.

Eradication is an absolute process, an “ all or

none ” phenomenon, restricted to termination of

infection from the whole world.

The term elimination is sometimes used to

describe eradication of a disease from a large

geographic region. Disease which are amenable

to elimination in the meantime are polio, measles

and diphtheria

Incubation period: time from exposure to

development of disease. In other words, the time

interval between invasion by an infectious agent

and the appearance of the first sign or symptom

of the disease in question.

Latent period: the period between exposure and

the onset of infectiousness (this may be shorter

or longer than the incubation period).

Diseases caused by fecal

contamination

Diseases to be covered in this section include:

1. Cholera

2. Giardiasis

3. Amoebiasis

4. Bacillary dysentry

5. Poliomyelitis

6. Enteric fevers

7. Food poisoning

RISK FACTORS

• Overcrowding(internally displaced people, refugee,

camps,

• Population gathering
• Etc)
• Inadequate quantity and/or quality of water
• Inadequate personal hygiene
• Poor washing facilities
• Inappropriate or poor sanitation
• Inadequate food safety
• Inappropriate funeral services for cholera victims

Cholera transmission

• Transmission occurs from man to man via

Fecally Contaminated Water Fruits & Vegetables

• Uncontrolled water sources such as wells, lakes, ponds,

streams and rivers pose a great threat.

• Contaminated Food Drinks: Ingestion of contaminated

food and drinks have been associated with outbreaks of

cholera.

• Bottle feeding could be a significant risk factor for

infants.

• Fruits and vegetables washed with contaminated water

can be a source of infection. After preparation, cooked

food may be contaminated through contaminated hands

and/or flies

Host Defenses

Gastric acid, mucus secretion, and intestinal

motility are the prime nonspecific defenses

against V cholerae.

Breastfeeding in endemic areas is important in

protecting infants from disease.

Disease results in effective specific immunity,

involving primarily secretory immunoglobulin

(IgA), as well as IgG antibodies, against vibrios,

enterotoxin and other products

Clinical picture

Incubation period is 2- 3 days

Develop in 3 stages

First Stage :

 There is passage of profuse watery stool. The watery

stool has classical rice water appearance

 The patient starts vomiting

 Severe cramps in the abdomen and limps develops

from loss of salts

Second stage

 Collapse from dehydration: the body is cold,skin is dry

and inelastic.The pulses are rapid and feeble with low

Bp or hypotension

Management of Cholera outbreak

Notify the sub county or county medical officer

Admit the patients on temporary hospitals

{school or a church} or cholera treatment

centres.

Isolate the patients to prevent transmission

Do not refer suspected cases. Increases the risk

of transmission

Take stool specimens for culture to the national

laboratory for confirmation

Prepare large amounts of rehydration fluid

Rehydrate patients with oral fluids to prevent

hypovolemic shock

Administer intravenous fluids for patients with

shock only for a short time

Monitor the patient frequently, and reassess their

hydration status at intervals.

Treat patients with cholera beds with central hole

through which continuous stools can pass into

the bucket and measured