Public health

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Questions and Answers

What is a carrier in the context of infectious diseases?

A person who has recovered from an infectious disease

A person infected and harboring a pathogenic organism without showing manifestations of disease (correct)

A person showing manifestations of disease

A case that is no longer infectious

What is the primary difference between an incubatory carrier and a convalescent carrier?

The age of the person

Their level of infectiousness

The type of disease they have

The stage of the disease they are in (correct)

What is a contact carrier?

A person who has never been infected

A person infected from a polluted environment

A person infected through contact with a case or carrier (correct)

A person showing symptoms of disease

What is the primary characteristic of a healthy carrier?

They are infected from a polluted environment Signup and view all the answers

How long can an untreated case remain infectious?

For a long period of time, even years Signup and view all the answers

What is the main difference between an untreated case and a carrier?

The presence of symptoms Signup and view all the answers

What is a common example of an acute, self-limited disease?

Influenza Signup and view all the answers

What is the importance of carriers?

They are infectious but show no symptoms Signup and view all the answers

What is the primary reason for excluding susceptible contacts from school in the early days of highly infectious diseases?

To prevent them from spreading the infection Signup and view all the answers

What is the goal of eradication of infectious diseases?

To get rid of the causative organism and the disease worldwide Signup and view all the answers

What is the purpose of bacteriological examination of contacts of enterica and diphtheria?

To prove they are not carriers Signup and view all the answers

What is the primary mechanism of transmission in Inutero Infection?

Through the placenta Signup and view all the answers

What is the purpose of isolating contacts of certain diseases?

To protect others from infection Signup and view all the answers

What is the goal of health education in community control measures?

To educate the community on specific prevention measures Signup and view all the answers

What is the outcome of Lethal Inutero Infection?

Abortion, stillbirth, or neonatal mortality Signup and view all the answers

What is the third way of Vertical Infection transmission?

Breast-feeding Signup and view all the answers

What is the measure of control of environment in community control measures?

Adequate ventilation and spacing Signup and view all the answers

What is the purpose of super chlorination of water supply?

To prevent the spread of infection Signup and view all the answers

What is the role of host factors in the infectious cycle?

To provide nonspecific defense mechanisms Signup and view all the answers

What is the purpose of epidemiologic study and investigation?

To trace sources and channels of infection Signup and view all the answers

What is the primary function of natural barriers of infection?

To prevent invasion of the body by organisms Signup and view all the answers

What is the bactericidal effect of sweat related to?

Skin defense Signup and view all the answers

What is the golden rule of treating others?

Treat others in a way that you think they want to be treated. Signup and view all the answers

What is the role of cilia of epithelial lining in the respiratory tract?

To help eliminate infection Signup and view all the answers

What is a key aspect of effective speaking?

Thinking before you talk. Signup and view all the answers

What is essential for effective listening?

Screening out distractions. Signup and view all the answers

What is the result of stimulation of the immune system?

Specific immunity production Signup and view all the answers

What is important for effective communication?

Being open to new ideas. Signup and view all the answers

Why is it important to manage your facial expressions?

To ensure consistency with your message. Signup and view all the answers

What is the term for infection transmitted through contaminated food or water?

Ingestion infection Signup and view all the answers

What is a key aspect of an effective attitude for communication?

Being committed to truthfulness. Signup and view all the answers

Which of the following infections can be transmitted through more than one mode?

Poliomyelitis Signup and view all the answers

What is the route of entry for arthropod-borne infection?

Percutaneous route Signup and view all the answers

What is the term for infection transmitted from mother to fetus during pregnancy?

All of the above Signup and view all the answers

What is the primary mode of transmission for tetanus?

Injection infection Signup and view all the answers

What is the term for infection transmitted through direct inhalation of droplet spray?

Direct droplet infection Signup and view all the answers

What is a predisposing factor for direct droplet infection?

Crowding in confined places Signup and view all the answers

What is the route of entry for in-utero infection?

Fetal circulation Signup and view all the answers

Study Notes

Types of Infection

Cases show manifestations of disease and are infectious for a varied period of time depending on the nature of the disease and whether specific therapy is available and properly given or not.
Untreated cases are usually infectious throughout the clinical course of the disease, which varies in different diseases.

Carriers

A carrier is an apparently healthy person who is infected and harbors a pathogenic organism in their body, without showing manifestations of disease, but is infectious and can spread infection.
Importance of carriers: they are clinically healthy, not known, move freely, are a large number, and are a dangerous group.
Types of carriers:
- Incubatory carrier: infectious during the incubation period.
- Convalescent carrier: a certain percentage of convalescents (recovered cases) continue to harbor the causative organism in particular foci for a varied period of time.
- Contact carrier: contacts of cases or carriers of some infectious diseases may be infected but not diseased.
- Healthy carrier: inhabitants of endemic areas of infectious diseases may get infected from a polluted environment.

Modes of Transmission

Ingestion infection (food-borne infection)
Arthropod-borne infection (insect-borne infection, vector-borne infection)
Contact infection (including percutaneous infection)
Occasional modes of transmission:
- Injection infection: a form of contact infection
- In-utero infection: congenital infection, vertical infection (including transplacental infection)

Entry of Infection

Respiratory tract: for respiratory (droplet) infection
Gastrointestinal tract: for ingestion infection
Percutaneous route: for arthropod-borne infection, wound infection, and injection infection
Skin and mucous membranes: for other contact infections
Fetal circulation: for in-utero infection

Droplet Infection

Modes of transmission:
- Direct droplet infection: both the reservoir of infection and the new host are found together within the same place
- Indirect droplet infection: reservoirs and hosts do not come together, infection is transmitted by airborne infection, contaminated articles, and fomites

In-Utero Infection

It is infection transmitted from the pregnant to the fetus either:
- Early infection in the first trimester, before formation of the placenta
- Trans-placental infection, after formation of the placenta
Hazards of in-utero infection: unfavorable outcome of pregnancy that may be either:
- Lethal: abortion, stillbirth, or neonatal mortality
- Sublethal: congenital anomalies and malformations (deformities)

Vertical Infection

Mother to infant infection, called “vertical infection”
Vertical infection is transmitted in three ways:
- In-utero infection
- Perinatal infection: infection acquired from the infected birth canal during childbirth
- Breast-feeding: infection through nursing (lactation of) the baby (CMV-HIV-HBV& HCV)

Exposed Host

The host is the third link of the infectious cycle
When infected, infection either passes unnoticed or is followed by disease, according to certain agent and host factors
Host factors are related to body resistance (nonspecific) and immunity (specific) factors

Defense Mechanism of the Body

Defense mechanism is made of two components:
- Natural barriers of infection:
  - Healthy epithelial surfaces (skin and mucous membranes) form the first line of defense that prevents invasion of the body by organisms
  - Skin: intact surface is a natural barrier (undamaged), bactericidal effect of sweat
  - Respiratory tract: defense is due to hair, cilia of epithelial lining, sneezing, and coughing help elimination of infection

Community Control Measures

Applied preventive measures: measures of primary prevention related to particular disease involving a group or community are applied
Control of environment: control of vehicles and vectors, e.g., adequate ventilation and spacing, super chlorination of water supply, and sanitary collection and disposal of community
Health education: specific prevention
Control measures:
- Case-finding and control of cases and contacts
- Epidemiologic study and investigation to trace sources and channels of infection
- Drastic control measures: to be taken if necessary, e.g., closing schools, and food markets

Eradication of Infectious Disease

It is getting rid of the causative organism, and consequently of the disease, in a certain area, country, or worldwide: no reported cases, nor reservoirs of infection
Eradication, however, has been achieved for a limited number of infections, otherwise it is practically difficult to fulfill, especially in developing countries

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