Midterm - Microbiology and Parasitology

Water

Is tested for contamination by checking for the presence of coliform bacteria (Coliforms), such as E. coli and other members of the family Enterobacteriaceae.

Water

Is the most essential resource for the survival of humanity!

Period Prevalence

Is the number of cases of a disease existing in a given population during a specific time period (e.g., during the year 2010).

Morbidity rate

Is the number of new cases of a particular disease that occurred during a specified time period per a specifically defined population (usually per 1,000, 10,000, or 100,000 population)

Incidence of a particular disease

Is the number of new cases of that disease in a defined population during a specific time period

Mortality rate

Is the ratio of the number of people who dies of a particular disease during a specified time period per specified population.

Epidemiologists

Study the factors that determine the frequency, distribution, and determinants of diseases in human populations.

Raw Sewage

consists mainly of water, fecal material (including intestinal pathogens), and garbage and bacteria from the drains of houses and other buildings.

Water

is considered potable (safe to drink) if it contains 1 coliform or less per 100 mL of water

Modes of Transmission

- Direct skin-to-skin contact. - Direct mucous membrane-to-mucous membrane contact by kissing or sexual intercourse. - Indirect contact via airborne droplets of respiratory secretions, usually produced as a result of sneezing or coughing - Indirect contact via food and water contaminated with fecal material. - Indirect contact via arthropod vectors - Indirect contact via fomites that become contaminated by respiratory secretions, blood, urine, feces, vomitus, or exudates from hospitalized patients. - Indirect contact via transfusion of contaminated blood or blood products from an ill person or by parenteral injection (injection directly into the bloodstream) using nonsterile syringes and needles.

Zoonotic diseases

Are diseases that humans acquire from animal sources.

Fomites

Inanimate objects capable of transmitting pathogens (e.g., bedding, towels, eating and drinking utensils, hospital equipment etc.)

Epidemiologists

Also develop ways to prevent, control, or eradicate diseases in populations

Epidemiology

Can be loosely defined as the study of disease

Rainwater and groundwater (from wells)

Can become contaminated by soil microbes and raw fecal material

- Lyme Disease - Malaria

Examples of arthropod-borne diseases

Physical factors (e.g., climate, season, geographic location), availability of appropriate reservoirs, sanitary and housing conditions, and availability of potable water.

Factors pertaining to the environment such as

Health status, nutritional status, hygiene, age, travel, lifestyle etc.

Factors pertaining to the host these include

e.g., virulence of pathogen, mode of entry, number of organisms

Factors pertaining to the pathogen

Sewage Treatment

Includes Primary, Secondary, and Tertiary sewage treatments

Zoonotic Diseases or Zoonoses

Infectious diseases that humans acquire from animal sources are called

Contagious disease

Is a communicable disease that is easily transmitted from person to person.

Pandemic

Is a disease that is occurring in epidemic proportions in many countries simultaneously. Examples include: - Influenza - The Spanish flu pandemic of 1918 more than 20 million people were killed worldwide (500,000 in the U.S.) - HIV/AIDS - Tuberculosis - Malaria

Point Prevalence

Is a number of cases of a disease existing in a given population at a particular moment in time (e.g., right now).

Communicable disease

Is an infectious disease that can be transmitted from one person to another.

Epidemic Disease

Is defined as a greater than usual number of cases of a disease in a particular region, usually within a short period of time example, the Legionnaires disease epidemic of 1976.

Endemic Disease

Is one that is always present within the population of a particular geographic area example, Gonorrhea.

Sporadic Disease

Is one that occurs only occasionally within the population of a particular geographic area example, Tetanus.

Humans , pets, farm animals, insects, arachnids

Living Reservoirs

Insects (e.g., Fleas, Mosquitoes, Lice) and Arachnids (e.g., Mites and Ticks)

Many different types of arthropods serve as reservoirs for infection, including

Zoonoses

May be acquired by direct contact with an animal, inhalation or ingestion of the pathogen, or injection of pathogen by an arthropod. Examples - Rabies - Lyme Disease - Others

Air, soil, dust, contaminated water and foods, insects, and infected humans

Nonliving Reservoirs

Sedimentation, Coagulation, Filtration, and Chlorination

The major steps in water treatment are

Reservoirs of Infection or simple Reservoirs

The sources of microorganisms that cause infectious diseases are many and varied they are known as Human carriers Passive carriers Incubatory carriers Convalescent carriers Active carriers Animals

Pathogen → A source of Pathogen (a Reservoir) → A portal of Exit → A mode of Transmission → A portal of Entry → A susceptible Host

There are 6 components in the infectious disease process

Vectors

When arthropods are involved in the transmission of infectious diseases they are referred to as