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