CHAPTER 11-EPIDEMIOLOGY AND PUBLIC HEALTH

Arthropods

are animals and as a group, they are so commonly associated with human infections.

Epidemic diseases

are diseases that occur in a greater than usual number of cases in a particular region, and usually occur within a relatively short period of time

Fomites

are inanimate objects capable of transmitting pathogens.

Zoonotic diseases (zoonoses)

are infectious diseases that humans acquire from animal sources.

infectious diseases

are responsible for approximately half the deaths that occur in developing countries

Dust particles

can carry spores of certain bacteria and dried bits of human and animal excretions containing pathogens.

Air currents and air vents

can transport respiratory pathogens throughout healthcare facilities and other buildings.

Passive carriers

carry the pathogen without ever having had the disease

HIV/AIDS, TB, and malaria

cause more than 300 million illnesses and more than 5 million deaths per year.

Raw sewage

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

Public health agencies

constantly strive to prevent epidemics and to identify and eliminate any that do occur.

Centers for Disease Control and Prevention (CDC)

employs many epidemiologists, and offers a 2-year, postgraduate course to train health professionals as Epidemic Intelligence Service (EIS) officers.

Convalescent carriers

harbor and can transmit a particular pathogen while recovering from an infectious disease

Ebola virus

has caused several epidemics of hemorrhagic fever in Africa.

Active carriers

have completely recovered from the disease, but continue to harbor the pathogen indefinitely.

Nonliving or inanimate reservoirs

include air, soil, dust, food, milk, water, and fomites.

Living reservoirs

include humans, household pets, farm animals, wild animals, certain insects, and certain arachnids (ticks and mites).

Communicable diseases

infectious diseases that are transmitted from person to person

Zoonotic diseases or zoonoses (sing., zoonosis)

infectious diseases that humans acquire from animal sources are

Vehicular transmission

involves contaminated inanimate objects ("vehicles"), such as food, water, dust, and fomites. Vectors - include various types of biting insects and arachnids.

Tertiary Sewage Treatment

involves the addition of chemicals, filtration (using fine sand or charcoal), chlorination, and sometimes distillation.

Airborne transmission

involves the dispersal of droplet nuclei, which are the residue of evaporated droplets, and are smaller than 5 m in diameter.

Endemic disease

is a disease that is always present within that population.

Pandemic disease

is a disease that is occurring in epidemic proportions in many countries simultaneously

Sporadic disease

is a disease that occurs only occasionally within the population of a particular geographic area

E. coli O157:H7

is a particularly virulent serotype of E. coli. It is also known as Enterohemorrhagic E. coli

Incubatory carrier

is a person who is capable of transmitting a pathogen during the incubation period of a particular infectious diseases.

Carrier

is a person who is colonized with a particular pathogen, but the pathogen is not currently causing disease in that person.

Botulism

is a potentially fatal microbial intoxication, caused by botulinal toxin, a neurotoxin produced by C. botulinum.

Smallpox

is a serious, contagious, and sometimes fatal viral disease prostration, severe backache, a characteristic skin rash

C. botulinum

is a spore-forming anaerobic Gram-positive bacillus.

Reservoir

is any site where the pathogen can multiply or merely survive until it is transferred to a host.

Anthrax

is caused by B. anthracis, a spore-forming, Grampositive bacillus.

Plague

is caused by Y. pestis, a Gram-negative coccobacillus. Predominantly a zoonosis and is usually transmitted to humans by flea bite.

Contagious disease

is defined as a communicable disease that is easily transmitted from one person to another

Water

is the most essential resource necessary for the survival of humanity

Point prevalence

is the number of cases of the disease existing in a given population at a particular moment in time.

Period prevalence

is the number of cases of the disease existing in a given population during a specific time period.

Mortality rate (death rate)

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

Epidemiology

is the study of factors that determine the frequency, distribution, and determinants of diseases in human populations, and ways to prevent, control, or eradicate diseases in populations.

Malaria

is the world's most important tropical parasitic disease, killing more people than any other communicable disease, except TB.

cryptosporidiosis

largest waterborne epidemic to occur in the United States was an outbreak of _)__ in Milwaukee, Wisconsin, in 1993, which affected more than 400,000 people.

Creutzfeldt Jakob (CJ) disease (C-J disease)

may be acquired by ingestion of prion-infected beef from cows with bovine spongiform encephalopathy.

Droplets

may be generated by coughing, sneezing, and even talking.

Botulinal toxin

may cause nerve damage, visual difficulty, respiratory failure, flaccid paralysis of voluntary muscles, brain damage, coma, and death within a week if untreated.

Septicemic plague

may cause septic shock, meningitis, or death

arthropod vector

may first take a blood meal from an infected person or animal and then transfer the pathogen to a healthy individual

Influenza ("flu") epidemics

occur in many areas during certain times of the year and involve most of the population because the immunity developed in prior years is usually temporary.

Incidence

of a particular disease is defined as the number of new cases of that disease in a defined population during a specific time period.

Communicable Disease Center

overall mission is to collaborate to create the expertise, information, and tools that people and communities need to protect their health

biological warfare (BW); biological warfare agents

pathogenic microorganisms sometimes wind up in the hands of terrorists and extremists who want to use them to cause harm to others. In times of war, the use of microorganisms in this manner is called ____, and the microbes are referred to as ____.

Epidemiologist

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

Pathologist

studies the structural and functional manifestations of disease and is involved in diagnosing diseases in individuals

Waterborne disease outbreaks

such outbreaks occur annually in the United States, associated both with drinking water and water that is not intended for drinking.

Bubonic plague

swollen, inflamed, and tender lymph nodes (buboes) that develop.

aeration

to encourage the growth of aerobic microbes, which oxidize the dissolved organic matter to CO2 and H2O.

Period & Point prevalence

two types of prevalence

2003 WNV epidemic

was even worse, with a total of 9,862 cases and 264 deaths. WNV epidemics occur each year in the United States.

2002 WNV epidemic

was the largest recognized arboviral meningoencephalitis epidemic in the Western Hemisphere and the largest WNV meningoencephalitis epidemic ever recorded.

1918 Spanish flu pandemic

was the most devastating pandemic of the 20th century, and is the catastrophe against which all modern pandemics are measured.

Cryptosporidium oocysts

were present in the city's drinking water, and people became infected when they drank the water

Pneumonic plague

which is highly communicable, involves the lungs. It can result in localized outbreaks or devastating epidemics.

Morbidity rate

which is usually expressed as the number of new cases of a particular disease that occurred during a specified time period per a specifically defined population.

settling tank

After either aeration or trickling filtration, the activated sludge is transferred to a ___, where any remaining solid material settles out.

coagulation or flocculation

Alum (aluminum potassium sulfate) is then added to coagulate smaller pieces of debris, which then settle to the bottom

1992 to 1993

An epidemic involving Escherichia coli O157:H7-contaminated hamburger meat occurred in the Pacific northwest.

Hantavirus Pulmonary Syndrome (HPS)

An epidemic of ___ in 1993 occurred on Native American reservations in the Four Corners region (where the borders of Colorado, New Mexico, Arizona, and Utah all meet).

West Nile virus (WNV) infections

An epidemic of ___ occurred throughout the United States in 2002. More than 4,100 human cases occurred that year, resulting in 284 deaths.

cryptosporidiosis

An epidemic of ____ (a diarrheal disease) occurred in Milwaukee, Wisconsin in 1993. It resulted from drinking water that was contaminated with the oocysts of Cryptosporidium parvum.

1976

An epidemic of a respiratory disease (Legionnaires' disease or legionellosis) occurred during an American Legion convention in Philadelphia, Pennsylvania. It resulted in approximately 220 hospitalizations and 34 deaths.

pathogen; a reservoir of infection; a portal of exit; mode of transmission; portal of entry; susceptible host

Chain of Infection

Communicable disease

If the infectious disease is transmissible from one human to another (i.e., person to person),

1992 to 1993

It resulted in approximately 500 diarrheal cases, 45 cases of kidney failure as a result of Hemolytic Uremic Syndrome (HUS), and the death of several young children.

Master of Science or Master of Public Health degree

MS or MPH

Secondary Sewage Treatment

The liquid (called primary effluent) then undergoes ___, which includes aeration or trickling filtration.

primary sludge

The material that accumulates at the bottom of the tank

colds and influenza

The most highly contagious diseases include ____, in which the respiratory viruses can be transmitted through the air on droplets of respiratory tract secretions.

Lyme disease

The most prevalent zoonotic infection in the United States is ____ one of many arthropod-borne zoonoses.

secondary effluent

The remaining liquid is filtered and disinfected (usually by chlorination), so that the effluent water can be returned to rivers or oceans.

sedimentation or settling

The water remains in a holding tank, where additional debris settles to the bottom of the tank

WHO

a specialized agency of the United Nations, whose missions are to promote technical cooperation for health among nations, carry out programs to control and eradicate diseases, and improve the quality of human life.

Trickling filters

accomplish the same thing (i.e., conversion of dissolved organic matter to CO2 and H2O by microbes), but in a different manner.

U.S. Department of Health and Human Services

administers the Public Health Service and CDC, which assist state and local health departments in the application of all aspects of epidemiology

Zoonoses

are acquired by direct contact with the animal, by inhalation or ingestion of the pathogen, or by injection of the pathogen by an arthropod vector.

B. anthracis, C. botulinum, V. major, and Y. pestis

Four pathogens that are potential BW and bioterrorism agents are ___.

effluent water

In other cities, ___ is used to irrigate lawns; however, it is expensive to install a separate water system for this purpose.

sludge

In some communities, the ____ is heated to kill bacteria, then dried and used as fertilizer.

Tertiary Sewage Treatment

In some desert cities, where water is in short supply, the effluent water from the sewage disposal plant is further treated, so that it can be returned directly to the drinking water system; this is a very expensive process.

Primary Sewage Treatment

In the sewage disposal plant, large debris is first filtered out (called screening), skimmers remove floating grease and oil, and floating debris is shredded or ground. Then, solid material settles out in a primary sedimentation tank. Flocculating substances can be added to cause other solids to settle out.

76 million;325,000;5,000

Investigators at the CDC^b have estimated that foodborne diseases cause approximately ___ illnesses, ___ hospitalizations, and deaths per year in the United States.

Foodborne disease outbreaks

Over 200 known diseases can be transmitted through food, caused by microbes (viruses, bacteria, parasites, prions) or toxins and metals.

Doctor of Philosophy degree

PhD or DPhil

biological terrorists or bioterrorists;bioterrorism agents

These people are referred to as ____, and the specific pathogens they use are referred to as ____.

1

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

vectors

When involved in the transmission of infectious diseases, these arthropods are referred to as ____.

Factors pertaining to the pathogen; Factors pertaining to the host; Factors pertaining to the environment

Whether or not an infectious disease occurs depends on many factors, some of which are listed here: