Chapter 14 Principles of Disease and Epidemiology
Two patients developed endophthalmitis within 24 hours after corneal transplant surgery. The corneas have been stored in buffered media with gentamicin. Each patient had received a subconjunctival injection of gentamicin after transplantation. Streptococcus pneumoniae was isolated from conjunctival swabs of the affected eyes of both patients and from donor corneoscleral tissue. The post-transplant infections could have been prevented by
Antimicrobial susceptibility testing of the bacteria before surgery
Communicable Disease
Any disease that can be spread from one host to another
Predisposing Factor
Anything that makes the body more susceptible to a disease or alters the course of a disease. Examples include gender, climate, age, fatigue, and inadequate nutrition.
Ehrlichiosis is transmitted by Ixodes scapularis ticks. This is an example of
Arthropod vector transmission (biological transmission method / based)
Which month is the number of cases of Lyme disease the greatest?
August
In a patient with bacteremia, you would expect to find
Bacteria in the blood
In a healthy human, resident microorganisms would be found in all of the following areas except
Bloodstream
What is the difference between Commensalism and Parasitism?
Both Commensalism and Parasitism benefit from the host; however, Parasitism harms the host where as the host is unaffected by Commensalism
Animal Reservoirs
Both wild and domestic animals are living reservoirs of microorganisms that can cause human diseases
Which one of the following diseases is noncommunicable?
Botulism
All members of the seven families for whom Mary Mallon prepared meals developed typhoid fever. Mary did not get sick. This is an example of a(n)
Carrier state
Why are carriers important reservoirs of infection?
Carriers are reservoirs of infection as they harbor the disease with them. They are important, because they are mobile and can potentially communicate the disease to various geographic areas as they move around in their life. For humans, if their field involves dealing with lots of people, that can be extremely important in terms of microbe transmission
Symptom
Change in body function that is felt by a patient as a result of a disease
Clostridium perfringens
Clostridium perfringens (C. perfringens) is a spore-forming gram-positive bacterium that is found in many environmental sources as well as in the intestines of humans and animals. C. perfringens is commonly found on raw meat and poultry. It prefers to grow in conditions with very little or no oxygen, and under ideal conditions can multiply very rapidly. Some strains of C. perfringens produce a toxin in the intestine that causes illness. How common is C. perfringens food poisoning? C. perfringens is one of the most common causes of foodborne illness in the United States
Infectious diseases which are easily passed from host to host within a population are best described as
Contagious
What is the difference between Communicable Diseases and Contagious Diseases?
Contagious diseases (such as the flu, colds, or strep throat) spread from person to person in several ways. One way is through direct physical contact, like touching or kissing a person who has the infection. A communicable disease is carried by microorganisms and transmitted through people, animals, surfaces, foods, or air. Communicable diseases rely on fluid exchange, contaminated substances, or close contact to travel from an infected carrier to a healthy individual
John Snow analyzed information on cholera victims. This is an example of
Descriptive epidemiology
Toxoplasmosis is transmitted to humans by cats. This is an example of
Direct contact
Inherited (genetic) Disease
Diseases caused by genetics
Which of the following definitions is incorrect?
Epidemic - the small fraction of a population that has a disease at a specified time
he science that deals with when diseases occur and how they are transmitted is called
Epidemiology
The term best associated with the cause of disease is
Etiology
Reservoirs of Infection Types
Human Reservoirs Animal Reservoirs Nonliving Reservoirs
Diagnosis
Identification of the disease
Any of the following may occur in diseases transmitted by vectors except
In biological transmission, the vector multiplies in the human host
Cooperation among Microorganisms
In some situations, one microorganism makes it possible for another to cause a disease or produce more severe symptoms
An infection that does not cause any signs of disease is a(n)
Inapparent infection (also known as Subclinical infection)
An infection transmitted by a hypodermic needle is transmitted by
Indirect contact
Vector transmission is not responsible for
Influenza
An example of descriptive epidemiology is
John Snow's study of the London cholera outbreak in 1848-1849
Emergence of infectious disease can be due to all of the following reasons. Which one can be affected by changing human behavior?
Lack of vaccination
The figure shows the locations of normal microbiota on and in the human body. Which of these locations has the largest numbers of resident microbiota?
Large intestine
Which of the following is NOT a communicable diseases?
Leukemia
Probiotics
Live microbes applied to or ingested into the body, intended to exert a beneficial effect
Which one of the following does not belong with the others?
Measles Others where - Brucella - Hantavirus - Yersinia pestis
Houseflies can transfer the pathogens of typhoid fever from the feces of infected people to food. This is an example of ____________ transmission.
Mechanical
Which of the following is not an example of microbial antagonism?
Microbes producing vitamins and growth factors that can be utilized by the host
Competition among microbes for nutrients and living space is called?
Microbial antagonism
Microbiomes
Microbial communities that live in and on the human body
he major significance of Koch's work was that
Microorganisms cause disease
Droplet Nuclei
Mucus droplets
In the human intestinal tract, E. coli produces vitamins beneficial to the host and can inhibit pathogen growth. In turn, the bacterium is supplied with nutrients and an environment for growth. This symbiotic relationship between E. coli and its host is an example of
Mutualism
Following coronary artery bypass surgery, seven patients develop Rhodococcus bronchialis infections. Cultures of the operating rooms, Nurse A, and Nurse B are taken. R. bronchialis grows from the hand and nasal swabs of Nurse A. The patients' infections are an example of a(n)
Nosocomial infection
Healthcare professionals who fail to use aseptic techniques can cause
Nosocomial infections
On October 29, Barbara participated in a study group for her Microbiology class. On November 1, Barbara had a "scratchy throat" when she swallowed. On November 2, Barbara had a headache, runny nose, and watery eyes. She was fully recovered on November 7. Identify the prodromal period for this infection.
Nov. 1
On October 29, Barbara participated in a study group for her Microbiology class. On November 1, Barbara had a "scratchy throat" when she swallowed. On November 2, Barbara had a headache, runny nose, and watery eyes. She was fully recovered on November 7. Identify the incubation period for this infection.
Oct. 29-Nov. 1
Opportunistic Microorganisms
Opportunistic pathogens do not cause disease under normal conditions but cause disease under special conditions
An epidemic disease of worldwide proportions would best be described as
Pandemic
Foodborne Transmission
Pathogens are generally transmitted in foods that are incompletely cooked, poorly refrigerated, or prepared under unsanitary conditions. Foodborne pathogens cause diseases such as food poisoning and tapeworm infestation
Waterborne Transmission
Pathogens are usually spread by water contaminated with untreated or poorly treated sewage. Diseases transmitted via this route include cholera, waterborne shigellosis, and leptospirosis
Which of the following is the third stage of a disease?
Period of illness
Nationally Notifiable Diseases
Physicians are required to report occurrence
Patterns of Disease
Predisposing Factors Development of Disease
The ingestion of lactic acid bacteria for the purpose of preventing colonization by intestinal pathogens such as Salmonella enterica during antibiotic therapy is an example of
Probiotics
Michael woke up feeling suddenly like he was getting a sore throat and a headache. Which stage of a disease's progression is he most likely in?
Prodromal period
Bacteriocins
Proteins that inhibit the growth of other bacteria of the same or closely related species, such as pathogenic Salmonella and Shigella
A continual source of infection is called a
Reservoir
The Spread of Infection
Reservoirs of Infection Transmission of Disease
The occurrence of streptococcal bronchopneumonia in an individual recovering from influenza is an example of a/an
Secondary Infection
The fungus Coccidioides immitis is found in the soil. Humans contract coccidioidomycosis by inhaling fungal spores. The reservoir for this disease is
Soil
Aseptic Techniques
Steps used to prevent contamination
Infections in which the pathogen is distributed throughout the body are referred to as "generalized infections" or
Systemic Infections
Which of the following diseases does not have a human reservoir?
Tetanus
The best definition of etiology is
The cause of a disease
Period of Illness
The disease is most severe. The person exhibits overt signs and symptoms of disease, such as fever, chills, muscle pain (myalgia), sensitivity to light (photophobia), sore throat (pharyngitis), lymph node enlargement (lymphadenopathy), and gastrointestinal disturbances. During the period of illness, the number of white blood cells may increase or decrease. Generally, the patient's immune response and other defense mechanisms overcome the pathogen, and the period of illness ends. If the disease is not successfully overcome (or successfully treated), the patient dies during this period
Case Control Method of Analytical Epidemiology
The epidemiologist looks for factors that might have preceded the disease. A group of people who have the disease is compared with another group of people who are free of the disease. For example, one group with meningitis and one without the disease might be matched by age, sex, socioeconomic status, and location. These statistics are compared to determine which of all the possible factors — genetic, environmental, nutritional, and so forth — might be responsible for the meningitis. Nightingale's work was an example of analytical epidemiology, in which she compared disease in soldiers and civilians
Cohort Method of Analytical Epidemiology
The epidemiologist studies two populations: one that has had contact with the agent causing a disease and another that has not (both groups are called cohort groups). For example, a comparison of one group composed of people who have received blood transfusions and one composed of people who have not could reveal an association between blood transfusions and the incidence of hepatitis B virus
Prevalence
The fraction of a population having a specific disease at a given time. Prevalence takes into account both old and new cases. It's an indicator of how seriously and how long a disease affects a population
Incidence
The fraction of the population that contracts a disease during a particular period of time; It is an indicator of the spread of the disease
Infection
The growth of microorganisms in the body
Pathogenesis
The manner in which a disease develops
Transient Microbiota
The microorganisms that are present in an animal for a short time without causing a disease
Mortality
The number of deaths from a specific notifiable disease
Mortality rate
The number of deaths resulting from a disease in a given period of time in relation to the total population
The morbidity rate is best defined as
The number of individuals, relative to the population, affected by a particular disease in a period of time
Morbidity rate
The number of people affected by a disease in a given period of time in relation to the total population
Which of the following is not necessary to satisfy Koch's postulates?
The organism must cause disease through toxin production
Sepsis
The presence of a toxin or pathogenic organism in blood and tissue
Herd Immunity
The presence of immunity in most of a population
Toxemia
The presence of toxins in the blood
Viremia
The presence of viruses in the blood
Human Reservoirs
The principal living reservoir of human disease is the human body itself
Chain of Transmission
The principal routes of transmission of nosocomial infections are (1) direct contact transmission from hospital staff to patient and from patient to patient and (2) indirect contact transmission through fomites and the hospital's ventilation system (airborne transmission) Fomites such as catheters, syringes, and respiratory devices can transmit nosocomial infections
Mechanical Transmission
The process by which arthropods transmit infections by carrying pathogens on their feet and other body parts
Symbiosis
The relationship between the normal microbiota and the host; the living together of two different organisms or populations
Spread of Infection
The spread of infection is best described as a chain with six links: 1. A pathogen or causative agent 2. A reservoir (human, animal, or environmental source of the pathogen) 3. A portal of exit from the reservoir 4. Mode of transmission 5. A portal of entry into a susceptible host 6. A susceptible host If you can break any link of the chain of infection, you can prevent the occurrence of new infection
Prodromal Period
The time following the incubation period when the first symptoms of illness appear
Incubation Period
The time interval between the actual infection and first appearance of any signs or symptoms of disease
Vehicle Transmission
The transmission of a pathogen by an inanimate reservoir
Droplet Transmission
The transmission of infection by small liquid droplets carrying microorganisms
Nonliving Reservoirs
The two major nonliving reservoirs of infectious disease are soil and water
Serovar
Variations within a species
Alfalfa sprouts were responsible for transmitting Salmonella to 32 people in four states. This is an example of
Vehicle transmission
Tim ate raw oysters at a local restaurant and has since discovered he contracted hepatitis A. Which mode of transmission is this?
Vehicle transmission
Two patients developed endophthalmitis within 24 hours after corneal transplant surgery. The corneas had been stored in buffered media with gentamicin. Each patient had received a subconjunctival injection of gentamicin after transplantation. Streptococcus pneumoniae was isolated from conjunctival swabs of the affected eyes of both patients and from donor corneoscleral tissue. This is an example of
a nosocomial infection
The difference between normal and transient microbiota is that normal microbiota
are permanently present
A disease that is constantly present in a population is called a(n)
endemic disease
Robert Koch demonstrated that infectious disease
is caused by a microbe growing in the body
Epidemiology Major Figures in History
* John Snow - Mapped the occurrence of cholera in London * Ignaz Semmelweis - Showed that handwashing decreased the incidence of puerperal fever * Florence Nightingale - Showed that improved sanitation decreased the incidence of epidemic typhus
Microbial Associations
* Symbiotic - Mutualism - Commensalism - Parasitism * Nonsymbiotic - Synergism - Antagonism
Extent of Host Involvement
1. A local infection affects a small area of the body; a systemic infection is spread throughout the body via the circulatory system. 2. A primary infection is an acute infection that causes the initial illness. 3. A secondary infection can occur after the host is weakened from a primary infection. 4. An inapparent, or subclinical, infection does not cause any signs of disease in the host.
Control of Nosocomial Infections
1. Aseptic techniques can prevent nosocomial infections. 2. Hospital infection control staff members are responsible for overseeing the proper cleaning, storage, and handling of equipment and supplies.
Microorganisms in the Hospital
1. Certain normal microbiota are often responsible for nosocomial infections when they are introduced into the body through such medical procedures as surgery and catheterization. 2. Opportunistic, drug-resistant gram-negative bacteria are the most frequent causes of nosocomial infections
Occurrence of a Disease
1. Disease occurrence is reported by incidence (number of people contracting the disease) and prevalence (number of cases at a particular time). 2. Diseases are classified by frequency of occurrence: sporadic, endemic, epidemic, and pandemic
Exceptions to Koch's Postulates
1. Microorganisms that are unable to be cultured on artificial media 2. When 2 or more organism work in synergy to cause a disease 3. Symptoms or diseases that can be caused by several microbes 4. Some pathogens can cause several disease condition 5. Ethical exceptions 6. Highly contagious, virulent, or dangerous strains (e.g small pox) - We obviously do not want to create more of a dangerous disease Chapter summary list: a) Koch's postulates are modified to establish etiologies of diseases caused by viruses and some bacteria, which cannot be grown on artificial media. b) Some diseases, such as tetanus, have unequivocal signs and symptoms. c). Some diseases, such as pneumonia and nephritis, may be caused by a variety of microbes. d). Some pathogens, such as S. pyogenes,cause several different diseases. e). Certain pathogens, such as HIV, cause disease in humans only
Emerging Infectious Diseases (EIDs)
1. New diseases and diseases with increasing incidences are called emerging infectious diseases (EIDs). 2. EIDs can result from the use of antibiotics and pesticides, climatic changes, travel, the lack of vaccinations, and improved case reporting. 3. The CDC, NIH, and WHO are responsible for surveillance and responses to emerging infectious diseases.
Development of Disease
1. The incubation period is the interval between the initial infection and the first appearance of signs and symptoms. 2. The prodromal period is characterized by the appearance of the first mild signs and symptoms. 3. During the period of illness, the disease is at its height, and all disease signs and symptoms are apparent. 4. During the period of decline, the signs and symptoms subside. 5. During the period of convalescence, the body returns to its prediseased state, and health is restored
Severity or Duration of a Disease
1. The scope of a disease can be defined as acute, chronic, subacute, or latent. 2. Herd immunity is the presence of immunity to a disease in most of the population
he best definition of commensal bacteria is
A bacterium that benefits from the host but does no harm to the host
Centers for Disease Control and Prevention (CDC)
A branch of the U.S. Public Health Service located in Atlanta, Georgia, is a central source of epidemiological information in the United States
Sign
A change due to a disease that a person can observe and measure
Epidemic Disease
A disease acquired by many hosts in a given area in a short time
Latent Disease
A disease characterized by a period of no symptoms when the pathogen is inactive
Acute Disease
A disease in which symptoms develop rapidly but last for only a short time
Zoonoses
A disease that occurs primarily in wild and domestic animals but can be transmitted to humans
Subacute Disease
A disease with symptoms that are intermediate between acute and chronic
Direct Contact Transmission
A method of spreading infection from one host to another through some kind of close association between the hosts; also known as person-to-person transmission
Opportunistic Pathogen
A microorganism that does not ordinarily cause a disease but can become pathogenic under certain circumstances
Fomite
A nonliving object that can spread infection
Which if the following is an example of contact transmission?
A person drinks from a cup used by another individual
Host
A person or an animal that affords subsistence or lodgement to an infectious agent under natural conditions
Syndrome
A specific group of signs or symptoms that accompany a disease
Parasitism
A symbiotic relationship in which one organism (the parasite) exploits another (the host) without providing any benefit in return. Many disease-causing bacteria are parasites
Commensalism
A symbiotic relationship in which two organisms live in association and one is benefited while the other is neither benefited nor harmed
Focal Infection
A systemic infection that began as a local infection
Which of the following is a fomite?
A towel
Relationships between the Normal Microbiota and the Host
A. The normal microbiota can prevent pathogens from causing an infection; this phenomenon is known as microbial antagonism. B. Normal microbiota and the host exist in symbiosis (living together). C. The three types of symbiosis are commensalism (one organism benefits, and the other is unaffected), mutualism (both organisms benefit), and parasitism (one organism benefits, and one is harmed)
Which of the following statements is true about nosocomial infections?
Acquired during the course of hospitalization
Primary Infection
An acute infection that causes the initial illness
Vectors
An arthropod that carries disease-causing organisms from one host to another via one of two methods: mechanical or biological
Inapparent Infection
An infection that does not cause a noticeable illness; also called an Subclinical Infection
Florence Nightingale compared disease statistics for soldiers before and after use of sanitation measures. This is an example of
Analytical epidemiology
Analytical Epidemiology
Analyzes a particular disease to determine its probable cause
Morbidity
(1) The incidence of a specific disease. (2) The condition of being diseased
Bacteremia
A condition in which there are bacteria in the blood
Endemic Disease
A disease that is constantly present in a certain population
Contagious Disease
A disease that is easily spread from one person to another
Noncommunicable Disease
A disease that is not transmitted from one person to another
Sporadic Disease
A disease that occurs occasionally in a population
Compromised Host
A host whose resistance to infection is impaired. Two principal conditions can compromise the host: broken skin or mucous membranes, and a suppressed immune system Patients with burns, surgical wounds, and suppressed immune systems are the most susceptible to nosocomial infections
Case Reporting
A procedure that requires health care workers to report specified diseases to local, state, and national health officials. Examples of such diseases are AIDS, measles, gonorrhea, tetanus, and typhoid fever. Case reporting provides epidemiologists with an approximation of the incidence and prevalence of a disease. This information helps officials decide whether or not to investigate a given disease
Mutualism
A type of symbiosis in which both organisms or populations are benefited
Malaise
A vague feeling of body discomfort
Reservoirs of Infection
1. A continual source of infection is called a reservoir of infection. 2. People who have a disease or are carriers of pathogenic microorganisms are human reservoirs of infection. 3. Zoonoses are diseases that affect wild and domestic animals and can be transmitted to humans. 4. Some pathogenic microorganisms grow in nonliving reservoirs, such as soil and water.
Classifying Infectious Diseases
1. A patient may exhibit symptoms (subjective changes in body functions) and signs (measurable changes), which a physician uses to make a diagnosis (identification of the disease). 2. A specific group of symptoms or signs that always accompanies a specific disease is called a syndrome. 3. Communicable diseases are transmitted directly or indirectly from one host to another. 4. A contagious disease is one that is easily spread from one person to another. 5. Noncommunicable diseases are caused by microorganisms that normally grow outside the human body and are not transmitted from one host to another
Koch's Postulates
1. The same pathogen must be present in every case of the disease. 2. The pathogen must be isolated from the diseased host and grown in pure culture. 3. The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal. 4. The pathogen must be isolated from the inoculated animal and must be shown to be the original organism.
Epidemiology
1. The science of epidemiology is the study of the transmission, incidence, and frequency of disease. 2. Modern epidemiology began in the mid-1800s with the works of Snow, Semmelweis, and Nightingale. 3. In descriptive epidemiology, data about infected people are collected and analyzed. 4. In analytical epidemiology, a group of infected people is compared with an uninfected group. 5. In experimental epidemiology, controlled experiments designed to test hypotheses are performed. 6. Case reporting provides data on incidence and prevalence to local, state, and national health officials. 7. The Centers for Disease Control and Prevention (CDC) is the main source of epidemiological information in the United States. 8. The CDC publishes the Morbidity and Mortality Weekly Report to provide information on morbidity (incidence) and mortality (deaths).
Disease
An abnormal state in which part or all of the body is not properly adjusted or is incapable of performing normal functions; any change from a state of health
Pandemic Disease
An epidemic that occurs worldwide
Chronic Disease
An illness that develops slowly and is likely to continue or recur for long periods.
Secondary Infection
An infection caused by an opportunistic microbe after a primary infection has weakened the host's defenses
Local Infection
An infection in which pathogens are limited to a small area of the body
Nosocomial Infection
An infection that develops during a hospital stay and was not present at the time the patient was admitted; infection associated with any health care facility. Nosocomial infections result from the interaction of several factors: (1) microorganisms in the hospital environment, (2) the compromised (or weakened) status of the host, and (3) the chain of transmission in the hospital
Health Care-associated Infection (HAI)
An infection that develops during a hospital stay and was not present at the time the patient was admitted; infection associated with any health care facility. Nosocomial infections result from the interaction of several factors: (1) microorganisms in the hospital environment, (2) the compromised (or weakened) status of the host, and (3) the chain of transmission in the hospital
Subclinical Infection
An infection that does not cause a noticeable illness; also called inapparent infection; also called an Inapparent Infection
Systemic (generalized) Infection
An infection throughout the body
Experimental Epidemiology
Begins with a hypothesis about a particular disease; experiments to test the hypothesis are then conducted with a group of people. One such hypothesis could be the assumed effectiveness of a drug. A group of infected individuals is selected and divided randomly so that some receive the drug and others receive a placebo,a substance that has no effect. If all other factors are kept constant between the two groups, and if those people who received the drug recover more rapidly than those who received the placebo, it can be concluded that the drug was the experimental factor (variable) that made the difference
Pathogens
Disease-causing microorganisms
Infectious Diseases
Diseases caused by microorganisms
Degenerative Diseases
Disorders affecting one or more body systems that develop as a patient age
Descriptive Epidemiology
Entails collecting all data that describe the occurrence of the disease under study. Relevant information usually includes information about the affected individuals and the place and period in which the disease occurred. Snow's search for the cause of the cholera outbreak in London is an example of descriptive epidemiology
Microbial Antagonism
Growth of some microbes prevents the growth of other microbes; also known as Competitive Exclusion
Competitive Exclusion
Growth of some microbes prevents the growth of other microbes; also known as Microbial Antagonism
Stages of a disease
Incubation Period Prodromal Period Period of Illness Period of Decline Period of Convalescence
Airborne Transmission
Refers to the spread of agents of infection by droplet nuclei in dust that travel more than 1 meter from the reservoir to the host. For example, microbes are spread by droplets, which may be discharged in a fine spray from the mouth and nose during coughing and sneezing. These droplets are small enough to remain airborne for prolonged periods. The virus that causes measles and the bacterium that causes tuberculosis can be transmitted via airborne droplets. Dust particles can harbor various pathogens. Staphylococci and streptococci can survive on dust and be transmitted by the airborne route. Spores produced by certain fungi are also transmitted by the airborne route and can cause such diseases as histoplasmosis, coccidioidomycosis, and blastomycosis
Morbidity and Mortality Weekly Report
The MMWR, as it is called, is read by microbiologists, physicians, and other hospital and public health professionals. The MMWR contains data on morbidity,the incidence of specific notifiable diseases, and mortality,the number of deaths from these diseases. These data are usually organized by state
Biological Transmission
The transmission of a pathogen from one host to another when the pathogen reproduces in the vector
Representative normal microbiota for different regions of the body
a) Bacteria on the surface of the nasal epithelium (b) Bacteria on the lining of the stomach (c) Bacteria in the small intestine
Carrier
Organism (usually refers to humans) that harbors pathogens and transmits them to others
Transmission of Disease
The causative agents of disease can be transmitted from the reservoir of infection to a susceptible host by three principal routes: contact, vehicles, and vectors 1. Transmission by direct contact involves close physical contact between the source of the disease and a susceptible host. 2. Transmission by fomites (inanimate objects) constitutes indirect contact. 3. Transmission via saliva or mucus in coughing or sneezing is called droplet transmission. 4. Transmission by a medium such as water, food, or air is called vehicle transmission. 5. Airborne transmission refers to pathogens carried on water droplets or dust for a distance greater than 1 meter. 6. Arthropod vectors carry pathogens from one host to another by both mechanical and biological transmission.
Normal Microbiota
The microorganisms that colonize a host without causing disease; also called normal flora. 1. Animals, including humans, are usually germfree in utero. 2. Microorganisms begin colonization in and on the surface of the body soon after birth. 3. Microorganisms that establish permanent colonies inside or on the body without producing disease make up the normal microbiota. 4. Transient microbiota are microbes that are present for various periods and then disappear Protect the host by a) Occupying niches that pathogens might occupy b) Producing acids c) Producing bacteriocins
Septicemia
The proliferation of pathogens in the blood, accompanied by fever; sometimes causes organ damage
Period of Convalescence
The recovery period, when the body returns to its predisease state
Pathology
The scientific study of disease
Period of Decline
The signs and symptoms subside. The fever decreases, and the feeling of malaise diminishes. During this phase, which may take from less than 24 hours to several days, the patient is vulnerable to secondary infections
Contact Transmission
The spread of disease by direct or indirect contact or via droplets
Indirect Contact Transmission
The spread of pathogens by fomites (nonliving objects)
Etiology
The study of the cause of a disease
