The ability of a microbe to cause disease.
The actual steps that are involved in the development of a disease.
A disease that occurs only occasionally.
The process where abnormal cells lose contact inhibition, potentially leading to cancer.
Age is a significant factor that can increase susceptibility to diseases.
Lifestyle choices can affect an individual's susceptibility to disease.
Yes, exotoxins can be neutralized by antitoxins.
Exotoxins are heat labile, meaning they can be destroyed by heat.
Hand hygiene refers to the practice of cleaning hands to remove dirt, bacteria, and viruses, thereby preventing the spread of infections.
The study of disease.
Communicable diseases that are easily transmitted from one person to another.
The Preferred Portal of Entry is a specific route through which many microbes must enter to cause disease; for example, Streptococcus pneumoniae can cause pneumonia when inhaled but generally does not cause disease when swallowed.
The science that studies when and where diseases occur and how they are transmitted in a population.
Virulence factors are components such as capsules, cell wall components, enzymes, and antigenic variation that enable bacteria to penetrate host defenses.
A pathogen must gain access to the host, adhere to host tissues, penetrate or evade host defenses, and damage the host.
The Pyrogenic Response is the body's reaction to endotoxins that leads to fever, which is a common response to infection.
The spread of pathogens by water contaminated with untreated or poorly treated sewage, exemplified by cholera.
Hosts with strong immune systems are better able to fend off pathogens, while those with weakened immune systems are more vulnerable to the support and reproduction of pathogens.
Dengue is an acute infectious disease that comes in two forms: dengue and dengue hemorrhagic fever, characterized by symptoms such as high fever, severe headache, backache, joint pains, nausea, vomiting, eye pain, and rash.
CPE (Cytopathic Effect) produced by RSV (Respiratory Syncytial Virus) refers to the observable changes in host cells that occur due to viral infection, often leading to cell death or dysfunction.
Transmission by a medium, including inanimate reservoirs such as water, food, air, blood, and other body fluids.
The three principal routes of transmission are Contact, vehicles, and vectors.
Toxins are harmful substances produced by pathogenic microorganisms that can damage host cells and tissues, leading to disease symptoms.
Adenoviruses appear as enlarged, rounded cells in grapelike clusters, with some producing a lattice-type arrangement of rounded cells. Development takes 4-7 days.
Coagulase is an extracellular enzyme that causes blood clotting.
M protein helps bacteria resist phagocytosis and improves adherence, as seen in Streptococcus pyogenes.
Fomites are inanimate objects or surfaces that can carry infectious agents and facilitate their transmission. Examples include bed rails, doorknobs, medical equipment, countertops, and light switches.
The study of the cause of disease.
A worldwide epidemic.
Lethal dose (of a toxin) = amount of toxin or pathogen necessary to kill 50% of the population in a particular time.
A change in body function that is felt by a patient as a result of disease.
There is no specific medication for treatment of a dengue infection. Persons should use analgesics with acetaminophen, avoid aspirin, rest, drink fluids, and consult a physician. Dengue hemorrhagic fever can be treated effectively with fluid replacement therapy if diagnosed early, but hospitalization is often required.
Capsules prevent phagocytosis, allowing bacteria like Streptococcus pneumoniae to evade the immune response.
Endotoxins are toxic substances bound to the bacterial cell wall and released when the bacteria die and the cell wall breaks apart.
Droplet transmission occurs when microbes are spread in airborne droplets or mucus that travel less than 1 meter from the reservoir, typically happening when people sneeze, cough, laugh, or talk.
The transmission of pathogens in foods that are incompletely cooked, poorly refrigerated, or prepared under unsanitary conditions.
The emphasis for dengue prevention is on sustainable, community-based, integrated mosquito control, with limited reliance on insecticides.
Toxins are poisonous substances produced by microbes that can cause damage to host cells.
A disease where symptoms develop rapidly but lasts only a short time, such as the common cold.
Residents are responsible for keeping their yards and patios free of sites where mosquitoes can be produced.
Infectious diseases that humans acquire from animal sources, with over 200 known zoonoses.
A measure or degree of pathogenicity.
Contact transmission requires close association between an infected and a susceptible host, which can occur through direct contact (e.g., handshaking) or indirect contact via fomites (e.g., tissues, needles, eating utensils, and money).
Pathogenic microorganisms are organisms that can cause disease in a host, including bacteria, viruses, fungi, and parasites.
Diseases that are not transmitted from one host to another.
Reservoirs are sources of microbes that cause infectious diseases, which can be human, animal, or non-living entities.
Immune evasion strategies are mechanisms used by pathogenic microorganisms to avoid detection and destruction by the host's immune system.
An abnormal state in which the body is not functioning normally.
Host antibodies can attach to the capsule of a microbe, facilitating phagocytosis by immune cells.
Adherence refers to the attachment between a microbe and host tissue, which is essential for infection.
Cytopathic effect (CPE) refers to the structural changes in host cells caused by viral infection, specifically in this case by Herpes Simplex Virus type 2 (HSV-2).
Diseases that can be transmitted from one human to another (i.e., person-to-person).
The development of disease.
Direct Damage refers to the killing of host cells through microbial metabolism and replication, as well as the penetration of pathogens through host cells causing damage.
Colonization of the body by pathogens.
Vector transmission is the process by which an animal, known as a vector, carries pathogens from one host to another, often involving insects like fleas and mosquitoes.
Exotoxins are poisonous proteins produced inside bacteria and released into host tissue, which are soluble in body fluids and rapidly transported throughout the body in blood or lymph.
Animal reservoirs refer to zoonotic diseases that may be transmitted to humans, such as Avian influenza (bird flu).
Kinases are enzymes that dissolve blood clots.
Portals of entry are the routes through which pathogens enter the human body, including orifices such as the respiratory tract, gastrointestinal tract, urogenital tract, skin, mucous membranes, and conjunctiva.
A disease that is constantly present in a particular area, such as the common cold.
Infectious dose = number of microbes required to produce infection in 50% of the population.
Pathogenic microorganisms cause diseases by invading host tissues, evading the immune system, and producing toxins or other harmful substances.
Skin serves as a barrier to microbes, with few able to grow on it; however, some microbes can gain access through hair follicles and sweat glands, especially if the skin is broken.
The spread of agents of infection by droplet nuclei in dust that travel more than 1 meter from the reservoir to the host, often occurring from sneezing and coughing.
Preventing epidemic disease requires a coordinated community effort to increase awareness about dengue/DHF, how to recognize it, and how to control the mosquito that transmits it.
CMV appears as plump, rounded cells in elongated foci parallel to the long axis of the cell. Development takes 7-10 days.
A disease that develops slowly and lasts for a long time, examples include Tuberculosis and hepatitis B.
A disease that has a period of no symptoms when the pathogen is inactive, with the potential to become active at some time.
An infection where pathogens are limited to a relatively small area of the body.
Factors in host susceptibility include age, immune status, and previous exposure to dengue virus serotypes.
Urine, semen, and vaginal secretions are common portals of exit for pathogens from the genitourinary tract.
Antigenic variation is the process by which a pathogen alters its surface antigens to escape attack by antibodies and immune cells.
The influenza virus undergoes constant genetic recombination, resulting in new spike proteins that cause new strains of flu.
A disease that presents no noticeable signs or symptoms.
The immune response is a specific defense mechanism involving the activation of lymphocytes and the production of antibodies to eliminate pathogens.
Endotoxins are part of the outer membrane of the cell wall of Gram-negative bacteria.
A disease acquired by many hosts in a given area in a short period of time, such as influenza.
The susceptible host is the human body, specifically someone who is at risk of infection. Infections may not occur even when pathogens enter a person with a normally functioning immune system, as the likelihood of infection depends on various factors related to the host, the pathogen, and the environment.
The likelihood of disease increases as the number of invading pathogens increases.
A change in a body that can be measured or observed as a result of disease.
Dengue hemorrhagic fever is a more severe form of dengue, characterized by a fever lasting from 2 to 7 days, followed by hemorrhagic manifestations such as easy bruising, bleeding nose or gums, and possibly internal bleeding.
Mechanical transmission is a method where a vector carries a pathogen on its feet to food, facilitating the spread of disease.
RSV shows syncytica, particularly in subconfluent HEp-2 cells, and may also appear as granular progressive degeneration. Development takes 3-5 days.
Non-living reservoirs include soil, water, food, air, dust, and fomites, which can transmit pathogens, such as cholera.
Modes of transmission refer to how the pathogen spreads from one host to another, primarily through the bite of infected mosquitoes.
Coughing or sneezing, which allows pathogens like the influenza virus to leave the body via respiratory droplets.
Collagenase breaks down collagen, which forms the connective tissue of muscles, skin, and other organs.
A biofilm is formed when microbes adhere to a moist surface containing organic matter, making them resistant to disinfectants and antibiotics.
Body secretions like saliva, sweat, tears, and gastric juices help to wash away pathogens and provide a hostile environment for them.
Blood can exit the body through biting arthropods and syringes or needles, facilitating the spread of pathogens.
The period of convalescence signifies when the individual feels better and returns to their prediseased state.
Granules found in the cytoplasm or nuclei of infected cells, indicative of viral infection.
LPS (lipopolysaccharide) can remain unaltered in sterile solutions even after bacteria die, making it essential to test medical devices and solutions for endotoxin due to its serious consequences at very low levels.
Gender is one of the factors that can influence an individual's risk for disease.
No, exotoxins do not typically cause fever.
The Parenteral Route refers to the entry of microorganisms through breaks in the skin, allowing microbes to be deposited directly into tissues beneath the skin or mucous membranes, such as through injections, bites, cuts, or surgery.
Humans can transmit diseases and may be ill themselves or asymptomatic; a carrier is a person colonized with a pathogen that is not currently causing disease.
Reservoirs of infection are the natural habitats where the pathogen lives and multiplies, often including mosquitoes like Aedes aegypti.
Dengue is transmitted to people by the bite of an Aedes mosquito infected with the dengue virus. The mosquito becomes infected after biting a person with dengue or dengue hemorrhagic fever and can transmit the virus to healthy individuals about a week later. Monkeys may serve as a reservoir in some regions.
Diagnosis of dengue infection requires laboratory confirmation, either by isolating the virus from serum within 5 days after onset of symptoms, or by detecting convalescent-phase specific antibodies obtained at least 6 days after onset of symptoms.
Waxes, such as those found in Mycobacterium tuberculosis, resist digestion by immune cells, aiding in bacterial survival.
The incubation period is the time between actual infection and the first appearance of signs or symptoms.
Residents of or visitors to tropical urban areas and other areas where dengue is endemic are at highest risk of becoming infected.
It is the easiest and most common portal of entry for pathogens because we breathe continuously.
The period of decline is when the individual begins to feel better after being ill.
An opportunistic infection that occurs after a primary (predisposing) infection.
A susceptible host is an individual who is at risk of infection due to a lack of immunity or other factors.
The process where neighboring cells fuse together, often as a result of viral infection.
Endotoxins are components of the outer membrane of Gram-negative bacteria, specifically Lipid A of Lipopolysaccharide (LPS).
Exotoxins are primarily proteins.
Endotoxins are heat stable, meaning they can withstand high temperatures.
Dengue is endemic in many tropical countries in Asia, Latin America, Africa, and the Caribbean, including Puerto Rico. Globally, an estimated 50 to 100 million cases occur each year, with periodic epidemics. The U.S. sees 100 to 200 suspected cases introduced annually by travelers.
Dengue and dengue hemorrhagic fever are caused by any one of four closely related flaviviruses, designated DEN-1, DEN-2, DEN-3, or DEN-4.
Portals of exit are the routes through which the pathogen leaves the reservoir, such as through the bite of an infected mosquito.
Portals of exit are specific routes through which pathogens leave the body, including secretions, excretions, discharges, or shed tissue.
An infectious agent is a pathogen that is present in sufficient numbers to cause infection.
A reservoir of infection is the natural habitat of the infectious agent where it lives, grows, and multiplies.
Virulent strains are capable of causing disease, whereas avirulent strains do not cause disease.
Cytotoxins are a type of exotoxin that kill or damage host cells.
A mode of transmission is the method by which an infectious agent is transferred from its reservoir to a susceptible host.
A portal of entry is the route through which an infectious agent enters a susceptible host.
Utilization of air conditioning or screened windows and doors reduces the risk of being bitten by mosquitoes indoors.
A portal of entry that bypasses the gastrointestinal tract, allowing pathogens to enter directly into the body, often through injections or wounds.
Endotoxins are composed of Lipid A of Lipopolysaccharide (LPS).
The Chain of Infection is an uninterrupted process that describes the development of an infection, consisting of six essential elements: infectious agent, reservoir of infection, portal of exit, mode of transmission, portal of entry, and susceptible host.
Biological transmission occurs when a pathogen reproduces within a vector and is passed to a new host through a bite.
Phenotypic characteristics of a microorganism that enable it to cause disease.
A susceptible host is an individual who is at risk of infection due to weakened defenses against pathogens.
The prodromal period is characterized by the development of mild signs and symptoms of some diseases.
An infection that spreads throughout the body.
An effect caused by viruses that leads to cell death in infected cells.
Neurotoxins are a type of exotoxin that affect the central nervous system.
Enterotoxins are exotoxins that affect the lining of the gastrointestinal tract, causing epithelial cells to discharge large amounts of fluids and electrolytes.
The inflammatory response is a protective reaction that occurs in response to tissue injury or infection, characterized by redness, heat, swelling, and pain.
Alterations on the surface of infected cells that can lead to their destruction by the immune system.
Factors that increase the risk for disease and make the body more susceptible to infections.
Exotoxins are toxic substances produced by both Gram-positive and Gram-negative bacteria, primarily released as by-products of growing cells.
Climate and environment are factors that can influence the risk of disease.
Yes, endotoxins are known to cause fever.
Endotoxins are components of the cell walls of Gram-negative bacteria, specifically the lipid portion of lipopolysaccharide in the cell wall known as lipid A.
A disease with symptoms that are between acute and chronic.
Portals of entry are the routes through which the pathogen enters a new host, typically through the skin via mosquito bites.
Saliva or feces serve as portals of exit for pathogens from the gastrointestinal tract.
A person who survives a bout of dengue caused by one serotype develops lifelong immunity to that serotype, but there is no cross-protection against the three other serotypes.
It is the second most favorable portal of entry because we eat and drink regularly, allowing pathogens to enter.
Lymphoid tissue plays a crucial role in the immune system by producing lymphocytes that help fight infections.
Interferon is produced by infected cells and triggers the host immune response against the virus.
The membrane covering the outer surface of the eyes, which can also serve as a portal of entry for pathogens.
The LAL assay is a test that uses horseshoe crab blood, which contains amoebocytes that will lyse and produce a clot in the presence of extremely low levels of LPS, indicating endotoxin presence.
Exotoxins are by-products of growing cells and are released into the surrounding environment.
No, endotoxins are not neutralized by antitoxins.
The six links in the Chain of Infection are: (1) infectious agent, (2) reservoir of infection, (3) portal of exit, (4) mode of transmission, (5) portal of entry, and (6) susceptible host.
Hyaluronidase hydrolyzes hyaluronic acid between cells, helping bacteria spread into surrounding tissues.
Epithelial tissue lining the respiratory, gastrointestinal, genitourinary tracts, and conjunctiva, serving as portals of entry for pathogens.
Visible signs or effects of viral infection that indicate the impact of viruses on host cells.
A portal of exit is the path by which an infectious agent leaves its reservoir to enter a susceptible host.
An acute infection that causes the initial illness.
A method of contamination where pathogens are transmitted through fecal material, playing an important role in the infection process.
It serves as the entry site for most sexually transmitted diseases (STDs).
Endotoxins are components of the bacterial cell wall that are released when bacteria die or lyse, and during bacterial multiplication, leading to various systemic effects.
Endotoxins stimulate macrophages to release high levels of cytokines, resulting in symptoms such as chills, fever, weakness, aches, blood clotting, tissue death, shock, and even death.
HSV presents clusters of rounded, ballooned cells with or without syncytica. Development takes 1-3 days.
Fomites are inanimate objects that can transmit pathogens and are commonly found in homes, offices, or hospitals.
Receptors are surface molecules on host cells that pathogens recognize and attach to, enabling infection.
Mechanical barriers include physical structures such as skin and mucous membranes that prevent pathogen entry.
During the period of illness, the individual is overtly ill, and the symptoms and signs of the disease are apparent.
Eliminating places where the Aedes aegypti mosquito lays her eggs, such as artificial containers that hold water, is the best preventive measure.
Items that collect rainwater or store water, like plastic containers and tires, can serve as breeding grounds for mosquitoes if not properly covered or discarded.
TSST-1 is an exotoxin produced by Staphylococcus that causes toxic shock syndrome.
The risk of dengue infection for international travelers appears to be small unless an epidemic is in progress.
Adhesins or Ligands are surface molecules on pathogens that bind specifically to host cell surface molecules, facilitating attachment.
They allow pathogens to survive and thrive in the host and make harmless organisms dangerous.
Exotoxins are toxic substances secreted by bacteria, which can be classified into various types based on their structure and functions, including cytotoxins, neurotoxins, and enterotoxins.
Hemolysins are enzymes that damage red blood cells.
Biofilms can cause problems for catheters and surgical implants as they serve as chronic reservoirs for infection.
Effects caused by viruses that result in damage to cells without causing cell death.
Normal flora refers to the beneficial microorganisms that reside in the body and help prevent the colonization of harmful pathogens.
Proper application of mosquito repellents containing 20% to 30% DEET on exposed skin and clothing decreases the risk of being bitten by mosquitoes.
Breakage and incorporation of oncogenes in the host cell's chromosomes, which can lead to cancer.
A person's immune, nutritional, and overall health status can influence their susceptibility to disease.
