Terms in Fish Pathology

Immunology

Clinical Immunology is concerned with the diagnosis and management of diseases arising from abnormal immune responses. In broad terms, these abnormalities may be the result of either under activity (immunodeficiency) or over activity (autoimmunity and allergy) of the immune system.

Pathology

is a medical specialty looking at disease processes and their cause. Body tissue, blood and other bodily fluids are analysed to assist medical practitioners in identifying the cause and severity of disease, and to monitor treatment. Pathology is the study and diagnosis of disease through examination of organs, tissues, bodily fluids and whole bodies (Autopsy). The term also encompasses the related scientific study of disease processes, called General pathology.

Pathogen

(from Greek pathos, suffering/emotion, and gene, to give birth to), infectious agent, or more commonly germ, is a biological agent that causes disease or illness to its host.^[1] The term is most often used for agents that disrupt the normal physiology of a multicellular animal or plant. a disease-producing agent; usually applied to a living organism. Generally, any viruses, bacteria, or fungi that cause disease.

A disease

is an abnormal condition of an organism that impairs bodily functions,^[1] associated with specific symptoms and signs.

which are easily recognizable on the outside of a fish include fin erosion and ulcers.

An infectious disease

is a clinically evident disease resulting from the presence of pathogenic microbial agents, including pathogenic viruses, pathogenic bacteria, fungi, protozoa, multicellular parasites, and aberrant proteins known as prions. These pathogens are able to cause disease in animals and/or plants.

Infectious pathologies are usually qualified as contagious diseases (also called communicable diseases) due to their potentiality of transmission from one person or species to another.^[1] Transmission of an infectious disease may occur through one or more of diverse pathways including physical contact with infected individuals. These infecting agents may also be transmitted through liquids, food, body fluids, contaminated objects, airborne inhalation, or through vector-borne spread.^[2]

A non-infectious disease

is a disease that may be caused by the environment (e.g skin cancer from radiation from the Sun) or from what we eat (e.g food poisoning) or malnutrition, lack of food (e.g Scurvy from lack of Vitamin C). Non-Infectious diseases can also be caused by genetic factors.

 

A symptom

(from Greek
σύμπτωμα) is a manifestation of a disease, indicating the nature of the disease, which is noticed by the patient. This may be contrasted to signs which are observed by a medical practitioner. A symptom is subjective,^[1] observed by the patient,^[2] and not measured.^[3]

syndrome

A set of symptoms or conditions that occur together and suggest the presence of a certain disease or an increased chance of developing the disease. A group of signs and symptoms that collectively define or characterize a disease or disorder; signs are objective findings such as weakness, and symptoms are subjective findings such as a feeling of fear or tingling in a finger.

An infection

is the detrimental colonization of a host organism by a foreign species. In an infection, the infecting organism seeks to utilize the host’s resources to multiply (usually at the expense of the host). The infecting organism, or pathogen, interferes with the normal functioning of the host and can lead to chronic wounds, gangrene, loss of an infected limb, and even death. The host’s response to infection is inflammation. Colloquially, a pathogen is usually considered a microscopic organism though the definition is broader, including feces, parasites, fungi, viruses, prions, and viroids.

a diagnosis

(plural diagnoses) has two distinct dictionary definitions. The first definition is “to recognize a disease or condition by its outward signs and symptoms”, while the second definition is “to analyze the underlying physiological/biochemical cause(s) of a disease. The nature of a disease; the identification of an illness.

ETIOLOGY

the cause or origin of disease. The study or theory of the factors that cause disease. Cause or origin. Specifically, all the causes of a disease or abnormal condition. Etiology: The study of the causes. For example, of a disorder. The word “etiology” is mainly used in medicine, where it is the science that deals with the causes or origin of disease, the factors which produce or predispose toward a certain disease or disorder. simply means the “study of first things.”. It is commonly used as a label for stories which are supposed to explain origins, such as origins of an ethnic group, a religion, or even of reality itself. There is also what is known as the etiological argument, an argument for the existence of god more commonly called the cosmological argument and which starts from the assumption of the existence of a First Cause and works from there. Etiology (alternately aetiology, aitiology) is the study of causation. The word is most commonly used in medical and philosophical theories, where it is used to refer to the study of why things occur, or even the reasons behind the way that things act, and is used in philosophy, physics, psychology, government, and medicine, and biology in reference to the causes of various phenomena.

ep·i·zo·ot·i·ol·o·gy

1. The science dealing with the character, ecology, and causes of diseases in animals, especially epizootic diseases.

2. The sum of the factors controlling the presence of a disease in an animal population.

• is a science which studies origin, distribution, frequency, development, determinants and extinction of animal health and disease at population level and based on their analyses defines and applies methods for creation, promotion, protection and restoration of population health by reducing, eliminating and eradicating diseases
  

Epidemic

affecting or tending to affect a disproportionately large number of individuals within a population, community, or region at the same time <typhoid was epidemic>. In epidemiology, an epidemic (from Greek
epi- upon + demos people) is a classification of a disease that appears as new cases in a given human population, during a given menistral period, at a rate that substantially exceeds what is “expected,” based on recent experience (the number of new cases in the population during a specified period of time is called the “incidence rate”). (An epizootic is the same thing but for an animal population.) The disease may or may not be contagious.

Endemic

in a broad sense, can mean “belonging” or “native to”, “characteristic of”, or “prevalent in” a particular geography, race, field, area, or environment; native to an area or scope.It also has two specific meanings:

• Endemism, an organism being “endemic” means exclusively native to a place or biota
  

• Endemic (epidemiology), an infection is said to be “endemic” in a human population when that infection is maintained in the population without the need for external inputs.
  
• Common diseases that occur at a constant but relatively high rate in the population are said to be “endemic.” An example of an endemic disease is malaria in some parts of Africa (for example, Liberia) in which a large portion of the population is expected to get malaria at some point in their lifetimes.
  
  • AN epidemic has occurred in a fish culture of Tilapia mossambica in Southern Rhodesia during June 1954. The disease had a mortality of more than 90 per cent of the exposed population.
    

  a chronic disease
  

  is a disease that is long-lasting or recurrent. The term chronic describes the course of the disease, or its rate of onset and development. A chronic course is distinguished from a recurrent course; recurrent diseases relapse repeatedly, with periods of remission in between. As an adjective, chronic can refer to a persistent and lasting medical condition. Chronicity is usually applied to a condition that lasts more than three months.
  

  an acute
  

  disease is a disease with either or both of:
  

1. a rapid onset;
   
2. a short course (as opposed to a chronic course).
   

This adjective is part of the definition of several diseases and is, therefore, incorporated in their name, for instance, severe acute respiratory syndrome, acute leukemia. The term acute may often be confused by the general public to mean ‘severe‘. This however, is a different characteristic. Acute hospitals are those intended for short-term medical and/or surgical treatment and care. Subacute is defined as ‘between acute and chronic: subacute fever symptoms; subacute endocarditis.’

Bleeding,

technically known as hemorrhage (American English), haemorrhage (British English), or hæmorrhage, is the loss of blood from the circulatory system.^[1] Bleeding can occur internally, where blood leaks from blood vessels inside the body or externally, either through a natural opening such as the vagina, mouth or anus, or through a break in the skin.

Necrosis

(in Greek Νεκρός = Dead) is the name given to accidental death of cells and living tissue. It begins with cell swelling, chromatin digestion, and disruption of the plasma membrane and organelle membranes. Late necrosis is characterized by extensive DNA
hydrolysis, vacuolation of the endoplasmic reticulum, organelle breakdown, and cell lysis. The release of intracellular content after plasma membrane rupture is the cause of inflammation in necrosis.

In contrast to apoptosis, cleanup of cell debris by phagocytes of the immune system is generally more difficult, as the disorderly death generally does not send cell signals which tell nearby phagocytes to engulf the dying cell. This lack of signaling makes it harder for the immune system to locate and recycle dead cells which have died through necrosis than if the cell had undergone apoptosis.

Hypertrophy

The enlargement or overgrowth of an organ or part due to an increase in size of its constituent cells. Hypertrophy is the increase of the size of an organ or in a select area of the tissue. It should be distinguished from hyperplasia which occurs due to cell division increasing the number of cells while their size stays the same; hypertrophy occurs due to an increase in the size of cells, while the number stays the same.excessive development of an organ or part; specifically
: increase in bulk (as by thickening of muscle fibers) without multiplication of parts.  exaggerated growth or complexity. e.g; Muscular hypertrophy, Ventricular hypertrophy etc.

 

Hyperplasia

(or “hypergenesis”) is a general term referring to the proliferation of cells within an organ or tissue beyond that which is ordinarily seen in e.g. constantly dividing cells. Hyperplasia may result in the gross enlargement of an organ, the formation of a benign tumor, or may be visible only under a microscope. Hyperplasia is considered to be a physiological response to a specific stimulus, and the cells of a hyperplastic growth remain subject to normal regulatory control mechanisms. This stands in contrast to neoplasia (the process underlying cancer and some benign tumors), in which genetically abnormal cells proliferate in a non-physiological manner which is unresponsive to normal stimuli.^[1] Hyperplasia is a fancy way of saying abnormal increase in cell numbers or cell numbers “gone wild” leading to a size increase of the affected tissue or organ; it can also be used as another term for benign growth, or tumor. Hyperplasia can be induced by many things, including chronic inflammation, hormone dysfunction, and irritants of many sorts. In humans some examples of hyperplasia are calluses (from abrasion), lipomas (fatty tumors), endometrial hyperplasia, and benign prostatic hyperplasia (BPH). Hyperplasia in fish is the fish’s response (1) to ward off or block something that irritates its tissues, whether externally or internally, or (2) to quickly heal an injured or irritated site. Localized hyperplasia can encapsulate holdfasts of parasites, and whole parasites such as ICH. If the irritant is in the water, more sensitive tissue like gill epithelium is usually affected first and worst. If hyperplasia is observed externally on the fish, then one might expect the gills to be in fairly bad shape with hyperplasia; such fish should not be bought, as they may not live long due to oxygen starvation. If the irritant, or toxin, is not strong enough to kill the fish, then hyperplasia may be induced. Hyperplasia can be accompanied by increased mucus production induced by the irritant; this additional mucus may also reduce oxygen uptake.

Hyperemia

Hyperemia is a condition in which blood congests in a particular area of the body. Hyperemia can be either active or reactive. Active hyperemia takes place during muscle contraction, which has earned it additional names, such a functional hyperemia and exercise hyperemia. Other cause of active hyperemia include an increase in mental, cardiac, or gastrointestinal activity. Active hyperemia becomes evident within seconds of increasing tissue metabolism, which also increases blood flow. This increased blood flow returns to normal when the metabolism is restored to normal. The severity of the active hyperemia is determined by the how much the metabolic activity is increased. With reactive hyperemia, also referred to as passive hyperemia, blood collects in an organ of the body in response to a blockage in the veins that are supposed to move the blood out. Reactive hyperemia usually takes place after a person experiences a period of ischemia, such as arterial occlusion. This leads to a shortage of oxygen, as well as an increase in the amount of metabolic waste that builds up in the organ. describes the increase of blood flow to different tissues in the body. It can have medical implications, but is also a regulatory response, allowing change in blood supply to different tissues through vasodilation.

Viral nervous necrosis disease (VNN)

has been reported in marine fishes such as parrot fish, groupers, flounders, sea bass, turbot, and striped jack since 1990. This disease caused high mortalities in the affected animals that were characterized by vacuolation in the retinal and brain tissue. Now, the causative agents of VNN were identified as a member of the family Nodaviridae. Even the nucleic acid sequences between fish nodaviruses are distinguishable, but they are closely related to each other in the coat protein region. IQ2000^TM VNN Detection and Prevention System is designed by this conserved region and it can detect the nervous necrosis viruses on striped jack (SJNNV), redspotted grouper (RGNNV), barfin flounder (BFNNV), Japanese flounder (JFNNV), and tiger puffer (TPNNV), and most kinds of the groupers in Taiwan.

Septicemia

is the presence of bacteria in the blood (bacteremia) and is often associated with severe disease. Septicemia is a serious, life-threatening infection that gets worse very quickly. It can arise from infections throughout the body, including infections in the lungs, abdomen, and urinary tract. It may come before or at the same time as infections of the bone (osteomyelitis), central nervous system (meningitis), or other tissues. The symptoms rapidly progress to shock with decreased body temperature (hypothermia), falling blood pressure, confusion or other changes in mental status, and blood clotting problems hat lead to a specific type of red spots on the skin (petechiae and ecchymosis). Septicemia is an infection located in the bloodstream. It can occur when an open wound gets infected or as a result of consuming bacteria through food. It can present itself in many ways, some of which are more obvious then others. Commonly, septicemia will occur as a result of an injury or open wound. Just as it’s important that we keep our cuts clean when we injure ourselves, it is equally important to keep a fish’s water clean when they are injured. If your fish becomes wounded (hurts itself, or fights with another fish) make sure you increase your water changes and keep toxins at bay by testing ammonia, nitrite and nitrate levels.

Fish may also acquire symptoms by eating foods infected with bacteria. To reduce the chances of sepsis caused by food bourn pathogens use caution when feeding live and frozen foods. Only buy live foods like blackworms and tubifex worms from a reputable source and take care of them by washing them well daily. Consider growing your own cultures as an alternative to buying live foods. If you keep frozen foods, never refreeze them after they thaw and throw away any thawed food after one day.

Sepsis

is a serious medical condition characterized by a whole-body inflammatory state caused by infection.

Sepsis is broadly defined as the presence of various pus-forming and other pathogenic organisms, or their toxins, in the blood or tissues.^[1] While the term sepsis is frequently used to refer to septicemia (blood poisoning), septicemia is but one type of sepsis.^[1][2]
Bacteremia specifically refers to the presence of bacteria in the bloodstream (viremia and fungemia are analogous terms for viruses and fungi). Bacteremia does not necessarily cause sepsis.

Edema

(American English), or œdema (British English), formerly known as dropsy or hydropsy, is the increase of interstitial fluid in any organ — swelling. Generally, the amount of interstitial fluid is determined by the balance of fluid homeostasis, and increased secretion of fluid into the interstitium or impaired removal of this fluid may cause edema. Edema has five pathophysiologic causes. It can be due to increased hydrostatic pressure, reduced oncotic pressure, lymphatic obstruction, sodium retention, or inflammation.^[1]

ascites

(also known as peritoneal cavity fluid, peritoneal fluid excess, hydroperitoneum or more archaically as abdominal dropsy) is an accumulation of fluid in the peritoneal cavity. Although most commonly due to cirrhosis and severe liver disease, its presence can portend other significant medical problems. Diagnosis of the cause is usually with blood tests, an ultrasound scan of the abdomen and direct removal of the fluid by needle or paracentesis (which may also be therapeutic). Treatment may be with medication (diuretics), paracentesis or other treatments directed at the cause.

Inflammation

(Latin, inflammatio, to set on fire) is the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. It is a protective attempt by the organism to remove the injurious stimuli as well as initiate the healing process for the tissue. Inflammation is not a synonym for infection. Even in cases where inflammation is caused by infection it is incorrect to use the terms as synonyms: infection is caused by an exogenous pathogen, while inflammation is the response of the organism to the pathogen. Inflammation can be classified as either acute or chronic. Acute inflammation is the initial response of the body to harmful stimuli and is achieved by the increased movement of plasma and leukocytes from the blood into the injured tissues. A cascade of biochemical events propagates and matures the inflammatory response, involving the local vascular system, the immune system, and various cells within the injured tissue. Prolonged inflammation, known as chronic inflammation, leads to a progressive shift in the type of cells which are present at the site of inflammation and is characterised by simultaneous destruction and healing of the tissue from the inflammatory process.

A lesion

is any injury or wound. It can also be described as a circumscribed area of diseased tissue or an isolated patch or infected area on the skin or elsewhere on the body. Throughout this website, lesion refers to any area of pathology (disease) – either internal or external. Disease in fish (as in other animals) can manifest itself in many ways. Sometimes lesions are not externally obvious. An example of a lesion which is readily seen on the outside of a fish includes gill hyperplasia.

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