Wildlife Disease Test 1

Etiology

The study of causation or origination of diseases.

Pathogenesis

The mechanisms that lead to the diseased state, including origin and development.

Vector

Any agent (human, animal, or microorganism) that carries and transmits an infectious pathogen into another living organism.

Vector-borne

Diseases caused by pathogens and parasites transmitted to humans through vectors.

Epidemiology

The study of the relationships of various factors determining the frequency and distribution of diseases in human communities.

Epidemic

The rapid spread of an infectious disease within a population within a short period of time.

Zoonosis

Infectious diseases of nonhumans that can be naturally transmitted to humans.

Epizootic

A sudden and unexpected outbreak of a disease in animals.

Avian Botulism

A disease caused by the ingestion of a toxin produced by Clostridium botulinum bacteria, affecting the nervous system and leading to paralysis in birds.

Rinderpest

A highly lethal plague known to cattle caused by the morbillivirus, transmitted through close direct or indirect contact.

Disease

Any impairment that interferes with or modifies the performance of normal functions, including response to environmental factors such as nutrition, toxicants, and climate; infectious agents; inherent or congenital defects; or combinations of these factors.

Impairment of function is a measurement of

Disease

Intrinsic and extrinsic factors

Disease can result from intrinsic factors such as inherited defects or degenerative changes due to age, or extrinsic factors such as viruses, bacteria, or contaminants that enter the body and cause injury.

Cost of disease

Diseases can have various impacts on different species and measuring disease can involve factors such as genetic diversity, energy allocation, and changes in energy use.

Epidemiological triangle

Concept that disease is the result of an interactive relationship among causative agent, animal, and environmental factors.

Causative agent

The organism or factor that causes a disease.

Zoonosis

A disease that can be transmitted between animals and humans.

Pathogenicity

The ability of a causative agent to cause disease.

Vector

An organism that can transmit a disease-causing agent from one host to another.

Case definition

A description of the criteria used to determine if an individual has a particular disease.

Primary cause

The principal factor contributing to the production of a disease.

Secondary cause

Additional factors that contribute to the production of a disease.

Predisposing causes

Factors that make an animal more susceptible to a specific disease without causing it.

Latent agents

Diseases caused by agents that may lie latent until precipitated by some other factor.

Chronic diseases

Diseases, such as neoplasia, where the cause is gone long before the disease occurs.

Ringworm in porcupines

A disease that causes severe lesions in porcupines and can lead to death if not treated. It is also zoonotic, meaning it can be transmitted to humans.

Transmission of diseases

The various ways in which diseases can be transmitted, such as person to person, rat to person, flea to person, flea to rat.

Nipah virus

A previously unknown virus that caused an outbreak in Malaysia in 1998, transmitted from pigs to people through direct contact, contaminated foods, and human to human.

Environmental changes and Nipah outbreak

Intense El Nino Southern Oscillation event, drought, and forest fires led to the destruction of fruit bat habitat, which contributed to the Nipah virus outbreak.

Hantavirus

A virus that causes severe, sometimes fatal hemorrhagic fever or pneumonia in humans, with higher incidence in environments severely disturbed by agriculture and with substantial loss of biodiversity.

Transmissible spongiform encephalopathies (TSE)

A group of diseases caused by prions, proteinaceous agents that lack nucleic acid and are categorized as non-infectious transmissible diseases.

Chronic Wasting Disease (CWD)

A neurological disease that affects deer, elk, and related species, caused by prions and transmitted through direct contact, environmental contamination, and contact with body fluids.

Direct and indirect life cycles

Parasites can have direct life cycles, transmitted directly between hosts, or indirect life cycles, requiring two or more hosts to complete their life cycle.

Obligate parasites

Parasites that require infection of an animal for their existence.

Winter tick

A tick species that impacts domestic livestock, deer, elk, bighorn sheep, and moose, causing anemia and death in ungulates.

Histomoniasis

A disease that infects gallinaceous birds and can have varying effects on populations, with severe disease occurring in some species like turkeys, grouse, and partridge.

Blackhead

A disease in birds characterized by listlessness, ruffled feathers, drooped wings, and sulfur-yellow feces. Also known as blackhead because it can cause cyanosis, although this is rare.

Heterakis gallinae

A cecal nematode (ascarid) that acts as a vector for blackhead disease in birds. It is responsible for the direct life cycle of the disease and can be carried by earthworms as a paratenic host.

Diagnostics for blackhead

Methods used to diagnose blackhead disease include microscopic examination for living flagellates/cysts, PCR, examination of cecal contents, and histopathology.

Control of blackhead disease

Blackhead disease can be controlled by not raising turkeys with chickens and implementing rotation pens. There are currently no treatments or drugs available for the disease.

Infection

The presence of an agent that has the ability to produce disease in or on an animal.

Infestation

The persistent presence of ectoparasites on an animal.

Disease

The occurrence of dysfunction caused by the presence of an organism.

Viruses

Infectious agents that contain either DNA or RNA, but never both. They are obligate parasites and form new virus particles called virions.

Ranavirus

A significant cause of mortality in frogs and toads, it can produce high mortality rates in tadpoles and adults.

Brucella

A gram-negative bacteria that can cause abortion, infertility, and neurological issues in various mammalian species. It is transmitted through ingestion, inhalation, and direct contact.

Fungi

Most disease-causing fungi are free-living saprophytes and opportunistic parasites. They can be spread through resistant spores and can cause chronic infections. Aspergillosis, caused by fungi in the genus Aspergillus, is a common mycotic infection in stressed birds.

Aspergillosis

A respiratory tract infection caused by a fungus that can be acute or chronic, commonly found in damp soils and decaying vegetation.

Transmission of aspergillosis

The spread of aspergillosis occurs through inhalation of spores or puncture wounds contaminated with spores.

Pathogenicity of aspergillosis

Inhaled spores of aspergillosis initiate a cellular response in the lungs, leading to air passage obstruction, respiratory difficulty, and eventually infection of other organs.

Clinical signs of aspergillosis

Symptoms of aspergillosis in birds include emaciation, weakness, open-mouth breathing, respiratory difficulty, and in later stages, diarrhea, vomiting, and neurological issues.

Aspergillosis signs

Acute forms of aspergillosis show deposits of fat, thickened air sacs, and dark red, firm lungs with yellow nodules. Chronic forms exhibit flattened, yellow cheesy-like lesions in the lungs and air sacs, as well as fungus growth on tissue.

Diagnosis of aspergilliosis

Aspergillosis can be diagnosed postmortem by observing typical lesions during necropsy or isolating the fungus from tissues.

Control of aspergilliosis

Spores of aspergillosis are widely distributed and can be found in moldy feeds, unclean brooders and incubators, and rotting agricultural waste. Regular cleaning of feeding stations is recommended to prevent infection.

Chytridiomycosis

A fungal disease that infects amphibians and is caused by Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal). It can lead to population declines, extirpation, and extinction.

Clinical signs of chytrid

Chytridiomycosis in amphibians can cause anorexia, lethargy, excessive shedding of the skin, muscle incoordination, dehydration, and death.

Control of chytrid

Effective control methods for chytridiomycosis in free-living populations have not been developed yet. Diagnosis can be done through the identification of stained spores, histology, cultures, positive antigen, and PCR.

Protozoa

Single-celled eukaryotic organisms, many of which are parasitic in vertebrates and invertebrates. They can have complex life cycles and some require multiple hosts to complete their life cycle.

Toxoplasmosis

A disease caused by the protozoan parasite Toxoplasma gondii, which affects a wide range of warm-blooded vertebrate hosts. Transmission occurs through ingestion of infective oocysts, cysts containing bradyzoites, or transplacental transmission.

Clinical signs of toxo

Toxoplasmosis can cause necrotizing encephalitis, pneumonia, hepatitis, and other manifestations depending on the host species. It can lead to severe population declines, extirpation, and extinction.

Species other than cats affected by toxo

Nearly any warm-blooded animal, including birds and mammals.

Macroparasites

Parasites that cause chronic infections and are typically long-lived.

Intensity of infection in protozoan infections is correlational to:

The number of parasites present.

Aggregated distribution

Parasites are usually concentrated in certain individuals.

Transmission

The small proportion of individuals with a high parasite load are responsible for the majority of parasite transmission.

Cysticercosis

A parasitic infection caused by the larval stage of the pork tapeworm, Taenia solium, which can occur in various tissues of the body.

Neurocysticercosis

A form of cysticercosis that affects the central nervous system and can cause neurological symptoms.

Clinical signs in humans of cystercycosis

Symptoms of cysticercosis in humans, including fever, headache, nausea, vomiting, seizures, and altered mental state.

Disseminated cysticercosis

A rare complication of cysticercosis where the infection can involve any organ and diffuse throughout the body.

Noninfectious transmissible diseases

Diseases caused by non-living factors, such as misfolded prion proteins, which can lead to conditions like Chronic Wasting Disease (CWD) and Creutzfeldt-Jacob disease.

Noninfectious causes of disease

Conditions not caused by living organisms, including genetic disorders, physical agents, deficiency of required nutrients, chemicals, and diseases of unknown causation.

Lead poisoning

Poisoning caused by ingestion of lead, which can affect various species, including birds and raptors.

Symptoms of lead poisoning in birds

Abnormal wing positions, bright green feces, paralysis of the digestive tract, seclusion, inability to fly, staggering gait, muscle wasting, coma, and death.

Necropsy findings in lead poisoning

Severe wasting of breast muscle, absent or reduced visceral fat, liver atrophy, enlarged gall bladder, impacted esophagus or gizzard, presence of lead pellets or particles, and signs of heart damage.

Pathogenesis

The biological mechanisms that lead to a diseased state, caused by multiple factors or processes and can be acute, chronic, or recurrent.

Virulence

The degree of pathogenicity of a microorganism, indicated by case fatality rates and/or its ability to invade the tissues of the host. It consists of infectivity, invasiveness, and pathogenicity.

Coincidental virulence

Noninfectious diseases that cause harm or cost to the affected animal, such as lead poisoning or traumatic injuries.

Behavioral avoidance

A defense mechanism where animals avoid contact with potential disease-causing agents through behaviors such as moving to different locations or avoiding dead animals.

Physical barriers

Physical structures or mechanisms that act as barriers to prevent the entry of pathogens into the body, such as mucus in the nasal cavity or acid in the stomach.

Innate responses

Non-specific immune responses that provide general protection against foreign threats, including inflammation and the removal of invaders.

Acquired immune responses

Specific immune responses that involve the recognition of individual invaders or foreign substances and the ability to remember and recognize them if encountered again. It includes humoral immunity (B-lymphocytes producing antibodies) and cell-mediated immunity (T-lymphocytes targeting and destroying infected or cancerous cells).

Trichinosis

A parasitic disease caused by the ingestion of Trichinella larvae through undercooked meat. It can affect both wildlife and humans, and diagnosis is done through direct examination of tissue or serological tests.

Heartwater

A tick-borne disease caused by the bacteria Ehrlichia ruminantium, characterized by fever, neurological signs, and high mortality rates in ruminants.

Leptospirosis

A bacterial infection caused by Leptospira bacteria, transmitted through contact with contaminated water, soil, or infected animals, and can cause a wide range of symptoms in humans.

Weil's disease

A severe form of leptospirosis characterized by kidney or liver failure, meningitis, respiratory distress, and potential death.

4 concepts to understand disease

1. Disease can be measured by impairment.

2. Disease can be genetic or environmental.

3. Diseases can have multiple cofactors

4. Damaged/altered functions in disease can be subtle

Three measures of a pathogenic disease

Infectivity, invasiveness, and pathogenicity.

Three factors in determining outcome between agent and animal

1. Amount of agent

2. Type of exposure

3. Degree of resistance

Three general types of causes

1. Primary cause

2. Secondary case

3. Predisposing cause

Symptoms of rinderpest

Necrotic lesions, anorexia, diarrhea

4 complications of determining causation of disease

1. Some agents will cause disease in some circumstances yet not others.

2. Some agents can lie dormant.

3. In chronic disease, the agent may be long gone.

4. Some diseases can result from a myriad of causes.

Unique pathogenic trait of protozoan infections

Intensity of infection (number of parasites) is directly correlated with severity of disease presented.

4 lines of defense against infectious disease

1. Behavioral avoidance

2. Physical barriers

3. Innate responses

4. Acquired immune responses

What kind of virulence do prions have?

Coincidental virulence

Primary defense against pathogens

Skin

Two main components of acquired (“specific”) immunity

1. Humoral defenses (B-cells produce antibodies).

2. Cell-mediated defenses (T-cells directly or indirectly attack or trigger attacks towards targets).

Increased white blood cell titers indicate:

An infection

Method of leveling antibodies present

Serology

5 factors that suppress immune function

1. Prior infections or coinfections.

2. Nutrition

3. Stress

4. Environmental contaminants

5. Gender of animal

Common event associated with zoonotic events of Leptospirosis

Floods