Small and Large Animal Diseases

Instructions
There will be two components to this research project:
1. A written research paper
2. A PowerPoint presentation to accompany the research paper
Part 1: Research Paper
A. Your research paper must contain a total of 10 diseases from the list of diseases below and according to the classifications listed below.
1. Species Classifications - Your paper must include 2 diseases for each of the following species:
a. Canine
b. Feline
c. Equine
d. Ruminant or swine
e. Exotics (can include avian, amphibian, reptile, or pocket pets)
2. Disease classifications - Choose the type and number of diseases as listed below:
a. Infectious / contagious (2)
b. Parasitic (2)
c. Immune-mediated (1)
d. Congenital / genetic (1)
e. Neoplastic (1)
f. Metabolic (1)
g. Toxic (1)
h. Degenerative or idiopathic (1)
B. Information to include for each disease
a. Causative agent/organism or mechanism
b. Main species affected
i. Select one species and discuss in detail the effects on that species
ii. Briefly mention other species that can be affected
c. Clinical signs and symptoms
. Discuss the primary signs of the condition as well as any secondary signs or conditions associated with it
d. Diagnostic tests
. Discuss the tests used to diagnose the conditions, including how the results of those tests confirm a diagnosis
e. Treatments
. List in detail all available treatments and what the prognosis may be
f. Prevention and/or control programs
. Vaccination
1. If there’s a vaccine available for the disease, explain the vaccine type used, its protocol, and how it works to create immunity. Discuss potential complications and failure of immune response, and why this would occur.
i. Zoonotic / contagious
1. If the disease has zoonotic potential, describe the occupational safety measures that need to be taken while in contact with the diseased animal. Also discuss educating owners on safety when they are caring for a pet with a zoonotic disease.
2. When discussing infectious diseases, explain how to prevent the spread to other animals in the hospital or herd.
Use the table on page 10 to help you organize your project.
INFECTIOUS/CONTAGIOUS
CHOOSE TWO DISEASES.
Anthrax
Aspergillosis
Avian influenza
Blastomycosis
Borreliosis (lyme disease)
Bovine spongiform encephalopathy
Brucellosis
Caprine arthritisencephalitis (CAE)
Caseous lymphadenitis
Chlamydia
Contagious tracheobronchitis (kennel cough)
Dermatophytosis (ringworm)
Equine infectious anemia
Equine influenza
Equine viral arteritis
Erysipelas Feline immunodeficiency virus (FIV)
Feline leukemia virus (FeLV)
Histoplasmosis
Leptospirosis
Newcastle’s disease
Pacheco’s disease
Panleukopenia
Paratuberculosis (Johne’s disease)
Parvovirus
Psittacosis
Q fever
Rabies
Salmonella
Scrapie
Streptococcus equi (Strangles)
Tetanus
Tyzzer’s disease
PARASITIC
CHOOSE TWO DISEASES.
Anoplura
Babesiacanis
Cheyletiella
Cnemidocoptespilae
Cryptosporidium
Ctenocephalides spp
Demodicosis
Dictyocaulus spp.
Dipylidiumcaninum
Dirofilariaimmitis Eimeria spp.
Fasciola hepatica
Giardia
Mallophaga
Oxyurisequi
Porocephaluscrotali
Rhipicephalussanguineus
Sarcoptes
Strongylus vulgaris
Taenia spp.
Toxoplasma gondii
Trichinellaspiralis
IMMUNE-MEDIATED
CHOOSE ONE DISEASE.
Atopic dermatitis
Equine immune-mediated myofascial syndrome
Equine recurrent uveitis (moonblindness)
Flea allergy dermatitis
Immune-mediated hemolytic anemia (IMHA) Immune-mediated polyarthritis/rheumatoid arthritis
Keratoconjunctivitissicca (KCS)
Lupus
Myasthenia gravis
Pannus
Pemphigus
CONGENITAL/GENETIC
CHOOSE ONE DISEASE.
Brachycephalic airway syndrome
Cleft palate
Congenital heart defects
Cryptorchidism
Entropion/ectropion
Hip dysplasia
Hydrocephalus
Panosteitis
Progressive retinal atrophy
Von Willebrand’s disease
NEOPLASTIC
CHOOSE ONE DISEASE.
Hemangiosarcoma
Lymphoma
Mammary gland tumors
Mast cell tumor
Melanoma Osteosarcoma
Sertoli cell tumor
Squamous cell carcinoma
Vaccine-related fibrosarcoma
METABOLIC
CHOOSE ONE DISEASE.
Addison’s disease
Bovine acetonemia (ketosis)
Cushing’s disease
Diabetes insipidus
Diabetes mellitus
Exertional rhabdomyolysis Exocrine pancreatic insufficiency
Hyperthyroidism
Hypocalcemia (milk fever in cattle/eclampsia in small animals)
Hypothyroidism
Scurvy
TOXIC
CHOOSE ONE DISEASE.
Acetaminophen
Anticoagulant rodenticide toxicity
Cyanide toxicity
Ethylene glycol Fescue toxicosis
Lead toxicity
Organophosphate toxicity
Theobromine
DEGENERATIVE/IDIOPATHIC
CHOOSE ONE DISEASE.
Aseptic femoral head necrosis
Degenerative myelopathy
Dilated cardiomyopathy
Eosinophilic ulcer (rodent ulcer)
Feline lower urinary tract disease (FLUTD)
Gastric dilatation and volvulus (GDV)
Hemorrhagic gastroenteritis (HGE)
Hypertrophic cardiomyopathy
Idiopathic epilepsy Intervertebral degenerative disc disease (IVDD)
Laminitis
Lenticular sclerosis
Megacolon/megaesophagus
Navicular disease
Osteoarthritis
Puppy strangles
Wobblers
Project Specifications
A. The Research Paper
1. The research paper must be word-processed.
2. The title page should contain the following information:
a. The title: VET224 Research Project
b. Name
c. Student number
d. The date the project is submitted
3. The paper should be easy to read size 12 font, double spacing, correct spelling, grammar, and sentence and paragraph structure. This includes the use of proper medical terminology as well as introduction and closing paragraphs.
4. The research paper should include at least five references. The information must be supported by trusted veterinary medical publications and websites.
5. Your references must be listed in APA format
B. The PowerPoint Presentation
1. Summarize the important points of your research paper as a PowerPoint presentation.
2. Utilize a title slide with the same information as your research paper title page.
3. Slide content should follow the same order as your research paper content. A slide with your references should also be included at the end.
4. Make sure the content is concise and easy to read and interpret. Do not crowd information on a slide.
5. Your PowerPoint must include pictures, graphs, tables, or other visuals to help illustrate the conditions being discussed. On slides with images, be sure to have a citation indicating the image’s source.
6. This presentation shouldn’t be an exact copy of your research paper. Summarize the information.
Grading Criteria
The following rubric will be used to grade your project.
Research Paper: 75 points
Objective Max. points A B C D
Identify and explain the causative agent/organism and mechanism of each disease 10 10–9 points: Causative agent/organism and mechanism of disease was correctly identified and explained correctly in maximum detail. 8 points: Causative agent/organism and mechanism of disease was correctly identified and explained correctly in adequate details. 7 points: Causative agent/organism and mechanism of disease was correctly identified but contained minimal explanation. 6–0 points: Causative agent/ organism and mechanism of disease was incorrectly identified, or the explanation was incomplete or incorrect.
Identify the main species and summarize other species that are affected by each disease 10 10–9 points: Main species were correctly identified and remained the focus for each disease.
Other applicable species were also correctly identified for each disease. 8 points: Main species were correctly identified and remained the focus for each disease.
Other applicable species weren’t identified for each disease. 7 points: Main species were correctly identified for each disease, but there were diseases where the main species didn’t remain the focus of the disease. Other applicable species were correctly identified and became the focus of some diseases. (e.g.: you state that Rabies is an infectious disease in dogs but then provide descriptions about cats throughout that part of
the paper) 6–0 points: Main species wasn’t correctly identified (e.g.: disease doesn’t affect the species used as the focus of
the disease)
Identify and explain the clinical signs and symptoms of each disease 10 10–9 points: All clinical signs and symptoms were correctly identified and explained in maximum professional detail.
Student took the extra step and explained the clinical signs in their own words, showing their understanding of the information they used from their sources. 8 points: Most clinical signs and symptoms were correctly identified and explained in adequate understandable detail. Only reference material was used, no additional explanation given. 7 points: Some clinical signs and symptoms were correctly identified and were explained in minimal or vague detail. 6–0 points: Few to no clinical signs and symptoms were correctly identified. Explanation was incorrect or was explained with incomplete or unclear details.
Identify and explain
diagnostic tests available for each disease 10 10–9 points: All diagnostic tests were correctly identified and the tests were explained with maximum detail. 8 points: Most of the diagnostic tests were correctly identified and explained with adequate understandable details. 7 points: Some of the diagnostic tests were correctly identified and explained with minimal or vague details. 6–0 points: Few to no diagnostic tests correctly identified. Explanation was incorrect or was explained with incomplete or unclear details.
Identify and explain the treatments and prognosis of each disease 10 10–9 points: Treatment and prognosis were correctly identified and the tests were explained with maximum detail. 8 points: Most disease prevention and infection control measures (at home/farm; in hospital; in the herd) were correctly identified and discussed with adequate understandable details. Vaccine availability was explained with adequate understandable details for each disease. Zoonotic potential was correctly identified and explained with adequate understandable details for each disease. (If a disease doesn’t have a vaccine or if it doesn’t have zoonotic potential these facts were stated and explained
with adequate detail for the disease). 7 points: Some disease prevention and infection control measures (at home/farm; in hospital; in the herd) were correctly identified
and discussed with minimal or vague details. Vaccine availability was explained with minimal or vague details for each disease. Zoonotic potential was correctly identified and explained with minimal or vague details for each disease. (If a disease doesn’t have a vaccine or if it doesn’t have zoonotic potential these facts were stated but not explained for
the disease). 6–0 points: Disease prevention and infection control measures (at home/farm; in hospital; in the herd) were incorrect or weren’t identified. Discussion was incorrect, incomplete or unclear. Vaccine availability wasn’t identified or explained for each disease. Zoonotic potential wasn’t identified or explained for each disease. (If a disease didn’t have a vaccine or if it didn’t have zoonotic potential these facts weren’t stated for the disease).
Prevention and infection control measures are identified and discussed for each disease. (This includes vaccine availability and zoonotic potential of each disease.) 10 10 – 9 points: Disease prevention and infection control measures (at home/farm; in hospital; in the herd) were correctly identified and discussed in maximum detail. Vaccine availability was explained in maximum detail for each disease. Zoonotic potential was correctly identified and explained with maximum detail for each disease. (If a disease doesn’t have a vaccine or if it doesn’t have zoonotic potential these facts were stated and explained in maximum detail
for the disease). 8 points: Most disease prevention and infection control measures (at home/farm; in hospital; in the herd) were correctly identified and discussed with adequate understandable details. Vaccine availability was explained with adequate understandable details for each disease.
Zoonotic potential was correctly identified and explained with adequate understandable details for each disease. (If a disease doesn’t have a vaccine or if it doesn’t have zoonotic potential these facts were stated and explained with adequate detail for
the disease). 7 points: Some disease prevention and infection control measures (at home/farm; in hospital; in the herd) were correctly identified and discussed with minimal or vague details.
Vaccine availability was explained with minimal or vague details for each disease. Zoonotic potential was correctly identified and explained with minimal or vague details for each disease. (If a disease doesn’t have a vaccine or if it doesn’t have zoonotic potential these facts were stated but not explained for
the disease). 6–0 points: Disease prevention and infection control measures (at home/farm; in hospital; in the herd) were incorrect or weren’t identified. Discussion was incorrect, incomplete or was unclear.
Vaccine availability wasn’t identified or explained for each disease. Zoonotic potential wasn’t identified or explained for each disease. (If a disease didn’t have a vaccine or if it didn’t have zoonotic potential these facts weren’t stated for
the disease).
Written communication 15 15–14 points: Writing was easy to understand, and the paper was well organized. No spelling or grammatical errors.
Proper sentence and paragraph structure.
No slang word or abbreviations used (without definitions given). Ideas that cannot be considered common knowledge are correctly cited and documented using APA format.
Secondary sources are present, and they’re used correctly and effectively to support the writer’s claims.
Citation of all sources include the use of intext (parenthetical) citations as well as quotations. The paper meets all requirements for types of references, title page, headings, etc. 13–12 points: Writing was easy to understand, and the paper was organized. Minor spelling or grammatical errors.
Minor errors in sentence and/or paragraph structure. No slang word or abbreviations used (without definitions given). The writer has attempted to use APA format to indicate borrowed content, but the formatting requires some correction.
Secondary sources are present, and they’re used correctly and effectively to support the writer’s claims.
Citation of all sources include the use of
in-text (parenthetical) citations as well as quotations. Meets most requirements for types of references, title page, headings, etc. 11 points: Writing was easy to understand, and the paper was organized. A few major spelling or grammatical errors. A few minor errors in sentence and/or paragraph structure. Use of slang word or abbreviations (without definitions given). The writer has attempted to use a citation and do cumentation format, but it doesn’t adequately credit the sources.
Secondary sources are present and identified, but citation and documentation is incorrect and requires revision. Meets some requirements for types of references, title page, headings, etc. 10–0 points: Writing was difficult to understand. The paper wasn’t organized, and the topics weren’t presented in a coherent order. There were many spelling or grammatical errors.
There were many errors in sentence and/or paragraph structure. Medical terminology was incorrect. Ideas that can’t be considered common knowledge are not cited and documented. The essay relies heavily on secondary sources with little to no focus on the writer’s claim or knowledge. Secondary sources are not cited or identified, resulting in plagiarism. Meets few requirements for types of references, title page, headings, etc.
Presentation: 25 points
5 points 4 points 3 points 2 points 1 point 0 point
Requirements All requirements were met: It was a summary of the paper and followed the same order of the paper, and there was a
title slide and graphics/images. Most require-ments were met. More than half of the require-ments were met. Less than half of the requirements were met. Few require-ments were met. No require-
ments were met.
Content All topics were covered fully and accurately for each disease. Most topics were covered fully and accurately. Few topics were covered fully/ briefly mentioned. All topics were mentioned but briefly or poorly discussed. Few topics were mentioned but not discussed. Content is inaccurate or topics not covered.
Use of graphics (images, pictures, charts, diagrams) Used graphics for each disease and all graphics were related to the topic and of good quality. Used graphics for each disease. Most graphics were related to the topic and of good quality. Used graphics for most diseases and all graphics used were related to the topic and of good quality. Used graphics for some diseases and most graphics related to the topic and were of good quality. Little use of graphics and/or graphics used weren’t relevant to the topic, or graphics were of very poor quality. Didn’t use graphics.
Organization/ Formatting Information was organized, easy to follow. Text size appropriate. Used headings, section separator slides, and “smart art”
to present information in a professional and organized manner. Content is organized; topics flow easily; text size appropriate. Bulleted lists were mainly used throughout presentation (little to no smart art etc.). Used headings and bulleted lists only. Lacks organization of topics; topics don’t flow and aren’t easy to follow. (no use of smart art, etc.). Text small on some slides. Some use of headings and bulleted lists, but topics don’t flow and aren’t easy to follow. (no use of smart art, etc.) Text small on some to many slides. Little organiza-tional structure. didn’t use bulleted lists or clear headings. Small text on all slides. Information was disor-ganized and hard to follow.
Small text, no bulleted lists, etc.
Resources Sources were cited correctly for both the information and images. Images were cited on the slide they appeared. Direct quotes were cited on the slide they appeared. A reference slide was included at the end of the presentation. Sources for images and information were cited on a reference slide but not on the slide where the image or direct quote appeared. Sources for images and directly quoted information were cited on the slides that they appeared, but no reference slide was given. Sources were cited for information on a reference slide, but images weren’t cited at all. Student cited images on reference slide but didn’t cite information on reference slide. No sources were cited for images or information.
Canine 1 Canine 2 Feline 1 Feline 2 Equine 1 Equine 2
Infectious/ Contagious 1
Infectious/ Contagious 2
Parasitic 1
Parasitic 2
Immunemediated
Congenital/ Genetic
Neoplastic
Metabolic
Toxic
Degenerative or idiopathic
Vaccine Available
Zoonotic

Ruminant/ Swine 1 Ruminant/ Swine 2 Exotic 1 Exotic 2
Infectious/ Contagious 1
Infectious/ Contagious 2
Parasitic 1
Parasitic 2
Immunemediated
Congenital/ Genetic
Neoplastic
Metabolic
Toxic
Degenerative or idiopathic
Vaccine Available
Zoonotic
A zoonotic disease can be transmitted from animals to humans and vice versa. Zoonotic diseases can be bacterial, mycotic, parasitic, or viral. Zoonotic diseases are especially important with respect to immunocompromised persons. Immunocompromised persons include
• Children—because their immune systems aren’t yet fully developed
• The elderly—because their immune systems are usually declining
• People infected with human immunodeficiency virus (HIV)—because they have suppressed immune systems
• People undergoing chemotherapy or radiotherapy— because they also have suppressed immune systems
Many other diseases exist but aren’t covered here; it’s unlikely that you would be exposed to many diseases unless you are in a research setting. The basics are presented here, to give you knowledge of potential hazards.
Epidemiology is the study of disease patterns within a population. Learning the basics of disease transmission— the source and mode of transmission—is the only way to determine how to prevent disease. You already know how some diseases spread, but it’s nearly impossible to cover epidemiology for every disease. Because zoonotic diseases not only affect animals but also people, we’ll focus on these diseases in this section. Unless otherwise noted, all of the following diseases occur worldwide.
Bacterial Diseases
Anthrax
The microorganism Bacillus anthracis, which is found in sheep, goats, cows, and other domestic and wild ruminants, causes anthrax. Anthrax is found worldwide, but human cases are rare. Infection with anthrax can occur through contact with bodily fluids from an infected animal or contact with contaminated soil. The bacterium is able to form spores that are relatively resistant to extremes of temperature, chemical disinfection, and desiccation (drying). These spores can remain dormant in the soil for many years until presented with favorable conditions for growth. During this time, they’re a potential source of infection for grazing livestock, which may ingest the spores from the soil or even from dirty feed. Biting flies and other insects can be mechanical vectors to transmit infection from one animal to another. Anthrax outbreaks occur most often after heavy rainfall or flooding in droughtstricken, dry, or dusty geographic areas. Rain, flooding, or wind disperses the anthrax spores from the surface of the soil. During dispersal, the spores may come in contact with or be inhaled by animals or humans.
Death in farm animals is often so rapid that no signs of disease are noticed until a carcass is found. The bacteria are destroyed through enzymatic decomposition in 1 to 2 hours as long as the carcass isn’t disturbed. However, once exposed to oxygen, the organisms form resistant spores that are difficult to destroy. The soil typically becomes contaminated from blood, predation, or necropsy (most large-animal necropsies are conducted outside). For this reason, necropsy is contraindicated in suspected anthrax deaths, and carcasses should be disposed of through burning.
For control of anthrax, exposure should be minimized. Highrisk personnel should be vaccinated. Animals in endemic areas (areas where disease is prevalent but has a low mortality rate) should be vaccinated. Infected herds should be quarantined, and carcasses infected with anthrax should be properly discarded (again, burning is recommended). Anthrax is a reportable disease, meaning a disease that may pose a risk to public health or the widespread health of animals, and must therefore be reported to the government when it occurs.
Avian Chlamydiosis (Ornithosis/Psittacosis)
The microorganism Chlamydia psittaci, also called Chlamydophilapsittaci, causes this reportable disease found in birds. The major concern regarding avian chlamydiosis is that psittacines (birds in the parrot family) are reservoirs of infection (animals most commonly implicated in disease transmission) because they make popular pets. Avian chlamydiosis is acquired through inhalation of contaminated feces and respiratory secretions. Respiratory secretions and feces from infected birds contain elementary bodies that are resistant to desiccation and can remain infective for several months. Because the organism is easily destroyed by heat, humans don’t acquire this disease from eating meat. This is a reportable disease in some states.
For control of psittacosis, the following measures are needed:
• Surveillance of large production facilities, such as turkey-breeding farms
• Strict quarantine guidelines for the importation of psittacines
• Quarantine of infected flocks; dead birds should be immersed in disinfectants to prevent organisms that may be in dried nasal and fecal excretions on the feathers from infecting humans by aerosolization.
• Education for all persons who work with birds
• Captive flocks should remain in enclosed spaces to prevent infection by wild birds.
Brucellosis
Brucella species—coccobacilli found worldwide in domestic and wild ruminants, horses, camels, dogs, swine, hares, and rodents—cause brucellosis. This disease is acquired through contact with contaminated feces or fluids. Control of brucellosis requires eradication of infected hosts and vaccination of susceptible animals.
Brucellosis tends to occur in humans as an occupational exposure (vulnerable workers include those in meatpacking and rendering plants, veterinarians, and livestock producers). This disease occurs in animals that come into contact with contaminated material. Humans can acquire brucellosis by
• Handling infected fetal membranes or newborns from infected mothers
• Drinking unpasteurized milk
The incidence of brucellosis in U.S. cattle has dropped greatly due to the test-and-slaughter program presently in force, in which any animal that has positive test findings undergoes euthanasia. Also, heifers (cows that haven’t produced calves and are less than 3 years of age) are required to be vaccinated between 4 and 12 months of age (before 8 months of age is ideal). This disease is reportable in all areas.
Campylobacteriosis
Campylobacter species, found worldwide in many birds and mammals, cause campylobacteriosis. Campylobacteriosis is transmitted by the fecal-oral route, consumption of contaminated food and water sources, or consumption of unpasteurized milk. The most likely source of infection in humans is from newly acquired puppies and kittens that have diarrhea. Some of these puppies and kittens can be asymptomatic carriers. Good hygiene, good food-preparation techniques, a clean water source, and drinking pasteurized milk can prevent the transmission of this disease. This is a reportable disease for humans in some states.
Cat Scratch Disease/Cat Scratch Fever
The microorganism Bartonellahenselae, which is found in cats, causes cat-scratch disease. This disease, found in the Northern Hemisphere, rarely causes a problem in cats. Humans seem to be the susceptible species. Humans can contract this disease when they’re scratched by a cat or have a skin cut that becomes contaminated with flea feces carrying Bartonellahenselae. Persons in the animal health-care business are at highest risk. Implementation of proper restraint procedures (including use of heavy gloves, if necessary) is the key to prevention. Good flea control will also assist in disease prevention. The final step after handling any animal is adequate hand-washing. Cat-scratch disease isn’t a reportable disease.
Capnocytophaga Infection
Infection with the microorganism Capnocytophagacanimorsus, which is found in dogs and cats, occurs as a result of bites or scratches. There have been several reported cases of healthy people dying from this infection, but immunocompromised people are more susceptible to infection by this elusive microorganism. The current theory is that humans who have defects in phagocytic function are unable to clear infections with this organism. Control of Capnocytophaga infections involves avoidance of cat and dog bites and scratches. This disease isn’t reportable.
Erysipelothrix Infection
The microorganism Erysipelothrixrhusiopathiae causes disease by exposure to the microorganism through broken skin. Erysipelothrix is associated with swine, lobster, crayfish, and other fish. Workers exposed to any of these animals should wear gloves and thoroughly cleanse any wounds they receive. The organism can survive in animal tissue if chilled, frozen, or cured. It can also persist in soil for up to a month. When humans contract this infection, it can sometimes be confused with anthrax. This disease isn’t reportable.
Pasteurellosis
Pasteurella species, found in domestic animals, cause pasteurellosis through bite wounds and inhalation of aerosolized particles. It’s suspected that pasteurellosis is most often transmitted by cats who hiss before biting, therefore aerosolizing the organism before the bite. Control of pasteurellosis involves avoidance of animal bites, especially dog and cat bites, and proper antiseptic cleansing of any wounds received. This disease isn’t reportable.
Q Fever (Coxiellosis)
The microorganism Coxiellaburnetii is responsible for Q fever, which is found worldwide except in New Zealand. The bacteria is present in ruminants’ birth fluids, placentae, urine, wool, hides, and in unpasteurized milk. The infectious variant is resistant to heat, drying, and many common disinfectants, and it remains viable for weeks to months in the soil. It can also be found in wild animals, cats, and birds. Q fever is highly infectious, and a single organism can reportedly cause infection via the aerosol route in humans. Ticks may transmit the disease among domestic ruminants, but ticks aren’t thought to play an epidemiologically important role in transmission of the disease to humans. High-temperature pasteurization effectively kills the organism. Proper protective equipment should be worn when exposure is possible. Using pasteurized milk should help prevent human contamination. This disease is reportable in areas where it’s endemic.
Rat-Bite Fever
The microorganisms Streptobacillusmoniliformis (Streptobacillosis) and Spirillum minus (spirillosis) cause rat-bite fever, which is found sporadically in rodents worldwide but is rare in the United States. Rat-bite fever is acquired through bites from rodents or ingestion of rodent-contaminated food or water. These organisms can be transmitted to dogs and cats when they catch rodents. Subsequently, dogs and cats can pass on this infection by biting a human. Control of this disease involves avoidance of rat bites and good rodent control around food and water sources. The human form of this disease is reportable nationwide.
Salmonellosis
Salmonellosis is caused by various serotypes of Salmonella, which are found worldwide in many animals. Salmonellosis occurs through consumption of contaminated food or contact with contaminated feces. In the past, human cases of salmonellosis were associated with the poultry industry. Today, with greater public education and better testing of flocks, salmonellosis caused by poultry is on the decline. Currently, reptiles have stepped up and become the new criminals implicated in human cases of salmonellosis. It’s recommended that immunocompromised people, who are at a greater risk for this disease, not live in households with reptiles. Human bathing areas and food-preparation areas shouldn’t be exposed to reptiles.
The fecal test that determines whether an animal has Salmonella spp. yields inconsistent results. Further, even if an animal’s test results are negative, the animal isn’t necessarily diseasefree, because Salmonella spp. can be shed intermittently. Most officials believe that a series of 3 to 5 negative test results are needed before an animal is truly considered negative. As with other microorganisms, it’s important to use good hygiene. Salmonellosis is a reportable disease in humans.
Tetanus
Tetanus is caused by a neurotoxin produced by the bacterium Clostridium tetani, which is found in herbivores. Contamination of broken skin with clostridial spores causes the infection. Horses, sheep, and goats seem to be the most susceptible to tetanus. Next in line of susceptibility come humans, and then cattle. Horses, sheep, and goats are routinely vaccinated. All humans are encouraged to receive a tetanus vaccination every 10 years, but anyone working in the animal health care profession should maintain current tetanus vaccination status, because the disease can be fatal. In fact, many places recommend vaccination every 5 years for people working with animals. For control of tetanus, good wound-cleansing techniques and maintenance of up-to-date vaccination status in susceptible species are recommended measures. Only oxidizing disinfectants, such as iodine or chlorine, dependably kill the spores of C. tetani. Tetanus isn’t a reportable disease.
Mycotic (Fungal) Diseases
Cryptococcosis
Cryptococcosis is caused by the fungal organism Cryptococcus neoformans, which is found worldwide in soil or plant material, especially if contaminated by bird droppings. Dogs and cats as well as humans can get cryptococcosis. Although cryptococcosis can be associated with any bird, the pigeon tends to be the primary source of infection. Disease transmission occurs through inhalation of contaminated material. The incidence of cryptococcosis among humans has increased greatly since the spread of AIDS. Immunocompromised people should be especially careful to avoid infection.
For control of this disease, avoid bird feces, disinfect soil with 3 percent formalin, and wet ground contaminated with bird feces before cleaning to prevent aerosolization of the fungus. The human form of cryptococcosis is reportable nationwide.
Dermatophytoses
Dermatophytoses are caused by the fungal organisms Microsporumcanis and Trichophyton spp. M. canis is found in dogs and cats, whereas Trichophyton spp. are found in rodents and ruminants. A few dermatophyte species are soil inhabitants. Indirect or direct contact with infected animals or their hair is the mode of transmission. Typically, immunosuppression in an animal can be a predisposition to these infections. Animals also can be asymptomatic carriers. Humans can also transmit this disease to animals.
For control of dermatophytoses, good sanitation techniques are needed. The fungal organisms causing this disease can be killed by bleach, so all laundry should be washed with bleach. In addition, carpets should be steam-cleaned and air filters should be changed. Dermatophytoses aren’t reportable unless outbreaks occur among humans.
Parasitic Diseases
Creeping Eruption
Creeping eruption is caused by Ancylostoma spp. (A. caninum, A. braziliense), which are the hookworms found in dogs and cats. Creeping eruption occurs when the skin is penetrated by larval stages of the parasite. The lifecycle of the parasites that cause creeping eruption begins when the eggs of the parasite are deposited on the ground in dog or cat feces. In 2 to 8 days, the egg hatches into a motile larva. Transmission occurs by either a dog or cat ingesting the larva or the larva coming in contact with and penetrating the skin. The larva then migrates to the small intestine, where it attaches and feeds on blood and then matures. The mature parasite can also reproduce at this site. The eggs are shed in the feces either 2 weeks after ingestion of the larva or 1 month after skin penetration by the larva.
Not all larvae migrate to the small intestine; some migrate to skeletal muscle and encyst (become encapsulated and inactive), or migrate to the mammary gland where they’re shed in the milk and passed on to puppies or kittens. In humans, the route of infection is usually through the skin, and the parasite rarely proceeds farther.
For control of creeping eruption, use appropriate anthelmintics (agents destructive to worms) in pets and good environmental sanitary techniques. This disease isn’t reportable.
Cryptosporidiosis
The microorganism Cryptosporidium spp., which is found in dogs, cats, calves, lambs, kids, and birds worldwide, causes cryptosporidiosis. This disease is contracted through the fecaloral route. The lifecycle of Cryptosporidium parasites begins with a thick-walled, sporulated oocyst containing four sporozoites, which is shed in the feces. This oocyst can remain viable in the environment unless it’s destroyed by extremes of temperature or desiccation.
When the oocyst is ingested, it ruptures, thus releasing the four sporozoites that invade the microvilli of the gastrointestinal tract. Each sporozoite undergoes four processes to produce both thin-walled and thick-walled sporulated oocysts. The thin-walled oocysts rupture without ever leaving the body and begin the process all over again, which is how autoinfection occurs. The thick-walled oocysts are shed in the feces to start the lifecycle from the beginning. Cryptosporidium may be found in soil, food, water, or on surfaces that have been contaminated with feces from infected humans or animals.
For disease control, proper sanitation techniques must be used. This disease is reportable in humans.
Giardiasis
Giardia species, found in dogs and cats worldwide, causes giardiasis through direct contact with infected animals or consumption of fecal-contaminated water. A trophozoite is a sporozoan nourished by its host during its growth stage. Giardia trophozoites are flattened on one side, which forms a sucker disk that allows for attachment to the intestinal mucosa. Mature Giardia oocysts usually contain two trophozoites that are shed in the feces. This cyst is the infective stage. Sometimes single trophozoites are shed, but they don’t last long in the environment and don’t cause infection. Cysts are susceptible to desiccation.
For control of this disease, fecal contamination of food and water sources should be prevented, and good sanitation techniques to keep the environment clean should be used. This disease isn’t reportable.
Hydatidosis
Hydatidosis, sometimes called echinococcosis, is caused by the Echinococcus species, found in carnivores worldwide. Transmission occurs through the fecal-oral route of the larval form of this organism. This disease can be transmitted to livestock by fecal-oral contamination from carnivores in pastures or grain bins.
The lifecycle of Echinococcus spp. requires definitive hosts and intermediate hosts. Definitive hosts are normally carnivores such as dogs, while intermediate hosts are usually herbivores such as sheep and cattle. In the natural lifecycle, gravid segments from Echinococcusgranulosus migrate out of a wolf in its feces. These gravid segments release their eggs. Wild herbivores come along to graze and eat the eggs. The eggs then mature into hydatid cysts (second-stage larvae). A predator comes along and eats the herbivore, ingesting the larvae that begin the lifecycle again.
This scenario has changed as humans have domesticated the land. The wolf visits a pasture and leaves behind gravid segments. Then sheep come along and ingest the eggs, which mature into hydatid cysts. If the sheep dies due to unrelated causes but part of its carcass is fed to a dog, the dog will become infected with Echinococcusgranulosus. Thus, the lifecycle continues with reinfection on the farm.
Echinococcusmultilocularis follows the same lifecycle, but this parasite infects foxes and rodents, who can then infect both cats and dogs. These species form alveolar hydatids, which rapidly prove fatal in humans because they’re much more invasive to the surrounding tissues in people than they are in animals.
For control of hydatidosis, good sanitation techniques should be used along with the use of proper anthelmintics in pets, control of stray carnivores, and not feeding pets livestock carcasses or uncooked offal (viscera). This disease isn’t reportable.
Scabies
The mite Sarcoptesscabiei, an ectoparasite, causes scabies. Notoedres or Cheyletiella mites may temporarily reside on humans, but these species don’t cause scabies. Sarcoptesscabiei is found worldwide on cattle, sheep, horses, goats, swine, and dogs. The disease occurs through contact with an infected animal. The female scabies mite is fertilized on the skin surface and begins to burrow into the epidermis, and the mite deposits eggs behind her as she burrows. The eggs produce larvae, which travel to the skin surface, pass through a nymph stage, and then to the adult stage. A scabies infection can result in a bacterial skin infection because it’s very pruritic. Scabies can move from species to species, but traveling among individuals of the same species seems to be easier.
For control of scabies, good sanitation techniques and parasiticides should be used. This disease is reportable in cattle.
Strongyloidosis
Strongyloidosis is caused by Strongyloidesstercoralis, which is found in carnivores and primates worldwide. Transmission occurs by skin penetration of the parasite’s larval stage. The lifecycle for the Strongyloides parasite is complex. The filariform (filament-shaped nematode) parasitic female produces eggs by mitotic parthenogenesis (reproduces by splitting, without sexual reproduction). The eggs hatch into homogonic (all alike—all female), rhabditiform (rod-shaped) larvae. In the environment, these larvae can go through two molts into infective filariform larvae or four molts into free-living males and females. When the infective filariform larvae find a suitable host, they penetrate the skin. They molt through two stages and start the lifecycle by mitotic parthogenesis. The free-living males and females mate and produce larvae that develop into infective filariform larvae. The infective filariform larvae can reinvade the host, causing an autoinfection.
For control of this disease, good sanitation techniques and appropriate anthelmintics must be used. Strongyloidosis isn’t a reportable disease.
Tapeworms
The larval forms (cysticercus) of Taeniasaginata and Taeniasolium cause this disease in cattle and swine. Tapeworms in humans are acquired by eating undercooked meat. Taeniasaginata and Taeniasolium follow the same lifecycle as Echinococcus spp. However, instead of forming into hydatids, they form into cysticerci (rounded cysts of the tapeworms) and use ruminants and swine as their intermediate hosts.
These two species of tapeworms come from humans. Cattle and swine are infected from eating foods contaminated with human feces.
For control of tapeworms, proper food-preparation techniques must be used along with inspection of slaughtered animals. This disease isn’t reportable.
Toxoplasmosis
Toxoplasmosis is caused by the organism Toxoplasma gondii and is found worldwide, primarily in cats. However, it can also be found in the muscle tissue of sheep, goats, swine, cattle, and chickens. This disease occurs either through consumption of undercooked meat or the fecal-oral route. The lifecycle for Toxoplasma gondii begins with a noninfective oocyst that’s passed in the feces of a cat. After 1 to 5 days, the oocyst sporulates and becomes infective. The sporulated oocyst contains two sporocysts, each of which contains four sporozoites. The sporulated oocyst is ingested and ruptures. The sporozoites enter the intestinal cells and lymph nodes to multiply. During this time, the sporozoites form tachyzoites (rapidly growing forms) that invade other cells of the body and continue to multiply. Finally, tissue cysts containing bradyzoites (slowgrowing forms) are formed in the brain, striated muscle, and liver, remaining viable for the host’s lifetime. Both tachyzoites and bradyzoites are infective when ingested. The tachyzoites can cross the placenta and infect the fetus. For this reason, pregnant women and immunocompromised individuals shouldn’t clean cat litter boxes.
For control of toxoplasmosis, proper food-preparation techniques should be used along with good sanitation. For humans, this is a reportable disease in some states.
Trichinosis
Trichinosis is caused by nematodes of the genus Trichinella, especially T. spiralis, which is found in swine and carnivores worldwide. Transmission occurs by eating undercooked meat. Trichinella parasites can infect any mammal, but they’re usually found in carnivores and animals that eat garbage or carrion, which is why trichinosis has historically been associated with pigs. Typically, the intermediate host of the parasite is infected by ingesting meat containing Trichinella cysts. The acid in the stomach dissolves the hard covering of the cyst and releases the larvae, which become adults in the gastrointestinal tract. The adults mate, and the new generation of larvae migrate to the circulatory/lymphatic system and are delivered to muscle tissue. The larvae penetrate the muscle tissue and align themselves along the muscle fibers. They then curl up and encyst. This can lead to death if the affected muscle is in the heart or diaphragm. The encysted larvae can remain viable in the muscles of a carcass for a long time, allowing predation or scavenging to continue the parasitic lifecycle. The predatory or scavenging animal ingests the cysts, where the digestive juices rupture the cyst and allow the larvae to continue the lifecycle.
For control of this disease, proper food-preparation techniques must be used. Currently, this disease isn’t reportable for humans.
Visceral Larva Migrans
The microorganisms Toxocaracanis and Toxocaracati, which are the roundworms of dogs and cats, respectively, cause visceral larva migrans. This disease occurs worldwide through ingestion of the larval stage of this parasite. Eggs from the roundworms of dogs and cats aren’t infective when they’re first shed. After 4 weeks, the eggs develop into larvae and become infective agents if ingested. The larvae migrate in the body and encyst themselves in tissue. Then in the last couple of weeks of pregnancy (for either the dog or cat), the larvae are reactivated and continue the lifecycle by passing into the mammary gland. The larvae are then shed in the milk to infect the puppy or kitten. The mother can also shed the eggs in her feces, and the puppy or kitten may ingest the eggs. The eggs of roundworms can remain viable in the soil for a long time. Human children typically are infected by eating contaminated soil. The parasite can’t complete its lifecycle in humans, but the larvae persist in tissues, provoking a granulomatous reaction before eventually dying. The symptoms and severity of the infection depend on the location of the larvae.
For control of visceral larva migrans, appropriate anthelmintics and good sanitation techniques should be used. This disease isn’t reportable.
Viral Diseases
Contagious Ecthyma (Orf)
Orf is caused by organisms of the genus Parapoxvirus, which are found in domestic and wild ungulates. Although this disease is found worldwide, it’s rare (transmission is through contact with lesions or the mucous membranes of infected animals). Sheep and goats seem to be the animals that usually develop orf. The typical presentation is crusting, proliferative lesions on the muzzle of young animals. The disease typically takes three to four weeks to run its course. Humans show the same types of lesions, which usually occur on the hands. An animal vaccine is available, but should be used only if the disease is persistent in the flock because the vaccine contains live virus.
For control of orf, use protective equipment. This disease isn’t reportable.
Herpesvirus Simiae (B Virus)
Herpesvirus simiae, also called monkey B virus or just B virus, occurs in primates from Africa and Asia, and research facilities that house primates. Transmission is through bite wounds or the aerosolized virus coming in contact with mucous membranes. In primates, this virus produces mild disease consisting of lesions in and on the mouth, with most of the lesions being on the tongue. The virus remains latent in the host and may reactivate from time to time, resulting in shedding of virus in saliva and/or genital secretions. Sexually mature macaques are more likely than immature animals to have been exposed to the virus.
This disease is easily transmitted from primate to primate. All infected primates, if not destroyed, should be kept in solitary confinement. Any macaque not known to be free of B virus should be regarded as infected, because viral shedding can occur without visible lesions. Direct handling of macaques should be minimized.
For control of Herpesvirus simiae infection, avoid bites and use protective gear for the prevention of disease transmission. Handlers should remove physically active animals from cages only with arm-length reinforced leather gloves. Handlers should be additionally protected with a long-sleeved garment to prevent scratches and a face shield. Isolate incoming primates for six weeks, and isolate any animals showing lesions. This is a reportable disease in humans.
Newcastle Disease
Newcastle disease is caused by Paramyxovirus, which occurs in birds worldwide. Transmission is through microorganism contact with the eyes. Clinical signs are extremely variable—from those that resemble a common cold to death—depending on the strain of virus, species and age of bird, concurrent disease, and preexisting immunity. The disease is transmitted through feces and secretions from the nose, mouth, and eyes. Therefore, the disease can be spread easily by mechanical means (that is, carried on the soles of the shoes). It spreads rapidly among birds kept in confinement. The virus can survive for several weeks in a warm and humid environment on birds’ feathers, manure, and other materials. It can survive indefinitely in frozen material. However, the virus is destroyed rapidly by dehydration and by the ultraviolet rays in sunlight. Birds (especially Amazon parrots from Latin America) illegally smuggled into the United States aren’t quarantined and tested by the USDA and therefore may carry an exotic strain of the virus.
Humans who have never been exposed to the Newcastle virus often develop temporary conjunctivitis (pinkeye) on first exposure. Typically, this first exposure is during vaccination of a flock or working with the virus in a research setting. Good hygiene is important in prevention. This disease isn’t reportable in humans, but it is in animals. Bird owners or veterinarians who suspect a bird may have Newcastle disease should immediately contact state or federal animal health authorities.
Rabies
Rabies is a reportable disease caused by Lyssavirus, which can occur in any mammal, but especially occurs in members of the Canidae family (dogs, wolves, foxes, coyotes, and jackals), cats, skunks, raccoons, mongooses, and bats. This disease is found almost worldwide, except in parts of the Pacific and Far East and some sections of Europe. Rabies-free areas are nearly all islands with strict quarantines and animal importation laws. Infection occurs through bite wounds and contact with the aerosolized virus. Once clinical signs of rabies are evident, a progressive and usually fatal encephalitis ensues (only six people are known to have survived clinical rabies in the United States, and all but one of them had some sort of vaccination). Human rabies is preventable with the proper and timely administration of post-exposure prophylaxis, consisting of repeated injections of rabies vaccine and human rabies immune globulin (HRIG).
Even though everyone has heard of rabies, people still die every year from rabies infection. Fifty-one cases of rabies were diagnosed in humans in the United States between 1990 and 2006. Six known cases of human-to-human transmission through corneal transplantation have been reported; one of these cases occurred in the United States. In 2004, four people in Oklahoma and Texas died after receiving donated organs from a patient who died after being bitten by a rabid bat.
Even if no neurological symptoms are present, an animal can’t be considered free of rabies. Latent infections can exist in animals that appear clinically healthy but shed the virus in their saliva. The most common form of transmission is through a bite wound. The bite is essentially a viral inoculation into the victim’s muscle. The virus replicates in the myocytes and then migrates up the peripheral nerves and into the central nervous system. After infecting the brain, the virus migrates to other body tissues along nerve pathways.
The CDC has been experimenting with providing oral vaccinations to wild animal populations in an attempt to eliminate the disease. Similar programs in Europe and Canada have led to some areas being declared clear of rabies virus. Vaccinations of companion animals are one of the most important steps in prevention of human cases of rabies. In the United States in 2006, 318 cases of rabies were reported in cats and 71 in dogs. There were 155 reported cases involving farm animals, including cattle, horses, and sheep.
Avoiding contact with wild animals whose disease status is unknown is another important step to take in preventing human exposure.
People at high risk of exposure to rabies, such as veterinary staff and animal handlers, should be offered rabies vaccine. The pre-exposure schedule for rabies vaccination is three doses: dose 2 is given 7 days after dose 1; dose 3 is given 21 or 28 days after dose 1. For people who may be repeatedly exposed to rabies virus, periodic testing for immunity is recommended and booster doses should be given as needed.
For control of rabies, ensure vaccination of all pets, avoid bite wounds, perform thorough cleansing when bites are sustained, and report the bite wound to local public health officials. To clean a bite wound, wash with soap and water for approximately 5 minutes. If available, a virucidal antiseptic, such as povidone-iodine, iodine tincture, aqueous iodine solution, or ethanol, should be applied after washing. When working with wildlife, use protective equipment. People at risk should be vaccinated.
Since the widespread vaccination of domestic dogs and cats and the development of effective human vaccines and immunoglobulin treatments, the number of recorded deaths in the United States from rabies has dropped from 100 or more annually in the early twentieth century to 1–2 per year, mostly caused by bat bites, which may go unnoticed by the victim and be untreated.
Summary
As you can see, there are numerous zoonotic diseases of which you should be aware to protect yourself. When in doubt, make sure you consult your supervisor to discover the precise protocol for each situation. Always use protective equipment and good sanitation techniques, and flush all wounds thoroughly.