Pathogens Part 2

Prions • A prion is an infectious particle (not a cell) made from an abnormally folded protein found on the surfaces of nerve cells. • Prions are highly resistant to heat, radiation, and disinfectants. • The best known prion forms holes in brain tissue, making the brain look like Swiss cheese. • The prion causes mad-cow disease and may cause some forms of Alzheimer's Disease. Ribbon diagram of prion* Viruses • A virus consists of a piece of genetic material (RNA) housed within a protective coat. Viruses are not cells. • The virus reproduces by hijacking the cell of another organism (host) and getting the host cell to reproduce more viruses. • Most viruses cause disease and are specific as to which type of cell they will attack. Rabies Virus Viruses • Symptoms of viral diseases are varied and related to the types of tissues that are infected. Viral diseases are commonly associated with infections of the skin, blood, liver, uterus, fetus, brain, lungs, stomach, and intestines. • Diagnosis is done by virus isolation, ELISA* and PCR* testing. A decrease in lymphocytes on a CBC can also indicate a viral infection. • Treatments are mainly supportive in nature. This can include administering fever reducers and allowing the animal to rest. Antiviral medications are being developed, but many are cost prohibitive. Antibiotics kill bacteria and have no effect on viruses. Horses can be infected by at least four different papilloma viruses that cause warts Common Viral Diseases Disease Body System Symptoms Examples Hepatitis General-many organs involved Vary from slight fever to death Infectious canine hepatitiscanine adenovirus 1 Anemia Blood Fever, weight loss, abortion, low iron level in blood Equine infectious anemia-equine infectious anemia virus Warts Skin Fibrous tumors of the skin an mucous membranes Papilloma virus Pox Skin Skin lesions-bumps, blisters, pustules, and crusts Cowpox Pneumonia Respiratory Labored or “flank” breathing, hard deep cough, fever, leukocytosis Bovine Respiratory Disease (BRD)Mannheimia haemolytica There are MANY viruses that cause Pneumonia Abortion Reproductive Loss of fetus Equine Rhinopneumonitisequine herpesvirus 1 Meningitis and encephalitis Nervous Invfammation of the brain covering causing blindness, paralysis, wobbling, seizures, coma and delirium Encephalomyelitis, distemper, parvovirus, swine pseudorabies Rabies Nervous Throat paralysis, behavior change, change in bark (dog), aggression in later stages, lack of fear Rabies virus Typically fatal Protozoa • Protozoa are unicellular microbes that can be parasites or predators of other microbes. Many are motile. Protozoa found in human stool sample • Most need a moist environment to live and many are transmitted through water. • Infections of small numbers of protozoa are common, they are seen quite often on microscopic fecal examinations with the animal showing no evidence of diseases. • Infected animals are recognized as carrier animals and as possible sources of infection for susceptible animals. Giardia Protozoa • Symptoms vary considerably depending on the protozoa involved but often include intestinal disorders such as diarrhea, weight loss, and anorexia. Some protozoa cause fever, flu-like symptoms, or anemia. Direct fecal smear stained to detect Cryptosporidium sp., a protozoan parasite. (Source: CDC) • Diagnosis is conducted through examination of blood, feces, or urine for the presence of the microscopic organisms. ELISA and PCR tests can also be done. • Many antiprotozoal agents are available for treatment of protozoal infections. Toxoplasmosis is a zoonotic parasite that causes disease in humans and animals Protozoal Diseases Disease Body System Symptoms Examples Giardiasis Digestive abdominal cramps, watery diarrhea, vomiting, flatus (gas), and fever Giardia lamblia Affects animals and humans Coccidiosis Digestive Thin, watery feces with considerable amounts of intestinal mucosa and blood Coccidia Eimeria and Isospora, affects animals and humans Tricnomoniasis Reproductive venereal disease characterized primarily by early fetal death and infertility Tritrichomonas Affects animals and humans Hexamitiasis Digestive Watery diarrhea, dry unkempt feathers, listlessness, and rapid weight loss despite the fact that the birds continue to eat Hexamita meleagridis in turkeys and other fowl Toxoplasmosis Multiple Systems Cough, fever, loss of appetite, and lethargy. Can be passed to fetus (congenital). Congenital toxoplasmosis can damage the baby's eyes, nervous system, skin, and ears. Toxoplasma gondii Zoonotic, affects animals and humans Babesiosis Circulatory Fever, anemia, sudden cardiac death Malaria-like (Malaria is a protozoal disease) Babesia microti in dogs transmitted by ticks Fungi • A single or multi-cellular microbe that can infect various tissues in animals. • Symptoms can include skin lesions, hair loss and respiratory or digestive system disorders. • Many antifungal drugs are available and can be used systemically as well as orally. Microsporum-the fungus that causes ringworm. Fungi • Diagnosis of fungal infections may be done by examination of skin lesions, fungal culture, biopsies, skin immunologic tests, or by blood tests. • Treatment of skin lesions in the patient usually includes a combination of anti-fungal drugs, topical medications and anti-fungal medicated shampoos for animals with skin lesions. • Systemic fungal diseases can be serious and result in severe tissue damage. A horse with a severe case of ringworm, which is cause by a fungus Treatment includes bathing with a medicated shampoo Fungal Diseases Disease System Symptom Examples Dermatophytosis or Ringworm Skin Circular skin lesions with hair loss, itching, pruritus may or may not be present Microsporum canis in dogs Dermatophilosis or Rain Gall/Rain Rot Skin Lumpy, crusty, lesions covered with hair that can be pulled off Dermatophilus congolensis has a variety of hosts-cattle, sheep, goats, and horses are affected most frequently; and pigs, dogs, and cats rarely Aspergillosis Respiratory Fever, cough, chest pain or breathlessness Aspergillus fumigatus in many species. Type of mold. Candidiasis or Yeast Infection Skin, Respiratory, Digestive Signs can be variable. Diarrhea and listlesses can be observed. Lesions of the skin and mucosae are generally single or multiple, raised, circular, white masses covered with scabs. Candida albicans in many species. Coccidiosis Digestive Diarrhea, dehydration, hemorrhaging, Eimeria and Isospora in cattle, sheep, goats, pigs, poultry, and rabbits