Zoonoses Midterms 1 - Introduction

ZOONOSES MIDTERMS1 MODULE 1 Introduction Etymology of "Zoonoses" - Comes from the Greek word "[zoon]," which stands for [animals] and "[noses]" for [ailments] - The study of animal diseases transmissible to humans - Encompasses diseases transmissible or shared in nature by animal...

ZOONOSES MIDTERMS1 MODULE 1 Introduction Etymology of "Zoonoses" - Comes from the Greek word "[zoon]," which stands for [animals] and "[noses]" for [ailments] - The study of animal diseases transmissible to humans - Encompasses diseases transmissible or shared in nature by animals and humans - As far back as the classical era, people observed that certain diseases seemed to pass from animals to humans, rabies serving as one example. However, it was not until the 19^th^ century that the concepts of microbes, contagion, infection, and transmission were elucidated in their modern form, paving the way for the fields of microbiology and epidemiology. - German physicist and researcher Rudolph Virchow coined the term [zoonosis] after noting parallels in a parasitic disease found in both pigs and humans: trichinellosis. Two Types of Zoonoses **[Direct Zoonosis]** - Also known as [orthozoonoses] - Needs only one animal host during transmission - Transmitted from an infected to a susceptible vertebrate host by direct contact, by contact with a fomite, or by a mechanical vector - May be perpetuated in nature by a single vertebrate species (e.g., dogs and foxes for rabies or cattle, small ruminants, or swine for brucellosis) - The infectious cycle requires only one vertebrate species to perpetuate - Rabies: dogs -\> humans - Leptospirosis: rats -\> humans **[Indirect Zoonosis]** - Needs two or more hosts during transmission - Invertebrate hosts are required during indirect transmission - Involves coming into contact with an area where infected animals live or roam, or by touching an object that bas been contaminated by an infected animal - Farmers, zoo or pet shop workers, and veterinarians have an increased risk of being exposed. They can also become carriers and pass those diseases to other people - Plague: rodents -\> flea -\> human - Dirofilariasis: dog -\> mosquito -\> human Nine Specific Types of Zoonoses 1. **Orthozoonosis** - From vertebrate hosts to humans through contact, fomites, or mechanical vector - Rabies in dogs, anthrax in cattle 2. **Cyclozoonosis** - Requires two or more vertebrate hosts but no invertebrate host during the cycle - Leptospirosis: rodent -\>dog -\> human 3. **Metazoonosis** - From invertebrate hosts to humans - Dengue (mosquito), Lyme disease (ticks) 4. **Saprozoonosis** - Acquired by man from non-animal reservoir - Soil, water, mud, plants, bird droppings, etc. - Cryptococcosis, meliodosis 5. **Anthropozoonosis** - Transmitted from animal/lower vertebrates to man - Shigellosis 6. **Zooantrhopozoonosis** - A.k.a. "[reverse zoonoses]" - Acquired by animals from infected humans through close contact - MRSA infection 7. **Amphixenosis** - Zoonosis maintained in both man and animals - Transmitted either direction - Mycobacterium bovis infection 8. **Anthroponosis** - Zoonosis transmitted from human to human - Rubella, smallpox 9. **Isozoonosis** - Diseases showing similar signs and pathology in both man and animals - Hypersalivation and anxiety in both man and dogs Seven General Etiologies of Zoonotic Diseases 1. Bacterial 2. Viral 3. Fungal 4. Worms 5. Chlamydia and Rickettsia 6. Protozoans 7. Prions Five Portas of Entry of Zoonotic Agents Into Humans 1. Skin and mucous membrane 2. Oral 3. Inhalation 4. Venereal 5. Inoculative Four Modes of Zoonoses 1. Ecological a. Ecosystem 2. Recreational b. Pets at home 3. Occupational c. Zoos, research facilities 4. Medical d. Xeno-transplantation Determinants of Zoonotic Diseases: Agents, Host and Environment **Cause** - An event or condition that contributes to disease occurrence **Triad/Main Determinants of Disease** - Agent: True cause of disease - Host: The one who manifests disease condition - Environment: Pertains to all external factors that contribute to the occurrence of disease Ten Classifications of Hosts 1. Definitive/Final 2. Primary/Natural 3. Secondary 4. Paratenic 5. Intermediate 6. Amplifier 7. Hibernating 8. Incidental 9. Link 10. Reservoir BACTERIOSES FROM COMPANION AND FARM ANIMALS Anthrax - Also known as - Woolsorters disease - Charbon - Malignant pustule - Malignant edema - Malignant carbuncle - Etiology - *Bacillus anthracis* - G+ bacterium that turns to spores upon exposure to air - Two Portals of Entry into the Human Body - Direct contact - Inhalation of Pores - Incubation Period - 2-5 days - 3 Clinical Forms - Cutaneous anthrax - Marked by formation of papule -\> vesicle -\> depressed eschar (edematous black lesion with depressed center) - Respiratory/pulmonary anthrax - Upper respiratory type, fever, fever, shock and death - Gastrointestinal anthrax - Violent gastroenteritis, vomiting, and bloody stool - Pathognomonic Signs of Anthrax in Animals - Blood oozing from normal body orifices (nostril, mouth, and anus) - Lacks rigor mortis (depletion of calcium in the body) - Decomposes rapidly - Gold Standard Test - Ascoli test - Precipitin test used in serological diagnosis of anthrax - Treatment - Penicillin - Control and Prophylaxis - Humans should prevent contact with infected animals - Disinfection of wool and fur with hot formaldehyde - Control and treatment of animal infection - Incineration of dead animals or the animals should be buried 2 meters deep with calcium oxide/lime Leptospirosis - Regarded as the most important occupational disease of humans causing: - Weil's Disease - Canicola Fever - Mildrop Syndrome - Cane Cutter's Fever - Rice Field Fever - Stuggart's Disease - Muddy Fever/Swamp Fever - Etiology - G- tightly coiled spirochete - Leptospira interrogans - Mode of Transmission - Direct contact of broken skin with urine - Direct contact with intact mucous membrane - Incubation Period - 1 day -- 2 weeks 2 Phases of Leptospirosis in Humans - Bacteremic/Leptospiremic Phase (agent is present in the blood from 7-10 days) - Icteric/Hepatonephritic Type (Weil's) - Fever, headache, myalgia, conjunctivitis, stiff neck, nausea, diarrhea, constipation, presence of skin petechiae, GI hemorrhages, protenuris, oliguria, anuria, azotemia, electrolyte imbalance - Anicteric type - Influenza-like syndrome like fever, myalgia, conjunctivitis, nausea, vomiting, stiff neck - Leptospiruric phase - Agent is shed in the urine for weeks to months; at this phase, the convalescent carrier should be given doxycycline to prevent further transmission to susceptible host - Gold Standard Test - Microscopic agglutination test (MAT) - Treatment - Doxycycline and ampicillin - Ampicillin (only IV) - Small Animals - Dihydrostreptomycin (large animals) - Control - Avoid exposure to floods - Prohylaxis -- Doxycycline Brucellosis - Undulant fever - Malta/Mediterranean Fever - Bang's Disease - Ram Epididymis - Etiology - B. abortus - B. suis - B. melitensis - B. canis - Mode of Transmission - Direct Contact with infected placenta and afterbirths of cattle, sheep, goat, pig, and dog during parturition - Incubation Period - 1 day -- 3 weeks - Clinical Signs and Symptoms - Irregular Fever - Febrile - Chill - Profuse Sweating - Weakness - Insomnia - Sexual Impotence - Constipation - Anorexia - Headache - Arthralgia - General malaise - Splenomegaly - Hepatomegaly/Jaundice - Nervous Sigs - Gold Standard Test: Rose Bengal Test (Brucellosis) - Treatment: Gentamicin - Control - Avoid contact with infected animals - Human and animal vaccination - Pasteurization of milk Plague - Wiped 1/3 of Europe's population - Bubonic plaque - Black death - Pestilential fever - Etiology - Yersinia pestis evolved into Yersinia pseudotuberculosis - G- non-motile coccobacillary to bacillary forms with little resistance to physical and chemical agents - Safety pin appearance - Mode of Appearance - Bites of oriental/black rat flea, Xenopsylla cheopis in wild rodents - Incubation Period - 2-6 days - 3 Forms of Plague and Their Clinical manifestations - Bubonic Plague -- marked by inflammation and swelling of peripheral lymph nodes (buboes) - Septicemic Plague -- rapid onset of nervous and cerebral symptoms - Pneumonic Plague -- complication of bubonic and septicemic plague, marked by dyspnea, coughing, expectoration, and pneumonia - Clinical Signs - Fever - Chill - Nausea - Headache/Cephalalgia - Generalized Pain - Diarrhea/Constipation - Frequent Toxemia - Shock - Arterial Hypotension - Rapid Pulse - Nervous Signs - Anxiety - Staggering Gait - Slurred Speech - Mental Confusion - Prostation - Treatment - Streptomycin, Tetracycline, Chloramphenicol - Control and Prophylaxis - Rodents and plague control Lyme Disease - Lyme Arthritis - Erythema chronicum migrans (ECM) with polyarthritis - Etiology - G- spirochete - Borrelia burgdorferi - Mode of Transmission - Tick Bites - Ixodes dammini - Incubation Period - 3-20 days - Clinical Signs - Cutaneous Signs - Red macule/papule formation - Bulls eye lesion - Systemic Signs - Fever, malaise, cephalalgia, stiff neck, myalgia, arthralgia and lymphadenopathy - Treatment - Doxycycline and Penicillin - Control and Prophylaxis - Doxycycline - Avoid tick bites - Apply repellants BACTERIOSES FROM COMPANION AND FARM ANIMALS GLANDERS This equine disease seen worldwide is also known as [farcy/cutaneous glanders], [equine nasal phtiasis], and [maliasmus] **ETIOLOGY**: *Burkholderia mallei* (formerly *Pseudomonas mallei*), which is a gram-negative non-motile bacteria that is not resistant to outside environments **MODE OF TRANSMISSION**: Direct contact with infected horse, inhalation of droplets **INCUBATION PERIOD**: [One (1) to fourteen (14) days] **CLINICAL SIGNS AND SYMPTOMS**: - Ulceration in one (1) or two (2) nostrils with oozing mucus (pathognomonic) in horses - In humans, there is mucopurulent discharges from nostrils with pneumonia, bronchopneumonia, or lobar pneumonia 1. **THREE TYPES OF GLANDERS** (classification is based on the onset and severity of disease): 1. Acute 2. Chronic 3. Subclinical **TREATMENT**: Carbopenicillins (carbenicillin and ticarcillin) **CONTROL**: - Avoid contact with infected horses - Eradication of animal sources **PASTEURELLOSIS** - **GEOGRAPHIC DISTRIBUTION**: Worldwide - **SYNONYMS:** [Shipping fever (cattle)], [hemmorrhagic septicemia (cattle and lamb)], [Pasteurella pneumonia (lamb)], [fowl cholera], [snuffles] - **ETIOLOGY/CAUSATIVE AGENT**: *Pasteurella multocida* (most important), also *P. hemolityca*, *P. pneuomotropica*, *P. ureae* (*Pasteurella spp*: small pleomorphic gram-negative non-motile bacillus with little resistance to physical and chemical agents and can survive briefly in external environments) - Normal inhabitant of oral cavity in dogs and cats - High level of Pasteurella in oral cavity of cats than dogs in which rabies is the primary concern - **MODES OF TRANSMISSION**: Bites and scratches (dogs and cats) - **INCUBATION PERIOD**: Hours only - **CLINICAL SIGNS AND SYMPTOMS**: - Swelling, reddening, intense pain in cutaneous bite region (can penetrate deep tissue layers) - In patients greater than 40 years old, may complicate to pulmonary diseases (pasteurellosis is a disease associated with immunosuppression): - Bronchitis - Bronchiectasis (dilation of bronchi) - Pneumonia - Septic arthritis - **TREATMENT**: Gentamycin and streptomycin - **CONTROL AND PROPHYLAXIS**: - Avoid dog and cat bites - Avoid immunosuppression CSD/ CAT SCRATCH DISEASE - **GEOGRAPHIC DISTRIBUTION**: Sporadic in North America and France - **SYNONYMS**: [Cat scratch syndrome], [cat scratch fever], [benign inoculation lymphoreticulosis] - **ETIOLOGY**: *Bartonella henselae* (responds to tetracycline like *Chlamydia sp.*) - **MOT**: Scratches and abrasions - **INCUBATION PERIOD**: [Seven (7) to twenty (20) days] - **CLINICAL SIGNS AND SYMPTOMS**: 1. (Humans) Regional lymphadenopathy without lymphadenitis 2. Most infections heal spontaneously 3. Systemic signs: Chills, anorexia, malaise, generalized pain, vomiting, stomach cramps) - **COMPLICATIONS**: 4. Parinaud's oculoglandular syndrome 5. Enchephalitis, osteolytic lesions, and thrombocytopenia purpura - **TREATMENT**: 6. Symptomatic (by administration of symptomatic drugs) 7. Antibiotics: Tetracyclines - **CONTROL AND PROPHYLAXIS**: - Avoid bites and scratches from infected cats RBF/RAT BITE FEVER - **Geographic distribution**: Worldwide - **ETIOLOGY**: *Streptobacillus moniliformis* and *Spirillum minus* (normally found in nasopharynx of rodents) - **SYNONYMS**: 1. *S. moniliformis* infection: Haverhill fever - Incubation period: [Two (2) to fourteen (14) days] 2. *S. minus*: Sodoku/Spirillum fever - Incubation period: [One (1) week to two (2) months] - **MODE OF TRANSMISSION**: Through rat bites, as the name implies - **CLINICAL SIGNS AND SYMPTOMS**: - *S. moniliformis* infection: 3. Influenza-like 4. Exanthema 5. Chills 6. Regional lymphadenitis 7. Migratory arthralgia 8. Recurrent fever - *S. minus* infection: 9. Sudden fever 10. Recurrent generalized exanthema eruptions at attacks of fever 11. Lesions heal during incubation period but eventually there is edematous infiltration that ulcerates then lymph node hypertrophies - **TREATMENT**: Penicillin and streptomycin combination - **CONTROL AND PROPHYLAXIS**: 12. Avoid rodent bites 13. Control of the rodent population 14. Pasteurization of milk **TULAREMIA** - In tularemia, man serves as accidental host only - **GEOGRAPHIC DISTRIBUTION**: Northern Hemispheres (Canada, USA, Russia, etc.) - **SYNONYMS**: [Francis ds], [deer fly fever], [rabbit fever], [Ohara disease] - **ETIOLOGY**: *Francisella tularensis*, a highly pleomorphic gram-negative non-motile bacillus that can survive for several weeks in external environment - **MODE OF TRANSMISSION**: Direct contact with infected rabbits, rats, squirrels; indirectly through mechanical vectors: rabbit ticks, horseflies, mosquitoes - **INCUBATION PERIOD**: [Three (3) to five (5) days] - **CLINICAL SIGNS AND SYMPTOMS**: - Rising and falling fever - Chills - Asthenia - Joint and muscle pain - Cephalalgia - Vomiting - **TYPES OF TULAREMIA**: - *Ulcerglandular* (most common): Marked by necrotic ulceration of lymph nodes near entry site (wound/abrasion) - *Glandular*: Absence of primary lesions marked by inflammation of lymph nodes - *Oculoglandular*: Primary lesion on lower eyelids - *Pulmonary*: Pneumonia in both lungs - *Typhoidal* - Acquired through ingestion of contaminated meat (Japan) - Marked by gastroenteritis, fever, toxemia, ulcerative lesion on mouth, pharynx, intestine - Also swelling of cervical, pharyngeal, and mesenteric lymph nodes - **TREATMENT**: Streptomycin and tetracycline - **CONTROL AND PROPHYLAXIS**: Avoid contact with infected rabbits, rats, squirrels, and tick bites (*Ixodes* and *Dermacentor* ticks) FOOD BORNE AND OTHER FORMS OF BACTERIOSES COLIBACILLOSIS **GEOGRAPHIC DISTRIBUTION:** Worldwide **SYNONYMS**: [Collibacteriosis], [colitoxermia], [white scour], [gut edema] **ETIOLOGY**: *[E.coli]*, a ubiquitous organism present in water, soil, and dust Five (5) strains of *E.coli* causing diseases: - *EPEC -- enteropathogenetic E.coli* - *ETEC -- enterotoxigenic E.coli* - *EHEC -- enterohemorrhagic E.coli* - *AEEC -- Attaching and Effacing E.coli* - *EIEC -- Entero-invasive E.coli* (most pathogenic strain) **MODE OF TRANSMISSION**: It is transmitted through [ingestion of food contaminated with intestinal contents] **INCUBATION PERIOD**: [Twelve (12) to seventy-two (72) hours] **CLINICAL SIGNS AND SYMPTOMS**: - *EPEC, ETEC, EHEC, AND AEEC strains:* - Vibrio cholera-like symptoms: profuse watery diarrhea - Vomiting and abdominal colic - Fever may not be present - Mucus and blood are absent in stool - *EIEC:* - Dysentery-like symptoms: nausea, vomiting, diarrhea, resulting to rapid dehydration - Mucus and blood are present in stool - "[Traveler's diarrhea]:" Acquired by man from industrial countries visiting endemic areas (including the Philippines) - **TREATMENT**: [Trimethoprim sulfamethoxazole (TMPs)] and [metronidazole] (DOC for protozoan and anaerobic bacterial infections) - **CONTROL**: (1) protection of food, (2) milk pasteurization, (3) mandatory meat inspection, and (4) maternal and child health provision, especially in hospitals (*E.coli* infection is a nosocomial/hospital-acquired infection, with *Klebsiella* and *Acinetobacter spp.* Infections) **SALMONELLOSIS** - It is an infection acquired through ingestion of food from infected animals - A benign disease and patient recuperation in two (2) -- four (4) days - **SYNONYM**: [Enteric epizootic typhoid], [Enteric infectious paratyphoid] - **ETIOLOGY:** The disease is caused by members of *Salmonella enteriditis complex*: a. *S. gallinarum* (chicken) b. *S. pullorum* (chicken) c. *S. abortus equi* (cattle) d. *S. Dublin* (pigs) e. *S. cholerasuis* (pig) - **MODE OF TRANSMISSION**: f. Ingestion of contaminated food such as pork, poultry products, beef, milk, and eggs g. Contact with dirty utensils and animal products h. Direct contact with infected poultry, pig, and cattle - **INCUBATION PERIOD**: [Six (6) to seventy-two (72) hours] - **CLINICAL SIGNS AND SYMPTOMS**: i. Sudden fever j. Cephalagia k. Myalgia l. Malaise m. Abdominal symptoms: abdominal pain, nausea, vomiting, and diarrhea - **TREATMENT**: [Chloramphenicol] (DOC in animals and humans); however, this antibiotic may cause aplastic anemia, but nevertheless still the recommended DOC for typhoid fever / salmonellosis in humans - **CONTROL**: Obtain salmonella-free food of animal origin **LISTERIOSIS** - **GEOGRAPHIC DISTRIBUTION**: Worldwide - **SYNONYM**: [Leukocytosis], [mononucleosis], [listerial infection (dog)], [listeriosis], [circling disease (animals)] -\> the latter is due to profession of the disease to meningoencephalitis - **ETIOLOGY**: *Listeria monocytogenes*, a mobile gram-positive aerobe and facultative intracellular parasite of the reticuloendothelial system; has "[tumbling mobility]" under microscope - **MODE OF TRANSMISSION**: Through ingestion of contaminated milk (soil, plants, mud, pasture, wastewater, and springs) - **INCUBATION PERIOD**: Twenty-one (21) days (average) - **CLINICAL SIGNS AND SYMPTOMS**: - Precedes miscarriage or birth - Women: fever, chill, cephalalgia, dizziness - Born infants: Listerial septicemia, with focal hepatitis necrosis and hydrocephalus (listerial meningitis) with classical "cigarette but lesion" on head (an important pathognomonic sign) - *Note: Toxoplasmosis and listeriosis can be acquired during pregnancy* - **TREATMENT**: TMPS, erythromycin, and ampicillin - **CONTROL**: - Newborn screening of meconium (first (1^st^) fecal matter) - Milk pasteurization - Rodent control **ERYSIPELOID/** **FISH-HANDLER DISEASE** - It is an infection acquired from fish and eggs; regarded as a benign infection that heals spontaneously - **GEOGRAPHIC DISTRIBUTION**: Worldwide - **SYNONYMS**: [Rosenbach's erysipeloid], [erysipelotrichosis], [erythrema migrans], [rose disease] (swine) - **ETIOLOGY**: *Erysipelothrix rhusiopathiae* (syn: *E. insidiosa*), a bacterium with "bottled brush colonies" in culture - Clarification of the causative agents: 1. *Human erysipelas*: *Steptococcus spp.* 2. *Animal erysipeloid*: *Erysipelothrix sp.* 3. *Swine erysipelas*: *Erysipelothrix sp.* - **MODE OF TRANSMISSION**: Direct contact with infected pigs, fish, mollusk, crustaceans, and poultry; marked by presence of localized lesions at the inoculation point - **INCUBATION PERIOD**: [Hours to seven (7) days] - **CLINICAL SIGNS AND SYMPTOMS**: Erythematous, edematous, painful lesion with violet coloration around the wound - **TREATMENT**: DOC for swine erysipelas is penicillin; in humans, lesions can be treated with topical penicillin/benzylpenicillin potassium or even mupirocin (as topical antibiotics) - Trihydrate form of penicillin is a tissue irritant and therefore less recommended as topical antibiotic - **CONTROL**: - Avoid contact with infected animals (pigs and fishes) - Appropriate treatment of wound **DERMATOPHILOSIS** - - - - 1. 2. 3. 4. - **MODE OF TRANSMISSION**: Direct contact with infected fleece and pelt - **INCUBATION PERIOD**: One (1) to two (2) weeks - **CLINICAL SIGNS AND SYMPTOMS**: Cutaneous lesions are non-specific, but there is a remarkable "desquamative pustular dermatitis" formation on infected skin of human - **TREATMENT**: Penicillin (as DOC); pen-strep combination recommended in both humans and animals - **CONTROL**: - Avoid handling animals with bare hands - Proper treatment of wounds (topical antibiotics) **MRSA INFECTION** - A zooanthropozoonosis/reverse zoonosis causing opportunistic infections in man and animals - **GEOGRAPHIC DISTRIBUTION**: Worldwide - **ETIOLOGY**: *Staphylococcus aureus* (**mecA gene** - as the basis to methicillin) - **MODES OF TRANSMISSION**: 1. Contact with asymptomatic carrier 2. Dog and cat can acquire infections from humans through droplets 3. Also present in horse, cattle, birds, poultry, turtle, and psittacine - **INCUBATION PERIOD**: [One (1) to two (2) weeks] - **CLINICAL SIGNS AND SYMPTOMS**: Localized skin and soft tissue infection that may later progress into invasive disease (septicemia and toxic shock syndrome) - **TREATMENT**: Higher generation antibiotics (quinolones) and rifampin - **CONTROL**: Avoid indiscriminate use of antibiotics as growth promotants, especially in pigs and poultry