Zoonoses

Rhabdovirus

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Disease: rabies

Vector: infected animals esp. racoons, skunks, bats, and foxes

Incubation: 10 days – many years but typically 3-7 weeks

Clinical manifestation:

Prodrome

  ~fever, malaise, nausea/vomit, skin sensitive to temp, pain at site of bite even after healing

CNS phase

  ~paresthesia, hydrophobia, rage alternating with calm, seizures, paralysis, tenacious saliva, death

Diagnosis:

– skin biopsy of posterior neck looking for Abs (using DFA)

– Negri bodies in neurons

Treatment:

– wound debridement

– human rabies immunoglobulin (HRIG)

– 4 doses of human diploid cell vaccine (HDCV)

Ehrlichia chaffeensis

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Disease: human monocytic ehrlichiosis

Vector: tick bite

Incubation: —

Clinical manifestation:

– fever

– leukopenia (left shift)

– thrombocytopenia

– rash

Diagnosis:

– IFA, PCR

– rarely see morula on blood film of buffy coat

Treatment:

– doxcycline

Notes:

– obligate intracellular bacteria

– replicates in host cell vacuole

Anaplasma phagocytophilium

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Disease: human granulocytic anaplasmosis

Vector: tick bite

Incubation: —

Clinical manifestation

– fever

– leukopenia

– thrombocytopenia

Diagnosis:

– see morula on blood film of buffy coat

– IFA, PCR

Treatment:  doxycycline

Notes:

– obligate intracellular bacteria which replicate while enclosed w/in vacuole

Rickettsia rickettsii

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Disease: Rocky Mountain spotted fever

Vector: tick bite from dog, wood, and lone star ticks

Incubation: 1 week

Clinical manifestation

– Macular rash starting on extremities and moving to torso

– rash starts blanching then becomes petechial

– other symptoms: vasculitis, fever, headache, myalgias, photophobia, nausea/vomit, confusion

Diagnosis:

– serology NOT USEFUL

– IFA or ELISA, need 4x rise

– DFA on rash biopsy (70% specific, 100% sensitive)

Treatment: doxycycline

Notes:

– looks like meningococcemia

– if unsure, give doxycycline w/ 3G cephalosporin

– replicates intracellularly in cytoplasm

Rickettsia prowazeki

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Disease: Louse-borne typhus

Vector: body louse feces contaminating scratched areas

Incubation: 1 week

Clinical manifestations:

– rash beginning on torso then moving to extremities

– other Sx: vasculitis, fever, malaise, HA, stupor, coma

Treatment: doxycycline

Notes

– obligate intracellular bacteria; replicates in cytoplasm of host endothelial cells

Coxiella burnetii

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Disease: Q-fever

Vector:

– inhaled tick products

– clues = exposure to livestock, airborne barnyard dust, contaminated milk

Incubation: 3 weeks

Clinical manifestation:

non-productive cough, hepatitis

– other Sx: vasculitis, rigors, HA, myalgias, endocarditis

Treatment: doxycycline

Notes:

– intracellular bacteria (not necessarily obligate)

– replicates in cytoplasm of fixed macrophages (liver, lungs)

Francisella tularensis

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Disease: Tularemia

Vector: tick bite from dog, wood, lonestar ticks or direct contact with infected rabbit tissues

Incubation: 3-5 days

Clinical manifestations:

– usually sever, sudden onset of fever, chills, HA, myalgias, fatigue

– ulceroglandular variety has ulcer at site of tick bite & painful regional lymphadenopathy

Diagnosis:

– abnormal liver enzymes

– serum agglutinins (not detectable for 10-14 days)

Treatment: streptomycin/tetracycline; NOT penicillin

Notes:

– varieties: ulceroglandular, typhoidal, pneumonic based on point of entry

– hunters or hide processers get it more frequently

Brucella melitensis (goats)

Brucella abortus (cattle)

Brucella suis (pigs)

Brucella canis (dog)

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Disease: brucellosis

Vector: reproductive tissue of ruminants; direct contact or ingestion of contaminated dairy products

Incubation: weeks

Clinical manifestation:

– undulant fever, depression, sciatica (sacroiliac tenderness)

– flu-like symptoms, hepatosplenomegaly, lymphadenopathy

Diagnosis:

– serology- be careful for false negative from prozone and false positive from cross-reactivity

Treatment:

– doxycycline and rifampin

Notes:

– multiplies in reticular endothelial system producing minute granulomas and abscesses

– common in vets and slaughterhouse workers

Leptospira interrogans (spirochete)

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Disease: leptospirosis

Vector: food/drink contaminated with urine of dogs, cattle, pigs, rats

Clinical manifestation

Biphasic disease (mild/moderate): fever, chills, abd. pain, headache, conjunctivitis

Weil’s syndrome (severe): impaired renal and hepatic function, jaundice, conjunctivits, hemorrhagic pneumonia

Treatment: PCN or doxycycline

Yersinia pestis (Gram + rod)

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Disease: bubonic plague

Vector: rat flea (Xenopsylla cheopsis)

Clinical manifestation:;

– tender, swollen fluid-filled lymph nodes, endotoxic shock, high fever, severe myalgia, tachycardia

Treatment: aminoglycoside + doxycycline

Pasteurella multocida

Capnocytophaga canimorsus

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Disease: infections from dog and cat bites

Vector: dogs, cats

Clinical manifestations:

– cellulitis, deep soft tissue infections

Treatment:;;-lactam +;;-lactamase inhibitor

Notes:

Pasteurella most common (esp cats); expect mixed infection

Bartonella bacilliformis

Bartonella quintana

Bartonella henselae

Disease: bartonellosis

Vector: Sand flea from peru, lice, and cat-associated fleas (feces) respectively

Clinical manifestations:

– Oroya fever, Verruga peruana (B. bacilliformis)

– relapsing high fever, myalgias w/ focal shin pain, HA, splenomegaly, endocarditis (B. quintana)

– children and young adults; cat scratch papules; regional lymphadenopathy 1-7 weeks after scratch (B. henselae)

Categories: Microbiology