Zoonoses – Microbiology – Flashcards

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)

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

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

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

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

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)

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

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

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

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

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

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)