Module 7 Week 3 - Microbiology/Viruses

Question 1

Viral exanthem

Answer 1

rash of viral origin

Question 2

Measles/ rubeola

Answer 2

Paramyxovirus
Classic childhood exanthem
Inc. (10-14 days)
Replicates in respiratory epithelium and lymph nodes
Secondary viremia (2 peaks)
Severe in people with vit A deficiency

Question 3

Measles

1. Prodromal stage

Answer 3

First 12 days
High fever, 3 c’s: coryza, cough, conjunctivitis
Koplik’s spots on buccal mucosa

Question 4

Measles

2. Rash

Answer 4

3-4 days start
Begins below ears, spreads, lesions may become merged
Highest fever

Question 5

Nematodes (roundworms)

Answer 5

complete digestive tract, separate sexes

Question 6

Lymphatic filariasis

Answer 6

caused by Wuchereria bancrofti (and other tissue-dwelling filarial nematodes), with humans the only host
-Bancroftian filariasis

Question 7

How do filarial larvae infect humans?

Answer 7

Mosquitoes transfer larvae to human skin, the larvae penetrate the wound (the mosquito does not directly inject them into the human)

Question 8

Acute manifestations of lymphatic filariasis

Answer 8

fever, swollen and painful lymph nodes and lymphatic vessels, nocturnal wheezing, edematous plaques on skin ~1-week length but may recur

Question 9

Chronic manifestations of lymphatic filariasis

Answer 9

results from obstruction by adult worms and recurrent inflammation:

• lymphedema
• elephantiasis (severe lymphedema, hardening of tissues and skin)

Question 10

Treatment of choice for lymphatic filariasis

Answer 10

DEC: diethylcarbamzine (can also be used in mass administration as prevention of infectious spread)
-surgery to drain fluid, remove fibrotic tissue

Question 11

Onchocerciasis (river blindness) is caused by:

Answer 11

Onchocerca volvulus, whose larvae are transferred by blackfly bites, riskiest near fast-flowing rivers. Humans are the only host for these larvae/worms

Question 12

Clinical manifestations of onchocerciasis

Answer 12

pathology results from an inflammatory response to dead/dying microfilariae:

• subcutaneous nodules
• skin disease, rashes, itching, cracking, depigmentation
• eye disease/blindness

Question 13

Treatment/prevention of onchocerciasis

Answer 13

avoid blackflies/blackfly control 
DOC: ivermectin (kills microfilariae and can be used for mass administration prevention)
also doxycycline (kills adult worms)

Question 14

Loa Loa

Answer 14

African eye worm, transmitted by deer flies, live in subcutaneous tissue, usually asymptomatic. DOC: DEC

Question 15

Mansonella

Answer 15

transmitted by midges and blackflies, usually asymptomatic, infect body tissues, itching, joint pain, swelling, etc. DOC depends on which species.

Question 16

Dirofilaria immitis

Answer 16

heartworm in dogs, transmitted by mosquitoes or flies, causes chest pain, granuloma “coin lesion”

Question 17

Trematodes (flukes)

Answer 17

parasitic worms, complex life cycles, snails are the 1st intermediate host, usually hermaphroditic except schistosomes

Question 18

Schistosome trematodes (blood flukes)

Answer 18

cause an immune response to entrapped eggs in the host
asexual reproduction in the snail
free-swimming larvae are called Cercariae

Question 19

Schistosoma mansoni

Answer 19

adults live in mesenteric veins of either small or large intestines

Question 20

Schistosoma haematobium

Answer 20

adults live in the venous plexus of the urinary bladder

Question 21

Schistosomiasis (Bilharzia) acute infection:

Answer 21

cercarial dermatitis - itchy rash at site of larval entry

Katayama fever - fever, chills, headache, myalgia, cough, diarrhea, hepatosplenomegaly

Question 22

Schistosomiasis (Bilharzia) chronic infection:

Answer 22

intestinal - abdominal pain, poor appetite, diarrhea
hepatic - hepatosplenomegaly, liver fibrosis, ascites
urinary - dysuria, hematuria, can lead to bladder cancer
complications - damage to the brain, lungs, reproductive organs, etc.

Question 23

Schistosomiasis treatment:

Answer 23

praziquantel

Question 24

spirochaetes

Answer 24

spiral shape, gram-negative, motile, flagella, produce zoonotic infections such as Borrelia and Leptospira

Question 25

Borrelia burgdorferi causes:

Answer 25

Lyme disease - carried by blacklegged ticks (nymphs) with mammalian reservoirs of rodents, deermice, etc.

Question 26

Early localized Lyme disease

Answer 26

3-30 days post-tick bite, erythema migrans rash, flu-like illness

Question 27

Early disseminated Lyme disease

Answer 27

secondary erythema migrans, arthralgia/arthritis in large joints, heart palpitations and dizziness, neurological: Bell’s palsy
dx - two-tiered serological testing

Question 28

Late Lyme disease

Answer 28

months to years after, severe arthralgia, chronic neurological problems with numbness, tingling, memory, etc.

Question 29

Post-Lyme disease

Answer 29

signs and symptoms that remain after treatment, muscle and joint pain, cognitive problems, sleep disturbances
may be an autoimmune disorder or a persistent, difficult to detect, infection

Question 30

TBRF: Tick-borne Relapsing Fever

Answer 30

Borrelia hermsii -NA west of Mississippi river, zoonotic
ground squirrel reservoirs, soft tick vectors
multiple febrile periods 1-3 days, neuro problems

Question 31

LBRF: Louse-borne Relapsing Fever

Answer 31

Borrelia recurrentis - human transmission via body lice, fever lasts 3-6 days, higher mortality rate than TBRF, more likely to have epistaxis, petechiae, and ecchymoses.

Question 32

Jarisch-Herxheimer reaction

Answer 32

a complication of antibiotic therapy- inflammatory response to rapidly released bacterial endotoxins (broken down spirochetes)

Question 33

Leptospira interrogans

Answer 33

Leptospirosis - shed in urine of carrier animals, rodents, etc, variable disease, antibiotics (risk of Jarisch-Herxheimer)

Question 34

Leptospirosis acute phase:

Answer 34

abrupt onset of fever, chills, headache, myalgia, etc. starts to go away

Question 35

Leptospirosis 2nd phase:

Answer 35

may develop meningitis, renal failure, liver failure, pulmonary disease, myocarditis, uveitis, etc.

Question 36

Rickettsia rickettsii

Answer 36

Rocky Mountain Spotted Fever - high fever, severe headache, rash spreading centripetally, doxycycline tx, rodents/rabbits carry American dog tick, wood tick, or brown dog tick vector, transovarial transmission
can be fatal in first 8 days of illness

Question 37

Rickettsia akari

Answer 37

Rickettsialpox - eschar formation at site of house mite bite, carried by house mouse or other rodents. doxycycline tx, fever, severe headache, pox-like rash, transovarial transmission in vector
self-limiting disease, no deaths

Question 38

Rickettsia prowazekii

Answer 38

epidemic typhus - louse born carried on humans, high fever, severe headache, rash spreading centrifugally, doxycycline tx.
recrudescent Brill-Zinsser disease (or sylvatic from flying squirrels)
no transovarial transmission in vector

Question 39

Rickettsia typhi

Answer 39

Murine/endemic typhus from fleas carried by rats, mice, cats, opossums, etc. doxycycline tx. milder symptoms, shorter course

Question 40

Ehrlichia chaffeensis

Answer 40

Human monocytic ehrlichiosis (HME) - fever, headache, rash in 20-30% of adult patients, doxycycline tx. Lone star tick, from deer, dogs, etc.
infects monocytes/macrophages

Question 41

Anaplasma phagocytophilum

Answer 41

Human granulocytic anaplasmosis (HGA) similar to HME, doxycycline tx. black-legged ticks on rodents, raccoons, etc.
infects neutrophils

Question 42

Anaplasmataceae properties

Answer 42

gram-negative, coccobacilli, obligate endosymbionts, grow in membrane-bound morulae

Question 43

Rickettsiaceae properties

Answer 43

gram-negative, coccobacilli, obligate endosymbionts, grow in cytoplasm or nucleus, predilection for endothelial cells, causing vasculitis