Blood Borne and Hemorrhagic Pathogens

Question 1

cat scratch fever

Answer 1

Bartonella henselae

Bacillary angiomatosis - in AIDs patients - skin lesion containing cenetral puncture would followed by swelling of the draining lymph nodes

dissemeniated -> immunocompetitant: bacteremia, osteomyelitis, pericarditis, cat scratch fever, asymptomatic

patient with vulvular lesion - endocarditis

Question 2

Leptospira interrogans

Answer 2

spirochete; exposure to contaminated fluid - dog or rat urine

found in non-chlorinated swimming pools, lakes and streams

leptospirosis - severe disease affecting primarily the liver, kidneys and nervous system (meningitis)

vaccine available for dogs, diagnosis by serology

Question 3

Rickettsia

Answer 3

small gram-neg rods but not stainable because of thin cell wall

obligate intracellular pathogens

tick or insect vectors

infects typically WBCs or endothelial cells

Question 4

Rocky Mountain Spotted Fever

Answer 4

Rickettsia rickettsii transmitted by tick bite

bacteria grow within endothelial cells and spread rapidly

unique rashes on hands & feet: due to vascular
infection / haematogenous spread

injury to lungs; CNS: seizures, coma; & renal
failure; rickettsial endotoxin > severe systemic complications

Question 5

Q (or “query”) fever

Answer 5

Coxiella burnetii

Found on the fur of farm animals

transmitted by inhalation of aerosolized dander and contaminated soil

Acute illness: pneumonia - sometimes fatal

Chronic form: usually cardiac problems - heamtogenous spread

diagnosis with serology - elevated phase 1 and 2 antibodies

Question 6

Ehrlichiosis - Type 1

Answer 6

Caused by Ehrlichia chaffeensis - infects monocytes

HME - human monocytic ehrilchiosis

Transmitted by the Lone Star tick - upper and lower midwest

acute febrile illness that can lead to leukopenia or thrombocytopena, acute weight loss and other flu-like symptoms
- rarely fatal but there are serious complications

bacteria appear mulberry-like in monocytes

Question 7

Ehrlichiosis - Type 2

Answer 7

Anaplasma
phagocytophila - it infects PMNs

HGE = Human Granulocytic Ehrlichiosis - Anaplasmosis

Transmitted by the deer tick - coastal northeast

acute febrile illness that can lead to leukopenia or thrombocytopena, acute weight loss and other flu-like symptoms
- rarely fatal but there are serious complications

bacteria appear mulberry-like in PMN

Question 8

Lyme Disease

Answer 8

Ixodid (deer) ticks:
Borrelia burgdorferi - spirochete, mostly N. America

endemic area; tick bite; presence of an
expanding erythematous rash (usually flat) - erythema migrans

headache, malaise, fever, myalgia, arthralgia

Question 9

Lyme Disease Ticks - geographical distribution

Answer 9

Ixodes scapularis – northeastern and midwestern
Ixodes pacificus – western USA
Ixodes ricinus – eastern & western Europe
Ixodes persulcatus: Asia & Australia

Question 10

Zika Virus

Answer 10

human-mosquito-human transmission cycle – Aedes mosquito

endemic - Puerto Rico and U.S virgin Islands

Pregnant women can pass the virus to the fetus during the pregnancy – found in the amniotic fluid and brains of micro-cephalic children

sexual contact - man to partner, present in semen longer than blood and can spread before symptoms.

clinical picture - fever, headache, arthralgia, myalgia, and a maculopapular rash

self limiting in adults

associated with Guillain-Barre-like syndrome

Question 11

Malaria:

Answer 11

Plasmodium - P. vivax, P. ovale, P. falciparum, P. malariae, P. knowlesi

Vector: Anopheles mosquito

Replicates in the blood and liver of humans, the salivary gland of mosquitos

clinical manifestations when parasite invades blood stream

Abrupt onset, HIGH fever, up to 104 F – drenching sweats, chills, myalgias, and arthralgias – 2 weeks after mosquito bite

splenomegaly - congestion caused by removal of damaged RBCs

Hepatomegaly - intrinsic liver infection by parasite

Hemoglobinuria and kidney damage from hemolysis of RBC’s “blackwater fever”

Question 12

P. vivax/ovale

Answer 12

Tertian fever every 48 hours – form dormant form/hypnozoite in liver

Question 13

P. malariae

Answer 13

Quartan fever – every 72 hours

Question 14

P. falciparum

Answer 14

most severe, irregular fever patterns, causes cerebral malaria

Question 15

What’s the laboratory stain for malaria?

Answer 15

Giemsa stain of peripheral blood – ring- form trophozoites, schizonts, gametocytes

serology can detect antibodies to plasmodium, but doesnt differentiate between active or previous infections

Question 16

Babesiosis

Answer 16

B. microti, B. divergens

Ixodes tick (deer tick)

most infections are asymptomatic - symptoms appear about 1-4 weeks after tick bites and persist for weeks.

at risk - asplenic, edlerly, immunocompromised

symptoms - fever, chills, myalgias and fatigue

complications - hemolytic anemia, thrombocytopenia, disseminated intravascular coagulation and possible organ failure

Question 17

What’s the laboratory stain for Babesiosis?

Answer 17

Giemsa stain of peripheral blood to detect ring forms in RBCs - tetrads or maltese crosses

Antibody detection tests and molecular techniques (PCR) in infected peeps with low levels (like symptomatic blood donors) and discrimination between p. falciparum and Babesia infections

Question 18

Chagas Disease - cause and modes of transmittion

Answer 18

Trypanosoma cruzi

aka American trypanosomiasis

vector - triatomid or kissing bug/reduviid bug

OR transfusion with infected blood or congenitally

T. cruzi causes Chagas Disease

flagellated protozoans

Question 19

African Sleeping Sickness

Answer 19

T. brucei causes African Sleeping Sickness

flagellated protozoans

transmitted by blood-feeding reduviid bugs, transfusion with infected blood or congenitally

Question 20

Chaga’s Disease - clinical presentation

Answer 20

acute phase - occurs immediately post infection, mild or asymptomatic. With symptoms - local lesion appear at site of inoculation, fever, anorexia and lymphadenopathy. Resolve in 2 to 3 months

chronic phase - years after acute phase, dilated cardiomyopathy, megaesophagus, hepatosplenomegaly, megacolon

Question 21

Laboratory confirmation of T. cruzi

Answer 21

Microscopic examination of a Giemsa stained blood smear

Question 22

Schistosomiasis

Answer 22

S. haematobium, S. japonicum, S. mansoni - trematode

host - human, intermediate host is the freshwater snail

adult male and female pair and live in human lymph vessels, release eggs - s. haematobium in the urine, s. monsoni and s. japonicum in the stool

disease is caused by immune reactions against eggs that lodge in the tissues

acute – weeks after infection: fever, cough, abdominal pain, diarrhea, rash/itchy skin, heapatosplenomegaly and eosinophilia

chronic – prolonged immune response and inflammation leads to a granulomatous condition and fibrosis - Urinary schistosomiasis can cause damage to kidneys, bladder and ureters.

diagnosis - microscopic identification of the eggs in stool or urine

Question 23

Lymphatic filariasis

Answer 23

caused by nematodes, roundworms, inhabit the lymphatics
most common species - wuchereria bancrofti and brugia malayi

vector - Aedes aegypti mosquito

Clinical Presentation - most people never develop clinical symptoms, some will develop late stage lymphedema

Hydrocele - blockage of the spermatic cord lymph which causes scrotal damage

elephantiasis - painful and disfiguring swelling of the limbs due to repeated skin and lymphatic reactions

Diagnosis - identification of microfilariae by microscopic examination of a giemsa-stained blood smear

Question 24

What are the different vectors for hemorrhagic viruses?

Answer 24

Ticks - crimean-congo hemorrhagic fever

mosquito - yellow fever, dengue fever, rift valley fever

Flies – Rift Valley Fever

rodents - hantaviruses, arena viruses, lassa fever

Question 25

Hemorrhagic Fever with Renal Syndrome

Answer 25

clinically similar to hantaviruses - includes disease like korean hemorrhagic fever, epidemic hemorrhagic fever and nephropathies epidemica

Causes an Interstitial Nephritis

transmitted by rodents - aerosolized urine, droppings, saliva, nest dust

Can be directly inoculated into broken skin or through mucous membranes

Question 26

yellow fever - transmission, endemic, reservoir

Answer 26

transmitted by mosquito bites -aedes

reservoir is nonhuman primates and mosquitos (since it can be transferred to progeny). causes “urban yellow fever” epidemics - travelers bring it in, transmission from human to human

mostly endemic in central Africa and north S. America

Question 27

yellow fever - disease course

Answer 27

acute - fever, muscle pain (backache), headache, shivers, loss of appetite, nausea or vomiting

acute improves after 3 to 4 days

Toxic phase - fever, jaundice, abdominal pain, with vomiting, bleeding from mouth, nose, eyes or stomach and kidney function deterioration

half patients in toxic phase die within 2 weeks

Question 28

yellow fever vaccination

Answer 28

live, attenuated virus - gives immunity within 1 week

single dose is good for 10+ years

serious side effects are extremely rare but the vaccine should not be given before 6 mo of age, pregnant women, immunocompromised or anyone with egg allergy

Question 29

Dengue Fever - transmission and areas endemic

Answer 29

tropical and sub-tropical regions, urban and semi-urban

Asian countries - leading cause of hospitalization and death among children

transmitted by aedes mosquito - incubation period is 8-10 days

theres 4 viruses, infections with one give lifelong immunity to that one but not to the others > re-infection increases risk of more serious disease

Question 30

Dengue Hemorrhagic Fever

Answer 30

potentially deadly complication of dengue fever

High fever

hemorrhagic with liver enlargement, severe cases see circulatory failure and bleeding occurs after 3 to 5 days of fever

Black stool, bleeding from nose, mouth, gums, skin bruising

most serious in children

Question 31

Dengue Fever - clinical presentation

Answer 31

mild febrile syndrome

OR

abrupt onset, high fever, severe headache, pain behind eyes, muscle and joint pains, rash

Question 32

Lassa Fever - epi

Answer 32

Arenavirus - zoonotic, no insect vector

rodents - natural reservoir, virus shed in urine and droppings

Multimammate rat of genus Mastomys

Contact with excretions or materials contaminated with excretions of an infected rodent (ingestion of food) or direct contact with broken skin

also, aerosolized, inhalation of tiny particles, person to person

West Africa, 80% infected have mild or no symptoms

others - severe multisystem disease

Question 33

Lassa Fever - disease, Dx, prevention

Answer 33

1-3 weeks after contact

fever, retrosternal pain, pharyngitis (sore throat), back pain, cough, abdominal pain, vomiting, diarrhea, conjunctivitis, facial swelling, proteinuria and mucosal bleeding

Dx - ELISA for IgM or IgG or Lassa Ag, viral culture, immunohistochemistry

prevention by avoiding the rat, not eating the rat, education

Rx - Ribavirin

Question 34

Ebola & Marburg viruses

Answer 34

4 subtypes, asymmetrical shape. Recent massive outbreak

most virulent pathogens of humans - severe hemorrhagic fever

case fatality rates are 80-90%

Category A bioterror agents

transmission is person to person, contact with blood or fluids

no carrier state

reservoir African fruit bats

diagnosis by ELISA (IgM), cell culture, RT-PCR

Question 35

ebola - clinical presentation

Answer 35

Ebola Hemorrhagic
Fever: severe, often-fatal
disease in humans and
non-human primates

incubation period 5-10 days

abrupt onset fever, malaise, myalgia, headache.

Nausea, vomiting, chest pain, a sore throat,
abdominal pain, and diarrhea

worsening into prostration, stupor and hypotension

conjunctiva hemorrhage, easy bruising, failure of venipuncture

jaundice, pancreatitis, severe weight less, delirium, multi-organ dysfunction