Blood Borne and Hemorrhagic Pathogens Flashcards
cat scratch fever
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
Leptospira interrogans
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
Rickettsia
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
Rocky Mountain Spotted Fever
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
Q (or “query”) fever
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
Ehrlichiosis - Type 1
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
Ehrlichiosis - Type 2
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
Lyme Disease
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
Lyme Disease Ticks - geographical distribution
Ixodes scapularis – northeastern and midwestern
Ixodes pacificus – western USA
Ixodes ricinus – eastern & western Europe
Ixodes persulcatus: Asia & Australia
Zika Virus
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
Malaria:
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”
P. vivax/ovale
Tertian fever every 48 hours – form dormant form/hypnozoite in liver
P. malariae
Quartan fever – every 72 hours
P. falciparum
most severe, irregular fever patterns, causes cerebral malaria
What’s the laboratory stain for malaria?
Giemsa stain of peripheral blood – ring- form trophozoites, schizonts, gametocytes
serology can detect antibodies to plasmodium, but doesnt differentiate between active or previous infections
Babesiosis
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
What’s the laboratory stain for Babesiosis?
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
Chagas Disease - cause and modes of transmittion
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
African Sleeping Sickness
T. brucei causes African Sleeping Sickness
flagellated protozoans
transmitted by blood-feeding reduviid bugs, transfusion with infected blood or congenitally
Chaga’s Disease - clinical presentation
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
Laboratory confirmation of T. cruzi
Microscopic examination of a Giemsa stained blood smear
Schistosomiasis
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
Lymphatic filariasis
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
What are the different vectors for hemorrhagic viruses?
Ticks - crimean-congo hemorrhagic fever
mosquito - yellow fever, dengue fever, rift valley fever
Flies – Rift Valley Fever
rodents - hantaviruses, arena viruses, lassa fever
Hemorrhagic Fever with Renal Syndrome
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
yellow fever - transmission, endemic, reservoir
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
yellow fever - disease course
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
yellow fever vaccination
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
Dengue Fever - transmission and areas endemic
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
Dengue Hemorrhagic Fever
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
Dengue Fever - clinical presentation
mild febrile syndrome
OR
abrupt onset, high fever, severe headache, pain behind eyes, muscle and joint pains, rash
Lassa Fever - epi
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
Lassa Fever - disease, Dx, prevention
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
Ebola & Marburg viruses
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
ebola - clinical presentation
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
