Bugs Flashcards
Ehrlichia chareensis infects ____ and causes a disease called _______
Ehrlichia chareensis infects monocytes and causes a disease called Human Monocytic Ehrlichiosis (HME)
Anaplasma phagocytophilum infects _____ and causes a disease called _____
Anaplasma phagocytophilum infects granulocytes (specifically neutrophils) and causes a disease called Human granulocytic anaplasmosis (HGA)
Malaria specied infect ____ cells and ____ cells
red blood cells and liver cells
Babesia microti infects ____ cells
red blood cells
Trypanosoma species infects ____ and _____
monocytes and macrophages
Leishmania species infect _____ and _____
macrophages and reticuloendothelial cells
Describe the characteristics of Ehrliciha:
obligate intracellular gram-negative bacteria
tick borne
Describe the characteristics of Anaplasma:
obligate intracellular gram-negative bacteria
tick borne
Where/when are cases of Ehrlichia most common?
Southeast to south central US
Most cases occur in the spring and summer
How is Ehrlichiosis transmitted?
Vector:
- Lone star tick (Amblyomma americanum)
- Has been described in other ticks as well
Animal reservoir:
- White tail deer
- Dogs
- Coyotes
Other routes:
- Maternal-child
- Blood transfusion
- Direct contact with slaughtered deer
Morulae:
Seen in monocytes with Ehrlichiosis infection and granulocytes with Anaplasmosis infection.
Vacuoles containing bacteria in infected cells.
How is Ehrlichoisis diagnosed?
Indirect fluorescent antibody (IFA) - Acute and convalescent serology
Examination of peripheral blood
PCR
Immunochemical staining in tissue
Clinical diagnosis
When/where are cases of Anaplasmosis most common?
Upper midwest and northeast US (some in Europe)
Spring/summer
[high seroprevalence, so likely lots of asymptomatic transmission]
How is anaplasmosis transmitted?
Vector:
- Deer tick or black legged tick (Ixodes scapularis)
- Tick may be co-infected with Borrelia or Babesia (a few % of ticks)
Animal reservoir:
- White-tailed deer
- Also rodents/small mammals
Other routes:
- Person-person (cluster in China)
- Blood transfusion
- Nosocomial
How is anaplasmosis diagnosed?
Smear (Detects morulae in 20-75% of cases)
PCR
Serology
Clinical diagnosis
Compare/contrast clinical signs and symptoms of Ehrlichosis and Anaplasmosis
Incubation period 1-2 weeks after bite of infected tick
May cause asymptomatic to chronic infection
Typically an acute febrile illness (most cases). Infections more severe in immunocompromised
Rash and GI symptoms more common in Ehrlichosis
____% of confirmed cases of Ehrlichiosis are hospitalized. Explain.
62% of confirmed cases are hospitalized
Delay in antibiotic therapy is associated with an increased risk of mechanical ventilation and prolonged hospital stay.
Estimated mortality rate 2-5% (likely over estimated)
Multiorgan involvement in fatal cases with most bacteria in spleen, LN and BM
What is the appropriate treatment for Ehrlichiosis and Anaplasmosis?
Doxycycline (or tetracycline) because it can get into the cells
Trophozoites:
Form of parasite that is motile, feeding, reproducing
-mastigotes:
Flagellated form/stage of parasite
Sexual stages of parasites:
merozoites, schizonts, gametes, oocysts
What disease is suggested by this peripheral blood smear?
Babesiosis (Babesia microti)
Characteristic tetrad and ring stage
How is Babesia transmitted?
Vector:
- Nymphal stage of the Deer tick or black legged tick (Ixodes scapularis)
- Ticks can also have Lyme, Anaplasma
- Few patients recall tick exposure
Animal reservoir:
- White-footed mice
Other routes:
- Blood transfusion
- Rarely, congenital
Where is Babesia most common?
Northeast and upper midwest
What are the clinical manifestations of Babesia?
Can be asymptomatic or present w/flu-like symptoms
Can cause hemolytic anemia w/dark urine due to lysed RBCs
Severe, life-threatenting disease in:
- patients without a spleen
- immunocompromized
- advanced age
How is Babesia diagnosed?
Smear:
- Detects infected RBCs
- Can be difficult to distinguish Babesia from Plasmodium
Serology:
- IFA detects antibody in ~88-96% of infected patients
PCR
Clinical diagnosis, malaria-like illness in Babesia endemic region.
It can be difficult to distinguish Babesia from _____ on a peripheral smear
Plasmodium
What is shown in this image?
This is an image of a macrophage infected with Leshmaniasis, containing amastigotes.
Note that each amastigote has a nucleus (red arrow) and a rod-shaped kinetoplast (black arrow). Visualization of the kinetoplast is important for diagnostic purposes, to be confident the patient has leishmaniasis.
Describe the clinical manifestations of Chagas Disease:
Acute and chronic stages. Acute may be asymptomatic or nonspecific flu-like symptoms, last ~2 months
Classic Romana’s sign, swelling of the eyelids near the bite or where the feces was rubbed into the eye
Chronic infection is usually asymptomatic but some patients develop myocarditis. Death from Chagas is usually due to cardiac pathology.
How is Chagas Disease diagnosed?
Describe the Malaria lifecycle in humans:
Sporozites are injected into the body by the mosquito. These travel to the liver, which is the first site of infection/the parasite replicates here. During this initial period, don’t know you’re infected (asymptomatic).
Merozites burst from the liver and begins replicating in RBCs - this is the stage associated with symptoms. See characteristic ring stage –> trophozite –> Schizont.
Some emerge as male and female gametocytes, which recombine in the malaria midgut. These can then travel to salivary gland of a new mosquito for uptake.
What is shown in this image?
Malaria
Fill in the table:
Describe the pathogenesis of severe malaria:
Parasite exports malaria proteins onto the surface of the RBC, specifically PfEMP1. This protein interacts with ligands on human cells, especially ICAM-1 and CR-1 (also CSA and CD36), which allows blood cell to stick to endothelial lining, resulting in clogging in microvasculature. Body causes a massive immune response. Many problems arise due to host response to the parasite, such as cerebral malaria, metabolic acidosis, and high mortality.
