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Flashcards in Steinhauer Deck (47)
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1

P. falciparum

Mostly tropics
30,000 merozoites from hepatic cycle
Like younger cells
Only see multiple ring form and gametocytes (banana shaped)
Only one to do the clumping and rosetting

2

P. vivax

Tropics but not that much in africa
10,000 merozoites per hepatic cycle
Like reticulocytes
Can relapse
See schizont and macrogametocytes
One ring

3

P. malariae

Cosmopolitan but spotty
Like older RBC

4

P. ovale

Can relapse
Likes young

5

P. knowlsi

Southeast asia

6

Anopheles

Face down, ass up, thats the way it likes to suck

7

Plasmodium life cycle

Mesquito injects sporozoits into human
Make it to liver by inducing parasitophorous vacuole
The replicate and release merozoites back into blood
Make it to blood cells and make trophozoites

8

Ring troph

Signet ring trophozoite
Hemozoin with schizont
Can reenter cycle or make micro/macrogametocyte which get picked up by mesquito

9

How long until you have malaria symptoms

14-35 days

10

Uncompliccated malaria

Acute fever
Paroxysms- chill then sweats
Vivax every 48 hours benign tertian
Falciparum every 72 hours malignant tertian
Due to TNF-a
Anemia

11

Complicated malaria

Organ failure
Cerebral- Neuro problems
Blackwater fever- Dark hemoglobinuria
Hyperparasittemia with 5% RBC infected

12

Why is P. falciparum more pathogenic

More merozoites, more invasion of RBC
PfEMP1- expression causes cytoadhesions=endothelium adhesions and rosetting and protects parasites from being cleared by spleen

13

Sticky cells and disease

TNF---iNOS which disrupts neurons- cerebral effects

14

Malarial relapse

Normally within 3-5 years
Have a dormant state in liver with clearance from RBC
P. vivax and ovale

15

Recrudescense

Low level in RBC with no hypnozoites
P. Falciparum

16

Plasmodium dx

Thick blood smear- recognize parasite
Thin blood smear- specific dx
Serological, PCR
Rapid- for falciparum (HRP2) and vivax

17

Genetic resistance to malaria

Sickle cell (PfEMP1 malformation, microRNA also disrupt parasite, and heme oxygenase 1 inhibits cerebral malaria)
Duffy blood groups (vivax and knowlesi)
Thalassemia
G6PDH

18

Duffy blood group

Genes common in africa, the reason why vivax doesn't exist there
Lack of receptors for parasite attachment

19

Host defense of plasmodium

Spleen clears infected cells
Ab- Premunition: asymptomatic parasitemia (not common with travelers)

20

Babesia microti

Northeastern and upper midwest

21

Babesia divergens

Midwest and europe

22

Babesio duncani

West coast

23

Babesiosis general

Flu like symptoms unless immunocomprimised
Most via tick (Ixode scapularis and pacificus), some from blood transfusion
Important host- Permyscu leucopis mouse, same as Borrelia

24

Babesiosis life cycle

After feeding, adult females drop off the third host to lay eggs (1), usually in the fall.  Eggs hatch into six-legged larvae (2)and overwinter in the larval stage. In the spring, the larvae seek out and attach to the first host, usually a small rodent (3). Later in the summer, engorged larvae leave the first host (4) and molt into nymphs (5), usually in the fall. The ticks overwinter in this stage. During the following spring, the nymphs seek out and attach to the second host (6), usually another rodent (e.g., a mouse) or lagomorph (e.g., a rabbit).  The nymphs feed on the second host and drop off later in the summer (7).  Nymphs molt into adults (7a-7b) off the host in the late summer or fall, and overwinter in this stage. The next spring, adults seek out and attach to a third host, which is usually a larger herbivore (including cervids and bovids), carnivore, or human (8). The adults feed and mate on the third host during the summer. Females drop off the host in the fall to continue the cycle.  Females may reattach and feed multiple times. The three hosts do not necessarily have to be different species, or even different individuals. Humans may serve as first, second or third hosts.

25

Babesia microti life cycle

The Babesia microti life cycle involves two hosts, which includes a rodent, primarily the white-footed mouse, Peromyscus leucopus, and a tick in the genus, Ixodes.  During a blood meal, aBabesia-infected tick introduces sporozoites into the mouse host .  Sporozoites enter erythrocytes and undergo asexual reproduction (budding) .  In the blood, some parasites differentiate into male and female gametes although these cannot be distinguished at the light microscope level .  The definitive host is the tick.  Once ingested by an appropriate tick , gametes unite and undergo a sporogonic cycle resulting in sporozoites .  Transovarial transmission (also known as vertical, or hereditary, transmission) has been documented for “large”Babesia spp. but not for the “small” babesiae, such as B. microti .
Humans enter the cycle when bitten by infected ticks.  During a blood meal, a Babesia-infected tick introduces sporozoites into the human host .  Sporozoites enter erythrocytes  and undergo asexual replication (budding) .  Multiplication of the blood stage parasites is responsible for the clinical manifestations of the disease.  Humans are, for all practical purposes, dead-end hosts and there is probably little, if any, subsequent transmission that occurs from ticks feeding on infected persons.  However, human to human transmission is well recognized to occur through blood transfusions .

26

Babesia dx

No hemozoin (may not see with falciparum)
Ring form can make tetrad/ maltese cross
Can have multiple rings per cell
Irregular circles

27

Pathogenesis of Babesia

Serologic testing IFA (ELIZA for B. microti)
Tick- 1-6 wks incubation
Symptoms: Intermittent fever, dark urine
1-20% RBC normally infected
Summer transmission

28

Erlichiosis chaffeensis

Rickettsial tick borne
Intracellular G-
Human monocytic ehlichiosis
Morula in monocyte
Amblyomma vector, deer reservoir
Gets worse with age
South midatlantic, north/south
Can get rash everywhere (also hands/feet)

29

Anaplasmosis phagocytophilum

Rickettsial tick borne
Intracellular G-
Human granulocytic anaplasmosis
Morula in granulocytes
Ixodes scapularis and pacificus vector and white footed mouse reservoir
Mostly Eastern states, more north
Gets worse with age

30

Erlichiosis symptoms

1 wk incubation
fever, chlls, headache, myalgia, malaise
Ambylomma americanum tick vector