Malaria

Question 1

Malarial Life Cycle - Mosquito

Answer 1

Sexual reproduction occurs in the mosquito

• Gametes are fertilized, producing ookinetes
• Ookinetes penetrate the mosquitoes stomach and form a zygote
• Sporozoites form within the Zygote, eventually rupturing and invading the salivary gland of the mosquito
• Sporozoites are injected into the new host when the mosquito bites them

Question 2

Plasmodium knowlesi

Answer 2

• Usually found in Macaques, comprises 70% of malaria cases in Southeast Asia, where other malarial stains are less common
• Transmitted via mosquitoes, from infected monkeys or humans
• Shortest incubation period of any malaria, 12 days; with a 24hr life cycle
• Under the microscope, appears the same as P. malariae, although the Merozites are much larger than any other species; only confirmed with PCR/molecular assays

Question 3

Malaria Symptomatology

Answer 3

Prodromal phase (nonspecific): Headache, Photophobia, Muscle aches, Anorexia, Nausea and occasional vomiting Paroxysmal phase (specific): Shaking chills and rigor stage, Hot stage: elevated body temp. (40C/104F), Sweating stage

Question 4

Serological techniques

Answer 4

Indirect Fluorescent Antibody (IFA)

Question 5

Molecular techniques

Answer 5

Recombinant DNA probes Ribosomal RNA probes

Question 6

Rapid tests

Answer 6

Usually used in field studies Plasmodial antigen detection Enzyme detection

Question 7

Malaria Complications

Answer 7

Anemia Cerebral malaria (falciprum) Renal failure (malariae) Blackwater fever Dysenteric malaria Algid malaria: hypotension, delerium Pulmonary edema Tropical splenomegaly syndrome (TSS) Hypoglycemia

Question 8

Babesiosis

Answer 8

Ixodes dammini (tick), sexual cycle: tick, Asexual cycle: mammalian host

Question 9

Babesia Reproduction

Answer 9

Sexual Reproduction: Occurs in the tick, Sporozoites are infective, Transmission through saliva by tick bite Asexual Reproduction: Occurs in rodents or humans, RBCs infected and destroyed, Sporozoites formed by binary fission

Question 10

Babesiosis Disease

Answer 10

Symptoms: Hemolytic anemia, Malaise, Fever and chills, Night sweats, Jaundice Illness: Usually mild without periodic symptoms, Self-limiting in healthy population, Fatal in aspleenic or immunocompromised, Can be contracted through blood transfusion

Question 11

Babesiosis Diagnosis

Answer 11

Giemsa-stained blood smears Tetrads or Maltese cross (ring forms face together and form a cross with their loop portions) in RBCs Should be diffferentiated from P. falciparum No stippling or pigment observed in RBCs

Question 12

Malarial Life Cycle - Human

Answer 12

• Injected Sporozoites enter hepatocytes and multiple asexually to form Merozoites
• The Merozoites burst from the hepatocytes and invade RBCs
• Within the RBCs, Merozoites become Rings → Trophozoites
• Trophozoites develop into Schizonts or Gametocytes

Question 13

Ring Stage

Answer 13

Young Trophozoite, still contains a vacuole

Question 14

Developing Trophozoite

Answer 14

Vacuole of Ring form fills in, adding to cytoplasm bulk, pigment begins to show

Question 15

Pigment

Answer 15

• Product of Hemoglobin digestion
• Golden brown, brown, or black

Question 16

Schizont

Answer 16

• Stage in which asexual reproduction takes place by the formation of Merozoites
• Characterized by nuclear division and differentiation of cytoplasm around the nuclei

Question 17

Gametocyte

Answer 17

Picked up by mosquito vector that initiates sexual reproduction within the mosquito

Question 18

Sporozoite

Answer 18

Infective stage, a product of sexual reproduction in the salivary gland of mosquitoes

Question 19

Schuffner’s Stippling

Answer 19

Granular eosinophilic stippling within an infected RBC

Seen in P. ovale and P. vivax

Question 20

Maurer’s Clefts

Answer 20

Clefts of eosinophilic stippling rarely seen in P. falciprum infections

Question 21

Prepatent Period

Answer 21

Time from infection until discovery in blood film

Question 22

Species that maintain a low grade Liver infection

Answer 22

Ovale and Vivax both maintain merozoites within hepatocytes, requiring a secondary medication for removal

Question 23

Smear Types and Purposes

Answer 23

Thick Smear - Assess level of infectivity

Thin Smear - Differentiation

Question 24

P. vivax Characteristics

Answer 24

• All stages can be seen with enlarged RBCs that may be oval, with dents from nearby cells
• Usually contain Schuffner’s Dots except in early ring stages
• Only infect reticulocytes so infectivity is low
• Developing Trophozoites are diffuse/ameboid/”stringy”
• Rounded/oval Gametocytes
• Fine brown pigment may be seen
• Mature Schizont contains 16 Merozoites
• 48hr asexual cycle

Question 25

*P. ovale* Characteristics

Answer 25

* All stages may be seen, one is usually predominant * Enlarged RBCs, can be oval or **fimbriated** (20%) * Schuffner's Dots present in all stages * Cytoplasm is rounded and compact * Only infect Reticulocytes, low infectivity level * Developing Trophozoites are similar to *P. vivax* but less ameboid * Gametocytes are rounded/oval * Small amounts of dark brown pigment * Mature Schizont contains **9** Merozoites * 48hr asexual cycle

Question 26

*P. malariae* Characteristics

Answer 26

* All stages can be present, one is usually predominant * Infected RBCs are normal-sized or smaller * No Schuffner's Dots * Only infects older, smaller RBCs, limiting infectivity levels * Developing Trophozoites are compact and show band forms * Compact and rounded cytoplasm * Gametocytes are rounded/oval * Coarse dark brown pigment usually present * Mature Schizont contains **9** Merozoites * 72hr asexual cycle

Question 27

*P. falciprum* Characteristics

Answer 27

* Usually only **Rings** and Gametocytes (Rarely) seen in PB * Infected RBCs maintain their size * No Schuffner's Dots, Maurer's clefts may be present * Infects all stages of RBCs, infectivity rate is extremely high * Developing Trophozoites usually not seen, with later stages only occuring in cappliaries of viscera * Compact cytoplasm * Classic banana-shaped gametocyte * Cotain black pigment * 48hr asexual cycle

Question 28

Relapse vs. Recrudesence

Answer 28

*P. vivax* is the relapsing malaria Other types "bloom" (Recrudesence) from incomplete therapy → failure to remove dormant stages in liver

Question 29

Malarial Immunity

Answer 29

Sickle Cell Trait Duffy Factor: lack "portal of entry" antigen of *P. vivax*

Question 30

Paroxysm

Answer 30

Period of chills and fever followed by profuse sweating

Question 31

Blackwater Fever

Answer 31

Complictaion of *P. falciprum* infection caused by a severe immune reaction Causes Hematuria and Hemolysis