Malaria Flashcards
Malarial Life Cycle - Mosquito
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
Plasmodium knowlesi
- 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
Malaria Symptomatology
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
Serological techniques
Indirect Fluorescent Antibody (IFA)
Molecular techniques
Recombinant DNA probes Ribosomal RNA probes
Rapid tests
Usually used in field studies Plasmodial antigen detection Enzyme detection
Malaria Complications
Anemia Cerebral malaria (falciprum) Renal failure (malariae) Blackwater fever Dysenteric malaria Algid malaria: hypotension, delerium Pulmonary edema Tropical splenomegaly syndrome (TSS) Hypoglycemia
Babesiosis
Ixodes dammini (tick), sexual cycle: tick, Asexual cycle: mammalian host
Babesia Reproduction
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
Babesiosis Disease
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
Babesiosis Diagnosis
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
Malarial Life Cycle - Human
- 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
Ring Stage
Young Trophozoite, still contains a vacuole
Developing Trophozoite
Vacuole of Ring form fills in, adding to cytoplasm bulk, pigment begins to show
Pigment
- Product of Hemoglobin digestion
- Golden brown, brown, or black
Schizont
- Stage in which asexual reproduction takes place by the formation of Merozoites
- Characterized by nuclear division and differentiation of cytoplasm around the nuclei
Gametocyte
Picked up by mosquito vector that initiates sexual reproduction within the mosquito
Sporozoite
Infective stage, a product of sexual reproduction in the salivary gland of mosquitoes
Schuffner’s Stippling
Granular eosinophilic stippling within an infected RBC
Seen in P. ovale and P. vivax
Maurer’s Clefts
Clefts of eosinophilic stippling rarely seen in P. falciprum infections
Prepatent Period
Time from infection until discovery in blood film
Species that maintain a low grade Liver infection
Ovale and Vivax both maintain merozoites within hepatocytes, requiring a secondary medication for removal
Smear Types and Purposes
Thick Smear - Assess level of infectivity
Thin Smear - Differentiation
P. vivax Characteristics
- 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
P. ovale Characteristics
- 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
P. malariae Characteristics
- 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
P. falciprum Characteristics
- 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
Relapse vs. Recrudesence
P. vivax is the relapsing malaria
Other types “bloom” (Recrudesence) from incomplete therapy → failure to remove dormant stages in liver
Malarial Immunity
Sickle Cell Trait
Duffy Factor: lack “portal of entry” antigen of P. vivax
Paroxysm
Period of chills and fever followed by profuse sweating
Blackwater Fever
Complictaion of P. falciprum infection caused by a severe immune reaction
Causes Hematuria and Hemolysis
