RANDOM

• Plasmodium spp.


  Causative agent of Malaria
• Malaria is the leading parasitic disease that causes mortality worldwide
• Malaria is identified by WHO as one of the three major infectious diseases
• Groups mostly affected by Malaria

  • Young children
  • Pregnant women
• Modes of transmission for Malaria

  • Infected female mosquito (genus Anopheles)
  • Anopheles minimus var. flavirostris
  • Anopheles litoralis
  • Anopheles maculatus
  • Blood transfusion
  • Sharing of syringes
• Ring forms (early trophozoites)

  • Ring-like appearance following invasion of RBCs
  • Giemsa stain: blue cytoplasmic circle connected with/to a red chromatin dot (nucleus)
• Developing trophozoites


  • Remnants of cytoplasmic circle and chromatin dot are present
  • Pigment (brown) is often visible
  • Amount of RBC space invaded is significantly larger than that of the ring form
• Immature schizonts


  • Unorganized with evidence of active chromatin replication
  • Visible cytoplasmic material surrounds growing chromatin
  • Pigment (brown) is often visible
  • Expands and occupies more space within the RBC
• Mature schizonts


  • Group of merozoites (fully developed stage)
  • Number and arrangement of these merozoites vary
• Microgametocytes


  • Typical microgametocyte is roundish in shape
  • P. falciparum is crescent-shaped
  • Large diffuse chromatin mass that stains pink to purple surrounded by a colorless to pale halo
  • Pigment is also present
• Macrogametocytes


  • Round to oval, except P. falciparum which is crescent-shaped
  • Compact chromatin mass is partially to completely surrounded by cytoplasmic material
  • Pigment (brown) is also present
• Specimen of choice for laboratory diagnosis

  • Giemsa-stained peripheral blood smear (PBS)
  • Thick smear: screening slides
  • Thin smears: differentiation of Plasmodium species
• Time of blood collection is crucial in detecting malarial parasites, with the greatest number of parasites present in the blood in between paroxysms

  
• Multiple sets of PBS are necessary to rule out malarial infections, with blood collected every 6-12 hours up to 48 hours before considering cleared/negative

  
• Other tests for malaria diagnosis

  • Serologic test
  • PCR techniques
  • Malarial RDT (Histidine rich protein II (HRP II), Plasmodium lactate dehydrogenase, Plasmodium aldolase)
• Clinical symptoms of malaria

  • Chills, fever, sweating, and extreme fatigue
  • Headache, lethargy, anorexia, ischemia, nausea, vomiting, diarrhea, anemia, CNS involvement, and nephrotic syndrome
• Individuals with erythrocyte structural abnormalities (e.g., Sickle cell anemia, G6PD, Thalassemia) show resistance to malarial infections

  
• Pre-patent period


  Interval from sporozoite injection to detection of parasite in the blood, ranging from 11 days to 4 weeks

  
• Incubation period


  Time between sporozoite injection and the appearance of clinical symptoms, typically 8 to 40 days
• Incubation period for different Plasmodium species

  • P. falciparum: average of 8 to 15 days
  • P. vivax: 12 to 20 days
  • P. ovale: 11 to 16 days
  • P. malariae: 18 to 40 days

  
• Stages of malaria treatment

  • Causal prophylactic drugs (prevent establishment of parasite in the liver)
  • Blood schizonticidal drugs (prevent or terminate clinical attack of parasite in the RBCs)
  • Tissue schizonticides (act on pre-erythrocytic forms in the liver)
  • Gametocytocidal drugs (destroy sexual forms of parasite in the blood)
  • Hypnozoitocidal/anti-relapse drugs (kill dormant forms in the liver)
  • Sporonticidal drugs (inhibit development of oocyst in mosquito's gut)

  
• Common anti-malarial drugs


  • Chloroquine (mainstay of anti-malarial drugs)
  • Chloroquine + Primaquine (prevention of relapse in vivax malaria)
  • Artesunate + Mefloquine (first line regimen for MDR Malaria)

  
• Plasmodium vivax


  • Associated with benign tertian malaria
  • Presence of Schuffner's dots (tiny granules; eosinophilic stippling)
  • Targets young/immature RBCs, causing distortion of RBCs
  • Most widely distributed malarial organism - tropics, subtropics, temperate regions
  • Blood samples may be taken at any time during illness
  • 10 to 17 days incubation period
  • Paroxysms typically occur every 48 hours
  • Symptoms include flu, nausea, vomiting, headache, muscle pains, photophobia
  • Chronic infection may result in serious damage to brain, liver, and kidney
  • Prevention and control measures include netting, screening, protective clothing, repellents, and mosquito control

  
• Plasmodium ovale


  • Associated with benign tertian malaria
  • Presence of larger and darker Schuffner's dots
  • Targets young/immature RBCs, causing distortion of RBCs with ragged cell walls
  • Found in tropical Africa, Asia, and South America
  • Blood samples may be taken at any time during illness
  • Paroxysms typically occur every 48 hours
  • Untreated patients experience infections that last approximately 1 year

  
• Plasmodium malariae


  • Presence of Ziemann's dots (fine dustlike dots)
  • Targets mature RBCs with well-established cell walls
  • Found in subtropic and temperate regions
  • Most encountered forms are developing trophozoite and schizont
  • 18-40 days incubation period, with paroxysms typically occurring every 72 hours, not associated with dormant hypnozoite

  
• Plasmodium falciparum


  • Associated with black water fever, malignant tertian malaria, aestivoautumnal malaria, subtertian malaria, falciparum malaria
  • Presence of Maurer's dots (dark staining, irregular to comma-shaped cytoplasmic dots)
  • Targets RBCs at any age, with no cell enlargement or distortion
  • Most encountered forms are ring and gametocyte
  • Found in tropical and sub-tropical regions, tend to occur on warmer months and early autumn
  • 7-10 days incubation period, with paroxysms typically occurring every 36-48 hours
  • Early flu-like symptoms, followed by chills, fever, severe diarrhea, nausea, and vomiting
  • Can cause malaria with kidney involvement, including hemoglobinuria

  
• Morphological forms of Plasmodium species

  • Ring forms
  • Developing trophozoites
  • Immature schizonts
  • Mature schizonts
  • Microgametocytes
  • Macrogametocytes

  
• Plasmodium ovale has a delicate cytoplasmic ring that measures approximately 1/3 the diameter of RBCs, with a single chromatin dot and a ring surrounding a vacuole, and possible accolé forms
• Plasmodium vivax has a ring that is larger, thicker, and more ameboid than P. ovale, with the ring appearance usually maintained until late in development
• Plasmodium malariae has a smaller ring than P. vivax, occupying 1/6 of the RBC, with a heavy chromatin dot and a vacuole that may appear filled in, and pigment that characteristically forms early

  
• Plasmodium falciparum has a ring-like appearance following invasion of RBCs, with no cell enlargement or distortion, and the most encountered forms are ring and gametocyte
• Plasmodium vivax


  • Brown pigment common
  • Round to oval
  • Eccentric chromatin mass
  • Delicate light brown pigment may be visible throughout cell
• Plasmodium falciparum


  • Scanty cytoplasm, small vacuole usually visible
  • Multiple rings common
  • Accolé forms possible
  • Circle configuration (one chromatin dot) or headphone configuration (two chromatin dots)
  • Heavy rings common (multiple rings common)
  • Fine pigment granules
  • Mature forms only seen in severe infection
  • Multiple chromatin bodies surrounded by cytoplasm
  • Only detected in severe infections
  • 8-36 merozoites (average, 24) in cluster arrangement
  • Only detected in severe infections
  • Sausage- or crescent-shaped
  • Dispersed central chromatin with nearby black pigment usually visible

  
• Babesia spp. is the causative agent of Texas Cattle Fever or Red Water Fever and Babesiosis
• Babesia spp. usually infects animals, whether wild and/or domestic
• Mode of transmission for Babesia spp.

  Tick bite (genus Ixodes) - HUMANS: accidental host

  
• There are approximately around 100 known species of Babesia, but only 4 has the ability to cause human infection

  
• Life cycle of Babesia spp.

  1. SEXUAL PHASE: occurs within vector (Tick)

  2. ASEXUAL PHASE: occurs within host (Mice, deer, cattle, dogs, humans)

  
• Trophozoites of Babesia spp.

  • Resembles a ring form of Plasmodium spp.
  • Blue cytoplasmic circle connected with or to red chromatin dot
  • Vacuole usually present
  • Does not contain Schüffner's, Ziemann's, or Maurer's dots

  
• Merozoites of Babesia spp.

  • Resembles four trophozoites attached by their respective chromatin dots in the shape of a Maltese cross