Blood Borne Parasites

• Many vector-borne diseases are preventable through protective measures and community mobilization
• Parasites are acquired by ingestion, insect bites or penetration of the mucous membrane or skin
• The two life stages of parasites are: trophozoite and cysts
• Trophozoite is the reproductive/feeding form
• Cyst is the protective/dormant form
• Plasmodium and barbesia are protozoa
• Protozoa have apicomplexa (apex) and complexus (infolds)
• Plasmodium species life cycle

  Infectious

  Asexual

  Diagnosis

  Sexual
• Malaria Clinical Presentation

  Chills

  Sweating

  Jaundice

  Dry cough

  Speen enlargement

  N/V

  Muscle Fatigue & Pain

  Back Pain
• Complications of Malaria

  Seizures

  Coma

  Organ Failure

  Anemia

  Cerebral Malaria
• The vector for plasmodium is the anopheles mosquito
• P. falciparum and P. malariae are predominantly in Africa and Asia
• P. vivax is predominantly in Latin America and India
• P. ovale is predominantly in Africa
• Incubation period for plasmodium is 2-3 weeks but may be months if malaria suppressant drugs were taken
• Clinical signs of infection associated with the liver phase of plasmodium

  None
• With plasmodium infection, parasite RBC are killed by direct parasite lysis
• In untreated patients with plasmodium, fever occurs in distinct paroxysms
• Tertian fever is associated with P. vivax and P. ovale
• Quartan fever is associated with P. malariae and P. falciparum
• Plasmodium can be diagnosed with thick and thin blood smears
• ParaSight F detects a protein HRP2 excreted by P. falciparum
• Ring Forms = Early Trophozoites

  A) Early trohpozoites

  
• P. falciparum gametocytes = DANGER FOR PATIENT

  
• Why is P. falciparum more deadly than the other species

  P. falciparum infects erythrocytes of ALL ages
• P. vivax only infects reticulocytes (via Duffy Ag)
• P. ovale only infects reticulocytes (different receptor from P. vivax)
• P. malariae attacks only senescent (elderly) cells
• P. falciparum alters the erythrocyte cell membrane causing it to adhere to capillary endothelial cells
• Sickle cell trait makes RBC less hospitable to P. falciparum
• Duffy antigens on RBC are absent in a majority of West Africans which protects against P. vivax
• Babesiosis is transmitted by the ixodes tick
• Babesiosis presents with fever, myalgia, fatigue and hemolytic anemia
• Babesiosis can be diagnosed by parasitized RBC on blood smear or PCR of blood
• Babesiosis is treated with azithromycin and atovaquone
• On histology, Babesiosis is associated with the Maltese cross

  
• Chagas disease is caused by Trypanosoma cruzi (kissing bug)
• Chagas disease is transmitted by reduviid bug bites and food contaminated with parasitized reduviid feces
• Chagas presents with Romana sign, fever, cardiomyopathy, and megacolon
• Chagas disease can be diagnosed with blood smear in early disease and is difficult to diagnose in chronic disease