PIROPLASM

• Piroplasms are intracellular parasites of blood cells, primarily erythrocytes, as well as some leukocytes
• Piroplasms


  • Small, piriform, round, or rod-shaped
  • Life cycle involves various vertebrate hosts and ticks
  • Reproduction in the vertebrate host is asexual (merogony) only. Sexual reproduction and sporogony occurs in ticks. Oocysts are absent
• Families of Piroplasms


  • Babesiidae
  • Theileriidae
• Babesia spp.


  Parasitize the red blood cells of various domestic animals and other mammals
• Babesia life cycle


  1. Merozoites occur in the erythrocytes where they multiply by binary fission, forming two or four new merozoites

  2. In the ticks, gametes are formed in the midgut lumen. The zygote penetrates the midgut cells and produce motile kinetes

  3. Kinetes can penetrate the ovary of female ticks (transovarial transmission)

  4. Kinetes also penetrate salivary glands where sporoblasts, later becoming sporozoites, are formed through sporogony
• Babesia species


  • Small Babesia: B. bovis, B. divergens
  • Large Babesia: B. bigemina, B. major
• Tick vectors of Babesia

  • Rhipicephalus
  • Amblyomma
  • Dermacentor
  • Haemaphysalis
  • Hyalomma
  • Ixodes
• General pathogenesis of babesioses

  • Main clinical feature is hemolytic anemia due to rapid destruction of parasitized RBCs
  • In acute cases, PCV may fall below 20%
  • Usual findings are hemoglobinemia, hemoglobinuria, and fever
  • At necropsy, carcass is pale and jaundiced, bile is thick and granular, and sub-epicardial and sub-endocardial hemorrhages may be present
• Babesia bovis


  Small species causing "red water" or tropical babesiosis; more pathogenic
• Babesia bigemina


  Cause of tick fever or Texas fever
• The earliest published report of B. bovis (previously B. argentina) was in a cattle in Nueva Ecija in 1960. The first documented report of B. bigemina was in 1975, which caused outbreaks in imported cattle.
• B. bigemina and B. bovis have been detected in cattle by PCR in Luzon (Quirino, Nueva Ecija, and CALABARZON provinces) and Visayas (Cebu, Iloilo, Negros Occidental and Negros Oriental).
• Pathogenic effects of Babesia

  • B. bigemina - mainly due to destruction of RBCs
  • B. bovis - alters infected RBCs by making them more rigid, adhesive, and formation of ridges. Can cause accumulation of parasitized RBCs in the microvasculature and can lead to complications such as cerebral babesiosis, respiratory distress syndrome, and multi-organ failure
• Babesia species in dogs

  • B. canis
  • B. rossi- most pathogenic
  • B. vogeli
  • B. gibsoni- small species
• Babesiosis of dogs


  Infection is generally classified as uncomplicated (consequence of hemolytic anemia) or complicated (multiple organ dysfunction syndrome)
• The first published report on Babesia canis was about hematological abnormalities in 291 dogs from Metro Manila. The parasite was identified through blood smear examination.
• Antibodies to B. gibsoni were first reported among dogs in Cavite in 2008.
• The first report on the molecular detection of B. vogeli was published in 2017 involving a study done in Cebu that utilized PCR.
• Molecular evidence on the presence of Babesia spp.in dogs was also obtained in studies done in Nueva Ecija, Metro Manila, and Laguna.
• Babesia caballi


  Causes equine babesiosis. B. equi is now classified as Theileria equi.
• Equine babesiosis


  • Tick vectors belong to genera Dermacentor, Rhiphicephalus, and Hyalomma
  • Intrauterine infection and blood transfusion are other means of transmission
  • Acute infection can cause anemia, thrombocytopenia, jaundice, hemoglobinuria, sweating, petechial conjunctival hemorrhages, swollen abdomen and posterior weakness
• Theileria spp.


  Infects the leukocytes (lymphocytes, histiocytes, macrophages) and erythrocytes, mainly of ruminants
• General life cycle of Theileria spp.

  1. Sporozoites infect lymphocytes

  2. Schizogony

  3. Merogony

  4. Gamogony and sporogony
• Theileria species


  • T. parva
  • T. annulata
  • T. orientalis/sergenti complex
  • T. hirci/T. lestoquardi
  • T. equi
• T. parva is present in East, Central, and Southern Africa. Mortality is 100% in infected cattle that are not immune.
• l cells


  • Particularly of lymphatic glands and spleen
• Zygote does not multiply, are much larger, and fewer
• Transovarial transmission in ticks does not occur
• General life cycle of Theileria spp.

  1. Sporozoites infect lymphocytes

  2. Schizogony

  3. Merogony

  4. Gamogony

  5. Sporogony
• Theileria spp.


  • T. parva
  • T. annulata
  • T. orientalis/sergenti complex
  • T. hirci/T. lestoquardi
  • T. equi
• T. parva


  Causes East coast fever, Corridor disease, Rhodesian tick fever
• T. annulata


  Causes Mediterranean coast fever, tropical theileriosis
• T. orientalis/sergenti complex


  Causes Oriental theileriosis
• T. hirci/T. lestoquardi


  Causes Malignant ovine/caprine theileriosis
• T. equi


  Causes Equine theileriosis
• T. parva is present in East, Central, and Southern Africa
• Mortality is 100% in T. parva infected animals
• T. parva infection


  1. Initially, the lymph node draining the tick bite site becomes enlarged, followed by fever

  2. At necropsy, atrophy of the cellular content of lymph nodes and spleen, pulmonary edema and emphysema, and hemorrhages on gastrointestinal mucosa and other organs may be seen

  3. Occasionally, nervous signs known as "turning sickness" have been reported
• T. annulata


  Reported mostly in countries bordering the Mediterranean Sea (North Africa, Sudan, Middle East, Ethiopia, Central, and West Asia)
• Fatality of T. annulata is lower, but may reach up to 70-90%