Plasmodium vivax: Morphology

Navigation

>Main malaria Index

>Main Species identification page

---

Morphology of Plasmodium vivax
(See Malaria Biology pages for an explanation of these stages)

---

The early trophozoite

• 
• 

The earliest ring forms may be indistinguishable from other species, but during this stage the parasite tends to aquire a more irregular forms and to show signs of modification of the erythrocyte (added dots, and altered size and shape).

• erythrocytes begin to show increased size and altered shape
• parasites retain a ring form but may aquire a more irregular form
• parasites are generally large - occupying up to half of the erythrocyte
• cytoplasmic Schüffner's dots may appear at this stage, although pigment is less uncommon

GALLERY

---

The late trophozoite

• 
• 

The later growth stage of trophozoites where parasites modification of the erythrocyte is seen with characteristic added dots and possible minor changes to red cell form:

• Parasites resemble early ring forms, but are thicker and may be slightly larger
• Additional blue/grey dots and clefts are seen in red cell cytoplasm when stained correctly
• These dots have low number a characteristic "dot" or "line" form Maurer's dots and clefts
• Size and shape of infected red cells is usually unaffected, but may become crenated
• The double dot, accolé, and multiple parasite forms remain present

GALLERY

---

The schizont

• 
• 

The schizont is the asexual form of the malaria parasite that will circulate in blood in most species, but is an uncommon feature in P.falciparum:

• Do not generally circulate in this species unless overwhelming infection
• The merozoites cluster "untidily" but may be numerous (8-16+ when mature)
• In this species the loose pigment may be seen in clumps between the parasites
• Red cell size is generally unaffected but red cells become pale as haemoglobin is metabolised by the parasites

GALLERY

---

The gametocyte

• 
• 

The sexual replication in P.falciparum is very distinctive and may be the only form visible (particularly of after treatment).

• male and femaie gametocytes have the appearance of rods although these may be distorted
• The rod shapes may become curved by the red cell membrane to give the characteristic "banana" form”
• The residual membrane (empty of haemoglobin) is often seen as a "blister" to one or both sides of the parasite
• The single chromatin area is in the centre of the parasite, often has pigment overlying it

GALLERY

---