Demonstration Sheets for Malaria (Apicomplexa Coccidea) (Lab 12)
Figures and page numbers from Roberts & Janovy 8th ed., 2009
All specimens (except for healthy tissue demos) this week are classified as: Phylum
Apicomplexa; Class Coccidea
Normal Human Blood
Do not mistake white blood cells (WBCs) for cells infected with malaria. WBCs
have nuclei that are stained purple by Giemsa stain.
H1155; 40X
Sickle Cell Anemia
This is a genetic condition found within the African-American community of
those with ancestors from West Africa. Without treatment, this condition is typically fatal
for those who are homozygous for the trait. The condition is usually not fatal for
heterozygous individuals who suffer “attacks”, but are more resistant to malaria.
Carolina 31-7374, 40X
Order Haemosporida
Ring Stage of Plasmodium falciparum
Ring stages of P. falciparum are smaller than those of the other species of human
malaria. Multiple infections of individual RBCs commonly occur with this species, a fact
that helps explain why P. falciparum is the most deadly of the four species that infect
people. See Plate 3 #8, #10 & #11 of your text.
92W 4620, oil
Order Haemosporida
Ring Stage of Plasmodium vivax
Early during development within host RBCs, malaria merozoites contain a
vacuole that does not stain as well with Wright’s stain as does the nucleus. This gives the
stage the appearance of a signet ring with the vacuole being the “hole” and the nucleus
the “jewel” of the ring. Ring stages of P. vivax are much larger than those of P.
falciparum and can almost completely fill the host RBC. See Plate 1 #5 & #12 in your
text.
92W 4660, oil
Order Haemosporida
Cerebral Malaria
Brain capillaries of host are blocked by red blood cells containing the parasites
(recognized by the sequences of “dots” formed by stained circular parasites). The outer
surfaces of parasitized red blood cells (RBCs) become “sticky” and adhere to capillary
walls especially in the central nervous system. Parasitized cells that are anchored in this
manner do not pass through the liver and spleen where damaged RBCs are removed from
circulation. The impairment of circulation, however, increases the likelihood of stroke.
See Figure 9.7 (p. 159).
92W 4700, 40X
Healthy Liver Tissue
One function of the liver is to remove toxins, such as hemozoin, from the blood.
As a consequence, many chemical compounds are concentrated in this organ. This slide
is presented for comparative purposes with the adjacent hemozoin slide.
Carolina 31-5400, 40X
Order Haemosporida
Hemozoin
The dark stains are NOT parasites but deposits of the iron-containing pigment
hemozoin. The pigment is an end-product of the degradation of hemoglobin by the
parasite. Recent evidence suggests that hemozoin inhibits the host’s immune response by
slowing the replication of antibody producing cells. See Figure 9.6 (p. 158).
92W 4701, 40X
Order Haemosporida
Pregnancy and Malaria
Placental tissue containing blood vessels of the mother that are filled with RBCs
infected with malaria and vessels of the infant that are free of the parasite. Pregnant
women are at especially high risk in malarious areas as their immune systems are
compromised during their pregnancies.
92W 4707, 40X
Order Haemosporida
Gametocyte of Plasmodium falciparum
Gametocytes of malaria fill and distort RBCs giving them a crescent-shaped
appearance. Once formed, gametocytes do not undergo further divisions in the human
host. It is the gametocytes that must be withdrawn from the peripheral blood during
feeding of the vector in order to maintain the life-cycle. Ring-stages that are consumed by
mosquitoes are digested. See Plate 3 #26 & #28 in your text.
92W 4623, oil
Order Haemosporida
Oocysts in hemocoel of Anopheles vector
This is a slide of the stomach of an infected mosquito with the oocysts (containing
sporozoites) developing outside the lumen in the body cavity. See Figure 9.3 (p. 153).
PS 745, 10X