Practical Parasitology2nd Stage

Lab 11: Malaria

University of Sulaimani

College of ScienceDepartment of

Biology

University of Sulaimani

College of ScienceDepartment of

Biology

Blood-dwelling Apicomplexa:Plasmodium spp.

Causative agent of malaria

Objectives: Students should be Objectives: Students should be able to:able to:• List Plasmodium spp that are infectious to human.• Describe sporozoite, hypnozoite, merzoite, and oocyst stages of Plasmodium spp.•Explain methods of transmission and diagnosis of Plasmodium spp.

Blood-dwelling Apicomplexa:Plasmodium spp.

• Malaria means “bad air”-• Malaria, which is transmitted by the female anopheles

mosquito, is the commonest insect borne diseases.• Its also the most deadly vector-borne disease in the

world.• A life-threatening parasitic disease and its a global

problem.• Malaria a major weapon of mass destruction.

Malaria

• 40% of the world’s population (2.4 billion) is at risk.

• 400-900 million people are affected worldwide. • Causes 1.5-2.7 million deaths annually (90%

Africa). • Children less than 5 years and pregnant women

mostly vulnerable.• Most prevalent in tropical and subtropical parts.•

Malaria

Please control malaria …

Causative parasite • Malaria is caused by species of Plasmodium spp.• Obligate intracellular parasite…• The genus Plasmodium contains 200 species.

– only four species are known to infect humans.•Plasmodium falciparum•Plasmodium ovale•Plasmodium vivax•Plasmodium malariae

Species Infecting Humans• Plasmodium falciparum

– Malignant tertian malaria • Plasmodium vivax

– Benign tertian malaria • Plasmodium ovale

– Benign Tertian or ovale malaria

• Plasmodium malariae– Quartan malaria

Common & Severe

Rare & Mild

• Pre-patent Period– Time taken from infection to

symptoms•Plasmodium falciparum 6-12 days

•Plasmodium vivax 10-17 days•Plasmodium ovale 12-16 days•Plasmodium malariae 28-30 days

Incubation Period

The HostsHuman:_ _ intermediate host._ asexual cycle

(schizogony cycle).

Female ANOPHELES MOSQUITOES:__ final hosts._ vector._ sexual cycle (sporogony).

Female Anopheline mosquito

Mother to child

(rare)Blood transfusion(rare)

Transmission of Malaria

Plasmodium life cycle

Infected mosquito bites human; sporozoites migrate through bloodstream to liver of human

Sporozoites undergo schizogony in liver cell; merozoites are produced

Merozoites released into bloodsteam from liver may infect new red blood cells

Merozoites are released when red blood cell ruptures; some merozoites infect new red blood cells, and some develop into male and female gametocytes

1 2

3

4

6

Merozoite develops into ring stage in red blood cell

Ringstage

Merozoites

Another mosquito bites infected humnan and ingests gametocytes

7

5 Ring stage transform to the trophozoite stage and divides, producing merozoites

Definitive host

In mosquito’s digestive tract, gametocytes unite to form zygote

8

Male gametocyte

Female gametocyte

Zygote

Sexualreproduction

Resulting sporozoites migrate to salivary glands of mosquito

9

Sporozoites in salivary gland

Asexual reproductionIntermediate host

Plasmodium life cycle

malaria_movie.swf

Plasmodium vivax & Plasmodium ovale

Hypnozoites

Hypnozoites: __Are liver dormant stages_Responsible for recurrence of malarial disease.

Exoerythrocytic Schizogony•hepatocyte

invasion•asexual replication

•no overt pathology

Erythrocytic Stage

•intracellular parasite undergoes trophic phase

•young trophozoite called ‘ring form’

•ingests host hemoglobin•hemozoin (malarial pigment)

Erythrocytic Schizogony•nuclear division

= begin schizont stage

•Produces merozoites

•erythrocyte rupture releases merozoites

•blood stage results in disease symptoms

Merozoite

Gametogenesis•occurs in mosquito gut

•‘exflagellation’ of microgametes are obvious•3X nuclear replication

•8 microgametes formed

TEM of two Plasmodium ookinetes

Immunostaining of an

ookinete

Ookinete

Plasmodium oocyst on the gut wall

Transmission•Sporozoites injected

with saliva

A smear of mosquito's salivary gland, Giemsa stain

Wet mount of mosquito's salivary

gland ,

Symptoms of Malaria• Fever is the most common symptom.

• Periodic episodes of fever alternating with symptom-free periods and this associated with synchrony of merozoite release.

• Other symptoms can include: chills, fatigue, weakness, headache, nausea, vomiting, diarrhea, muscle pain, mental status changes.

• Manifestations and severity depend on species and host status• Immunity, general health, nutritional

state, and genetics

Malarial ParoxysmPeriodicity

the attacks occur every second day with the "tertian" parasites (P. falciparum, P. vivax, and P. ovale) and every third day with the "quartan" parasite (P. malariae).

Malarial Paroxysm

Periodicity:_– Days 1 and 3 for:_– Plasmodium vivax– Plasmodium ovale– Plasmodium falciparum

Tertian malaria

Days 1, 3, 5, 7, 9,……….

48 hrs.

Days 1, 4, 7, 10,……….

72 hrs.

–Days 1 and 4 for Plasmodium malariae

Quartian malaria

Malaria Parasite Erythrocytic Stages

Ring form

Trophozoite

Schizont

Gametocytes

Mer

ozoi

t

es

Malaria Diagnosis• Clinical Diagnosis• Malaria Blood Smear• Fluorescent microscopy• Serology• Polymerase Chain Reaction

Blood Smear:_ _ Remains the “gold standard” for

diagnosis.

Remember: B.F.F.M. B.F.F.M.=Blood Film For Malaria

References• Schmidt GD, & Roberts LS. (2005). Foundations of Parasitology. 7th ed.

McGraw Hill. Boston.• Satoskar AR, Simon GL, Hotez PJ, & Tsuji, M. (2009). Medical Parasitology.

LANDES, Bioscince. Boston.• Gillespie S, & Pearson RD. (2001) Principles and Practice of Clinical

Parasitology. John Wiley & Sons Ltd. Chichester.• Plorde, JJ. (2004). Sporozoa. In: Ryan, KJ. Ray, CG. Sherris Medical

Microbiology: An Introduction to Infectious Diseases. 4th ed. MCGRAW-HILL. New York.

• http://www.dpd.cdc.gov/dpdx/ • http://www.stanford.edu/group/parasites/Parasites2006/• http://emedicine.medscape.com/article/784065-media• http://ipmworld.umn.edu/chapters/curtiscf.htm• http://www.medicine.cmu.ac.th/dept/parasite/framepro.htm.• http://en.impact-malaria.com/iml/cx/en/layout.jsp?scat=77824861-679A-

433D-B435-9BD832B97130.• http://www.cdfound.to.it/• http://www.imbb.forth.gr/people/inga/index.htm

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