Chapter 5
The Eukaryotes of Microbiology
Figure 5.1 Malaria is a disease caused by a eukaryotic parasite transmitted to humans by mosquitos. Micrographs
(left and center) show a sporozoite life stage, trophozoites, and a schizont in a blood smear. On the right is depicted a
primary defense against mosquito-borne illnesses like malaria—mosquito netting. (credit left: modification of work by
Ute Frevert; credit right: modification of work by Tjeerd Wiersma)
Chapter Outline
5.1 Unicellular Eukaryotic Parasites
5.2 The Parasitic Helminths
5.3 Fungi
5.4 Algae
5.5 LichensIntroduction
Although bacteria and viruses account for a large number of the infectious diseases that afflict humans, many serious
illnesses are caused by eukaryotic organisms. One example is malaria, which is caused byPlasmodium, a eukaryotic
organism transmitted through mosquito bites. Malaria is a major cause of morbidity (illness) and mortality (death)
that threatens 3.4 billion people worldwide.[1]In severe cases, organ failure and blood or metabolic abnormalities
contribute to medical emergencies and sometimes death. Even after initial recovery, relapses may occur years later. In
countrieswheremalariaisendemic,thediseaserepresentsamajorpublichealthchallengethatcanplaceatremendous
strain on developing economies.
Worldwide, major efforts are underway to reduce malaria infections. Efforts include the distribution of insecticide-
treated bed nets and the spraying of pesticides. Researchers are also making progress in their efforts to develop
effective vaccines.[2]The President’s Malaria Initiative, started in 2005, supports prevention and treatment. The Bill
and Melinda Gates Foundation has a large initiative to eliminate malaria. Despite these efforts, malaria continues to
cause long-term morbidity (such as intellectual disabilities in children) and mortality (especially in children younger
than 5 years), so we still have far to go.
- Centers for Disease Control and Prevention. “Impact of Malaria.” September 22, 2015. http://www.cdc.gov/malaria/malaria_worldwide/
impact.html. Accessed January 18, 2016. - RTS, S Clinical Trials Partnership. “Efficacy and safety of RTS,S/AS01 malaria vaccine with or without a booster dose in infants and
children in Africa: final results of a phase 3, individually randomised, controlled trial.” The Lancet 23 April 2015. DOI: http://dx.doi.org/
10.1016/S0140-6736(15)60721-8.
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