Download Unicellular-and-multicellular-eukaryotic

Unicellular and multicellular eukaryotic
microorganisms
Debate Paper: Causing Disease by protists
Protists are unicellular and multicellular eukaryotic microorganisms. Protists
are divided into two sub groups - protozoa and algae. They cause diseases in
human, animals and plants. Even though, protozoa do not have many toxic
virulence factors, they lead to diseases by pathogenesis. They are the best
compared to bacteria, viruses and fungi because of the unique life cycle
phases. Protists can survive in environment as a cyst form and inside the
host as a trophozoite. The three phases that help protozoa to survive in
different environments and cause diseases includes sporozoite, tachyzoite
and merozoite. Protozoa are the best because they cause malaria, diarrhea,
dehydration, necrosis and complications in pregnancy. On the other side,
algae produce many toxins that cause poisoning in fish and slurred speech,
paralysis in humans.
Malaria is one of the diseases caused by protozoan Plasmodium species. It
can transmit by mosquito to human. In mosquito plasmodium are in
sporozoites form inside the oocyst. When mosquito bite to human,
sporozoites travels to liver and infects the liver tissue. In the liver sporozoites
become merozoites and enter into bloodstream where they infect red blood
cells. These red blood cells break apart and can cause anemia or coma in
human. Since they replicate in red blood cells, immune system can not
destroy the plasmodium. In Africa and some part of Asia, more children and
pregnant women are suffering of malaria and anemia due to contaminated
water, mosquito and lack of vaccine (Rogerson).
Neurological disorder is the second reason protozoa are best causing
diseases. Toxoplasma gondii causes necrosis and necrotizing lesions in
humans and animals. Toxoplasma is found as a sporozoite in cats which pass
thru feces. In human, sporozoites become tachyzoites in intestine. These
tachyzoites enter into macrophages (white blood cells) and spread through
out body to form necrosis of tissue. Toxoplasma can survive longer in
seawater as oocysts form and in mice stay up to 6 months as bradyzoite
form. Giardia Lamblia causes diarrhea, dehydration and nausea. Giardia can
survive in external environment such as water in cyst form and internal such
as intestine in trophozoite form (Lindsay).
Neurotoxic shellfish poisoning is caused by algae. Karenia brevis produce
brevetoxin which cause poisoning in fish and slurred speech, nausea and
vomiting in human. Brevetoxin disturb the transportation of sodium in nerve
membrane (Watkison).
On the other hand, viruses need particular protein or receptor to bind the
host. They depend on host for replications and to become pathogens.
Immunity and vaccine can prevent cause disease. Envelope viruses can not
survive for long time in water. Moreover, bacteria has short life cycle up to 22
minutes. Bacteriophage can treat bacterial infection but not protists. Viruses
and bacteria can not do asexual production and need DNA or RNA, and
transcriptions factors for replications. Fungi can damage skin or cause topical
disease. They are limited to surface of the host but the not inside to blood
Sporozoite, tachyzoite and merozoite or bradyzoite are eco-friendly for
protozoa that do not harm each other and recycle one phase to other phase.
Lindsay DS, Dubey JP. “Long-term survival of Toxoplasma gondii sporulated
oocysts in
seawater.” 2009 Aug; 95(4):1019-20. GALILEO
Rogerson J. Stephen. “Malaria in pregnancy and the New born.” 2010;
659:139-152.
Watkinson, Reich A, Fleming LE, Hammond R. “Neurotoxic shellfish
poisoning.” 2008
July; 6(3): 431-55