Protozoan Diseases
(Protos: First, zoans:animals)
Ø Protozoans These are the diverse group of eukaryotic
organisms and are unicellular in nature with a size 10-15 mm. The body is covered with an exoskeleton made up of silica or calcium carbonate.Mostly these are found in moist environments,
fresh water, marine water, soil, decaying organic matter and inside the plants
& animals. These were first observed by A.V.Leewenhoek and named them as animalcules later the name was introduced
by Goldfuss and unicellular nature
was identified by Von Siebold.
ØDiseases caused by protozoans in Human beings
|
Disease
|
Protozoan
|
Mode of infection
|
Affected part
|
Life Cycle
|
Incubation period
|
Symptoms
|
Preventive & Control measures, Treatment(Antibiotics)
|
|
Malaria
|
Plasmodium
falciparum
|
Sporozoites
|
Liver & RBC’s
|
Man,
Female Anophelus mosquito
|
9 – 14
days
|
Cold
stage: Severe chill, Shivering
Hot
stage: High fever, rise in pulse
Common:
Head ache , Vomting
|
Elimination of
mosquitoes by sprayinhd insecticides/kerosene,growing GAMBUSIA fish which
feeds the mosquito larvae.
Sulfodoxin,
Mefloquine,
|
|
Amoebiasis
|
Entamoeba
histolytica
|
Contaminated
food with faeces & oral faecal matter.
|
Intestine
|
Man
|
10 – 16
days
|
Abdominal
pain, diarrhoea,vomting etc.,
|
Washing hands before
& after taking the food, using boiled water for cooking & drinking,
avoid eating raw vegetables.
Metranidazole, Iodoquinol.
|
NOTE: For all of these
diseases, fever and head ache are common symptoms Ø Diseases
·
Malaria
It is a communicable disease caused by a protozoan Plasmodium falciparum by living in the liver. There are about 300 million people affecting with this
disease in the world per year.
Ø Life Cycle
o
Sporozoites
of the mosquito are transmitted to the humans by the mosquito bite.
o
Sporozoites enters into the liver and multiplies
(5-7 hours) forming thousands of merozoites
within 20 -30 minutes.
o
Merozoites burst out of the liver into the blood stream and invade the RBC’s, develop into gametocytes.
o
Gametocytes
are taken up by the mosquito from the human when it takes the blood meal.
o
Oocyst develops
in the gut wall divides and produces 10,000
sporozoites within 1 – 2 minutes.
o
Sporozoites releases and moves to the salivary glands, ready to infect
another person.
·
Amoebiasis
It
is caused by a protozoan parasite Entamoeba
histolytica by living in the intestine and produces cysts which are passed
from the body in the form of stool. They are about 100 million people are affecting with this disease per year.
Ø Life Cycle
o
Cysts ingested with food or water contaminated
with human faecal matter.
o
Cysts enter to the small intestine by releasing
an enzyme histolysin in the stomach and releases trophozoites which colonizes
the large intestine.
o
Trophozoites will reproduce and invade the blood
vessels of large intestine and be transported to the to the other organs of the
body. 
| 
