PARASITIC PROTOZOAPARASITIC PROTOZOA

Biology of the protozoa:Biology of the protozoa:

Protozoa are unicellular Protozoa are unicellular animals that occur singly animals that occur singly

or in colony formation.or in colony formation.

MORPHOLOGY:MORPHOLOGY:

The vital functions of the protozoa are The vital functions of the protozoa are carried out by the protoplasm.carried out by the protoplasm.

Protoplasm is differentiated into Protoplasm is differentiated into nucleoplasm and cytoplasm.nucleoplasm and cytoplasm.

Physiology:Physiology:

All essential metabolic, reproductive, and All essential metabolic, reproductive, and protective functions are carried on by either protective functions are carried on by either specialized properties of the protoplasm or by specialized properties of the protoplasm or by structural and functional adaptations known as structural and functional adaptations known as the organelles.the organelles.

Pseudopodia produce amoeboid movements in Pseudopodia produce amoeboid movements in sarcodina, cilia rhythmically propel the infusoria, sarcodina, cilia rhythmically propel the infusoria, and flagella the mastigophoraand flagella the mastigophora

Transmission:Transmission:

The parasites pass from host directly The parasites pass from host directly or through food and water after an or through food and water after an extracorporeal existence.extracorporeal existence.

Pathology and Symptomatology:Pathology and Symptomatology:

Protozoa, in contrast to worms, multiply in Protozoa, in contrast to worms, multiply in their hosts, so disease can result from their hosts, so disease can result from infection initiated by only a few organisms.infection initiated by only a few organisms.

Diagnosis:Diagnosis:

Clinical impressions should always be Clinical impressions should always be confirmed by laboratory diagnosis that confirmed by laboratory diagnosis that identifies the parasite in intestinal contents identifies the parasite in intestinal contents or in blood and tissues.or in blood and tissues.

Immunity:Immunity:

Natural resistance may be lowered by Natural resistance may be lowered by malnutrition, concurrent disease, or malnutrition, concurrent disease, or immunosuppressive drugs.immunosuppressive drugs.

Protective immunity often develops to Protective immunity often develops to protozoan infections involving the blood protozoan infections involving the blood and tissues.and tissues.

Prevention:Prevention:

The usual methods of reducing the The usual methods of reducing the sources of infection, blocking the channels sources of infection, blocking the channels of transmission, and protecting the of transmission, and protecting the susceptible host are employed.susceptible host are employed.

INTESTINAL AND LUMINAL INTESTINAL AND LUMINAL PROTOZOAPROTOZOA

AMEBAS:AMEBAS:

Members of this group of protozoa, which Members of this group of protozoa, which includes many free-living and parasitic includes many free-living and parasitic amebas, are probably the most primitive of amebas, are probably the most primitive of animal forms.animal forms.

6 species of Amebas in Man6 species of Amebas in Man :1.Entamoeba histolytica, 2.Entamoeba :1.Entamoeba histolytica, 2.Entamoeba

coli, 3.Entamoeba gingivalis, coli, 3.Entamoeba gingivalis, 4.Dientamoeba fragilis, 5.Endolimax nana, 4.Dientamoeba fragilis, 5.Endolimax nana, 6.Iodamoeba butschilii.6.Iodamoeba butschilii.

Entamoeba gingivalis trophozoitesEntamoeba gingivalis trophozoites

Life Cycle:Life Cycle:

The resistant infective cysts, formed in the The resistant infective cysts, formed in the lumen of the large intestine, pass out in lumen of the large intestine, pass out in the feces, and are immediately infective.the feces, and are immediately infective.

Human beings are the principal host and Human beings are the principal host and source of infection.source of infection.

Entamoeba histolytica Life CycleEntamoeba histolytica Life Cycle

Pathology:Pathology:

The pathogenic activities of E. histolytica The pathogenic activities of E. histolytica depend upon 1.the resistance of the host, depend upon 1.the resistance of the host, 2.the virulence and invasiveness of the 2.the virulence and invasiveness of the amebic strain, and the 3.conditions in the amebic strain, and the 3.conditions in the intestinal tract.intestinal tract.

Symptomatology:Symptomatology:

The clinical response is exceedingly The clinical response is exceedingly variable, depending upon the location and variable, depending upon the location and intensity of the infection.intensity of the infection.

Asymptomatic infections are the most Asymptomatic infections are the most common, especially in temperate zones.common, especially in temperate zones.

Diagnosis:Diagnosis:

The final diagnosis of amebiasis rests The final diagnosis of amebiasis rests upon the identification of the parasite an upon the identification of the parasite an the feces or tissues, and serologic studies. the feces or tissues, and serologic studies. All available methods should be exhausted All available methods should be exhausted before accepting a clinical diagnosis. On before accepting a clinical diagnosis. On the other hand, diagnosis by therapy must the other hand, diagnosis by therapy must be resorted to occasionally.be resorted to occasionally.

Prevention:Prevention:

Carriers should be removed from the food-Carriers should be removed from the food-handling occupations, instructed in handling occupations, instructed in personal hygiene and, treated.personal hygiene and, treated.

Effective environmental sanitationEffective environmental sanitationBoiling waterBoiling water