Giardiasis is the most common protozoal infection of the

human intestinal tract and it is found worldwide.

In the present study, a community-based prospective

study was conducted among randomly selected 600 persons

aging from one upto 50 years old. Generally, prevalence rate

was 22.3% and it is considered a high rate of infection.

Subgrouping of selected persons was done and showed that

giardiasis is more common in children group (12.3%) than

adult group (10%)). Also subaging of children group showed

high rate in children aging between 5-15 years than children

less than 5 years (10%o), 50% of infected adult group showed

+ve clinical manifestation with the diarrhea being the lesser

complaint.

             By a calibrated microscope, it was observed that there are

two different sizes of Giardia lamblia cyst, so that many

investigations were done to show differences among the two

isolates, these comprise:

(1) Animal inoculation: three groups of rats were used, one

group was given large cysts, another group was given small

cysts and the 3rd group was1 given trophozoites.

- Only the rat group, which was given the large Giardia cysts

took the infection and gave histopathological changes in

their intestinal villi.

-Trophozoites were found also adherent to gastric mucosa,

which was confirmed by histopathological and scanning

electron microscopic study.

 

- Histopathological study of the small intestine wasdone.lt

was observed also that cyst morphology was. similar to

human Giardia infection. •  ELISA tests for    of coproantigen in the stools.

Three' samples were 'used, 1st containing large cysts, 2nd

containing small cysts and!3rcJ cbntaining trophozoites. All

samples containing large cysts gave positive ELISA copro-

antigen, one sample only containing small cysts showed

positivity, and nonets the Trophozoite samples gave +ve

result.'            %-«r

-6 samples with negative microscopic examination were

positive ELISA technique.

  • These results revealed high sensitivity of ELISA technique

    for Giardia diagnosis and also explained the pathgenicity

    of the large cysts as it gave positive immune test.

  • SDS-PAGE for protein analysis ;p£darge, small cysts and

trophozoites: It showed different banding pattern among

the three samples with marked difference between protein

distribution of large and small cysfs.- Besides, the large

cysts contained antigens, which are considered important

antigens for immune.'response as 83,88,50 KDa antigens.

  • Large sized cysts and trophozoites contain an antigen 83

KDa (VSPH 7) which may be used in the future as vaccine |

for giardiasis.

From the results of the present study an explanation of the

presence different clinical patterns of giardiasis from | asymptomatic cases upto severe diarrhea with!

malabsorption is due to the presence of two strains of I