Cryptosporidiosis is a disease caused by a coccidian parasite that

causes diarrhea in wide range of vertebrates worldwide . The concept of

cryptosporidiosis has been changed from that of the rare and

asymptomatic infection to an important cause of severe longstanding

diarrhea in man specially in immunocompromised hosts. The diseaes is

of particular importance in early childhood. Due to the recent

increasingly higher incidence of infection by Cryptosporidium sp., it is

important for the physicians and clinical laboratories to be aware of the

appropriate diagnostic techniques for identification the organism in

routine stool examination . The present work , therefore , aimed at

evaluation of some oocysts staining techniques in stool as well as to find

out the role of the level of a Cryptosporidium specific coproantigen in

the diagnosis of the infectios .

During the present study, diarrheic stool sample ,were collected

from fifty immunocompromised children ranging in age from few months

to ten years (34 males, and 16 females) attending Sohag University

Teaching Hospital from the period of May to August ,1995.Out of these

children 22 were aged few months up to one year, 15 aged from one to

two years , 5 aged from two to four and 8 aged from four up to ten

years.

Out of the examined children ,34 were suffering from malnutrition

, 9 from nephrotic syndrome and 7 were recieving cytotoxic drugs .

Regarding the type of feeding 21 children were depending on bottle

feeding, 12 were breast feeding and 17 were weaned, morever ten

apparantly healthy children of the same age group (3 males & 7 females)

were used as normal control.

Stool samples were tested for Cryptosporidium oocysts by

staining with modified Zeihl-Neelsen acid fast technique safranine,

Methylene blue and negative staining...On the other hand the samples

were tested for Cryptosporidium specific cproantigen by ELISA

assessment.

Oocysts of Cryptosporidium were identified in 22% of cases and

2 and of the ten controls by using modified Zeihl-Neelsen staining .

Safranin Methylene blue staining identified only 12% of cases while all

 

Controls were negative . Negative staining illustrated oocysts in only 4% of

Cases and all controls ,were negative .  

Using ELISA assessment forspecific Cryptosporidium antigen in

faecal samples illustrated different levels of infection in 38% of cases

and in three controls .

Form the previously mentioned data it was assumed that:

The best staining technique was the modified Zeihl-Neelsen

technique which was shown to be superior to safranin methylene blue

and negative staining . the latter was shown to be the poorest method for

identification of oocysts in stools and it was suggested to be better used

in identification of bigger faecal cysts as these of Entamoeba histolytica

and Giardia lamblia . However the following disadvantages were

experienced in the different staining techniques:

  • (

  1. Presence of strach granules which retained pale red colour

    with Zeihl-Neelsen acid fast stain .Unless careful decolourization

    is used, their presence may lead to false positive diagno sis .

  2. As previous authors indecated, some Cryptosporidium strains

    are not acid fast, thus false negative results might be obtained .

  3. Fluctuation in the number of daily output of oocysts or

    intermittent oocysts shedding might also represent a major

    difficulty in accurate identification of oocysts by staining

Using ELISA assessment of Cryptosporidium specific

cproantigen yeilded the best results as 38% of cases were found positive

for infection , (While the best staining technique has shown only 22%

positive cases)’. Moeover , using the visual and specrophotometric

methods for reading the ELISA , it was possible to divide the positive

cases quantitavely into mild (O.D. 0.05-1.00} mederate (O.D. 1.00-3.00)

and severe cases (O.D. more than 3.00) and thus it was possible to study

the level of infection in different age groups .

 

 

Under different feeding habits and different causes of

immunodeficiency . Thus most of the infected cases were in the age one-

two years . Regarding the cases of immunodeficeincy, the present data          indicated that more thaji half of the nephrotic syndrome cases suffered  

from cryptosporidiosis , while malnutrition ranked second (38.2%) and

lastly the use of cytotoxic drugs in (14.3%) of infected cases ,        ?

j.

Feeding habites jwere shown in the present study to be an

important predisposing factor in Cryptosporidium infection . Thus in

children depending totally on breast feeding , only one case was found

mildly positive . Higher rates of infection were detected among weaned

children (41.2%) and bottle feeding (52.3%) . The last two categories

are at risk due to pollution and contamination of their food with

infective oocysts .