Diagnosis of Cryptosporidium parvum with microscopy, striptest, ELISA and real-time PCR
Abstract number: p857
Vastert D., Brinkman M., Wilke H., Mulder B.
Cryptosporidium parvum remains largely under diagnosed in current routine diagnostic procedures in microbiology laboratories. We compared four different diagnostic methods for the detection of C. parvum in faeces in both acute and chronic diarrhoea.
Microscopic examination (Auramin stain confirmed by Kinyoun stain), Crypto-strip (Coris Bioconcept), ELISA (Novitec Cryptosporidium ELISA) and real time PCR for the detection of C. parvum were compared.
Five hundred and fifteen faeces were included. One hundred and fifty-four watery specimens from acute diarrhoea were sent for bacteriological examination and 361 triple faeces test (TFT)-samples, representing a more chronic form of diarrhoea, were sent to the parasitology department. Using real time PCR as the gold standard, the positive predictive values of microscopy, Crypto-strip and ELISA were 100%, 85%and 99%, respectively. The sensitivities of microscopic detection, Crypto-strip and ELISA were 37%, 78% and 71%, respectively, while the specificities of the three methods were never lower than 98%. Remarkably, the majority of the positive Cryptosporidium samples were not found in watery stools, as described in all textbooks, but rather in loose to mushy stools (57%). Furthermore, the majority of the positive watery samples were not sent for parasitological examination but only for bacterial culture.
The widely used microscopy is a very specific but less sensitive method for the laboratory detection of C. parvum in faeces. Both ELISA and Crypto-strip have good sensitivity and both positive and negative predictive values. Real time PCR is a very sensitive and specific method for the detection of C. parvum. The majority of positive Cryptosporidium samples were found in mushy stools from children younger than 10 years old. Examination of watery stools sent only for bacteriological examination, for the presence of C. parvum yields additional positive samples which would otherwise not have been detected.
|Session name:||XXIst ISTH Congress|
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