Under-notification of cryptosporidiosis by routine clinical and laboratory practices among non-hospitalised children with acute diarrhoea in Southern Spain.

INTRODUCTION: In a prevalence study of 400 stool samples from non-hospitalised children under 7 years of age with diarrhoea, the presence of Cryptosporidium was evaluated.
METHODS: In addition to standard microbiological analyses used for testing for bacteria, parasites, adenoviruses and reoviruses, all samples were re-evaluated for the presence of Cryptosporidium by means of microscopy using a modified acid-fast staining technique, a rapid immunoassay for the qualitative detection of C. parvum and Giardia lamblia, the ImmunoCard STAT! test, and nested polymerase chain reaction (PCR). For identifying the genotypes of Cryptosporidium, the gene 18S ssu rRNA was amplified and sequenced.
RESULTS: Thirty-two samples were positive by microscopy, 26 by immunoassay and 61 by nested PCR. Twenty-seven of these organisms were identified as Cryptosporidium hominis, 31 as Cryptosporidium parvum and, in four samples, it was impossible to identify the species. C. parvum was significantly more frequent in girls and C. hominis was significantly more frequent in boys (Fisher's exact test, p = 0.034). Although Cryptosporidium is only notified in a very small number of patients (1-4%) with diarrhoea in Spain, the microorganism was identified by nested PCR in 15.1% of the samples.
CONCLUSION: This study, therefore, highlights the under-notification of infections caused by Cryptosporidium in Southern Spain and poses the question of whether its routine testing should be carried out in cases of gastroenteritis in children.