Diagnosis rests on the microscopic identification of larvae (rhabditiform and occasionally filariform) in the stool or duodenal fluid. Examination of many samples may be necessary, and not always sufficient, because direct stool examination is relatively insensitive, with a single sample only able to detect larvae in about 25% of cases. It can take 4 weeks from initial infection to the passage of larvae in the stool. The stool can be examined in wet mounts: * directly * after concentration (formalin-ethyl acetate) * after recovery of the larvae by the Baermann funnel technique * after culture by the Harada-Mori filter paper technique * after culture in agar plates Culture techniques are the most sensitive, but are not routinely available in the West. In the UK, culture is available at either of the Schools of Tropical Medicine in Liverpool or London. Direct examination must be done on stool that is freshly collected and not allowed to cool down, because hookworm eggs hatch on cooling and the larvae are very difficult to distinguish from Strongyloides. Finding Strongyloides in the stool is negative in up to 70% of tests. It is important to undergo frequent stool sampling as well as duodenal biopsy if a bad infection is suspected. The duodenal fluid can be examined using techniques such as the Enterotest string or duodenal aspiration. Larvae may be detected in sputum from patients with disseminated<unk> . Given the poor ability of stool examination to diagnose Strongyloides, detecting antibodies by ELISA can be useful. Serology can cross-react with other parasites, remain positive for years after successful treatment or be falsely negative in immunocompromised patients. Infected patients will also often have an elevated eosinophil count, with an average of absolute eosinophil count of 1000 in one series. Eosinophilia of a gastrointestinal infection may fluctuate in response to larval output, or may be permanently lacking in some disseminated infections. Hence lack of eosinophilia is not evidence of absence of infection. The combination of clinical suspicion, a positive antibody and a peripheral eosinophilia can be strongly suggestive of infection. It would be greatly useful to have significant advances in the sensitivity of the means of diagnosis, as it would also solve the challenging problem of proof of cure. If definitive diagnosis is solved then it stands to reason that proof of cure becomes easily realizable.
Strongyloidiasis
Thelaziasis
Opisthorchiasis
Helminthiasis
Clonorchiasis
Necatoriasis
Taeniasis
Isosporiasis