Manual of basic techniques for a health laboratory - libdoc.who.int

7. Examination of urine 2497.2.8 Detection of Schistosoma haematobium infectionIn countries where schistosomiasis is endemic, urine specimens are examined foreggs of Schistosoma haematobium. Trophozoites of Trichomonas vaginalis may also beseen. Microfilariae of Wuchereria bancrofti and Onchocerca volvulus may also be foundin the centrifuged sediment of urine from patients in countries where filariasis isendemic.The first indirect evidence of Schistosoma haematobium infection is haematuria and/or proteinuria, which is detectable using a urine dipstick (see section 7.2.2). Grosshaematuria indicates heavy infection.The two methods used for detection of ova of Schistosoma haematobium are sedimentationand filtration. The sedimentation method is less sensitive but is cheaperand simpler to perform. The filtration technique is used when quantitative informationis required for epidemiological surveillance purposes.Materials and reagents● Microscope● Microscope slides● Coverslips● Centrifuge (sedimentation method)● Conical centrifuge tubes, 15ml (sedimentation method)● Filter holder, 13 or 25mm diameter (filtration method)●●●●●●Membrane filter, 12–20mm pore size (nylon or polycarbonate) or Whatman No.541 (or equivalent) filter-paper (filtration method)Conical flask for urine collectionPasteur pipettes (sedimentation method)Plastic syringe, 10ml (filtration method)Lugol iodine, 0.5% solution (reagent no. 37) (filtration method)Formaldehyde, 37% solution.MethodCollection of urine specimensThe number of ova in the urine varies throughout the day; it is highest in urineobtained between 10:00 and 14:00. The specimen should therefore be collectedbetween these times and should consist of a single terminal urine specimen (seesection 7.1.1) of at least 10ml. Alternatively, a 24-hour collection of terminal urinecan be made (see section 7.1.1).The whole specimen must be examined, as it may contain only a few ova. Ask thepatient to collect the urine in a clean flask or bottle. Examine the specimen at once.If the urine cannot be examined for an hour or longer, add 1ml of undiluted formalin(37% formaldehyde solution) to each 100ml of urine. This will preserve anyeggs that might be present.Note: If formalin is not available, 2ml of ordinary household bleach can be addedto each 100ml of urine.Warning: Formalin and bleach are corrosive and must not be swallowed.