A 25-year-old man from the Philippines develops Katayama syndrome 6 weeks after swimming in a river. His eosinophil count is 8.2 × 10⁹/L. Schistosome ...

Question

A 25-year-old man from the Philippines develops Katayama syndrome 6 weeks after swimming in a river. His eosinophil count is 8.2 × 10⁹/L. Schistosome serology is positive but stool and urine microscopy are negative. Why are microscopy results negative?

Accepted Answer

Egg production by adult worms begins approximately 6-8 weeks after cercarial penetration; during Katayama syndrome, worms are still maturing and have not yet started producing eggs in sufficient quantities for detection by microscopy

Answer

The patient does not have schistosomiasis

Answer

Microscopy cannot detect schistosome eggs

Answer

Eggs are only detectable by PCR

Answer

The laboratory made an error

uk-dtmh MCQ (SBA): Negative Microscopy in Katayama

A 25-year-old man from the Philippines develops Katayama syndrome 6 weeks after swimming in a river. His eosinophil count is 8.2 × 10⁹/L. Schistosome serology is positive but stool and urine microscopy are negative. Why are microscopy results negative?