My dear Keith
21 Queen Anne Street,
Cavendish Square, W.
25th August, 1908.
243
Opisthochis
In answer to your query about Opisthochis (Distomm) Sinensis the proper way to go to work would be to ascertain by the comparison of the records of a number of cases the district or districts in which the infection is acquired; to go there and study the fresh water fauna especially the mollusca to determine which of them is the most likely intermediary and then to experiment with it.
Meanwhile experiments might be made in Hong Kong to find out how long the eggs took to hatch out from the eggs. This could easily be done by mixing the faeces of patients having Opisthorchis Sinensis with fresh water; shaking it up a little and changing the water frequently at least once a day decanting it off the faeces.
That is how I should set about such an enquiry.
The invertebrate intermediary must be sought for in the endemic district, not in Hong Kong. Very likely it does not occur there.
Yours, &c.
(Sgd) PATRICK MANSON.