Six species of Paragonimus have been reported in Thailand: P. siamensis in cat, bandicoot and rat; P. bangkokensis in mongoose; P. harinasutai in cat and dog (experiment); P. macrochis in bandicoot and rat; P. westermani in tiger and P. heterotremus in cat, dog and man. It is interesting to note that in 1965 two immature P. heterotremus worms were recovered for the first time in man, namely in subcutaneous swellings in a boy; in 1981 nine mature P. heterotremus worms were expectorated after
praziquantel treatment. P. heterotremus has been postulated to be the main cause of human
paragonimiasis in Thailand. The clinical manifestation of
paragonimiasis heterotremus is similar to
paragonimiasis westermani. In the 1960's and 1970's
bithionol was used to treat
paragonimiasis, the cure rate was only 50-60%, and side effects including
urticaria,
rash,
abdominal pain,
nausea,
vomiting, diarrhoea and
dizziness were common. In the past 4 years,
niclofolan and
praziquantel (2-cyclohexyl-carbonyl-1,2,3,6,7,11b-hexahydro - 4H - pyrazino [2,1-a]isoquinolin-4-one,
EMBAY 8440,
Biltricide) have been used. A single dose of 2 mg/kg
body weight of
niclofolan yielded 100% cure rate.
Praziquantel at dosages of 3 X 25 mg/kg
body weight daily for one day and two days gave 80% and 100% cure rates, respectively. The eggs disappeared in 2-3 weeks with improvement of symptoms and signs, but radiologically lesions took a few months or more to clear, depending on size and severity. Side effects in the
niclofolan group were higher; in the
praziquantel group side effects were minimal and no toxic effects were detected.