A 10-year study of Giardia intestinalis infections in adults was condu
cted in the Dakshina Kannada District of Karnataka State, South India.
Coproparasitological investigations were made on 10000 stool specimen
s collected from selected patients. The infection rate was 37.1% with
a male disease rate of 91.4%. The highest incidence rate was recorded
in the age group 15-26 years. A possible reason for this preponderance
of giardiasis in these males, is discussed. The optimum time for tran
smission appeared to be during the warmer months of the year (May to O
ctober) which coincided with the greatest amount of rainfall. The most
common symptoms were abdominal discomfort, flatulence, diarrhoea, wei
ght loss and anorexia. The predominating symptoms in our series varied
with socio-economic level. There appeared to be some correlation betw
een the clinical manifestations and the immune status of the individua
l.