158 
Development of ffooJi-ivorm.s 
The incidence of infection in North Queensland does not differ from 
that in other infected countries. As usual children are more liable to 
infection, but adults are by no means exempt and indeed some of the 
most severe cases occur in the latter. 
The people of North Queensland are not below the average in 
intelhgence but they have that freedom and carelessness of tempera¬ 
ment frequently met with amongst white people in tropical countries. 
On the other hand the absence of cheap coloured labour makes it 
necessary that almost everybody in the country should do a certain 
amount of manual labour. While this is good in so far as it ensures 
that nearly everyone shall have a fair amount of bodily exercise, yet 
it results, at the same time, in many of the more menial tasks being 
neglected or inefficiently performed. In nothing is this more noticeable 
than in the ordinary hygienic arrangements. The disposal of night 
soil and household refuse is usually very tardy. Tin cans and other 
discarded articles of household use are allowed to accumulate indis¬ 
criminately and for indefinite periods. Rainwater collecting in those 
forms frequent breeding places for domestic mosquitoes. Bath and 
sink washings are allowed to escape on to any convenient spot in the 
garden or yard, or they are carried away to some distance in an open 
drain. Although the danger from these sources may not be very 
great, still they const!tutq^ favourable places for the development of 
hook-worm larvae should such gain access, and as it is a common 
practice for children to go about barefooted the risk of infection is not 
negligible. A more important danger is met with during the rainy 
season when for days and even weeks the ground may remain thoroughly 
sodden and numerous pools of various sizes are formed. This, needless 
to say, provides the ideal condition for the development of the parasites. 
It is a matter of observation that the great majority of cases of heavy 
infection occur near the end of the rainy season and for two months 
or so thereafter. 
The original source of infection is faecal matter charged with eggs 
from an already infected person. This, however, is not immediately 
infective, for the eggs and the larvae which are hatched from them 
must undergo a process of development which usually takes from five 
to seven days. Towards the end of this period the larvae begin to 
escape from the faecal matter provided the environment is favourable, 
i.e. containing sufficient moisture and without deleterious conditions 
being present. Thereafter they may remain alive possibly for as long 
as a year, or even longer, and may wander over very considerable areas. 
