"كتيّب الجزيرة العربية. مجلد II. ١٩١٧" [‎٣‎٧‎١] (٥٤٢/٣٧٥)

HYGIENE AND DISEASE 371
the unprotected sleeper. The net protects the user from the mos
quitoes which convey malaria and filarial blood-worms, as well as
from snakes and ticks. Native servants will find a way of fixing it
up in camp, and this must be done before dark. The edges should
be tucked under the mattress, not allowed to hang down to the
ground. Care should be taken to kill any mosquitoes which enter
with the sleeper, and to prevent any part of the body resting against
the net, which should always be stretched tight. When holes appear,
which they are sure to do, the tissue surrounding the hole should
be caught up and tied round with string, so as to close the aperture
completely. A net with holes is nothing but a mosquito-trap. The
careful and intelligent use of a mosquito-net is the first essential of
health in Tropical Africa.'
Other protective measures are : (1) the choice of a dry camping-
ground, at a fairly high level, free from stagnant waters, and at
least a mosquito's flight away—say a quarter or half a mile—from
a native village ; (2) special care, in the evening, to protect face,
hands, and ankles against mosquitoes ; (3) the use of quinine as
a protective drug. Note, that quinine is not a mere ' tonic ' : it has
a direct specific action on the Plasmodium malariae, such as salvarsan
has on the spirochaetes of syphilis.
Blackwater fever, which used to be regarded either as a rare form
of malaria, or as a result of too much quinine, is now held to be
a separate disease, due to a special infection, or possibly a parasitized
Plasmodium, but usually occurring in old malarial cases. It may
lie latent in a man, till fatigue, or chill, or perhaps an unusual dose
~ of quinine, makes it flare up. The onset, in most cases, is sudden,
with shivering and pain, and a high temperature; the skin may be
■ jaundiced ; and the urine is dark-red or almost black, due to the
presence of altered blood,
sasefc Ophthalmia. This general word is used of all forms of inflam
mation of the surface of the eye. In all tropical countries, neglect
. of cleanliness and sanitation makes ophthalmia terribly common,
especially among the children. Dust and dirt and the glare of the
■ sun favour infection ; and flies carry it on their feet from case to
. - case. In gonorrhoeal ophthalmia, a man may convey the germs of
gonorrhoea to his eyes by rubbing them with unwashed fingers.
Oriental Sore ('Aleppo boil', 'Baghdad boil', ' Delhi boil').
" ^ l oca li z ed infection of one or more points of skin, causing a very
I®! 1 indolent ulcer. The germs which cause it resemble those of a con-
- stitutional disease of the tropics, called kala-azar ; and belong to
he the genus Leishmania. Moreover, it is undoubtedly conveyed by
u a biting insect. I Dr. Wenyon, who made experiments with it on
a a 2