XXV 
MOSQUITOES 
3Q 
colour being due to the presence of the colouring 
matter of the blood. The presence of haemoglobin in 
the urine comes about in this way. When cattle are 
bitten by the blue tick this arachnid may infect it with 
the disease-producing parasite known as a piroplasni : 
these micro-parasites multiply rapidly, invade, and 
destroy the red corpuscles of the blood. As a result, 
the red colouring matter (haemoglobin) is excreted with 
the urine. The remains of the disintegrated corpuscles 
are retained by the spleen or by the liver, and the 
disturbance this causes in the latter organ leads to 
jaundice, which is a clinical feature often present in the 
late stages of this disease. 
Ked-water is a disease widely spread in North 
and South America, India, China, Queensland, Great 
Britain, and all over Africa. In South Africa it has 
been known since 1870; it was imported with oxen 
from Madagascar (Theiler). Treatment is useless in 
dealing with the disease, which can only be eradicated 
by destroying the ticks which transmit it. 
East Coast Fever is a formidable disease, and has 
caused the deaths of many thousand head of cattle in 
East Africa: it is due to the entrance of a minute 
parasite into the red corpuscles of the blood subsequent 
to infection from the bite of a tick, but the parasites 
do not lead to the destruction of the corpuscle. In 
this disease peculiar bodies are found in the lymph 
glands and spleen, known as Koch’s granules, which are 
regarded as characteristic of East Coast E’ever. The 
transmitter of this disease is a brown tick belonging to 
the group Ehipicephalidae: this tick is widely dis¬ 
tributed in South and East Africa. 
The difficulty of eradicating this disease may be 
appreciated when we realise “ that one infected tick is 
capable of transmitting it.” 
Mosquitoes are blood-sucking insects, and a constant 
source of annoyance to human beings, for their bites are 
irritating and in some instances dangerous to health and 
