Distribution of Tropical Diseases in Africa. 433 
politically known as Egypt will be considered under the 
head of the Soudan. 
1. The Delta.—This area is humid, but the annual rainfall 
is only about 7 inches. Northerly winds prevail. The 
mean annual temperature is about 69° F., and the diurnal 
variation slight. 
2. The Valley of the Nile—The climate in this district is 
very different. The country may be practically said to be 
rainless. At Cairo there are only four or five showers a 
year, and in Upper Egypt but one or two. The mean annual 
temperature at Cairo is about 72° F., but the variation 
between night and day is very great. At Cairo the tem- 
perature may be as high as 110° F., but in the winter it may 
fall to below 32° F. The marked feature in the Nile Valley 
is the inundation of the country by the Nile, which begins to 
rise about the middle of June, reaches its height at the 
beginning of October, when it commences to fall, and it must 
be remembered that in Upper Egypt the river forms the sole 
source of the water-supply to the country. There is probably 
no other country in the world where the population is so 
dependent upon a single river, and unfortunately the Nile is 
habitually polluted with all kinds of filth, which has a 
great effect on the health of Egypt, for during the summer 
months, when the Nile is low, the people practically imbibe a 
solution of filth. This faulty water-supply undoubtedly 
causes the tremendous mortality amongst the child popula- 
tion. Out of 1000 children born in Egypt, 496 die before the’ 
age of five years (H. R. Green). It would be quite possible, 
although the cost would be great, to improve the water- 
supply ; there are no insuperable engineering difficulties to 
be encountered. 
3. The Hastern Desert and the Red See coast are drier and 
hotter than the Nile Valley itself. This notwithstanding, 
the country is salubrious. The heat from January to April 
is almost insupportable, especially during the southern 
khamseen, which is a dry scorching wind. 
With regard to the diseases prevalent in these regions, 
typhoid fever, relapsing fever, and. dysentery are very pre- 
valent throughout the whole country, and simple febriculas 
