In the Aden Settlement’s Annual Report for 1892-93 the Senior Medical Officer was at a loss to explain the probable cause of the high incidence of malaria, or ague as it was often referred to, amongst the British element of the garrison.

“It has been suggested that probably malarial poison was set free by the disturbance of the ground caused by the works of the new fortifications, but had this been the case, ague should have been more prevalent at Steamer Point than at the Crater and Isthmus, whereas the contrary is the case. Out of 1354 cases of ague, 834 were at Crater or Isthmus and 518 at Steamer Point. The only disturbance of the ground at Crater was the erection of the new lines for the Native Infantry and at the Isthmus the construction of a new rifle range.

Whatever the causes of the prevalent malaria may be, they occurred at the Isthmus Position in the most violent and concentrated form, and to judge by recent experiences, this position must be one of the most poisonous hot beds of malaria to be found in the world.

It had to be abandoned in 1891 owing to the great prevalence of fever amongst troops. It was last year reoccupied by a detachment of the Liverpool Regiment, and the Medical Officer who was there at the time informed me that in May last year every man there, including officers, their servants and the Native Establishment, was attacked by ague.”

It was to be another four or five years before Sir Donald Ross in India deduced that the malaria parasite was transmitted by mosquitoes. The current thinking on the causes of malaria was that it was carried in tainted air from spores released from newly dug earth or rock – hence the reference to disturbed ground.

In another article I discuss the rainfall statistics for Aden from 1882 to 1937. The long-term expectancy of annual rainfall in Aden is around two inches, although in the 10 years from 1911 it would not even quite average an inch. The problem in the early 1890s was that in the calendar year 1890 no less than over 12 inches of rain fell in Crater, including 7.76 inches in March. Early 1891 was another period well outside the norm, especially for Sheikh Othman. The majority of this quantity of rain would have fallen in two or three storms. (A few years ago I remember reading that Aden had had a similar very rainy period.) The aftermath of this quantity of rain would have provided ideal conditions for the breeding of malaria-carrying mosquitoes, which in any case were endemic to the area.

By A.I. Mansur