﻿186 JAS. J. SIMPSON — ENTOMOLOGICAL 



V. — Insect-borne Diseases in Man and other Animals. 

 Malaria. 



As in all West African Colonies, malaria is by far the most prevalent 

 iosect-borne protozoal disease, but owing to the free use of quinine and 

 prophylactic measures, such as the adoption of mosquito-nets and mosquito- 

 proof rooms, and also more sanitary conditions, which tend to reduce the 

 number of mosquitos, this disease does not now account for nearly so many 

 invaliding^ and deaths as formerly. In spite of the length of time since the 

 connection between Anopheline mosquitos and malaria was established, it is 

 surprising how little is still known of the actual species which are implicated 

 in its transmission in Africa. A fruitful line of research, and one by no means 

 difficult to accomplish, would be the wholesale dissection of the various species 

 of Anophelines found in each and every district, in order to ascertain which 

 species, and what percentage of specimens, contain sporozoits of the malaria 

 parasite. 



Yellow fever. 



There is still some difference of opinion as to whether this disease is actually 

 endemic in West Africa, but that it does exist in that region there is now no 

 doubt, and further, it is becoming more and more evident that it has a strong 

 hold. The number of cases among the native population is very small, but 

 among Europeans it is relatively very heavy. Southern Nigeria has not suffered 

 so much as the Gold Coast, Sierra Leone and the Gambia, but two cases occurred 

 in Lagos in July and September, 1910, in which the symptoms were strongly 

 indicative of this disease. The degree of immunity of the natives is still a 

 matter under discussion, and whether the children harbour the parasite, as in 

 the case of malaria, is absolutely unknown. It has been shown, but not in 

 West Africa, that this disease is transmitted by Stcgomyia fasciata, but there 

 is no evidence to justify our supposing that this is the only transmitting agent. 

 In another section I have discussed briefly the distribution of Stegomyia in 

 Southern Nigeria. 



With the continual intercourse of natives between the various West African 

 colonies, there is a constant risk of this disease spreading, and it may be 

 that many natives harbour the parasite without themselves showing any 

 symptoms of the disease ; if so, the risk to Europeans is very much greater. 

 Since it is known that the disease is transmitted by Stegomyia Jasciata, and that 

 this species is so common all along the coast, and when the number of 

 European deaths from this cause during the past year is recalled, it is surely 

 not too much to say that every effort should be made to diminish the number of 

 mosquitos. It is gratifying to note that the Government of Southern Nigeria 

 has not been behind in this work, and that recently a quarantine station has been 

 erected in one of the side creeks near Forcados, away from the beaten track. 



Sleeping Sickness. 



This disease seems to be far from common in Southern Nigeria. Several 

 doubtful cases in natives have been recorded, but not within recent times has 



