204 



that it has been entirely suppressed. A modern water supply is being 

 installed in the city, but until it is in operation strict supervision of all 

 water containers will be maintained so as to prevent the breeding of 

 Stegomyia. The responsibility for the continued maintenance of the 

 work was taken over by the Government on 29th November 1920. 



During 1920, yellow fever occurred in Salvador and Guatemala, 

 and a few cases were reported from Nicaragua. As a result of prompt 

 action in the former States, the disease had almost entirely disappeared 

 by the end of the year. Anti-mosquito measures, including control 

 by means of fish, are to be continued for at least a year after the dis- 

 appearance of the last case of the disease. In Nicaragua and Honduras 

 anti-mosquito work was carried on throughout 1920. Protective 

 measures were also successfully employed in Peru and Brazil, but in 

 Peru the disease reappeared in February 1921 at a point south of the 

 region previously infected. 



In July 1920 a special commission began investigations in Nigeria, 

 Dahomey, the Gold Coast, Senegal, and the Belgian Congo, but no 

 authentic cases of yellow fever were observed, although statistics 

 indicate that yellow fever, or an infection closely allied to it, had 

 existed endemically and epidemically for many years. The study of 

 yellow fever in this area is likely to prove a most arduous task and will 

 require prolonged local residence ; the commission only remained 

 fifteen weeks on the West Coast of Africa. It is suggested that another 

 body of investigators be sent to undertake the work and to suggest 

 definite measures for the suppression of the disease should it be found. 



Lavier (G). Les Parasites des Invertebres Hematophages. — Lah. 



Paras. Fac. Med., Pans, 1921, 218 pp. 



The parasites of blood-sucking invertebrates can be divided into 

 two categories. The first includes those that are common to both 

 vertebrates and invertebrates, that is, those that the invertebrate is 

 capable of transmitting. These parasites can again be divided into 

 two classes according to their behaviour in the invertebrate host ; 

 that is, those that undergo no development in the invertebrate but are 

 mechanically transmitted to a vertebrate, and those that develop 

 in the invertebrate from harmless to dangerous forms capable of 

 pi'oducing disease in a vertebrate. In some cases the intermediate 

 host is exclusive, as in the case of the parasites of human malaria, 

 which develop always in Anopheles, and of certain trypanosomes 

 which can develop only in Glossina ; others have a wider choice 

 of hosts, such as Trypanosoma cntzi, which can develop in many 

 species of Reduviids, some species of Cimex and certain Acarids. 



The parasite can be transmitted from invertebrate to vertebrate 

 by a simple puncture, when it is injected with the saliva or by regur- 

 gitation of the stomach contents ; or by a similar biological process 

 producing a similar result, such as the piercing of the Dutton membrane 

 in the proboscis of the mosquito by the escaping Filaria, or the passage 

 of spirochaetes in the coxal fluid secreted by Ornithodonis when 

 engorging. It may also be transmitted by crushing the invertebrate 

 host, such as the louse, which may then contaminate the skin with 

 liquid harbouring Treponema recurrentis ; or by ingestion of the 

 invertebrate, in such cases as the dog swallowing fleas and becoming 

 infected with Dipylidium caninnm or the rat with Trypanosoma 

 lew I si. 



