110 



possibility of the infection having been acquired from men invalided 

 home in consequence of malaria. 



Anopheles bifurcatus and A. pliimbeus have been found in the 

 neighbourhood, but not A. macuUpennis. The first mentioned is 

 an active malaria carrier abroad, but has not been proved to be so 

 in England. 



James (Lt.-Col. S. P.). Malaria contracted in England, — Trans. Soc. 

 Trop. Med. Hyg., London, xii, no. 3, 17th January 1919, pp. 37- 

 51. 



The total number of civilian cases of malaria for 1918 in England 

 was 67, 43 of which are believed to have contracted the disease in 

 or before 1917. The majority of cases occurred in north-east Kent. 

 In England it is probable that two independent conditions of malaria 

 have to be dealt with. One is due to a foreign strain of the parasite 

 arising from the importation of exotic malaria and the other a true 

 indigenous malaria due to a parasite which has always been in the 

 country. The latter seems to be localised in certain streets and 

 houses, which would seem to indicate that the mosquito concerned 

 spends most of its life in the immediate vicinity of the place where 

 it obtained its first meals of blood. 



In 1918 most relapses occurred in April and May, although adult 

 Anophelines were not found in dwelling houses until July. The 

 first found in June were only in stables. Anopheles maciilipennis 

 seems to be the sole agent of infection in Queenborough. Measures 

 were at once taken to discover and control the cases and carriers. 



During the discussion following this paper, Mr. A. J. Grove stated 

 that three areas, in Essex, Kent and near Shrewsbury in Shropshire, 

 had been selected for observations. The first two of these had a pre- 

 vious history of malaria, and the third had not, being selected to serve 

 as a sort of control. The results obtained showed a marked decrease 

 in the numbers of A. maculipennis until the end of May, the new brood 

 appearing at the beginning of June and reaching its maximum about 

 September, after which the numbers began to decline. Although 

 A. bifurcatus and A. plumbeus were sometimes found in numbers, 

 counts of these species could not be made. Larvae of A. bifurcatus 

 were found in decreasing numbers until the end of April, after which 

 they apparently disappeared until June ; those of A. plumbevs were 

 not found at all and those of A. maculipemyiis from May to September. 

 The chief factors necessary for a building to be favoured by 

 mosquitos are the continued use of the building by animals ; the 

 absence of draughts, particularly near the roof ; comparative stability 

 of temperature ; and the intensity of light. The invasion of houses 

 is probably associated with the swarming of the insects for pairing 

 purposes. 



Capt. A. Macdonald stated that he had found A. maculipennis during 

 the winter in the warmth and shelter of stables and that during warm 

 weather it wandered into houses ; A. bifurcatus on the other hand 

 is very seldom found in human dwellings. He was of opinion that 

 malaria has occurred in the British Isles in the past, and that, given 

 a coincidence of optimum conditions, extensive but temporary 

 epidemics of the disease might arise. 



