203 
diffluent. The blood gives the usual picture of secondary anemia. 
The lymphoid elements are but slightly involved; the liver is con- 
gested and the seat of cloudy swelling, and the kidneys are sometimes 
swollen and show glomerular nephritis. 
The period of incubation appears to be from a few days to thirty 
days, usually about fifteen. 
On account of the large number of cases of Malta fever in the 
military and naval population of the island of Malta a commission 
was appointed b}^ the admiralty, the war office, and the civil govern- 
ment of Malta in 1904 for the purpose of studying this disease with 
a view especially of determining the source of infection. This com- 
mission has issued six reports. These reports include a minute study 
of the general sanitary conditions of the island of Malta, the prev- 
alence of the disease there, the various experiments upon the viability 
of the organism under many conditions, and experimental work upon 
susceptible animals. The following data in regard to the relation of 
goat’s milk to the spread of Malta fever are largely drawn from these 
reports and, in many instances, are taken verbatim from the reports. 
Until the researches of the commission the means of infection were 
not definitely known. Various theories had been suggested, such as 
the agency of biting insects, the ingestion of infected food and drink, 
the breathing of infected dust, and contacts. 
Epidemiological studies having shown that, while the consumption 
of infected milk may and probably does account for Malta fever 
among the Maltese, yet many cases occur among the military and 
naval population in Malta which can not be attributed to this cause. 
Accordingly a study of mosquitoes as possible carriers of the 
d/. melitensis was begun. 
The il/. melitensis was recovered four times from a total of 896 
mosquitoes dissected. Deducting from these 896 mosquitoes those 
collected where there was no case of Malta fever or where the cases 
were mostly chronic we would have 4 infected mosquitoes out of 450 
collected in presumably infected places. This result was not unex- 
pected considering the small numbers of the specific organisms found 
in the peripheral blood of Malta fever patients. The mosquitoes 
could not be infected in great numbers or the disease would be much 
more prevalent than it is at present. 
Captain Kennedy ® was able experimentally to infect a monkey as 
the result of bites of mosquitoes {Culex pipiens) which had fed on 
patients suffering from Malta fever. An attempt to infect a monkey 
by bites from artificially infected mosquitoes, however, failed. 
^ Reports of tlie commission * * * for the investigation of Mediterranean 
fever ♦ * Part 4, 1906, p. 187. 
