THE BACILLUS MELITENSIS 797 



Diagnosis can be made by agglutination and isolation of the 

 organisms. According to Wright and Semple, 5 Bassett-Smith, Eyre 6 

 and others, the agglutinins in the blood are very high and may be 

 detected in dilutions of 1 :1,000 or over, even as early as the end 

 of the first week. 



Blood cultures may be positive very early in the disease. Later, 

 the organisms appear in the urine. 



Epidemiology. It seems to be unquestionable at the present time 

 that the disease is transmitted chiefly by the ingestion of the milk 

 of infected goats, and according to Eyre the goat is the natural 

 host of the infection, keeping the disease going in endemic regions. 

 Apparently a very large percentage of the goats in infected regions 

 are infected. According to Castellani and Chalmers in Malta 50 

 per cent of the goats are infected, and in parts of Northern Africa 

 the percentage of infection in goats as indicated by various re- 

 searches ranges from less than 4 to 34 per cent. 



Since goats' milk is. a common human food in these regions, the 

 spread of the disease by this means is natural. 



There are probably carriers among goats and human beings that 

 recover. Among other forms of transmission, direct infection from 

 individual to individual probably takes place, and indirect infection 

 through food and flies is not out of question. 



It has been suggested that mosquitoes, too, may transmit the 

 disease and Eyre states that it has been possible to demonstrate 

 the organisms in the stomachs of a number of different mosquito 

 species. 



However, it seems quite clear that the most important method 

 of transmission is by means of infected milk. 



Immunity. It is the general belief that one attack of Malta 

 fever protects against a second attack. However, there are a great 

 many cases in which the fever recurs several times in the same 

 individual in the form of relapses and recrudescences. The inter- 

 missions between such attacks often last for months. Prophylactic 

 vaccination has not yet been carried out on a sufficiently large scale 

 to permit the formulation of conclusions. 



5 Wright and Semple, Lancet, 656, 1897. 



6 Eyre, etc., Report of the Mediterranean Fever Commission, 1907. 



