1374 THE ENTEROIDEA GROUP OF TROPICAL FEVERS 



disease most commonly in the dry season, when it is spread by dust 

 and flies, and the natives in the wet season, when it may be due to 

 water contamination. 



With regard to meteorological conditions, we have observed that 

 anything which prevents the heavy rainfall at the proper season 

 tends to an increase in the enteric, dysentery, etc., rates; and, 

 absurd though it may read, certain observations which we made 

 some years ago led us to believe that the eruption of Mount Pelee 

 may have had a disturbing effect upon the meteorological con- 

 ditions, producing less rainfall, and preventing the filthy drains and 

 other places being properly flushed, and thus indirectly causing 

 an increased incidence of epidemic intestinal diseases. 



Pathology. — Enteric fever is a septicaemia which is produced by 

 the bacilli already mentioned entering the body by the mouth, and 

 passing into the small intestine and colon, the lymphoid tissue of 

 which they invade. In this tissue they increase in number, and 

 pass via the lymphatics to the abdominal lymphatic glands and 

 spleen, in all of which they multiply. No doubt they very soon 

 reach the blood, but are probably quickly destroyed and their toxins 

 neutralized, and so long as this continues the patient is without 

 definite signs of the disease. This constitutes ' the period of in- 

 cubation ' or latency, and may possibly be the explanation of those 

 persons who, though chronic carriers of virulent typhoidal germs, 

 maintain that they themselves have never had any illness. 



If the quantity of antitoxin substances produced are only suffi- 

 cient barely to neutralize the toxins, then an ambulatory or an 

 abortive attack may ensue. 



When, however, the bacilli multiply in such numbers that, 

 though still largely destroyed by the b act erioly sins of the blood, 

 there is insufficient antitoxin to neutralize their liberated toxins, 

 then the fever begins. The possible explanation of the intermittent 

 type of the fastigium of the tropics is that the supply of antitoxic 

 substances in the blood waxes and wanes. The evidence in favour 

 of the above theory is the presence of the bacilli in the faeces in the 

 incubation period, the presence of enlarged Peyer's patches, 

 mesenteric glands and spleen found accidentally in post-mortem 

 examinations of people who have died from other causes, and in 

 whom enteric fever was not suspected; the possibility of cultivating 

 the bacilli from specimens of the circulating blood obtained during 

 the first week of the fever; and the constant necessity for immediate 

 dilution of this blood if a successful culture is to be obtained. 



Relapses can be explained as being due to any cause which so 

 disturbs the metabolism of the body that the antitoxin production 

 decreases, and the germs again gain entrance to the blood in such 

 quantity as to produce fever. 



The endotoxin contained in the bacilli has a markedly stimulant 

 effect upon endothelial cells, causing them to swell and to block 

 small lymph capillaries, thus causing patches of focal necrosis in the 

 liver. 



