PARATYPHOID FEVER is the name given to a set of intestinal diseases clinically very like typhoid fever and caused by specific organisms akin to the bacillus typhosus. Three distinct organisms have been identified as causing these diseases and they have been designated as bacillus paratyphosus "A," "B" and "C," and the fevers they cause are therefore known as paratyphoid "A," "B" and "C" respectively.
All three paratyphoid organisms can be distinguished from B. typhosus by biochemical tests and B. paratyphosus "A" can be distinguished from "B" and "C" by the same means, but for the identification of the last two organisms serological methods have to be employed. The biochemical substances used in differentiat ing these organisms from one another are the sugars, glucose, mannite and dulcite, dissolved in a broth medium, and milk. B. typhosus produces acid in glucose and mannite whereas the para typhoid organisms produce acid and gas in all three sugars. Again B. paratyphosus "A" turns milk acid, whilst the other paratyphoid organisms turn it first acid and then alkaline.
The anatomical lesions in the paratyphoid fevers resemble those found in typhoid fever and chiefly consist of inflammation and ulceration of the lymphoid tissue of the intestinal canal, especially in the lower part of the small intestine, and of the enlargement of the spleen and mesenteric glands. In paratyphoid "B" fever the ulceration often spreads into the large intestine.
The symptoms of the paratyphoid fevers are generally those of a mild form of typhoid fever, the only difference being one of degree, but it must be remembered that they may be just as severe and followed by the same complications as typhoid.
The incubation period averages between 5 and 21 days and the onset of the disease causes lassitude, headache, nose bleeding, pain in the back with sometimes a shivering fit and a sudden rise of temperature. Early and well marked gastro-intestinal symp toms, such as diarrhoea and vomiting, suggest a paratyphoid "B" infection. The characteristic "rose spots" of typhoid fever are
not always present but on the other hand they may be very plenti ful and by no means confined to the abdomen but spread over the neck, face and arms. They may also be very much larger than the usual rose spots and resemble the rash of measles. The mental condition, when impaired, may vary between dulness and delirium, according to the severity of the disease. The temperature often reaches its highest point shortly after the onset of the disease in contradistinction to the gradual rise in typhoid fever. It is usually of shorter duration, more irregular, and may return to normal suddenly instead of gradually as in typhoid fever. The pulse is slow and follows the variations of the temperature.
Diarrhoea is a fairly constant symptom and the stools resemble pea soup, have a putrid smell and may contain fragments from the inner coat of the intestine. Fresh blood may also be seen in the stools due to the erosion of a blood vessel in one of the intes tinal ulcers. Ulceration may proceed so far as to cause a perfora tion into the abdominal cavity which leads to local or general peritonitis. The average time during which active symptoms of the disease are present is from 9 to 14 days. The complications of paratyphoid fever are those of typhoid fever though there is a greater tendency towards abscess formation in the former.
It should be possible to isolate the causal organisms, at one stage of the disease or another, from the blood, the urine and the stools and it is the persistence of the organisms in the latter situations which produces the paratyphoid carrier. The treatment of paratyphoid fever is identical with that of typhoid fever. Par tial protection against the paratyphoid fevers can be obtained by anti-paratyphoid inoculation but the specific organism must be used in making the vaccine. In practice a combined vaccine is used which includes the paratyphoid and the typhoid organisms.
(For Bibliography see TYPHOID FEVER.) (N. T. W.)