The course of the disease is chronic and may last for twenty to thirty years, death usually resulting from some intercurrent disease.
At present the actual transmitter of Espundia is not known with certainty. Various sand-flies (Simulidæ) have been suspected of transmitting the disease, though so far proof is wanting. It has also been suggested that the natural food sources of some Simulidæ known to bite man, namely, certain snakes[450] and lizards,[451] are possible reservoirs of the disease.
Prophylactic measures would seem to consist in the immediate disinfection of insect bites by tincture of iodine, and by avoidance of areas known to be infested with snakes and lizards, and insects that prey on them and man indifferently. The destruction of the primary lesion as soon as detected is essential, and the isolation of advanced cases of the disease seems advisable.
V.—SPIROCHÆTOSES.
A. Relapsing Fevers.
The relapsing fevers of Europe and of America, due to Spirochæta recurrentis and S. novyi (probably a race of S. recurrentis), present much the same symptoms, which differ in some respects from those due to S. duttoni, the excitant of “tick” or “relapsing” fever in Africa (see pp. [116]–122).
The incubation period of S. recurrentis varies from two to twelve days, during which time a very slight indisposition may be noticed. The onset is usually sudden, with severe headache, pains in the back, limbs and stomach and a feeling of weakness. There is a rise of temperature to 103° F. or 104° F., and the temperature continues high till about the sixth or seventh day. The skin is yellowish, hot and damp; a rash, disappearing on pressure, may occur on the trunk and legs, nausea is always present and thirst is usual. The liver and spleen both enlarge. The number of respirations and pulse-rate become increased. On the sixth or seventh day a crisis occurs. There is violent perspiration, with a rapid fall of temperature, pulse and respiration become normal and the patient sleeps and awakes better. Improvement continues for some days, and recovery may ensue, but usually about the fourteenth day relapse occurs, lasting usually three or four days. A second relapse is unusual. Numerous complications are known, e.g., bronchitis, pneumonia, diarrhœa and dysentery.
With regard to treatment, the specific appears to be salvarsan. Castellani and Chalmers recommend salvarsan administered intravenously. Intramuscular inoculations (for example, into the buttock) of a suspension of “606” in oil can also be given. The drug is very efficacious, but large doses should not be given. An intravenous injection of 4 or 5 gr. does not give rise to unpleasant symptoms but is sufficient to effect a cure.
The incubation period for the American form of the disease is at least five to seven days, and the first attack lasts about five to six days. The treatment is by salvarsan as detailed previously.
As relapsing fever is spread by body lice and possibly by bugs, preventive measures are directed against these insects. Strict cleanliness of person, clothing, bedding and dwellings is essential. Furniture, e.g., wooden bedsteads, liable to harbour such insects should not be used.