Hygiene and public health / by Louis C. Parkes.

  • Parkes, Louis Coltman, 1857-1942.
Date:
1889
Catalogue details

Licence: Public Domain Mark

Credit: Hygiene and public health / by Louis C. Parkes. Source: Wellcome Collection.

    400/512 (page 380)
    Preventive inoculations may be made with attenuated virus, i.e., with cultures of the microbes weakened by exposure of successive generations to heat, not sufficient to destroy them altogether, or by growing the microbes in culture media medicated with some antiseptic, or by passage of the microbes through animals of different species; or the inoculations may be made with the solu- ble chemical poisons produced by the virus during its growth in nutrient media. Preventive inoculations by the latter means alone have already been carried out in the case of anthrax, chicken cholera, diphtheria, and mouse septicaemia; and the attenuated virus of rabies (Pasteur's method) is probably only the chemical pro- ducts of the microbes growth, and not any form of the microbe itself. Communicable Diseases. Small-pox and Vaccination. The incubation period of small-pox is about 12 days; when the virus has been inoculated, the incubation is shorter—only 7 or 8 days. Small-pox is communicable from the earliest appearance of the symptoms, and the ordinary duration of infectiveness is from 3 to 4 weeks. There can be little doubt that the contagion is most active, and the infectivity greatest, during the period of maturation and crusting of the pustules. The virus is contained in the breath of the patient and in the skin eruptions, and may be conveyed for considerable dis- tances through the air in the dried epithelial scales and pus cells from the crusted pocks. The exceptional incidence of small-pox in the imme- diate neighbourhood of some of the London small-pox hospitals (investigated originally by Dr. Thorne Thorne),