Abstract
FOR adequate control of infectious disease, early and accurate diagnosis is of great importance, but clinical differentiation is not always easy in the early stages. Thus smallpox, even of the severe type, may be mistaken for chickenpox. Some years ago M. H. Gordon described a ‘flocculation’ test for smallpox, which was later investigated by W. L. Burgess, J. Craigie, and W. J. Tulloch: the last two authors have now extended and amplified the earlier observations. The technique of the test is, in brief, as follows: crusts obtained from the pocks are dried and finely powdered; the powder is extracted with ether and then with saline for some hours; the mixture is frozen, thawed, and centri-fuged to remove particulate matter. Series of dilutions of the extract are made in saline: to one antivaccinia serum is added, to the other normal rabbit serum, and both sets are incubated for about 18 hours at 45°-55° C. Flocculation occurs in the first series at high dilutions of the extract if the crusts were obtained from a case of smallpox, but is not seen in the second series to which normal rabbit serum was added.
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Diagnosis of Smallpox*. Nature 129, 226–227 (1932). https://doi.org/10.1038/129226a0
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DOI: https://doi.org/10.1038/129226a0