Abstract
Epidemiological studies of acute anterior poliomyelitis in the United States have suggested that the virus of this disease is more widespread than is indicated by the incidence of clinical cases (Frost, 1 Aycock 2 ). Aycock and Kramer 3 interpreted the high proportion of serums from “normal” persons of Georgia that neutralized the virus, as meaning that a large number of persons in the Southern United States are exposed to the virus, thereby acquiring an immunity with a low attack rate. They concluded that the extent of the distribution of the virus in warmer climates is equal to that in cooler climates. Soule and McKinley 4 have reported that of 8 Porto Ricans without history of attack or exposure to this disease and whose serums were examined for their neutralizing property, all gave positive results.
The understanding of the epidemiology of poliomyelitis is assisted by studies in the geographical distribution of the disease. It occurred to us that we might get data by examining the serums of “normal” natives of West Africa for neutralizing properties. We obtained specimens through the courtesy of Dr. J. B. Rice of the Firestone Plantations of Liberia and Dr. W. A. Sawyer of the International Health Division of the Rockefeller Foundation. The technic is that which has been standardized for similar purposes in this laboratory, with the use of the virulent Rhoads' PMV strain of virus. One part of 1.25% suspension of monkey cord is mixed with 3 parts of serum; the mixture is incubated 2 hours at 37°C. and held in the refrigerator over night. Two cc. of the mixture is injected intracerebrally into Macacus rhesus. Temperatures and observations are recorded daily for 6 weeks.
Get full access to this article
View all access options for this article.