Further studies on the yellow fever haemagglutination test

Summary

• (1)

  (1) Throughout the southern regions of the Gold Coast, agreement between yellow fever P.T. and H.A.I. results is sufficiently close for the latter to be used as an indication of immunity levels in the population. Near the northern boundaries of the Gold Coast this relationship does not hold, and reliance on H.A.I. results would give very misleading results.

• (2)

  (2) To guard against possible confusion due to the presence of serologically related viruses, it is suggested that every fifth serum from adults, and possibly all sera from children, showing a positive H.A.I. result, should be checked by yellow fever protection tests. Similar or more frequent checks should be carried out in areas where there is evidence of recent virus infection.