African desert dust in the Caribbean atmosphere: Microbiology and public health

Air samples collected on St. John in the U.S.Virgin Islands were screened for the presenceof viable bacteria and fungi to determine ifthe number of cultivatable microbes in theatmosphere differed between ``clear atmosphericconditions'' and ``African dust-events.'' Resultsindicate that during ``African dust-events,'' thenumbers of cultivatable airborne microorganismscan be 2 to 3 times that found during ``clearatmospheric conditions.'' Direct microbialcounts of air samples using an epifluorescentmicroscopy assay demonstrated that during an``African dust-event,'' bacteria-like andvirus-like particle counts were approximatelyone log greater than during ``clear atmosphericconditions.'' Bacteria-like particles exhibitingautofluoresence, a trait of phototrophs, wereonly detected during an ``African dust-event.''