The microbiological analysis of Sahara dust and its association with asthma in Barbados

Sahara or African dust originates on the African continent and its transported across the North Atlantic to Barbados and other Caribbean Islands by the North East Trade Winds. The amount of dust deposited in Barbados has shown a steady increase over the years and so has the incidence of respiratory disease and asthma. This study investigated the monthly variation of the concentration of Sahara dust in the atmosphere the presence of micro-organisms in it. It also examined whether there was any association between these and asthmatic attendances at the Asthma Bay of the Accident and Emergency Department of the Queen Elizabeth Hospital (QEH). During the one year study period, dust deposition was lowest during February and March 1996 and heaviest during April to July 1996 with the peak in April. The peak in April did not coincide with any noticeable increase in asthma attendances during that month. A total of 289 dust samples were collected and cultured. The cultures grew mainly bacillus species and fungi, including several species of Aspergillus. 43 samples (14.8 percent) grew bacilli and fungi and 5 (1.7 percent) grew organisms other than bacilli and fungi, such as micrococci. More colonies of fungi were isolated during the early part of the year and more bacilli were found during the latter part of the year when there was the peak attendance at the QEH Asthma Bay. It is concluded that the content of Sahara dust may be of greater importance to the development of asthma than the concentration of the dust.(AU)