Several
findings of epidemiological research indicate that exposure to high
concentration of microorganisms frequently leads to allergies, asthma,
hay fever (Bjornsson et al., 1995; Newson et al., 2000), pneumonia (Siersted and Gravesen, 1993), and many other health side-effects, including infections (Renn et al.,
2001). In recent years, dramatic increase in the number of allergic
reactions to fungal sores has been reported, and young people do
constitute a large group of allergic sufferers, whose symptoms persist
throughout the year (Jain, 2000). It has also been established that
bioaerosols may account for 10-20% of all endemic
nosoeomial infections
(Brachman, 1970). Respiratory illness and lung diseases are among the
most widely studied bioaerosol-associated diseases, acute toxic effects,
allergies and cancer (Douwes et al., 2003, Stetzenbach et al., 2004). While several bacterial such Staphylococcus aureus, Sphigonomas Paucimobilis and Pseudomonus aeroginosa are known to cause the majority of nosocomial infections (Gilbert et al.,
2010). Also, various metabolites secreted by microorganisms such as
endotoxins, (membrane lipopolysachrides shed by Gram-negative bacteria)
and fungal mycotoxins can also trigger respiratory problems
(Braun-Fahrlander, et al., 2002; Jie, et al., 2011).
The closest known association of human disease of microbial origin and
dust storms are the outbreak of meningitis (primarily due to Neissenia
meningitis infection) that occurs within the “meningitis belt” of the
North Africa (Sultan et al., 2005). These outbreak occur
frequently in the Sahel region of North Africa between the months of
February and May and affects as many as 200,000 individuals annuals
(Sultan et al., 2005; Molesworth et al., 2003).
Isolates of Neisseria meningitis have also been retrieved from
settled-dust samples from Kuwait together with other pathogens such as Staphylocus aureus (wide range of infections) and Ralstonia paucula
(e.g, Septicemia, Peritonitis). Bacterial species have also been
collected in the air of Bamako, Mali during strong dust events (Kellogg et al., 2004) as well as in the African dust corridor over the mid-Atlantic ridge (Griffin, et al.,
2006). In the atmosphere over the USA virgin Islands the opportunistic
pathogen Pseudomonas aeroginosa, which can cause fatal infection in burn
patients, has been isolated (Rahn, et al., 1977), whereas several pathogens have also been identified in the atmosphere of Erdemli, Turkey (Griffin, et al., 2007) and crete, Greece (Polymenakou, et al.,
2008), during dust events. A detailed overview of studies associated
with desert dust transportation of microorganisms and their implications
for human health has been presented by Griffin et al., (Griffin, et al., 2007).
In the last decades, there have been increasing numbers of reports of
marine diseases and epidemics, affecting a wide range of organisms, such
as plants, invertebrates and mammals (Griffin, et al., 2004; Harvell, et al.,1999).
Several attempts have been made to connect these diseases with climate
change whereas special attention has been given on identifying possible
connections among dust, iron, microbes and climate change. Recent
studies have assumed that the iron carried with desert-dust, in addition
to triggering harmful algal blooms can also trigger growth of
opportunistic marine microbial pathogens that may be present in the
transported dust or may already exist in the ecosystem (Hayes, et al., 2001).
The first substantial evidence of a microbial link was provided when the terrestrial fungus Aspergillus sydowii,
which is unable to reproduce in seawater but can be carried with dust
storms, was identified as the causative agents of sea fan disease (Smith
et al., 1996). Furthermore, a strong connection between
African desert dust and Caribbean coral reef decline was also
demonstrated when Shinn et al., 2000) noticed that a relation
between two decaded of corel reef decline and the coincident increase in
African dust being monitored by Prospero, J.M. 2006 for more than
40years in Barbados. Because of these investigations, scientists have
started to connect several diseases of marine organisms to microbial
pathogens that have been identified in dust storms (Griffin, et al.,
2004). According to this review, the microbiological research conducted
till date has identified wide range of airborne pathogenic
microorganisms that move great distances through the atmosphere and
these more risk-oriented studies need to be conducted.
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