Microorganisms in desert dust: are they dangerous for human health?
DDT sprayed in Africa against malaria has been found in the fat of polar bears. What about desert sand storms?
Desert dust is the dust resulted from the mobilization of soil into the atmosphere, which occurs primarily in arid regions such as deserts, especially in the presence of high energy winds. These winds can also cause dust storms that can be so powerful as to disperse significant amounts of soil across very large areas, including oceans. While the atmospheric pathways of desert dust clouds have been extensively researched in the past years, it is still largely unclear how desert dust affects human health, and specifically there have been few studies regarding the presence of microorganisms in desert dust and their impact on health.
The main sources of desert dust are the largest deserts on Earth, which are located in North Africa and Asia: they are the Sahara and Sahel deserts in Africa, and the Gobi, Takla Makan, and Badain Jaran deserts in Asia. The African deserts are responsible for 50-75% of desert dust worldwide, but the process of desertification that has occurred in Asia for the past 20 years has caused the dust activity in that region to increase. The main difference between these two regions is that while dust storm activity is a seasonal event in Asia, being more prominent during the spring and causing effects in America and in the Pacific and Atlantic oceans, it occurs year-round in the Sahara and Sahel deserts, impacting air quality in Africa, the Middle East, Europe, Asia, the Caribbean, and America..
There are two components in desert dust that can negatively affect human health: micro particles (. It is easy to assert the damage made by micro particles: they can cause irritation, allergic reactions and asthma, which has a higher prevalence in areas frequently impacted by desert storms such as the Middle East and the Caribbean.
The health impact of microorganisms is much trickier to study: while desert soil is rich in bacteria, viruses and fungi, it is important to ascertain how many of them are harmful for humans, and how many can actually arrive at their destination alive. There is also another aspect that might make dust storms dangerous for human health: the inhalation of dust particles might cause abrasion of the nasal mucosa, allowing bacteria that might normally reside on the surface of the mucosa to enter the bloodstream, causing infections or making them worse. So far, hundreds of bacteria and fungi present in desert dust have been identified and studied, while the presence of infectious human viruses in dust storms has yet to be investigated.
There are many different techniques used to detect and analyze microorganisms in desert dust, such as gravity deposition and volumetric assays for detecting and morphologic and sequence-based identification for analyzing.
These techniques have allowed scientists to prove the presence of live bacteria in desert dust, but no study so far has been able to definitively link their presence to outbreaks of diseases in humans. While there have been outbreaks of meningitis in the so-called “meningitis belt” of North Africa, in fact, there is still no definite proof that the outbreak was caused by the inhalation of Neisseria meningitidis present in desert dust. Among the other bacteria found in desert dust there are Staphylococcus aureus, Acinetobacter calcoaceticus and Staphylococcus xylosus; according to most studies, though, a relevant percentage of these bacteria are opportunistic pathogens, meaning that they don’t usually cause diseases in humans unless there are other concurrent causes, such as a depressed immune system, while only 5% of the bacteria found in desert dust are actual human pathogens.
The number of studies conducted on this matter is still small, but it seems plausible that there is some degree of risk associated with dust-borne microorganisms, especially for the young, old and immunocompromised.
Among the fungi commonly found in desert dust, Coccidioides immitis is one of the most well-known and studied; it is also the only fungus that has been definitively linked with an outbreak of disease in humans. These outbreaks have been observed after large dust storms in California, with a sharp increase in the incidence rate of coccidioidomycosis, a disease that shows a definite difference in racial susceptibility, with Asians and black people being the highest risk groups. Similar outbreaks have been observed following exposure to earthquake-generated dust clouds, which are also common in California.
For a long time, the desert has been believed to be inhospitable and incapable to host a rich and diverse microbial community; today we know that this is not true, and we are only beginning to understand the risks connected with their presence in the air due to desert storms. There are a lot of questions that still need to be answered: how can we prevent outbreaks of diseases due to desert dust? How are people who move to desert areas affected by these pathogens? How does climate change influence desert dust?
While research is progressing on the matter, it is advised to efficiently protect the respiratory tract from the fine dust during sand storms, specially for people prone to allergies and asthma, in order to limit the exposition as much as possible. U-earth biotechnologies has developed a new biotech dust mask called U-mask which has an innovative extra Bio-active layer which provides the highest protection available today on the market in dust masks, allergy masks and anti pollution mask. U-mask efficiency is better than any N95 and N99 face mask on the market and the internal Bio-activated layer will remain active for one year after opening the package.
Fine dust unfortunately is also able to travel into ducted air and reach indoor environments. This is probably the most dangerous form of dust, PM 2,5 and finer, which can cross the blood brain barrier.
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