Thursday, 26 March 2009

Awareness of Aspergillus contamination of marijuana grows

An example of moldy conditions used for some marijuana cultivation
We reported in this blog around a year ago that one of the hazards of smoking marijuana was the possibility that the smoker would also inhale spores of the Aspergillus fungus (among others). Just like any other plant material after harvest and before it is fully dried out marijuana is an ideal food for Aspergillus - the fungus grows quickly and will sporulate once the food supply starts to decline. Those spores are extremely tiny and will penetrate the deepest parts of the smokers lungs.

Health effects of this can start with the development of allergies, increase asthma symptoms, cause severe asthma by fungi growing within the lungs, allergic bronchopulmonary aspergillosis (ABPA) and so on. All of these can happen to people who have completely healthy immune systems - these are not invasive infections but are chronic debilitating illnesses with no cure yet devised. People who do have a poor immune system i.e. transplant recipients, people being treated for some types of cancer, people on high doses of steroids are much more at risk of an invasive infection, so inhaling spores is a very bad idea!

Marijuana is particularly prone to fungal growth as it is often grown and prepared by amateurs who have limited idea of the dangers Aspergillus can bring or how to avoid them. Storage is also an issue - if it becomes damp the fungus can grow all over again. Up until now there has been no known effort to establish the levels of Aspergillus in marijuana.

News this week is that a laboratory has been set up on California, USA to advise users of this material on the levels of contamination in samples of the drug that the users bring in. Legality aside this can only be a good thing for the marijuana users of that area, perhaps partially akin to the handing out of free sterile syringe needles to IV herione accicts?

Thursday, 19 March 2009

The solution to toxic Aspergillus is... more Aspergillus!

Growth of Aspergillus on crops is common when drought conditions predominate. This is possibly because lack of water weakens plants and make them more vulnerable to growth of the fungus.
This causes a major problems when the Aspergillus species growing on the crop starts producing toxins - something the fungus commonly does when it is stressed by - for example - low levels of moisture.
Fungal toxin levels allowed in crops such as peanuts and corn are strictly controlled by the authorities so the crops are tested rigorously prior to sale. Crops containing higher levels of toxin are worth less than crops with low levels of toxin - toxins cost the farmer money and reduce the amount of crops available for human consumption in the US. NB poorer countries have to buy in some of the cheapest crops they can find and they are often those with higher levels of toxin - thus introducing higher levels of toxins into their food system - this problem effects everyone around the world.
What to do? A simple solution has been investigated and found success - spray the crops and soil with a strain of Aspergillus that doesn't produce toxins! Crucially a strain of Aspergillus that grows more quickly than toxin-producing strains has been isolated and sprayed onto corn crops. At harvest time on sprayed crops no toxin has been detected compared with levels detected in neighbouring fields that exceeded admissable levels - a resounding success.

No chemicals, relatively cheap to produce and sustainable.

Friday, 13 March 2009

Decline in autopsy rate leads to underdiagnosis of fungal disease?

Surgeon at Wythenshawe Hospital, Manchester, UKAutopsy rates in many European, Asian and American countries have declined steadily - down to 3% in Germany by 1999 compared with 10% as recently as 1980. Overall rates are much higher in the United States but there has still been a major decline from 67% to 26% between 1989 and 2003.

Reasons for this decline are given as a dislike amongst the public for them to be carried out, the introduction of requirement for consent by next of kin and the cost of performing an autopsy.

Statistics show that 20-30% of patients who die in hospital have lesions or infections that are only detected via autopsy - many of which are fungal infections. The rates of fungal infection causing death are therefore underestimated in the collection of national statistics unless autopsies are performed.

National health provision, medical education and training in many countries is driven in part by 'cause of death' statistics, so under-representation of fungal infections in these figures leads to inadequacies in many areas, not least that of ensuring a clinician has accurate statistics on which to base clinical judgement.

Read more on this subject here.

Monday, 2 March 2009

Aspergillus, Asthma and the House Dust Mite

The house dust miteHouse dust mites are thought to be the leading cause of asthma in the home. They excrete an allergen in their faeces which is a major trigger for asthma and also contributes to hay fever and atopic dermatitis. They may look fearsome but they are tiny (half a millimetre in length) and otherwise quite harmless.

Dust mites have a particularly intimate relationship with ourselves as they feed on the flakes of skin we shed every day. A human being sheds more than one gram of skin cells per day (up to half a kilo per year!!) so there is plenty of food for them in pretty much every household. Half a kilo is enough to feed a million mites!

Beds are a favourite mite home as they prefer warm moist places. This is also a time when we can be at our most vulnerable to ingesting the allergen via breathing them in as we lie on contaminated pillows and bedlinen - there is some suggestion that we eat a few every night too! Once ingested allergy can slowly build up in some people, and of course for asthmatic people it can act as a trigger for an attack.
The dust mite allergen is easily removed by washing so it is clear that regular washing of the bed linen will keep allergies at bay.

Skin cells are pretty indigestible so it is interesting to note that mites seem to rely on Aspergillus repens to turn them into a more nutritious meal. A. repens is commonly found in house dust and uses its highly efficient digestive enzymes to break down stubborn material such as skin cells prior to absorbing the nutrients - feeding on dead matter is what Aspergillus has evolved to do over millions of years.

The mites live alongside the fungus and eat the partially digested skin cells, thus making it much easier for them to eat and taking advantage of the much higher nutritional content.

This relationship begs a question about which came first, the mite or the fungus! These observations suggest that the mite would do less well if the fungus was not present. There is evidence that mites do less well in drier atmospheres such as those found at higher altitudes, but then the fungus would also struggle to thrive as it is dependent on moisture to grow - perhaps that is part of the reason the mites cannot survive?

Perhaps antifungal bed linen would be a good idea alongside frequent cleaning of the bed (patent pending)!

Moulds may make a larger contribution to asthma than simply as allergen providers - we know that moulds also cause significant allergies on their own but it looks like it is pretty difficult to separate the importance of mould from that of how it supports the life of the mite. Controlling both the fungus and the mites might be a helpful strategy for improving levels of asthma in the home.

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