This October, I will be discussing human fungal infections. Although fungi can be extremely problematic for certain species of animals and plants, fungi cause humans relatively few problems. There are roughly 300 species of fungi that cause disease in humans, but the most common ones cause nuisance infections of the skin. About 20-25% of the global population has a fungal skin infection like ringworm, athlete’s foot, and similar diseases. Although annoying, these infections are not very severe. There are a few fungi that cause more severe diseases, but these are much less common. The most dangerous type of fungal infections are the opportunistic infections. These are caused by normally benign fungi that take advantage of unusual conditions, such as when a patient has a weakened immune system.
Tagged: fungal fiends
Chytridiomycosis is a disease causing precipitous declines in frog and salamander populations on a global scale. There are two fungi responsible for this disease: Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandivorans (Bsal). The former can infect all amphibians while the latter infects only salamanders and newts. Both of these pathogens belong to the fungal phylum Chytridiomycota. Fungi in this phylum (“chytrids”) have a very simple cell structure and produce spores with flagella. Because of this, they can easily swim through water and infect amphibian hosts.
This emerging fungal disease of ash trees was first reported in 1992 in Poland. Over the past 24 years, Hymenoscyphus fraxineus has spread throughout Europe and (with the help of the invasive Emerald Ash Borer beetle) is now poised to eradicate ash trees from the entire continent.
Snakes of the Eastern United States are dying of a disease called Snake Fungal Disease (SFD). Recently, the cause of SFD was identified as the fungus Ophidiomyces ophiodiicola. This fungus normally contributes to the decomposition of dead animals, but has for some reason been infecting live snakes since the early 2000’ SFD is primarily characterized by a severe rash on the snake’s skin, although it may also affect the snake’s eyes or even liver. The infection often results in death and in some species the mortality rate appears to be 100%.
Witches might not be real, but witches’ brooms certainly are – and they’re destroying chocolate! Yes, Halloween’s favorite treat (chocolate) is suffering at the hands of a disease with a Halloween-themed name: Witches’ Broom Disease. Witches’ brooms are actually fairly common and occur on many different plants. In chocolate trees (Cacao trees, Theobroma cacao, whose genus name literally means “food of the gods”), witches’ brooms are caused by the fungal pathogen Moniliophthora perniciosa and have an enormous economic impact on chocolate production in Central and South America.
The banana that you know and love may soon be a thing of the past. I know, you probably think that I’m exaggerating the threat to this ubiquitous crop, but the possibility of bananas disappearing from grocery shelves forever is very real. In fact, it nearly happened once before. Here is a brief history of the modern banana: in the 1950’s, bananas were wiped out by a disease called Panama Disease. To save the crop, a resistant variety was discovered. Today, Panama Disease has evolved to attack the resistant variety, thus threatening to decimate banana production for a second time. This time, however, there is not a fallback option.
Frosty Pod Rot, caused by the fungus Moniliophthora roreri, is one of the most significant pathogens of cacao trees (Theobroma cacao). The disease has been around a long time: it was first recognized in Ecuador in 1917 and first described in 1933. roreri likely evolved in Columbia, where the greatest diversity of the species is located and where cultivated cacao trees grow near closely related trees. Up until the 1950’s, Frosty Pod Rot was limited to northwestern South America. Since then, it has spread throughout Central America and into Peru and Venezuela. In these areas, Frosty Pod Rot is the most destructive cacao disease, resulting in the loss of about 30-40% of total production. The disease has not yet made it to Asia or Africa, where most of the world’s chocolate is produced, but it may just be a matter of time.
Imagine for a moment that it is the late 17th century and you live in rural America. Your day starts off like any other day: you wake up, have breakfast, and begin working on your farm. However, before too long your daughter starts behaving oddly. At first she just seems agitated, but her symptoms quickly escalate. She convulses, hides under the table, yells unintelligibly, and complains of a prickly sensation in her arms and legs. Terrified, you call for the town doctor. The doctor has never seen a disease like this before and cannot find anything physically wrong with your daughter. After a while, he comes up with the only possible cause: witchcraft. Just then, one of your neighbors bursts in, looking for the doctor. His daughter has been exhibiting the same symptoms! You look at his frightened face and realize what you have to do: in order to protect...
Note: This is an archived post. You can find the current version of this post here. Coffee Rust (la roya in Spanish) is a disease of coffee plants that is caused by the fungus Hemileia vastatrix. If you enjoy a fine cup of coffee, then this is one fungus you should be very interested in. The Coffee Rust is currently ravaging coffee trees in Central America, where 60% to 75% of the region’s crops are infected with the pathogen. The result of this has been a 15% drop in Central America’s coffee output and a corresponding loss of more than 100,000 jobs over the last two years. The high-end Arabica trees are particularly susceptible to the disease. America’s major coffee producers have been able to find enough coffee to meet demand without a noticeable impact on price*, but smaller, specialty brewers are having a harder time. And we haven’t seen...
The fungus Pseudogymnoascus destructans is the causal agent of White-Nose Syndrome (WNS) of bats. WNS is most destructive to bats during the winter. Its primary effect on bats is to change their behavior during winter. Bats with WNS are observed to wake up frequently, fly around during the day, and cluster near the entrances to their hibernacula during the time that they should be hibernating. This extra activity kills bats in two ways. For one, they could either freeze to death while flying around outside. Alternatively, the extra activity could deplete their fat reserves and the bats could starve to death.