Julie G - Microbigal!
- Dec 9, 2021
- 5 min read

Natural diversity of microbial parasites (Part II) - Special Guest Blog by Maria Martynova

While there are beneficial microbes that harmoniously coexist with humans, there are also microorganisms that have a parasitic lifestyle. Parasitism is a relationship between two organisms, a host and a parasite, in which a parasite benefits from this interaction, while a host is harmed. Even though some of them are truly scary and untamed, others were “domesticated” by scientists over decades and present less danger today. Let’s dive deeper and learn about some of these unique microscopic parasites that will make you gasp for air!

In this part, we continue talking about microbial parasites, and we will be discussing fungal and bacterial parasites.

1. Real-life zombies- Cordyceps fungi

Losing your mind to a Zombie plague is a terrifying concept we have all thought of. For ants, however, this is not just science fiction, it is their reality. Once even more terrifying is that their Zombie plague isn’t just losing your mind, but having it controlled by a fungal invader! Cordyceps is a genus of fungi notoriously known for infecting insects. Although this genus has a worldwide distribution, it is most prominent in areas with high humidity and temperatures. After the infection, Cordyceps change the behavior of ants, making them lose their sense of direction. Once this change is noticed by other members of a colony, there is no love for the afflicted, ants banish the “zombie ant” to prevent the spread of infection and to protect the colony. The fungus compels the outcast to climb to the top of the nearest plant latching on with a death grip until well...it dies. Happily placed in optimal conditions for growth, and now without a body to control, the fungus continues to reproduce, eventually bursting out of the ant’s body to release millions of fungal spores to infect other hosts. For more information see our tragic story on Annie The Ant and her unwanted friendship with Cory the Cordyceps.

Source: Erich G. Vallery, USDA Forest Service via Wikimedia Commons

2. Bacteria and humans vs mosquito-borne dieseases - Wolbachia

Did you know that humans and parasites can play on the same team to defeat a common enemy? For example, Wolbachia bacteria and its peculiar survival mechanism inspired scientists to develop methods that reduce the incidence of mosquito-borne diseases. With the right approach, it turns out that even parasites can be beneficial to humans!

Wolbachia is a parasitic microorganism that only uses egg cells to get passed on to its host’s offspring. It means that only female hosts are suitable for proliferation. In the case when Wolbachia infects a male host, this bacterium can alter a biological gender of a host, thus ensuring that an infected host will be able to produce eggs in the future - essentially, it does a gender reassignment procedure!

When it comes to mosquito-borne diseases, only female mosquitoes spread infections, and most of them are viral in nature. Mosquitoes pick up and spread viruses from feeding on infected people, and with the current rapid rates of globalization and travel, viruses spread very quickly.

Using microbial parasites to fight other microbial parasites, SMART!

Source: Scott O’Neill via Wikimedia Commons

As an example, Dengue fever is now considered the most critical mosquito-borne viral disease in the world. Scientists discovered that when virus-infected mosquitoes carry Wolbachia bacteria in their cells, the bacterium competes with viruses, ultimately preventing the development of the virus. This, of course, leads to a lower incidence of diseases. This method has been proven to be safe for people, animals, and the environment.

3. False trials - Claviceps purpurea

Salem Witch Trials, which occurred in Salem, Massachusetts, left a significant mark in human history, and even today researchers keep returning to the events of that period to study them in greater detail. Nowadays, being accused of witchcraft and subjected to death by burning is a bizarre idea. However, back in the 17th century, it was a pretty reasonable and justified type of public punishment. Due to fear and strong religious beliefs, people of Salem did not hesitate to execute anyone, who seemed “different” from the rest of the villagers.

Some theories suggest that The Salem Witch Trials might have had more to do with a hallucinogenic fungus Claviceps puppurea found on rye. Ingestion of this fungus causes a disease called ergotism (before, it was known as St. Anthony’s fire). It was prevalent in regions of high rye-bread consumption. Toxins produced by the fungus have similar effects to those of LSD drugs.

Source: http://www.botany.hawaii.edu/faculty/wong/BOT135/LECT12.HTM

Therefore, weird and peculiar behavior was something “normal” for a person who consumed infected rye crops.

Unfortunately, people at that time did not know much about toxins and parasitic fungi, and a lot of innocent victims were erroneously executed.

To learn more about The Microbe Moment of The Salem Witch Trials check Professor Xi’s lecture on the topic!

4. Switch from a friend to a foe - Candida albicans

Thanks to numerous studies on the human microbiome, we know that our bodies harbor billions of microorganisms, such as bacteria, fungi, and even viruses. Beneficial contribution of these organisms to our health is the basis of the symbiotic relationship that exists between humans and microorganisms. Most of the time they cause no issues, but it is possible for overgrowths and infections to happen.

Normally, fungal species of Candida genus are a part of the natural microbiome. But don’t be fooled, they are notorious troublemakers! Once our immune system response is compromised or not strong enough, fungi will quickly attempt to overgrow and take up some extra space and resources. Take, for example, Candida albicans - a fungus that causes a widely common disease called athlete’s foot. It is estimated that 3 to 15% of the population are affected with this condition.It usually begins between the toes, and occurs in people, who wear tight socks and whose feet become sweaty. The infection is most prevalent in athletes, however, anyone can be affected by this disease. Available over-the-counter medication takes the infection under control rather quickly, but C. albicans, like any other fungi, is contagious. It can be transmitted through contact with an infected person or through contaminated surfaces, such as towels, showers, and floors.

Source: https://en.wikipedia.org/wiki/Candida_albicans#/media/File:Candida_Gram_stain.jpg

5. Silent trouble - Borrelia burgdorferi

If malaria is prevalent in the countries of the Southern Hemisphere, the Northern Hemisphere is famous for Lyme disease. This disease is transmitted by ticks, but, once again, do not rush to blame these unfortunate animals. They are themselves infected with a parasitic bacterium Borrelia burgdorferi. Like in the case with malaria, ticks are vector animals, whose sole purpose is to transmit a disease.

Of course, not all ticks are infected, and, thus, not every tick bite will expose you to Lyme disease. However, for a tick to transmit B. burgdorferi, it has to be attached to a body for at least 24 hours. This is why it is so important to remove ticks right away and to check your body daily if you spend a lot of time outdoors and live in an area with a large tick population. Tick bites are painless and often go unnoticed. Each year approximately 476,000 Americans are diagnosed and treated for Lyme disease. Symptoms of the infection do not appear right away (it usually takes from 7 to 21 days for the signs to show up), and the most distinct symptom is a skin rash that forms a red “bullseye” structure on the skin.