Humans evolved in the parasitic worms, and immune response was educated in these parasitic worms. Ecologist Kevin Lafferty said there are more than 100 human-specific parasites. Lafferty says parasites are the most common way to live on planet Earth. Science usually focuses its efforts on searching for what he calls free-living species. In the bird, the parasites grow new until it goes number two again, and then the cycle repeats. Most of the parasites are worms.
Parasites are blood-sucking worms and disease-carrying microorganisms. They usually survive by living off a host at the host’s expense. In many cases, they can weaken and ultimately kill the host. The parasites might not always be bad news. They can be harnessed to serve more honorable purposes altogether in certain circumstances.
Are some parasites good for you?
While parasites are generally associated with negative health effects, certain parasites can benefit their hosts. These parasites are referred to as mutualistic parasites or symbionts. Here are a few examples of parasites that can provide benefits to their host organisms:
Gut Microbes: The human gastrointestinal tract has many microorganisms, including bacteria, viruses, fungi, and other parasites. While some organisms can cause disease, many play crucial roles in maintaining health. Gut microbes aid in digestion, produce vitamins, help regulate the immune system, and compete against harmful pathogens. Some parasites, such as certain species of intestinal worms, have been shown to modulate the immune response and potentially protect against autoimmune diseases and allergies.
Bacteriophages: Bacteriophages, also known as phages, are viruses that infect bacteria. Although they are not technically parasites strictly, they can be considered beneficial parasites. Phages help control bacterial populations, maintain bacterial diversity, and prevent the overgrowth of harmful bacteria. Phage therapy, using phages to treat bacterial infections, is being explored as a potential alternative to antibiotics.
Leeches: Leeches are blood-sucking parasites known for their anticoagulant properties. While their bites may be unpleasant, leech saliva contains compounds that prevent blood clotting and promote blood flow. Medicinal leeches, such as microsurgery and limb reattachment, are used in certain medical procedures to enhance blood circulation and aid wound healing.
Mites and Skin Microbiota: The human skin is inhabited by a diverse community of microorganisms, including mites, bacteria, and fungi. Some mites that live on the skin, such as Demodex mites, are considered commensal parasites. They feed on dead skin cells and sebum, and their presence is generally harmless and even regarded as normal. Additionally, the skin microbiota, composed of beneficial bacteria and fungi, play a role in maintaining the skin’s barrier function and protecting against pathogens.
The idea of using parasites isn’t a new one like the humble leech. It’s a real bloodsucker attaching itself to anything fleshy that comes it is way. It is good for the leech but not so good for the unwitting animal as they risk the effects of blood loss and infection of open wounds. But bring the leeches into a more sterile setting. These suckers can do much more good than their replication suggest.
Though it might sound gross, leeches are used in the operating theatre to keep blood flowing during plastic and reconstructive surgery. When body parts are attached, surgeons find it easy to get the blood flowing through the arteries but not so easy to hook up the veins to get it flowing again. When it bites down, it injects a powerful chemical that stops blood clotting. The wound can bleed for hours and hours, preventing blood from pooling and damaging tissue and giving the veins time to heal.
In Western countries, at least improved hygiene and sanitation seriously reduced the parasitic worms. A rise in bowel disorders has accompanied the rise of domestic hygiene. Some think it’s the loss of helminths at the root of the problem. The theory goes that as the worms wriggle through the body, they damage the tissues, which triggers a particular immune response.
The immune system continually fixes the worms’ cause and reduces inflammation, protecting against these unpleasant and painful bowel diseases. So-called Hellmann’s therapy is being researched and developed at the moment.
They have promised, but there’s a long way to go before scientists fully understand the impact and benefits of parasitic worms. Hopefully, find a way of using them without eating the worms or letting them crawl through the skin. The parasites are useful more than human health. Insects are not immune to parasitic infection.
Parasitic wasps can target fellow insects and lay their eggs inside them. When the larvae hatch inside the insects’ bodies, they have already prepared a Goulet meal of insect innards to eat before facing the world. The more of these murderous larvae, the fewer insects. So the parasites can and have been used to control insect populations.
A Phidias curve eye attacks a Fedeli-eat crop, preventing farmers from using pesticides. The researcher thinks infecting humans with hookworms might cure them. Helmets are small worms. Some research suggests that once inside the body, these tiny worms cause anti-inflammatory responses in humans and even flick a switch in the immune system. They’ve used worms to anecdotally cure chronic diarrhea, colitis, and other stranger things. Even leeches are used to draw blood and help skin grafts.
There are even symbiotic relationships between two organisms. The red-billed oxpecker sits on the backs of larger animals in sub-Saharan Africa and eats the ticks biting through the larger fellow’s skin, which is pretty nice.
Benefits of parasites
In Thailand in 2010, an outbreak of mealy bugs threatened the local cassava crop. Instead of using pesticides, nearly a quarter of a million parasitic wasps were unleashed to target the unwanted bugs with great success. Killing off insect pests isn’t all these parasitic wasps are useful for. With a high-tech twist, they can even be used to detect drugs.
The small stingless micro plight is Crockett’s wasp usually uses its antennae to track down its favored caterpillar hosts. By sniffing out a chemical in their poo. But scientists have trained them to track down an entirely different chemical that doesn’t lead to a host but illicit drugs.
So while there’s no doubt that parasites can still live up to their gruesome reputation with a bit of control and plenty of imaginative thinking, they might be able to redeem themselves.
Parasites don’t cut most of our favorite creature lists. We don’t know their crucial and surprising role in ecosystems. Tiny parasitic worms must move from land to water to mate. The worm infects crickets to get there, prompting them to fling themselves into streams.
The sacrifice delivers the worm to water, and the unlucky crickets provide up to sixty percent of the endangered fish’s food supply. Parasites like this one may be critical to the functioning of many ecosystems. But they have historically been left out of the maps scientists create to help understand energy flow through a habitat.
Ecologists have built hundreds of food webs. In the salt marshes of Southern California, a trematode worm moves from one host to another as it develops, living in snails as larvae and reproducing only in the gut of shorebirds. It makes the transition through an unusual route: The fish’s brain. Fish with parasites on the brain are likelier to flash their silvery bellies toward the sky, a beacon to hungry birds overhead. The result: Infected fish are up to 30 times more likely to get caught, delivering the parasite to its final avian home.
Parasites may regulate population numbers by feeding their host species and competing with others for food. The enhanced complexity is obvious in the few cases where parasites have been added to food webs. Some parasites even benefit humans directly.
Reference: Borgsteede FH. The effect of parasites on wildlife. Vet Q. 1996;18 Suppl 3:S138-40. PMID: 8933697.