It’s a common fear that flies can lay eggs or maggots in humans. The thought of fly eggs hatching under your skin is repulsive. But is it really possible for flies to use humans as hosts for their eggs? Let’s examine the evidence.
Can Flies Lay Eggs in Living Humans?
The short answer is no, flies cannot lay eggs in living, intact human skin. Here’s why:
Flies Cannot Penetrate Living Human Skin
Flies do not have the ability to penetrate living human skin with their ovipositors (egg-laying organs). Human skin, when intact, serves as an impenetrable barrier against fly eggs being laid internally.
However, there are some flies in the genus Cuterebra, known as botflies or warble flies, that can infest animal hosts by attaching their eggs to the skin. The larvae then burrow into the host. But human botfly infestations are extremely rare and involve contaminated clothing or travel to tropical areas where botflies reside. Healthy human skin resists egg implantation.
Flies Prefer Decaying Material for Egg Laying
Flies are attracted to dead and decaying organic material for laying their eggs, not living tissue. They detect suitable egg-laying sites based on visual cues, attraction to odors, optimal moisture level, and temperature.
Living humans do not provide the optimal conditions or attractants that flies seek when depositing eggs. Flies deposit eggs on decaying matter like feces, dead animals, garbage, rotting fruit/vegetables, etc.
Human Immune System Rejects Foreign Bodies
Even if a fly was somehow able to penetrate the skin barrier and insert eggs, the human immune system would quickly attack the invading foreign bodies. Foreign objects like splinters and slivers trigger an inflammatory response.
The body would treat fly eggs in human skin as invaders and destroy them. There would be redness, swelling, heat, pain and discharge until the eggs were eliminated.
Can Flies Lay Eggs in Open Wounds or Orifices?
While intact human skin prevents fly egg laying, there are some situations where flies can opportunistically lay eggs in or around openings or wounds:
Open Wounds
If skin is disrupted due to cuts, sores, ulcers etc., flies may lay eggs in the open wound. The moisture, warmth and nutrients of an open wound can attract egg-laying.
However, even shallow wounds typically heal quickly enough to prevent extensive maggot infestation. The eggs or freshly hatched maggots would get flushed out by wound drainage/bleeding.
Body Orifices
Flies have been known to lay eggs in or near ear canals, nasal passages, eyes, mouth, penis and vagina. Mucus membranes do not provide the barrier protection of intact skin. Still, infestations in orifices are very rare.
Cases are Usually Associated With Prolonged Helplessness
In most reported cases where flies laid eggs in open wounds or orifices, the human host was in an extremely helpless state for a prolonged time. Examples include the elderly, infants, immobilized patients, homeless individuals, those with mental disability, etc.
If a person cannot fend off the flies for days at a time, then eggs may eventually get laid in openings. But for most healthy, mobile individuals, prompt washing and wound care prevent infestations.
Can Maggots Infest Living Humans?
If flies do succeed in laying eggs in a wound or orifice, maggots can develop:
Brief Survival if Eggs Are Laid in Living Tissue
In living tissue, maggots may survive only briefly. As soon as the eggs hatch, the body mounts an immune attack against the maggot larvae. There would be intense inflammation, discharge and sloughing off of tissue surrounding the larvae.
So maggots in living tissue do not survive long. They get expelled by the body quickly.
Maggots Feed on Dead Tissue in Wounds
However, maggots can develop more extensively in dead tissue within wounds. The larvae secrete enzymes that break down and digest dead tissue, leaving living tissue largely unharmed.
In fact, medical maggots have been used to help clean out necrotic tissue from non-healing wounds. Still, the number of larvae is controlled so that they do not invade living tissue and healthy wound healing can occur.
Maggots Don’t Feed on Living Tissue
Maggots do not consume living tissue – they feed only on dead tissue, dried blood and wound exudate. So even if maggots hatch in a wound, they cannot burrow deeper into living flesh or spread under the skin. They are contained to the wound surface and surrounding dead tissue.
Rare Cases of Larvae Invasion Into Body Cavities
There are extremely rare reports of maggots invading into body cavities through openings:
Gastrointestinal
Swallowing fly eggs could lead to maggots developing internally. There are isolated case reports of maggots found in the oral cavity, throat, esophagus, stomach, small bowel and colon after eggs were ingested.
Vomiting up larvae occurs as they irritate the lining. Maggots in the GI tract may also get defecated out.
Ear Canal and Sinus Cavities
If flies lay eggs deep in the ear canal or sinus cavities, larvae invasion into the head cavities is possible. This is extremely rare and mainly reported in cases where mental disability or prolonged unconsciousness prevented people from dislodging the eggs. Symptoms include headache, discharge and irritation until the larvae are removed.
Urinary Tract and Vagina
There are occasional reports of maggots in the urethra, bladder or vagina after flies lay eggs in the openings. Larvae get washed out in the urine flow. Urinary tract maggots could potentially lead to bladder infection. Genital myiasis usually resolves quickly with wound care and washing.
So internally, maggots do not survive for long before getting expelled. The cases are very rare and related to inability to keep flies away from orifices.
Risk Factors for Myiasis
While fly larvae infestation (myiasis) in humans is uncommon, there are some risk factors:
Impaired Self-Care
Those who cannot adequately care for themselves and maintain good hygiene are most at risk:
– Elderly with disabilities
– Bedridden patients
– Alcoholism, drug abuse, mental disability
– Homelessness
Poor Living Conditions
People living in unsanitary conditions without adequate facilities have increased risk:
– Slums
– Refugee camps
– Rural villages
– Overcrowded facilities
Warm Climate
Fly populations thrive in warmer environments. Myiasis is more common in tropical regions.
Skin Disruption
Open wounds, ulcerations and skin disease make egg laying more likely. Burns, traumatic injuries, skin cancers, dermatitis etc. allow flies access.
Body Orifices
Ear canal, eyes, nasal passages and sinuses are susceptible, especially if blocked by debris. Cases have also been reported in the urethra, vagina and GI tract.
Symptoms of Myiasis
Here are symptoms that my signal maggots have infested dead tissue:
Movement Under Skin
The larva wriggling beneath the skin can produce creepy, crawling sensations. Discharge and bleeding may occur at sites.
Pain and Discomfort
As the larvae feed and move, there is pain and itching. Large masses of maggots can erode tissue.
Unpleasant Odor
The larvae and their waste products produce foul odors of decaying tissue. Odor increases as wounds accumulate serosanguinous discharge.
Tissue Destruction
Maggots tunnel into necrotic flesh. Their enzymes liquefy tissue. The wound grows larger and deeper.
Secondary Infection
Bacterial superinfection can set in as maggots disrupt protective barriers. This causes fever and increased redness/swelling.
So sensations of crawling, itching, pain, odor and wound changes should prompt investigation for possible maggots.
Maggot Infestation Treatment
Here are approaches for dealing with myiasis:
Manual Removal
Use gloved hands or forceps to pick out visible larvae. Place in sealed container to prevent escape/reinfestation. Check wound carefully to remove all maggots.
Suffocation
Applying oil, petroleum jelly or adhesive to wound seals off air supply to larvae. Use fingers to scrape off and remove dead maggots.
Surgical Debridement
For heavy infestation, surgical removal may be needed. Necrotic tissue also gets debrided to allow wound healing.
Topical Irritants
Applying alcohol, chloroform, turpentine, ether or other irritants can drive maggots to the surface. Flush them off afterwards.
Oral Ivermectin
For maggots internally or difficult to remove externally, ivermectin drug kills larvae. A single oral dose treats the infestation.
Antibiotics
If bacterial superinfection is present, antibiotic creams or oral antibiotics treat secondary infections.
Prompt, thorough removal of larvae prevents extensive tissue erosion. Good wound care and hygiene prevent reinfestation.
Prevention of Myiasis
Here are tips to avoid maggot infestation:
Practice Proper Hygiene
– Bathe regularly
– Wash wounds well with disinfectant
– Clean linens, clothing after contamination
– Change wound dressings frequently
Sanitation Measures
– Disinfect potentially contaminated surfaces
– Screen windows and use insecticides
– Dispose waste properly in sealed bags
– Improve general sanitation
Protect Vulnerable Body Sites
– Gauze in nose, ears and wounds
– Diapers or pads for incontinence
– Protective masks if necessary
Prompt Wound Care
– Clean and dress wounds promptly
– Seek medical care for non-healing wounds
– Debride necrotic tissue
– Manage complicating diseases like diabetes
Good hygiene and wound care provide the best protection against maggot infestation!
Conclusion
In summary, here are the key points about flies and maggots infesting humans:
– Healthy, intact human skin prevents flies from laying eggs
– Open wounds and orifices allow opportunistic egg laying
– Maggots do not survive long in living tissue
– Maggots feed only on dead tissue, not living flesh
– Cases of myiasis are very rare and related to impairment
– Symptoms include crawling sensations, odor and tissue damage
– Treatment involves manual removal and wound care
– Prevention emphasizes hygiene, sanitation and prompt wound care
While the thought of flies laying eggs and maggots burrowing in living humans is terrifying, it rarely occurs. Taking appropriate precautions allows prompt removal of any larvae before extensive damage happens. So there is no need for most people to worry about flies treating them like rotting carrion and infesting them with maggots!