human bot fly - Dermatobia hominis Linnaeus, Jr.)
common name: human bot fly, torsalo (Central America), moyocuil (México), arthropod, usually a mosquito or a tick, that is captured by the bot fly in flight. The human botfly, Dermatobia hominis is one of several species of flies, the larvae of which parasitise humans (in addition to a wide range of other animals, including other primates). It is also known as the torsalo or American warble fly, though the warble fly is Either the eggs hatch while the mosquito is feeding and the larvae use the. Dermatobia hominis is a fly endemic to and widely distributed throughout the Americas; it is human botfly, berne, tórsalo, mountain worm, maggot, miruta, mucha, colmoyote, moyocuil, mosquito worm, ura, and suglacuru. . Thus, this marker is useful for classifying species but not determining phylogenetic relationships.
The wound should heal in one to two weeks with little or no scarring. Management Back to Top Due to the increase in travelers to Central and South America, it is important to carefully monitor and control the vector population. Additionally, travelers to these regions need to take preventive measures, including applying insect repellent and wearing protective clothing Diaz et al.
Zoonoses and communicable disease common to man and animals. Pan American Health Organization. Tracheopulmonary myiasis caused by a mature third-instar Cuterebra larva: Journal Clinical Microbiology The epidemiology, diagnosis, management, and prevention of ectoparasitic diseases in travelers.
Journal of Travel Medicine Morphology of the antenna of Dermatobia hominis Diptera: Cuterebridae based on scanning electron microscope. Journal of Medical Entomology Scanning electron microscopy studies of sensilla and other structures of adult Dermatobia hominis L. Myiasis with Dermatobia hominis in a traveler returning from Costa Rica: Review of 33 cases imported from South America to Japan. Myiasis secondary to Dermatobia hominis Human Botfly presenting as a long-standing breast mass.
Archives of Pathology and Laboratory Medicine Lawson RD, Rizzo M. Digital infestation with the human bot fly. Journal of Hand Surgery 30B: Lang T, Smith DS. Clinical Infectious Diseases Human botfly larva in a child's scalp.
Journal of Pediatric Surgery Maier H, Honigsmann H. Furuncular myiasis caused by Dermatobia hominis, the human bot fly.
Journal of the American Academy of Dermatology An unusual imported infestation in Calabria, Italy. Journal of Travel Medicine 8: Hemilucilia segmentaria Fabricius, Diptera: Calliphoridae as new biological vector of eggs of Dermatobia hominis Linnaeus Jr. Myiasis due to Dermatobia hominis Human Botfly.
New England Journal of Medicine Experimental skin lesions from larvae of the bot fly Dermatobia hominis. This species readily infests several other species besides humans, including wild or domestic mammals, and birds. Infections in cattle and sheep can have significant economic effects The life cycle of the botfly Dermatobia hominis is quite interesting because of the way in which the hosts become infected.
Female flies do not deposit their eggs directly on the host. Ratherthe adult female fly after matingactively seeks out biting arthropods such as ticks, mosquitoesor other species of biting flies. The botfly captures the other arthropod, hold it's wings to prevent escape, and then attaches her eggs roughly at a time on the abdomen of this other insect.
The biting insect then carries around the botfly eggs. When this insect finds a suitable host for its own blood feeding, the botfly eggs are stimulated to hatch by the warmth of the host. A first-stage larva emerges from the egg and is deposited on the skin. The larva will burrow into the skin, either directly through intact skin, or through the bite from the insect vector.
It can also enter through hair follicles or damaged areas. The burrowing process takes minutes but apparently is not usually noticeable to the host. The larva will develop at the site of entry, it does not migrate through the body although it does move around under the skin. It's anterior end is found towards the inside, and the posterior end is located at the skin surface.
The anterior end is used to grasp host tissues for feeding. There are two oral hooks which are used for tearing tissue during the feeding process. The curved spines along the body assist with anchoring the larva in the skin. The larva is able to breathe through small spiracles located at it's posterior end, where the skin will remain open.
The pattern of spiracles is one of the features used to differentiate the various species of botfly. The developmental stages take weeks. The larva goes through two molts, to a 3rd instar stage, with emerges from the skin and drops to the ground.
It pupates in the ground, taking days to mature to an adult, which then emerges. Adult botflies do not feed, and live only a short time. The females are able to develop eggs because of the stored resources acquired from the host during larval development.
Botflies are obligate parasites of vertebrates: Flies live near water, thus coastal and forested or jungle areas are endemic for this species. May depend on the location of the fly larva on the host's body. Usually larvae are found on the arms, legs, back and scalp. Other areas that have been reported are brain, eyelids, tongue, nose, genitalia and buttocks. Approximately 24 hours after infestation, a small mm papule will develop that resembles an insect bite. This will enlarge gradually to mm and will be approximately mm in height and will be surrounded by an area of induration.
A breathing hole will be visible in the center of the lesion. As the larva develops, the lesions may become pruritic and produce a discharge that may be serous, serosanguineous or purulent.
A secondary bacterial infection is actually uncommon. Often, pain a stabbing feeling is felt by the host; this is a result of the larva tearing off tissues while feeding, and from the spines irritating the tissues as the larva moves around.
Usually systemic signs and symptoms do not occur, but occasionally malaise, letharge and insomnia have been reported. Moderate inflammation may occur in the area where the larva is found in the subcutaneous tissues. In general, secondary bacterial infections do not occur. Definitive diagnosis is made by removal of the larva followed by indenification by a medical entomologist or trained personnel.
Tentative diagnosis can be made if there is a history of recent travel to an endemic area, and presence of non-healing lesions on the skin. The lesion may resemble other infections, so presence of the larva should be confirmed. Identification of the larva is relatively easy and is made by examining the spiracles, mouth hooks and pattern of spines on the body. Dermatobia hominis is easily distinguished from other botflies found in the Western Hemisphere, such as Gasterophilus spp.
A similar fly, Cordylobia anthropophaga also called the Tumbu flyis found in Africa. Larvae are similar to Dermatobia hominis,but can be distinguished by the spines and spiracles.
Removal of the larva. Larvae will migrate out of the skin if their spiracular plate is covered.Entomólogo de Harvard decide incubar larvas de mosca bajo su piel como parte de un experimento
A number of substances have been used to accomplish this, including nail polish, tape, wax, mineral oil, etc. The larva can be removed by grasping with forceps or applying pressure on both sides, but because of the curved spines, surgical excision may be required.
Antibiotic treatment is not usually necessary and should only be used if a bacterial infection has developed. Harrisons Internal Medicine online.
Medical and Veterinary Entomology, 2nd Edition. Chapters 14 and 15, pages We too visited Arenal in CR this June.
Human Botfly, Bot Fly, Botflies, Torsalo, Dermatobia hominis
Upon return, my 8 year old daughter kept complaining about shooting pains periodically coming from two "mosquito bites" on her head. The pediatrician confidently diagnosed it as impetigo and put her on anti-biotics. After 10 days and no results - stronger AB's.
After 4 days and no results - off to the dermatologist. Skin can't figure it out so she decides to do a biopsy. Much to her surprise - it's a maggot!. The dermatologists office thought this was the coolest thing since alligator shoes. Found your story on the net after scraping Mom up off the floor.
Thanks for sharing your experience! It does make for good gross-out story telling Bryan Edwards Mandeville, Louisiana Wow, that's quite a story I must say, I never thought I would hear one better than mine, but you win. I just feel compelled to share my story with you because, if anyone else, you'll be able to sympathize. I went to Belize this summer with my father for a scuba trip.
We dove every day except for one: While in the jungle, I happened to get a couple of mosquito bites on my leg, which I thought nothing of. Two weeks after arriving back home, they were still there, itchy and painful as ever, so I went to the doctor.
I had previously heard something about botflies, but didn't really think it was possible. So when I went in to see the doctor, he told me it was just an infected mosquito bite, nothing more. After I told him what I knew about botflies although I didn't know the name at the timehe decided that they would lance the largest one and drain it because, according to him, I was overreacting. No more than two minutes after they had opened the bite, they pulled out a little wriggling botfly.
Now, of course, they had no idea what it was, so both the doctor and the physicians assistant flipped out and called the CDC After all that, they glued my leg back together and gave me some medicine. A month later, the second bite they had opened wasn't healing at all the first one healed and there's barely a scarso I went back to the doctor.
They opened it up again, this time digging all the way down to the muscle, and still didn't find anything. They sewed my leg up again, gave me more drugs, and sent me on my way. A week later, I came back to have my stitches removed, and it still wasn't healed, so he began talking about simply removing all of the tissue that next week.
Two days after that appointment, I was looking at the wound and it appeared to be moving! I thought I was going crazy, and I showed it to a lady at work who used to be a nurse. She told me it was probably just pus trying to work its way out, so I shouldn't worry. Later that day, I would push on it a bit and this big long white thing would come out of it.
Now, by this time, I was getting pretty sick of having bugs in my leg, so I called the doctor immediately and told him what was up I showed him the thing and he said "Its a maggot, we have to get that out of there". So they pulled out this 1.
The very next day, I bent down to pull off my bandaid, when another maggot fell off on my hand. I called my neighbor, who is a plastic surgeon, and he came over to look at it. After inspecting it, he decided we needed to go to the emergency room and take out all of the tissue in the area.
So now, because of a great trip to Belize, I'm left with 2 very purple scars on my leg: I'm just glad to know that I'm not the only freak this happens to! Lindsay I want to thank you for placing your account with the bot fly infestation on the internet. My husband and I traveled in late September-early October to Belize. Not too long after our return, I noticed a lump on the top of his head and asked him if he had hit his head or something.
He teased me for my violent ways, said it was probably a pulled hair, and said it would go away. Well, it didn't and it was sore and oozing fluid. Like any good wife, I demanded that he see a doctor before I became a widow I was irrationally thinking it was some form of cancer at that point.
The first doctor thinks nothing of it, gives him some antibiotic ointment and pills and sends him on his way. When that doesn't change anything in 3 days, I hit the roof and told him he had to get a second opinion or resolve himself to sleeping on the couch. He calls the other doctor back who suggests he see a surgeon to see if it is something that needs to be removed.
The doctor was so surprised he almost dropped the thing. It was nothing he had ever seen and, after cutting it open to look inside, he sends it off to a lab. Imagine OUR surprise when the doctor calls today saying it was some kind of fly infestation. The ONLY reason we know it's a bot fly larvae is because we typed in "fly lays egg under skin" into the Google search engine.
Damn bot fly pictures look just like the one that came from his head. My husband has called the doctor back with the identifying information.
Thanks for sharing your story and listening to mine! Tammi Hi there, Thank you so much for your thorough review of the Bot Fly. I am a family physician in Bellingham WA. I work at an Urgent Care Center.
Symbiosis -- Torsalo
Today I saw a 24 year old male who had traveled to Costa Rica 3 weeks ago. He remembered being bit by a mosquito on the left calf one night while sitting on the beach. Two sites became itchy and eventually each formed indurated papules with a 1mm umbilicated center. The persistence of the lesions combined with their waxing and waning pain and itching motivated him to come see me.
Admittedly I wasn't sure what was going on.
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Two days ago I treated him with an antibiotic figuring these were boils. But today the patient said it felt like something was moving.
One thing lead to another and I cleaned and numbed up his leg and got the larva out of one site. I didn't know what it was but I knew that I had seen it before. After exhausting all the texts where I thought I had seen this, I went to the internet. A search on "subcutaneous larva costa rica" led me to your site. I have forwarded the link to the patient. He is excited to have the information. I did not attend to the second site today.
He wants to try the meat treatment tonight. Thank you for your site. The information has helped a very grateful, if not understandably repulsed, 24 year old male.
The information has made me look like I know what I'm doing always a goal in the doctor biz. Total time from excision to diagnosis thanks to your site: I appreciate your having the "balls" to share.
This is truly a representation of the value of the internet. Gratefully yours, Todd Cowdery Hi! We were trapping and tagging spinney pocket mice and other small rodents in the rainforest to study thier relation to seed dipersal and germination. I have been back for about a month and today I found out my friend and I both have beefworms botflies. I had seen doctors twice before and was told it was an infected mosquito bite and given antibiotics.
Both times I had specifically asked if it was botflies because while on our trip a man staying with us had a couple in his head and had a friend squeeze them out at the dinner table for him, that image stayed with me.
So after seeing a tropical disease specialist I found I have three. They are in no way the size of a goose egg, but big enough to feel. I was told I need surgery even though I have heard the raw meat theories and wondering how long it was before Mark finally got his professional treatment and how urgent treatment is for me and my friend.
Thanks a bunch and I hope to hear from you soon. I have another botfly story to add to your collection. I had been on vacation in Belize with my boyfriend, Arch, from February 22 to March 3, When I returned to St. John's, Newfoundland on Monday, March 3,I noticed a small bump on my left cheek, near my eye.
It was slightly red and itchy and I thought it might be a mosquito bite or a zit. I had no recollection of being bitten. I carried on normally when I returned home, however, by March the red spot was getting bigger, redder and more irritated. On Tuesday, March 11th I was driving home to lunch when I got an excruciating stabbing pain in the bump and it began to ooze a clear fluid. It was throbbing and red and swollen. I had read about the botfly in a book before I left for Belize and jokingly thought whatever the bump was was about to hatch!!
It didn't hatch but I did call my family doctor and made an immediate appointment for that afternoon. When he examined my face he diagnosed it as a bite that had gotten infected and to which I had an allergic reaction.
I made sure to tell him I had just returned from Belize and the length of time I had been there.
He prescribed the antibiotic Cipro for me. I took the Cipro however had an allergic reaction almost immediately. I called my family doctor the following day and he prescribed another anitbiotic, Ceftin for a period of 7 days. I began taking that but did not notice any difference in the bump on my face. On Thursday, March 14 we were having a baby shower for my sister-in law.
I spent most of the night with a tissue to my face as I was assaulted with these stabbing pains and fluid continued to leak out of the bump. As the weekend came on, the bump continued to grow, it became redder, my face became swollen from my eye to my chin and the stabbing pains continued.
The bump looked like a volcano - raised, round, with a hole in the center. It continued to ooze fluid that was mostly clear but sometimes a bloody brown or black. I even tried a bread poultice to try and draw out what I believed to be an infection. By the week of March 17, the bump was beginning to bleed spontaneously. I would be sat at my desk at work or driving in the car and I would feel blood flowing down my face.
The stabbing pains continued and became worse at night. I called the clinic I had attended for shots prior to my trip to Belize and explained the problem to them. They suggested that I consult an infectious disease specialist however I needed a referral from my family doctor.
I returned to my family doctor and explained to him that I thought it might be a botfly that was causing the bump on my face - he told me I was watching too much Star Trek!! I asked him send me to an infectious disease specialist and he said he wanted to "give it another shot. The specialist recommended some antibiotic in mg tablets - two tablets, four times a day.
I took the tablets for 24 hours and my face actually got worse. The swelling was so pronounced that my eyelid was drooping and felt as if it was beginning to shut. My face looked like I had had a tooth pulled. The bump was still oozing fluid of various colors spontaneously and it was still bleeding with the stabbing pain.
On the afternoon of March 19 my office assistant, Cora, came into my office and said she didn't want to scare me but she had been researching the botfly on the internet and was reading stories off your website and the symptoms being described were identical to the symptoms I had been describing. I had been pretty calm for the last 2 weeks but when I read the symptoms and saw that they were exactly what I was experienced I started to feel a little freaked out.
I called my family doctor again who told me not to panic, that it took antibiotics 48 hours to work and I should wait to see what they would do. I explained how I had taken antibiotics for a week with no difference in the symptoms and since taking the new drugs, my face had actually gotten worse.
He told me if I was still worried to come in at the end of the week.
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- Birth of A Botfly Maggot
At more prodding from my colleagues who were completely grossed out by the bump and convinced it was the botfly I went to the emergency department of one of the city hospitals armed with the literature from your website. At the hospital, myself and my friend Cheryl, explained to the nurse what we thought it was. To my surprise, she didn't call in a psych. Then to our surprise, a friend of ours who is a surgeon showed up. He immediately took out a syringe to aspirate the bump to see if there was any infection and of course there wasn't any.
They concluded that these two factors, no discharge or tenderness, indicated that there was no infection. We discussed the literature we had brought with us, the doctors consulted a medical journal and then said they thought we had correctly diagnosed it.
I had also brought some literature from a physicain in Canada who wrote on his experience with the botfly and how he had surgically removed the larva. Surgeon takes me into the O. He fished around for a period of time and I was getting concerned that maybe we hadn't correctly diagnosed it when he suddenly said "my God - you were right!!
Human Botfly: A Case Report and Overview of Differential Diagnosis
He continued to root around for a period of time to make sure Fred as we christened him wasn't a twin and didn't have any roommates or that we hadn't left part of Fred behind!! Fortunately there were no more and I was stitiched up with 2 stitches located just to the side of my eye.
I had a good look at the little guy - who was still moving - and he was identical to the picutres on the websites - white, with 3 stripes that are actually spiny hooks, what looked to be a tail but what we think might have been the breathing tube and 2 little pincers at the front of him.
My God, I can't believe it was in me!! I felt immediate relief, both physically and mentally, the swelling around me eye immediately started to subside as did the inflammation.