What Do Nasal Parasites Look Like?

Nasal parasites range from rice-grain-sized fly larvae with visible mouth hooks to translucent, segmented tongue worms, dark rubbery leeches, and threadlike nematodes barely visible without magnification. There is no single “look” because several completely unrelated organisms can colonize the nasal passages and sinuses of humans or animals. What you would actually see depends on which creature is involved, how long it has been there, and whether it is a larva, adult, or something in between.

Fly Larvae Are the Most Common and Most Recognizable

When people picture a nasal parasite, they are usually thinking of maggots. The medical term for fly larvae infesting living tissue is myiasis, and the nasal passages are one of the areas flies target. The larvae are typically white to yellowish-white, cylindrical, and segmented, looking much like the maggots you would find on spoiled food but often slightly larger. Under close inspection, housefly larvae show degenerated head structures with claw-like mouth hooks and small valves at both the front and back ends of their bodies.¹ Those hooks are how the larvae anchor themselves into the nasal mucosa, which is part of what makes them so difficult to simply pull out.

Different fly species produce larvae that look subtly different. The Old World screwworm fly, Chrysomya bezziana, deposits larvae that burrow into necrotic tissue and can cause extensive destruction of the palate and surrounding structures.² Sheep botfly larvae (Oestrus ovis) go through three stages inside nasal and sinus cavities, growing larger and more spiny with each molt. At the third and final stage, they are dark, stocky grubs covered in rows of small spines that help them cling to tissue. In one veterinary case, a goat expelled these third-stage larvae through forceful sneezing.³ The same fly occasionally infests humans, especially people who live or work around livestock.

Regardless of species, the visual signature of nasal myiasis is the same: soft, pale, wriggling bodies with segmented ridges, usually found in clusters rather than individually. A single infestation can involve dozens of larvae. In one reported case, a patient expelled roughly 50 larvae within fifteen minutes after nasal irrigation with an ivermectin solution.⁴

Leeches in the Nose

Nasal leeches are a different visual experience entirely. The species most commonly reported in human nasal passages is Dinobdella ferox, a leech found in freshwater across parts of South and Southeast Asia. People pick them up by drinking from or bathing in streams and ponds where juvenile leeches are small enough to enter the nostrils. Once inside, they attach to the mucous membrane and feed on blood, growing substantially over days to weeks.

A nasal leech looks like a dark, rubbery, elongated slug, usually dark brown or blackish-green, and it stretches and contracts as it moves. In a self-infestation study, the researcher documented that a parasitizing leech could hide from nasal endoscopy despite eventually growing large enough to protrude from the nostril.⁵ That ability to retract deep into the nasal cavity is part of why these infestations sometimes go undetected for weeks. The leech anchors with a sucker at one end and extends the other end to breathe, occasionally poking out before pulling back in. If you spot one, you would see a glistening dark body, wider than a maggot and with a smooth, unsegmented surface rather than the ridged appearance of fly larvae.

Tongue Worms Look Nothing Like Worms

Pentastomids, commonly called tongue worms, are among the more bizarre nasal parasites. Despite their name, they are not worms at all. They are arthropods distantly related to crustaceans, and their appearance reflects that oddness. The nymphs of Linguatula serrata, one of the best-studied species, are translucent, flattened, and segmented, with annular rings covering their bodies. Females measure roughly 3 to 5.5 millimeters long and under a millimeter wide, while males are slightly smaller.⁶ Under magnification, you can see two pairs of sharp hooks near the mouth, rows of tiny spines along each body ring, and pairs of sensory papillae dotting the ventral surface. To the naked eye, they look like tiny, flat, semi-transparent ribbons with a vaguely shrimp-like quality.

Linguatula serrata is primarily a parasite of dogs and livestock, with humans serving as accidental hosts. Human infection, called linguatulosis or halzoun, typically happens through eating raw or undercooked liver containing nymphs. The parasites then migrate to the nasopharynx, causing irritation, sneezing, and a sensation of something crawling in the throat or nose. They are far less common than fly larvae in human cases but striking to encounter because they look so alien.

An even more unusual pentastomid, Rileyella petauri, parasitizes sugar gliders in Australia. It is the smallest known adult pentastomid, and gravid females specifically migrate to the nasal sinus of the host.⁷ This species does not infect humans but illustrates how varied the pentastomid body plan can be across hosts.

Nematodes and Other Worms

Several species of roundworms can take up residence in nasal tissue. These are what most people would recognize as “worms” in the traditional sense: long, thin, threadlike creatures. Trichosomoides nasalis, a nematode studied in rodents, migrates from muscle tissue to the nasal mucosa, where adult females embed themselves in the pseudostratified epithelium lining the nasal cavities. Some have been found coiled within the thin epithelial layer, stretching it visibly.⁸ This particular species does not infect humans, but it gives a good picture of what nasal nematodes look like in tissue: pale, hair-thin, and often curled within the mucosa rather than freely dangling in the airway.

In dogs, the nasal capillary worm Eucoleus boehmi is a well-known parasite of the nasal sinuses. The adults are threadlike and difficult to see directly, so veterinarians typically diagnose infection by finding eggs in nasal discharge or feces. The eggs are distinctive: roughly 54 to 60 micrometers long, clear to golden in color, with a delicately pitted surface that under electron microscopy looks like a fine mesh surrounding small pores.⁹ That pitted eggshell is one of the features that separates this species from related worms under a microscope.

Parasites You Cannot See With the Naked Eye

Not all nasal parasites are visible to the unaided eye. Two of the most medically serious organisms that can affect the nasal area are protozoans: Leishmania species and Naegleria fowleri. Neither looks like a “worm” or a “bug” because they are single-celled organisms, invisible without microscopy. What you can see, however, is the tissue damage they cause.

Mucocutaneous leishmaniasis, spread by sandfly bites, can destroy the nasal septum, leaving a visible perforation. Clinical examination in affected patients has revealed thick yellow discharge along the nasal and throat structures, along with erosion of the cartilage dividing the nostrils. The parasite itself, Leishmania braziliensis or related species, is only visible inside cells on a biopsy slide, where it appears as tiny round bodies clustered within immune cells.

Naegleria fowleri, the so-called “brain-eating amoeba,” enters through the nose when contaminated warm freshwater is forced up the nasal passages. It is responsible for primary amoebic meningoencephalitis, a rapidly fatal infection of the central nervous system.¹⁰ The amoeba itself is microscopic and will never be something a patient spots in the mirror. By the time symptoms appear, the organism has already traveled along the olfactory nerve to the brain. This is worth mentioning because many people searching for nasal parasites are worried about waterborne organisms, and understanding that the dangerous ones are invisible helps distinguish real threats from the more dramatic but usually treatable visible parasites.

What Symptoms Might Make You Look in the First Place

Nasal parasites usually announce themselves through indirect signs before anyone sees the actual organism. The most commonly reported complaints across case studies include nosebleeds, a foul smell from the nose, facial pain, difficulty breathing through one or both nostrils, and a sensation of something moving inside the nasal cavity. In myiasis cases, patients sometimes describe worms emerging from the nostril spontaneously, especially during sneezing. One case involved a teenager who noticed worms coming out of her right nostril, along with a continuous dull ache spreading over the cheek and under the eye on the same side, facial swelling, and a foul odor.¹¹

Leech infestations tend to present primarily with recurrent nosebleeds, since the leech’s feeding causes ongoing blood loss. The bleeding may start and stop unpredictably because the leech secretes anticoagulants while feeding and then detaches temporarily. Pentastomid infections cause intense sneezing, throat irritation, and sometimes a choking sensation. Nematode infections in animals produce chronic nasal discharge and sneezing, though human nasal nematode cases are rare enough that a clear symptom profile has not been established.

The common thread is that persistent, unexplained nasal symptoms, especially when one-sided, should prompt a look with an endoscope. Many nasal parasites hide deep enough in the passages that a flashlight and a mirror will not reveal them. In the leech self-infestation study, even formal nasal endoscopy missed the parasite on some examinations because the leech retracted deep into the cavity.⁵

How They Are Removed

Treatment depends entirely on what is living in there. For fly larvae, the first-line approach is mechanical removal: a clinician uses forceps under endoscopic guidance to pull larvae out one at a time. This often fails when larvae are deeply embedded or present in large numbers. The mouth hooks that anchor larvae into tissue make forceps extraction painful and sometimes incomplete. When mechanical removal does not work, nasal irrigation with an ivermectin solution has proven effective, causing larvae to detach and be expelled. In one reported case, crushing ivermectin tablets into saline and using the mixture as nasal drops prompted the patient to expel larvae, with the remainder cleared by suction afterward.¹² Oral ivermectin is often given alongside the local treatment.

Older remedies that still appear in the literature include topical application of turpentine oil, ether, chloroform, and other irritating substances designed to suffocate or repel larvae.¹³ Mixtures of chloroform and turpentine, ethylene chloride, ether with cocaine, and lidocaine have all been documented.¹⁴ These work by making the local environment intolerable for the larvae, causing them to release their grip and migrate outward where they can be suctioned or sneezed out. Broad-spectrum antibiotics are generally given alongside any removal procedure to prevent secondary bacterial infection in the damaged tissue.

Leech removal is more straightforward in principle but tricky in practice. Applying salt or a local anesthetic to the leech usually causes it to release its sucker. Attempting to yank it off without making it detach first can leave the mouthparts embedded in the tissue, leading to prolonged bleeding and infection risk. Pentastomids and nematodes in the nasal passages are rare enough in humans that treatment is largely case-by-case, often involving antiparasitic drugs and surgical removal of accessible specimens.

Who Is at Risk and Why

Nasal myiasis occurs worldwide but is far more common in tropical and subtropical regions where flies are active year-round. The people most vulnerable are those who cannot protect themselves from flies: the very old, the very young, people with debilitating illnesses, and individuals who sleep outdoors or in poorly screened environments. Patients with pre-existing nasal conditions, open wounds on the face, or foul-smelling nasal discharge attract egg-laying flies. Diabetes, which impairs wound healing and immune function, appears repeatedly as a comorbidity in case reports of nasal myiasis.¹³

Leech infestations cluster geographically around areas where people rely on natural freshwater sources for drinking and bathing. Children and agricultural workers who wade in streams are most commonly affected. Pentastomid infections are linked to dietary habits, particularly the consumption of raw liver in parts of the Middle East and North Africa. Naegleria fowleri infections, while geographically widespread in warm freshwater, are extremely rare but associated with activities that force water up the nose, like diving into warm lakes or improperly using neti pots with untreated tap water.

Nasal Parasites in Animals

Many of the organisms that occasionally affect humans are routine parasites in animals, and some nasal parasites are exclusively veterinary problems. Oestrus ovis, the sheep botfly, is the classic example. It is an obligate parasite of sheep and goat nasal cavities, meaning it cannot complete its life cycle without a ruminant host. The fly deposits live first-stage larvae directly into the nostrils, and the larvae develop through three stages inside the sinuses before being sneezed out to pupate in the soil. Affected animals show mucous or pus-like nasal discharge, frequent sneezing, head shaking, and sometimes incoordination.³ Herders in endemic areas learn to recognize the behavioral signs and sometimes see expelled larvae on the ground after a particularly violent sneeze.

Dogs deal with their own nasal parasites. Eucoleus boehmi inhabits the nasal sinuses and frontal sinuses, causing chronic sneezing, nasal discharge, and occasionally reverse sneezing. Because the adult worms are so thin, diagnosis relies on spotting eggs in nasal swabs or fecal flotation tests. The pitted, golden-colored eggs are the diagnostic hallmark.⁹ Linguatula serrata nymphs are found in the nasal passages of dogs, wolves, and foxes as well, where they can reach larger sizes than in accidental human hosts.

For pet owners, the practical point is that chronic sneezing and nasal discharge in a dog, especially one that spends time outdoors in rural or semi-wild environments, should not automatically be chalked up to allergies. A nasal parasite is a real possibility, and the diagnostic workup usually involves a nasal flush or endoscopy, sometimes revealing organisms that look startlingly like the ones documented in human cases.

1
PubMed Central. A case report of nasal myiasis caused by Musca domestica in a patient with respiratory failure
2
Frontiers in Medical and Clinical Sciences. Extensive Palatal Necrosis Due to Chrysomya bezziana Myiasis: A Detailed Case Report
3
Himachal Journal of Agricultural Research. Oestrus ovis Larvae in Nasal Cavity of Goat: A Case Report
4
PubMed Central. Treatment of nasal myiasis with ivermectin irrigation
5
Parasitology. Beyond the epistaxis: voluntary nasal leech (Dinobdella ferox) infestation revealed the leech behaviours and the host symptoms through the parasitic period
6
PubMed Central. Characterization of the Tongue Worm, Linguatula serrata (Pentastomida), Identified from Hares (Lepus europaeus) in Romania
7
PubMed. Rileyella petauri gen. nov., sp. nov. (Pentastomida: Cephalobaenida) from the lungs and nasal sinus of Petaurus breviceps (Marsupialia: Petauridae) in Australia
8
PubMed Central. Trichosomoides nasalis (Nematoda: Trichinelloidea) in the murid host Arvicanthis niloticus: Migration to the epithelium of the nasal mucosa after intramuscular development
9
Parasite. First report of Eucoleus boehmi (syn. Capillaria boehmi) in dogs in north-western Italy, with scanning electron microscopy of the eggs
10
PubMed Central. A review of the mechanism, diagnosis, and treatment of Naegleria fowleri infection
11
PubMed Central. Nasal myiasis with orbital and palatal complications
12
IP Journal of Otorhinolaryngology and Allied Science. A case report on use of ivermectin as nasal drop in a case of nasal myiasis
13
PubMed Central. Management of nasal myiasis and type 2 diabetes mellitus: A rare case and review article
14
International Archives of Otorhinolaryngology. Nasal Myiasis: Case Report and Literature Review