Human Encounter with a Horsehair Worm Nematomorpha: Is There a Reason To Worry? PMC
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The worm was brought to the Public Health Institute of the University of Niš, Serbia, where macroscopic and microscopic analysis of the parasite´s morphometric characteristics was performed. The sample was sent to the Institute of Histology and Embryology of the University of Niš, Serbia, for histological analysis. PCR and molecular barcoding is potentially very helpful in identification, but as the COI gene of no Spinochordodes species has been sequenced before, there is no basis for comparison right now. Pieces of the worm were prepared for scanning electron microscopy (SEM). They were dehydrated in an increasing ethanol series, critically point dried and coated with gold in a sputter coater. The observation took place using a JEOL JSM 5300 SEM at 20 kV and digital images were taken.
Pests of Homes, Structures, People, and Pets
Horsehair worms occur in knotted masses or as single worms in water sources such as ponds, rain puddles, swimming pools, animal drinking troughs, and even domestic water supplies. Adult worms measure 1/25 inch in diameter and may reach 1 foot or more in length. An old and still common misconception is that these long, thin, brown to blackish worms develop from horsehairs that fall into water. Because horsehair worms are parasites of invertebrates, especially certain insects, they are commonly encountered in agricultural areas, particularly those having water-impoundment and irrigation facilities. At the water, the horsehair worm emerges from the insect's body and swims away, an essential step in the life cycle of this internal parasite.
These 6 images show the moment when parasites burst from their hosts — and they're scary - Livescience.com
These 6 images show the moment when parasites burst from their hosts — and they're scary.
Posted: Tue, 31 Oct 2023 07:00:00 GMT [source]
Description of horsehair worms
The approximately 320 remaining species are distributed between two families,[24] within the monotypic class Gordioida. There are several published case reports in which gordiids were found in patients urin immediately after urination (Schmidt-Rhae-sa, 2003; Burger, 1972). Clinical manifestations in humans were reported as well (in the form of vague pain in the lower abdomen) immediately before the release of parasites via urin (Burger, 1972; Carvalho, 1942). However, the potential symptoms and signs of infection have to be taken with caution, because unrelated health complaints and diseases might have been present.
Damage caused by horsehair worms
In summary, there is no evidence for a parasitation of humans by gordiid worms. Both the patient and his physician should be informed that horsehair worms do not pose a health risk for humans and the environment. Detection and identification of these pseudoparasites necessitate multidisciplinary collaboration, i.e. professional and scientific evidence relevant for the health of individual people and for the general population. Human encounters with horsehair worm do not threaten human health and do not pose a public health issue.
The paraffin blocks were cut on the Leica microtome in order to obtain 5 μm thick tissue sections. The obtained paraffin sections were deparaffinized (in the thermostat at 64°C and xylene) and rehydrated in a series of descending concentrations of alcohol (100 %, 96 %, and 75 %) and distilled water. The sections were then stained with hematoxylin and eosin (HE), dehydrated in the ascending concentrations of alcohol (75 %, 96 % and 100 %), cleared in xylene and mounted with cover slips by using Canada balsam.
Life Cycle
The underside of an injured cockroach from which a horsehair worm has just emerged. The top view of an injured cockroach from which a horsehair worm is emerging. The worm tissue samples were fixed in 10 % buffered formalin and routinely processed to paraffin blocks.
Habitats and Hosts
Adult horsehair worms hibernate through the winter and lay millions of eggs in the water after mating in the spring. Larvae that hatch from the eggs swim in the water until they are ingested when insects come to the water to drink, or the newly hatched larvae form cysts on plants near the water. Cysts eaten by a grasshopper or cricket dissolve inside the insect gut, allowing the juvenile worm to bore through the gut wall and into the host's body cavity. The worm absorbs nutrients directly through the body wall and lives for 2 or 3 months before emerging to start the cycle over. Horsehair worms are sometimes found in streams and ponds, but are usually noticed in watering troughs, bird baths, swimming pools, pet dishes, sinks, and bathtubs. Horsehair worms develop as parasites inside crickets, grasshoppers, katydids, beetles, cockroaches and even sowbugs and spiders.
Household insects
These long, slender creatures are harmless so there is no need for control. Their presence indicates that a cricket or some other host insects got in the container and died, releasing the worm. The horsehair worms are not a problem but contamination from other sources can be. Control of horsehair worms in natural water sources is impractical. Furthermore, the worms can be beneficial, because they will parasitize a few pest insect species, although their effect on natural invertebrate populations is minimal.
Human Encounter with a Horsehair Worm (Nematomorpha): Is There a Reason To Worry?
Horsehair worms parasitize only invertebrates such as insects. To complete their life cycle, the worms must infect large invertebrates that are relatively long lived. Generally, horsehair worms aren't considered an effective biological control agent, because they parasitize only a small percentage of a host population. About three months after the horsehair worm parasitizes a host, the host is impelled to seek out water. Adult worms are free-living in water and don't feed, but they can live many months. They overwinter in water or mud, and the cycle repeats itself the following spring.
Insects infected with horsehair worms die as a result of the parasite. Horsehair worms are white when they first emerge from the host's body but turn yellowish-tan to brownish-black after a short time. The worms often squirm and twist in the water, knotting themselves into a loose, ball-like shape, resembling the "Gordian Knot." Another name for the horsehair worm is the Gordian worm. We report here a specimen of the horsehair worm (Gordiida, Nematomorpha) Spinochordodes bacescui (Căpuşe, 1965) found in a patient´s urine. This is the first record of this species from Serbia and the sixth gordiid species known in Serbia. It is discussed that there is no evidence that gordiids are parasites of humans.
Notable is the absence of a dark, ring-like pigmentation which is present in gordiids of several other genera. The histological analysis revealed the presence of the cuticle, muscular layer, parenchyma and ventral nerve cord, which corresponded to the microscopic structure of horsehair worms (Nematomorpha) (Fig. 2A, B). Paired dorsolateral cavities within the parenchyma, the testes (Fig. 2B); are absent in anterior sections (Fig. 2A). The analysis of the digital SEM images established that the specimen belongs to Spinochordodes bacescui (Căpuşe, 1965) (formerly Dacochordodes bacescui) (Fig. 3A, B).
Sometimes the host directly ingests the larvae, which immediately move into their parasitic stage and develop within that host. After the egg of the horsehair worm hatches, an aquatic insect, such as a mayfly nymph, eats the preparasitic larva. T begin to develop until a host such as a mantid that the horsehair worm can parasitize eats the mayfly.
Instead, gordiids parasitize terrestrial insects, which release their mature gordiid parasite into water and may thereby also use containers in human surroundings. Pseudoparasites, such as Spinochordodes bacescui, do not pose a threat to human health nor are they a serious public health issue. Horsehair worms develop as parasites in the bodies of grasshoppers, crickets, cockroaches, and some beetles.
Once in the mantid, the horsehair worm grows to an adult and emerges when the mantid seeks water. The worm was 12 cm long and 0.3 cm wide along the entire length. The body was dark brown, cylindrical and with uniform diameter along the entire length (Fig. 1A). Individual parts of the worm were observed under a light microscope.
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