Ocular toxocariasis
Ocular toxocariasis is a lesion of the organ of vision by migrating larvae of Toxocara canis helminth worms. The natural owner of Toxocara is the canine family (dogs, wolves, jackals), less often cats are carriers of worms. The larvae do not seek to enter the human body, and infection occurs most often by accident. Toxocara cannot develop into an adult in the human body.
Eye damage by toxocara larvae is observed quite rarely, no more than 9% of all toxocariasis recorded in humans.
Ocular toxocariasis develops most often when a small number of larvae enter the human body. In the eye, no more than one larva is predominantly found. The overwhelming number of cases is older people, although children are also susceptible to infestation.
All cases of ocular toxocariasis are usually divided into 2 basic groups:
- Chronic endophthalmitis with exudation;
- Solitary granulomas.
The first cases of ocular toxocariasis were described not so long ago, in the 50s of the last century. Moreover, patients were admitted to ophthalmologists with a diagnosis of retinoblastoma and Coates disease. Later, however, they found nematode larvae and hyaline capsules.
Content:
- Causes of ocular toxocariasis
- Symptoms of ocular toxocariasis
- Treatment of ocular toxocariasis
Causes of ocular toxocariasis
The causes of ocular toxocariasis lie in the entry of the worm larva into the human body and in its further migration to the organ of vision. Infection with toxocars occurs through the fecal-oral route.
Possible sources of invasion:
- Soil containing helminth eggs. It can be introduced into the human digestive tract if the rules of personal hygiene are not followed, when poorly processed berries, fruits and vegetables are eaten.
- For some psychological illnesses, for example, when people eat the earth.
- Toxocara eggs are carried by dogs, including puppies. In addition to being contained in their feces, eggs are often attached to their fur. Therefore, contact with animals can be dangerous, especially if you do not thoroughly wash your hands with soap and water afterwards.
- Toxocara eggs are carried by cockroaches. They eat them, after which they seed human food with viable eggs.
At risk of contracting ocular toxocariasis are veterinarians, workers at animal receptions, children aged 3 to 5 years, hunters, summer residents, gardeners and other farmers.
In a dog's body, Toxocara migrates according to the following scheme: GI tract> portal vein> liver> right atrium> lungs> trachea> larynx> esophagus> stomach> intestines, where the toxocara ultimately turns into a sexually mature individual. There are no conditions in the human body for the worm to complete its life cycle. Therefore, toxocara migrates in the human body until it stops in one or another organ under the influence of the immune system, which will prevent it from moving further. After that, the larva of the worm creates a dense capsule around itself and becomes inactive for a long time. However, in the organ where she stopped, chronic inflammation begins. In this case, we are talking about the eyes.
Symptoms of ocular toxocariasis
Symptoms of ocular toxocariasis in humans may be as follows:
- A sharp deterioration in vision, up to its partial or complete loss. In most cases, only one eye suffers.
- Bulging of the eyeball from the orbit.
- Severe conjunctival hyperemia.
- Redness of the eyelids, their swelling.
- Severe pain in the eyes of a bursting character.
- Strabismus.
- Blurred vision.
When the organ of vision is damaged by the larvae of the worm, granulomas are found in the posterior part of the eye, chronic uevitis, endophthalmitis, keratitis, optic neuritis, migrating larvae in the vitreous body.
In childhood, ocular toxocariasis manifests itself mainly in strabismus; when the larva moves, the patient develops a migrating scotoma.
Treatment of ocular toxocariasis
Treatment of ocular toxocariasis in both children and adults is reduced to the appointment of subconjunctival injections with the steroid Depo-Medrol. This glucocorticosteroid drug allows you to relieve inflammation from the eyeball and eliminate the worm larva. However, the basis of treatment is most often surgery. In case of retinal detachment, laser correction is indicated.
For the first time, a 13-year-old girl was successfully cured of ocular toxocariasis back in 1968. She was injected with Depo-Medrol subconjunctivally. However, in some cases the effect of this drug is absent. Therefore, doctors recommend implementing the same scheme for the treatment of ocular toxocariasis as for getting rid of visceral parasitic invasion. That is, patients are prescribed a standard anthelmintic regimen consisting of combination therapy.
To get rid of the patient from toxocariasis, Mintezol (Thiabendazole), Vermox (Mebendazole) and Ditrazine (Diethylcarbamazine) are prescribed. The dose is calculated depending on the person's body weight.
There is also information about the successful disposal of patients from ocular toxocariasis using photo- and laser coagulation. These procedures destroy toxocar granulomas (shells in which the larvae of worms are located).
As for the prognosis for recovery, it depends on the severity of the disorders caused by the parasite larva and on the duration of the invasion.
Author of the article: Danilova Tatyana Vyacheslavovna | Infectionist
Education: in 2008 received a diploma in the specialty "General Medicine (General Medicine)" at the Russian Research Medical University named after NI Pirogov. Immediately passed an internship and received a diploma of a therapist.
