Ocular porcine cysticercosis

Brief introduction of cysticercosis in the eye Pig cysticercosis parasitic in the eye causes eye cysticercosis, such as parasitic eyelids, it can be a painless, non-red swelling mass. When parasitic on the conjunctiva, the conjunctiva is congested and edematous and has a foreign body sensation. basic knowledge The proportion of illness: 0.03% Susceptible people: no special people Mode of infection: digestive tract spread Complications: vitreous opacity, retinal detachment, cataract, glaucoma, optic atrophy

Causes of cysticercosis in the eye

Dietary infection (65%):

An animal such as a pig or a wild boar is an intermediate host of a chain-like aphid. The human is a terminal host or an intermediate host. The human cysticercosis is caused by the ingestion of food contaminated with eggs or segments of pigs, when After the eggs or segments are swallowed, the eggs act in the small intestine through the digestive juice, the embryonic membrane ruptures, and the six hooks escape, and then use the small hooks and secretions to invade the small intestine wall, and the blood and lymph circulation to various parts of the body. Disperse, parasitic on various organs and tissues of the body. In the parasitic part, the worms gradually grow up, and the cells in the body dissolve to form a cavity filled with liquid. About 10 weeks later, they develop into adult cysticercus, and at this time, people become the middle of pork mites. The host, suffering from cysticercosis, but it can no longer develop into aphids, no spread of meaning, when people eat uncooked pork containing cysticercosis, the cysticercosis through the digestive juice, its head section turned out, adsorbed The intestinal wall and the neck segment gradually split to form a series of body segments. After about 2 to 3 months, they develop into adults. At this time, people become the ultimate host of pork aphids, suffering from intestinal ascariasis, and aphids can lay eggs with feces. Contagious.

Environmental factors (35%):

Epidemiological investigation of Cysticercus cellulosae shows that the only source of infection is caused by patients with chain-like tsutsugamushi disease. The eggs excreted in the patient's feces are contagious to the person and its surrounding population, and it is parasitic in the small intestine. The longer the risk of cysticercosis occurs, the human cysticercosis can be caused by autologous infection, or it can be infected by other organisms, including autologous infection and autologous infection. The infection from the body is caused by the reverse motility of the intestines of patients with tsutsugamushi disease. The eggs and the segments are reversed from the intestine into the stomach and cause self-infection. The infection from the in vitro infection is caused by the contamination of the tsutsugamushi patients with autologous eggs. Food causes self-infection, his body infection is allogeneic infection, the patient himself has no intestinal ascariasis, but the food is infected with the food of the chain-like tapeworm eggs in the feces of others. The infection of the cysticercosis is the most important. Infection route, patients with cysticercosis have 28.6% to 67.3% of patients with chain-like ascariasis, and the importance of self-infection in pathogenesis can be seen.

Pathogenesis

The cysticercosis of the eye is the same as the systemic infection. The six hooks invading through the intestinal wall can flow into the ophthalmic artery with the blood through the internal carotid artery, and distribute to all tissues that are dominated by the ophthalmic artery, especially the short ciliary artery, which is contaminated. The most chances are, short ciliary artery branch, high blood flow, relatively slow flow rate, easy to enter the choroid to the subretinal, or through the retina into the vitreous, develop into subretinal or vitreous cysticercosis, There is also a small part of the retina that enters the retina through the central artery. It is parasitic between the retinal nerve fiber layer and the inner limiting membrane in front of the retina. It can also swim into the vitreous to become a vitreous cystice, and other tissues in the eye including the eyelid, conjunctiva, and iliac tissue. It can be infected by the corresponding vascular system. The parasitic cysticercosis can cause mechanical damage to the ocular tissue in the eye. It can also cause immune inflammatory reaction of the uveal retina by allogeneic antigen. In addition, due to the toxic effects of the metabolites of the worm, It can cause toxic damage to the ocular tissues, especially the toxic products released by the decomposition of dead worms. Serious.

Eye cysticercosis prevention

Do not swallow foods that contain eggs or sections mixed with Ascaris.

Eye cysticercosis complications Complications vitreous opacity retinal detachment cataract glaucoma optic atrophy

Intraocular inflammation can lead to vitreous opacity, proliferative adhesions, secondary retinal detachment, cataracts, secondary glaucoma, and optic atrophy, which can eventually cause eyeball atrophy and blindness.

Symptoms of cysticercosis in the eye Common symptoms Visual field changes Congestive uveitis nodules Ciliary congestion retinal edema Retinal detachment

Different stages of cysticercosis infection can have different clinical manifestations.

1. Symptoms: The cysticercus in the eye is very small in the early larvae, or the worm is located in the periphery of the fundus. At this time, the patient has no self-conscious symptoms. When the growth of the worm increases, it will lead to progressive painless vision loss, but The cysticercosis, which is parasitic in the posterior part of the fundus, especially in the macula, often shows symptoms very early. The patient complains that there may be a gradually increasing circular or elliptical shadow in front of the eye, vision loss, visual distortion, parasitism under the retina. Or local retinal detachment may occur in the corresponding site of visual field defects, the cystic sac of the optic disc site often causes quadrant visual field defects, in general, the worm is encapsulated by the capsule, the patient can tolerate, once the larvae die, the capsule is released The toxic products can cause severe uveal and intraocular inflammation, ciliary body congestion and pain, extreme vision loss or even blindness. Due to the large range of corpus callosum, patients often feel deformed in front of the eyes. The round spherical shadow is swimming, the vitreous is turbid, and there is a diffuse floating mosquito.

2. Seen in the eye: The worms and related lesions of the cysticercosis in the eye can be found by microscopy with ophthalmoscope and slit lamp.

(1) intravitreal cysticercosis: in the case of less opacity of the vitreous, with the ophthalmoscope or slit lamp three-sided examination can be found in the vitreous body with a spherical or elliptical gray-white translucent capsule, the capsule wall is smooth, the edge There is often a golden pearl-like reflection. Careful observation of the capsule can have spontaneous peristalsis. Sometimes the triangular head section can be seen to sway and oscillate in the vitreous.

(2) suboccipital cysticercosis: a spherical or elliptical yellow-white bulge is visible under the retina, which is vesicle-like, with a clear boundary and a golden reflective edge. The retinal blood vessels twitch and crawl on the surface of the bulge. Retinal edema, exudation or small piece of bleeding, careful observation of the capsule has a sense of peristalsis;

(3) Intraretinal cystic sac: The sac is located between the inner limiting membrane of the retina and the layer of retinal nerve fibers, also known as the anterior capsule of the retina. A clear gray-yellow vesicle-like bulge is visible on the surface of the retina, and there is a golden yellow color. Reflective edge, due to the limitation of the inner limiting membrane, the capsule is relatively fixed, no migration, but there is still a sense of peristalsis.

(4) cystic sac in the anterior chamber: the slit lamp microscope can see the swimming worm in the anterior chamber, accompanied by a heavier anterior uveitis reaction, mainly iritis, ciliary congestion, anterior chamber More KP and inflammatory cells exuded, the glint was obvious, the irritation was severe, the visual acuity decreased significantly, and the cysticercus of the optic disc was often from the central artery, parasitic around the optic disc, causing optic disc edema or deformation, accompanied by Visual field defect.

Intraocular cysticercosis is the first to affect the retina and vitreous. In addition to the typical capsule morphology, it is often accompanied by varying degrees of vitreous opacity, retinal edema, exudation and detachment, and the vitreous is gray-white dusty turbid. Degrees vary, severe membranous fibrosis can occur, causing traction retinal detachment, subretinal cysticercosis often travels due to worms, displaced retinal detachment, when the worm moves to other places, the original retina Reset, retinal detachment occurs in the new parasitic site.

3. Seen from the whole body: The cysticercosis parasitic on the body surface can touch circular or elliptical nodules in the skin and muscles of the patient's eyelids or skin. The number varies from 5 to 15 mm and sometimes disappears on its own, but New nodules are constantly produced. If accompanied by brain cysticercosis, there may be neuropsychiatric symptoms such as headache, dizziness, and epilepsy. If there is intestinal parasitic parasite, white patches may be found in the feces.

Examination of cysticercosis in the eye

1. Laboratory examination: It is helpful for the diagnosis of cysticercosis in the whole body, but it is not specific to the eye. For those with intestinal ascariasis, eggs or segments can be found in the feces. Eosinophilia, indirect hemagglutination (IHA) and enzyme-linked immunosorbent assay (ELISA), IHA is simple, sensitive and specific, and the positive rate is 85%. The titer is 1:64, which can determine the diagnosis. The sensitivity and specificity of ELISA are the same as IHA. The positive average titer is higher than IHA. For intraocular cysticercosis, if the blood test immunology is positive, Can help the diagnosis, but the negative can not completely rule out the disease, immunological detection has the possibility of a false negative reaction, so the diagnosis must be combined with clinical comprehensive analysis.

2. Biopsy: For subcutaneous nodules of the skin, including eyelids and conjunctiva suspected cysticercosis, routine biopsy should be performed. The pathological sections are characterized by cystic sacral sacs in the cystic cavity. Translucent cysts contain There is an opaque inwardly folded head section with four suction cups and a small hook and loop. The outer part of the cyst is a layer of tough fibrous tissue envelope with lymphocytes, plasma cells, eosinophils and macrophage infiltration.

3. Fluorescein fundus angiography: For the subcapsular sacral sac, the early vesicles of the fluorescein angiography are obscured by weak fluorescence, and the retinal vascular fluorescence filling in front of the sac is still visible normally. Fluorescence can occur at and around the cysticercosis. Leakage, the surface of the capsule can show uniform or uneven strong fluorescence, and some do not show fluorescent staining. In the vicinity of the worm and the place where the protozoa is located, the choroidal atrophy of the retina is often seen. Fluorescence, late fluorescent staining, or signs of translucent fluorescence or staining reflect the shifting characteristics of the worm.

4. Sonography examination: B-mode ultrasound is a real-time imaging, showing the shape, positional relationship and living conditions of the cysticercus of the eye, especially the worm wave with characteristic diagnostic significance. Can not be seen or not obvious, and the discovery rate of B-ultrasound can reach 68%, the typical intraocular cysticercus can detect strong echo spherical spot in the slender aura, and the vitreous cystic sac in the living state can see the unique aura. And cysticercosis, the intracranial cystic sac is located between the retinal nerve fiber layer and the inner limiting membrane, the shallow layer of the spherical wall is membranous bulge, and its ultrasonic scanning features the membranous ultrasound band is slender, lacking posterior movement, The dead worm body is strongly echoed with sound and shadow, and there is no peristalsis. The cysticercus of the sac is parasitic on the extraocular muscle or muscle attachment. Due to the tissue reaction of the vesicle, the acoustic image shows thickening of the eye muscle. The spherical spot of the capsule is large and small.

5. Imaging examination: CT and MRI techniques have a special diagnostic value for the combination of other parts, especially the brain, in addition to the good display of the cysticercus of the eye. It can not only see the shape and position of the worm. And the survival status, and its complications such as cerebral edema, hydrocephalus, etc. can also be more accurate judgment, CT and MRI have become an indispensable means of examination for cysticercosis, according to the location of the cysticercosis and the condition of the lesion, CT And MRI also has different performances. The surviving cysticercus vesicles and their cephalic sections have a distinctive diagnostic significance. The intraocular survival of cysticercosis, CT often appears as a ring-shaped low-density area with a bit of high-density shadow. The dead worms often have calcified plaques, and the CT shows high-density areas. The enhanced scans are not enhanced. The M1-test T1-weighted vesicles are low-signal, and the head segments are high-signal, contrasting, T2-weighted vesicles. It is a high signal. CT and MRI have similar imaging features in patients with cystic cercariae.

Diagnosis and identification of cysticercosis in the eye

According to the results of the fundus examination of the slit lamp microscope and the ophthalmoscope, the diagnosis can be made according to the special shape and peristaltic phenomenon of the cysticercosis, but in the case of vitreous opacity or severe uveitis reaction, the fundus cannot be peeped, or the edema around the insect body is infiltrated. More out, cover the worm body, can not observe the peristalsis, especially if the death of the worm is difficult to determine, then special examination is needed to assist in the diagnosis.

After the death of the worm, it should be differentiated from choroidal osteoma and foreign body in the wall, mainly relying on medical history and hematology.

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