Intracameral - British Journal of Ophthalmology · reported cases of intraocular gnathostomiasis are rare. Lid swelling and intraocular parasites are the two major ocular manifestations,

British Journal of Ophthalmology, 1987, 71, 618-622

Intracameral gnathostomiasis: a cause of anterioruveitis and secondary glaucomaSOMCHAI KITTIPONGHANSA,' ARPORN PRABRIPUTALOONG,'SUCHART PARIYANONDA,2 AND ROBERT RITCH1

From the Departments of 'Ophthalmology and 2Parasitology, Faculty of Medicine, Srinagarind Hospital,Khon Kaen University, Khon Kaen, Thailand, and the 'Department ofOphthalmology, the New York Eye andEar Infirmary, New York, USA

SUMMARY Recognition of parasitic diseases by Western physicians is becoming increasinglyimportant because of increased international travel and the recent influx of refugees from Southeast Asia. We describe two patients who presented with acute anterior uveitis and secondaryglaucoma caused by intracameral third stage larvae of Gnathostoma spinigerum. The parasiteswere successfully removed, with preservation of good visual acuity. The initial infection may occurthrough consumption of contaminated water and/or raw or undercooked foods, while the eyesmay be involved even years later. Accurate diagnosis and surgical removal of the parasites maysave life.

Human infestation by the spiruroid nematode,Gnathostoma spinigerum, has been frequentlyreported in Asia. The usual mode of infection isbelieved to be ingestion of raw, inadequately cookedor fermented fish or meat. Systemic manifestationsinclude migratory cutaneous swelling and eosino-philic myeloencephalitis. Ocular involvement occursincidentally to systemic migration of the parasite andmay occur years after the initial infection. Theincrease in tourism to, and refugees from, South-eastAsia make it likely that cases of gnathostomiasis willbecome more frequent in the western hemisphere.We report two cases of intracameral third stagelarvae of gnathostoma resulting in acute anterioruveitis and secondary glaucoma. In both cases theparasites were successfully removed and good visualacuity restored. Detection of parasites on ophthalmicexamination and surgical removal may prevent fur-ther systemic damage and even death.

Case reports

CASE IA 61 year-old woman presented with an eight-dayhistory of pain and loss of vision in her left eye. Twoweeks previously she had noted a painful cutaneousCorrespondence to Somchai Kittiponghansa, MD, Department ofOphthalmology, Faculty of Medicine, Srinagarind Hospital, KhonKaen University, Khon Kaen 40002, Thailand.

swelling on her left hand. The swelling disappearedseveral days later without treatment.On examination the right eye was normal. Visual

acuity in the left eye was hand movements. Intra-ocular tension was 40 mmHg. The anterior chambercontained a fibrinous exudate. An inactive, curvi-linear, living parasite about 5 mm long was seen at thetemporal side of the pupillary border (Fig. 1).Multiple fenestrations caused by parasitic migrationwere present on the iris surface.

Fig. 1 Case 1. The livingparasite about mm long at thetemporal side ofthepupillary border.

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Intracameralgnathostomiasis: a cause ofanterior uveitis and secondary glaucoma

The patient was treated with oral glycerin andacetazolamide. The white cell count was 8-8 X 109/l,with 40% neutrophils, 51% lymphocytes, 3% mono-cytes, 5% eosinophils, and 1% basophils. Urineanalysis and chest x-ray were normal.Under general anaesthesia a corneoscleral section

of 3 clock hours was made. The worm became activeand migrated to the site of the surgical incision,where it was captured by its cephalic portion with lenscapsule forceps. Postoperatively the patient wastreated with topical dexamethasone, neomycin, andatropine, together with oral acetazolamide andprednisolone 30 mg daily. Her visual acuity improvedto 6/18. Fundus examination revealed a normal opticnerve head and no evidence of parasitic tracks in theposterior segment. Over the following year a maturecataract developed in the affected eye.The living parasite was transported in 0-85% NaCI

to one of us (SP) for identification. It was fixed in5% formalin and mounted in polyvinyl alcohol-lactophenol. It was identified as the third stage larvaof Gnathostoma spinigerum and measured 4-5 mmlong and 0*6 mm wide (Fig. 2).

CASE 2A 32-year-old woman complained of blurred visionand pain in her left eye for one month. Two monthspreviously she had had itching and cutaneous swellingaround the left eye. Cellulitis presumptively causedby gnathostoma had been diagnosed and predni-solone 30 mg daily had been given for symptomaticrelief.

Examination revealed visual acuity 6/60 in the righteye and 6/36 in the left. The intraocular tension was17 mmHg in the right eye and 43 mmHg in the left.Old central corneal scars were present bilaterally.The conjunctiva of the left eye was injected and thecornea oedematous. The anterior chamber wasclouded by a fibrinous exudate and an immobile,coiled worm approximately 5 mm long was present in

Fig. 2 Case 1. The worm consists ofthreeparts. Thestomais anterior. Thesecondpart is the cephalic bulb, measuring0-20 by 0-33 mm, and consisting offour rows ofsinglepointed hooklets with rathersmaller size in thefirst row oftheanterior end. The thirdpart is the body, consisting ofmanysinglepointed cuticularspines in transversefashion withclearly seen cervical sac along oesophagus.

Fig. 3 Case 2. The inactive livingparasite in the inferiorportion ofthe anterior chamber.

the inferior portion of the anterior chamber (Fig. 3).Approximately 10 perforating holes caused byparasite migration were noted on the iris.The patient was treated with oral glycerin and

acetazolamide. The white cell count was 11 7 x 10/l,with 75% neutrophils, 14% lymphocytes, 4%monocytes, and 7% eosinophils. Urine analysis andchest x-ray were normal.The parasite was removed from the anterior

chamber as in the previous case and sent alive to oneof us (SP) for identification. Postoperatively thepatient was treated in the same manner as the firstpatient. Her vision improved to 6/24. The optic nervehead was normal and there was no evidence of aparasitic track. The lens has remained clear for twoyears.The worm was processed as in the first case and

identified as the third stage larva of G. spinigerum,5*2 mm long and 0-7 mm wide. (Fig. 4)

Fig. 4 Case2. Composite microscopicalpicture ofthe thirdstage larva ofG. spinigerum.

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Discussion

Gnathostoma is an intestinal nematode of carnivores.Gnathostoma spinigerum is the most common tissueparasitic infection in Thailand and the second mostcommon ocular parasite. The worm was first de-scribed in 1836 by Richard Owen, who discovered itin a stomach nodule of a tiger'. The first humaninfection was reported in 1889 by Levinsen (cited byLeiper2), who studied a single immature wormobtained from the breast abscess of a Thai woman.There have since been reports of immature wormsrecovered from skin, internal organs, nervous system,and eye.3 The first human case of intraocular gnathos-tomiasis was reported in Thailand by Rhithibaed andDaengsvang in 1957.4 Subsequently sporadic cases ofintraocular infection have been reported from dif-ferent parts of Asia.58The central region of Thailand is one of the most

important endemic areas of this parasite in Asia.Much of the food and drinking water in this region isobtained from fresh water rivers and lakes, andintestinal parasitic infestation is common.The parasite lives encysted in the gastric mucosa of

dogs, cats, and wild felines (Fig. 5). The red-orangeworm measures about 4-5 mm long and 0.5 mm wide.The head bulb contains rows of hooklets and thebody contains numerous spines. The ova are passedin faeces and hatch in fresh water to first-stage larvae.These are ingested by the copepod cyclops, the firstintermediate host, in which the second-stage larvaedevelop. The cyclops are in turn eaten by fresh-waterfish, frogs, snakes, and eels, the second intermediatehosts, in which the infective third-stage larvae

GNATHOSTOMIASISGnathostoma spinigerum

Dog,Cat

Fish, t Man

Chicken I

Copepods

Egg(passed in feces)

Larva MigransEyeBrain

Aquatic Larva

Fig. 5 Life cycle ofG. spinigerum.

develop.9 Vertebrates such as cats and dogs completethe cycle. Man may become a facultative host byeating raw, infected intermediate hosts, such asfresh-water fish, frogs, and snakes. If intermediatehosts are eaten by paratenic hosts, such as ducks andchickens, the third stage larvae cannot undergofurther development. They can, however, infect theparatenic hosts and in turn infect man if the paratenichosts are eaten raw or insufficiently cooked. InThailand more than 36 species of fresh water fishhave been found to be infected with the third-stagelarvae. "'The infection is more common in women than in

men, perhaps owing to transmission via skin penetra-tion during food preparation or from contaminatedwater containing infected copepods. " The third stagelarvae cannot complete their cycle in man, and theymigrate for years, causing inflammation in multipleorgan systems. 12The clinical manifestations of gnathostomiasis

include migratory cutaneous swellings, abdomino-pulmonary hypereosinophilic syndrome, and fataleosinophilic myeloencephalitis."-'5 Damage mayoccur in any organ due to random migration of theparasite through the body. Recurrent migratorycutaneous swellings and eosinophilia in a patientliving in or having travelled to an endemic area makethe diagnosis likely. Symptoms often begin in theevening, perhaps due to increasing motility of theworms at this time. Skin testing with the third-stagelarval antigen supports the clinical diagnosis when itis positive.

Despite the fact that the north-eastern region ofThailand is a major endemic area of gnathostomareported cases of intraocular gnathostomiasis arerare. Lid swelling and intraocular parasites are thetwo major ocular manifestations, and may resultin orbital cellulitis, uveitis, hyphaema, vitreoushaemorrhage, and central retinal artery occlusion.The lid swelling is accompanied by itching, redness,and pain, which may be mild to severe. It is thoughtto be an allergic response occurring after the parasitehas moved away, and it is useless to search for theparasite at that site. The intraocular parasite may befound in either the anterior or posterior segment.The larvae may migrate into the eye along the opticnerve or directly penetrate the sclera, resulting intraumatic retinal holes, vitreous haemorrhage, andiris perforation. Fibrous bands may extend from thepoint of entry into and through the vitreous. Mostcases are presumptively diagnosed on the basis ofthe clinical picture, the high percentage of bloodeosinophils, and the history of migratory swelling inrelation to food habits and residence. Definitivediagnosis rests on the recovery and identification ofthe parasites.

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Our two patients had the same clinical pictures ofacute anterior uveitis with secondary glaucomabut with normal eosinophils. The unusually loweosinophil count in our patients may be due to thefact that the parasites were in the anterior chamber,which is avascular, the cellular response thereforebeing much less than when the parasites are presentin vascular tissues or spaces. The parasites were seenlying inactive in the anterior chamber. However, thenumerous iris holes in both cases are suggestive ofhighly active worms at the initial stage of ocularinvolvement. In the absence of a visible parasite inthe anterior chamber the presence of numerous irisholes can be the basis of diagnosis of parasitic ocularinfestation. Anterior uveitis may be present after theparasite has migrated away. The fibrinous exudateand higher intraocular pressure may have led to thecessation of active migratory behaviour and thus tosuccessful removal.More commonly, removal of the parasite is

thwarted by the escape of the parasite from the eye.Freezing the active worm with cryoapplication priorto its removal is usually considered in order toprevent death from systemic migration of theparasite. Failure to remove the parasite may lead tocerebrovascular accident if the parasite migratesinto the central nervous system.'6 To increase thesuccess of removal, ocular manipulation should bekept at a minimum during the procedure. For thisreason we favour removal under general anaethesiainstead of retrobulbar block. Corneal wetting andanterior chamber irrigation should be avoided asmuch as possible to minimise activation of theparasite.There is no specific therapy other than surgical

removal. Subcutaneous administration of Ancylol(2,6-diodo, -4 nitrophenol) given subcutaneouslyhas been effective in experimentally infected cats.'7Since the parasite can migrate rapidly, immediatesurgery is required.

In our cases the parasites were successfullyremoved with lens capsule forceps without cryoprobeapplication. Intraocular tissue damage was slight inthe first case, as hyphaema from an iris tear. Visualacuities were restored to 6/18 and 6/24 in the first andsecond patients respectively. However, complicatedcataract with subluxation was later observed in thefirst patient and was attributed to the parasites ratherthan surgical trauma. The worms removed from thetwo patients were the third stage larvae.The source of infective larvae in these cases could

be from impure water or pickled fresh water fish."The abundance and variety of infected intermediatehosts reinforce the position of parasitic infections as amajor health problem of Thailand.

Prevention depends on avoidance or adequate

cooking of such food as fresh water fish, snails,and pork. Better sewage disposal and the treatmentof drinking water may prevent the spread of parasitesin the community.

Gnathostomiasis is rarely diagnosed in Europe andthe United States. However, not only may ocularinvolvement occur several years after the initialinfection, but it may be the presenting sign of apreviously silent infection.'9 Increasing world travel,importation of food, and the influx of refugees fromSouth-east Asia demand greater awareness of theparasitology of this region." Gnathostomiasis shouldbe included in the differential diagnosis of anterioruveitis with or without glaucoma in patients who havetravelled to South-east Asia. Multiple iris perfor-ations are diagnostic of a migrating parasite if nonecan be seen at the time.G spinigerum may live for years in man, causing

larva migrans and perhaps fatal eosinophilic myeloen-cephalitis. No antiparasitic drugs are available totreat ocular involvement, and therapeutic successdepends on early and complete surgical removal.Because the eye is the only site at which directvisualisation and surgical removal are possible,ocular examination is crucial to proper diagnosis andtreatment, which may be lifesaving.This work was supported in part by the Glaucoma Foundation.

References

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2 Leiper RT. The structure and relationships of Gnathostomasiamensis (Levinsen). J Parasitol 1909; 2: 72-7.

3 Tansurat P. Human gnathostomiasis. i Med Assoc Thai 1955;38: 25-32.

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Acceptedfor publication 13 August 1986.

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