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Revista do Instituto de Medicina Tropical de São Paulo

On-line version ISSN 1678-9946

Rev. Inst. Med. trop. S. Paulo vol.53 no.5 São Paulo Sept./Oct. 2011 



A historical note on an imported case of loiasis in Rio de Janeiro, Brazil, 1964


Nota histórica sobre caso importado de loíase no Rio de Janeiro, Brasil, 1964



Antonio GiardulliI,II*; Guilherme Dolanda Paulo FilhoII,*; Giovanni Nicola Urberto Italiano ColombiniI; Walter de Araújo Eyer-SilvaI;Carlos Alberto Basilio-de-OliveiraI

IHospital Universitário Gaffrée e Guinle, Universidade Federal do Estado do Rio de Janeiro, Rio de Janeiro, RJ, Brasil
IIClínica de Olhos Paulo Filho, Rio de Janeiro, RJ, Brasil





Loiasis is a filarial disease transmitted by the Chrysops spp. tabanid flies in West and Central Africa. It is most commonly diagnosed by the clinical manifestations of Calabar swellings (transient localized inflammatory edema) or, most dramatically, by the appearance of a migrating worm through the conjunctival tissues or the bridge of the nose. We report the case of a 35-year-old resident in the city of Rio de Janeiro who displayed a moving Loa loa in the bulbar conjunctival tissue two years after returning from a six-month trip to Uganda. Surgical removal of the worm was performed.

KeyWords: Brazil; Loa loa; Loiasis; Uganda.


A loaíase é uma filaríase transmitida por tabanídeos (mutucas) do gênero Chrysops na África central e ocidental, comumente diagnosticada pela apresentação clínica de edema de Calabar (edema inflamatório transitório e localizado) ou, mais dramaticamente, pela migração de um verme adulto pelo tecido conjuntival ou asa do nariz. Descrevemos o caso clínico de um paciente do sexo masculino, 35 anos, residente no Rio de Janeiro, que se apresentou com um verme adulto de Loa loa migrando sobre o tecido conjuntival bulbar dois anos após retornar de uma viagem de seis meses de duração a Uganda. Procedeu-se a remoção cirúrgica do verme.

doi: 10.1590/S0036-46652011000500010




The African eye worm Loa loa belongs to the family Onchocercidae, superfamily Filarioidea. It is found only in Africa, most commonly around the Gulf of Guinea, but extends into Central Africa into Chad, Sudan and Uganda4,6,20. It is transmitted by tabanids belonging to the genus Chrysops, which possess mouth parts that can produce a painful bite. Most infected people are asymptomatic or present only mild signs and symptoms. Adult Loa loa live and move around the subcutaneous tissues of humans. The female produces embryos (microfilariae) which circulate in the blood stream with a diurnal periodicity and may be ingested by the day-biting vector fly during a blood meal. The microfilariae undergo a developmental cycle in the thoracic musculature of the vector and after 10 to 12 days reach the infective stage which can be transmitted to another human host during a subsequent bloodmeal4,6,20.

Diagnosis is usually made on the basis of clinical manifestations of transient localized inflammatory edema (Calabar swellings) and the appearance of a migrating worm through the conjunctival tissue across the eyeball or over the bridge of the nose. Clinical features of loiasis may appear as soon as five months after infection or as late as 17 years6,20. Surgical removal of the migrating worm when it passes under the conjunctiva most readily relieves symptoms. Diethylcarbamazine is the only macrofilaricidal drug and thus the only drug enabling the definitive cure of patients, although it can produce severe meningoencephalitis in heavily infected subjects and is considered contraindicated in areas where onchocerciasis is endemic13. We wish to report an imported case of loiasis diagnosed in Rio de Janeiro in 1964. This case has been previously presented by late Professor Antonio Paulo Filho, Head of the Ophthalmology Department at Hospital Gaffrée e Guinle, in his Memorial Jubilee publication volume9 and is not available in current electronic databases. He personally asked one of us (CABO) to report the present case in the medical literature.



The patient was a 35-year-old previously asymptomatic Spanish male who resided in Rio de Janeiro and displayed in March 1964 an intensely pruritic discomfort of a few hours duration in his right eye. He also referred foreign body sensation, photophobia and watering. He reported that in the previous few weeks he had experienced recurrent bouts of such crises which used to last for only a few minutes. There were no complaints in the left eye. He had returned from Uganda two years previously, where he served as a precision technician during a period of six months.

On examination, visual acuity was normal in both eyes (with lens correction for farsightedness). There were also no abnormalities on optic fundus, cornea, anterior chamber, aqueous humor, and no signs of uveitis. Marked conjunctival congestion in the palpebral and fornix area was recorded. Examination of the bulbar conjunctiva showed a long, freely moving adult worm (Fig. 1). Attempts to remove the worm were unsuccessful. The patient was then immediately referred to the surgical room. Due to its extreme mobility, successful removal was accomplished only after local anesthesia and conjunctival fixation of the worm with a suture line (Fig. 1). Microscopic examination of the parasite found that the morphologic features of the worm were consistent with an adult female Loa loa. Further details on such analysis are unavailable. The patient did not report other signs of loiasis. No blood sample had been taken to seek microfilariae and no information on follow-up is available.




We are unaware of previous descriptions of loiasis in Brazil. Imported cases of Loa loa are rarely reported from the Americas7,17. In the United States, for instance, only 42 cases were referred to the National Institutes of Health between 1976 and 199010. The ease of modern international travel and the growing cultural and economic relationships between Brazil and west and central African countries may expose Brazilian travelers to diseases such as loiasis while visiting endemic countries. Besides the classical features of Calabar swellings and actively migrating worms through subcutaneous or conjunctival tissues, loiasis should also be considered in cases of generalized pruritus, eosinophilia, and urticarial vasculitis in patients with a history of even short periods of travel to endemic areas. Interestingly, our patient seems to have acquired loiasis in Uganda, a country where this filarial disease is only rarely reported4,5,11,16.

The diagnosis of loiasis in a case such as this should generally be straightforward. Attempts to remove the worm should be performed for parasitological analysis and to rule out artifacts3. However, physicians need also be aware of a variety of other helminth infections that can compromise ocular tissues in a resident of Brazil with a history of travel to Africa. Mansonella perstans adult worms are largely non-pathogenic and live in serous cavities. They may produce small, yellowish bodies in the bulbar conjunctiva known as bung-eye, Kampala eye worm, or Ugandan eye worm2. Onchocercal adult worms tend to aggregate into palpable subcutaneous nodules and eye damage is mediated primarily by microfilariae21. Under unusual circumstances, an adult Bancroftian filariasis worm may cross the conjunctival tissue14. However, concomitant evidence of acute or chronic lymphatic disease elsewhere would be expected. Dracunculiasis may occur anywhere in the subcutaneous tissue and may emerge in the orbit21, but it is much larger than Loa loa and most frequently affects the foot or lower leg. Toxocara larvae are much smaller and may appear in the anterior chamber20. It may cause a granulomatous process around the macula known as ocular larva migrans21. Trichinosis larvae are also much smaller and characteristically produce circumorbital edema and chemosis1. Dirofilaria species may present as a nodule in the conjunctiva or eyelid or an adult worm may be found in eye tissues. They tend to be large, robust worms with distinctive longitudinal and circular cuticular ridging15. Cysticercosis21, schistosomiasis18, echinococcosis19 and sparganosis12 may also present as cysts, nodules or tumors in eye tissues. Migrating infective larvae of hookworms and Strongyloides stercoralis are the cause of cutaneous larva migrans and larva currens, respectively. They move much more slowly, cause significantly worse subcutaneous irritation and should have a much shorter incubation period than Loa loa. These larvae may occasionally invade sub-retinal tissues to cause diffuse unilateral subacute neuroretinitis and optic disc edema8.



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Correspondence to:
Prof. Carlos Alberto Basilio-de-Oliveira, Serviço de Anatomia Patológica, Hospital Universitário Gaffrée e Guinle, Uni-Rio
Rua Mariz e Barros 775, 20270-004 Rio de Janeiro, RJ, Brasil.

Received: 10 April 2011
Accepted: 25 July 2011



* in memoriam

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