TRANSACTIONS OF THE ROYAL SOCIETY OF TROPICAL MEDICINE AND HYGIENE (2002) 96,654

Case report: intraocular localization of Mansonella perstans in a patient from south Chad

Enrico Rino BreganP , Tiziana Ceraldi’ , Angelo Rovellini’ and Chiara Ghiringhelli’ ‘Emergency Medicine Division, Ospedale Maggiore IRCCS, Milan, Italy; ‘Hc?pital de Goundi, Association Tchadienne Communaute’ pour le Progrk, Chad

Abstract A case of Mansonella perstans infection with visual impairment and a retinal lesion is described. After a course of diethylcarbamazine and a further course of mebendazole the symptoms improved and the microfilariae blood concentration decreased. The symptoms and response to antifilarial treatment strongly suggested the intraocular localization of an M. perstans worm.

Keywords: filariasis, MunsoneZZuperstans, intraocular localization, diethylcarbamazine, mebendazole, Chad

Introduction Mansonella perstans is widely distributed across the

centre of Africa, parts of Central America, the Carib- bean and north-east South America. Adult worms have rarely been recovered from humans; they reside in the body cavities (pleural, peritoneal, and pericardial) and in the mesentery, perirenal, and retroperitoneal tissues and occasionally they have been found subcutaneously. Microfilariae (mf) are liberated unsheathed from fe- males and circulate in the blood without regular periodi- city. Mansonella perstans is capable of inducing a variety of symptoms including angioedema swellings much like the ‘Calabar swellings’ of loiasis, pruritus, fever, head- ache, pain in bursae and/or joint synovia, or, in serous cavities, severe abdominal pain especially in the liver region. Nodules in the conjunctiva, swelling of the eye- lids and proptosis have also been attributed to M. perstans infection (BAIRD et al., 1988). Eosinophilia is often present. Diagnosis is made by recovering mf from the blood.

Case report A 36-year-old man was admitted to the outpatient

clinic at the Goundi Missionary Hospital (Association Tchadienne Communautk po& le Frog&s), Moyen Chari Sanitarv District in the south of Chad. in Mav 200 1. He complained ofvisual impairment in thk left eye, ocular and abdominal pruritus, and abdominal pain. He hadbeenpreviouslytreatedwithacourseofdiethyicarbam- azine (DEC) forM. perstans filariasis in January 200 1.

A blood sample was taken at 11:OO and examined microscopically as a thick blood film stained with Giemsa’s solution (dilution 1: 10, for 10 min) and a thin blood film stained with conventional May Grunwaldi Giemsa’s stain. The thick blood film revealed the pre- sence of M. perstans mf, with an approximate concen- tration of 250 mf/mL. No other species of mf were found in 200 uL of blood. The differential white blood cell count wa@s 33% neutrophils, 3% eosinophils, 0% basophils, 62% lymphocytes, and 2% monocytes.

A visual acuity test showed a reduction of visual acuity to 4/10 for the left eye, while that of the right eye was 9/10. No abnormalities were observed during examination of the anterior left eye chamber. Inspec- tion of the fundus of this eye showed a narrow, white, motionless, linear, prominent lesion of about 6-7 mm (2 papillary diameters) in length, located in the nasal area, at a distance of 3 mm (i.e. one papillary diameter) from the optic papilla.

The patient was treated with a second course of DEC (400 mg daily in 2 doses for 18 d, after a 3 d dosage increase). By the end of the treatment the pruritus had remitted, visual impairment and visual acuity persisted unchanged, the iM. perstans mf burden was sianificantlv reduced (about 15 mf/mL), and the periph&al blodd eosinoph‘il count had de&eased to approximately 1%. The patient complained of an ab-

Address for correspondence: Dr E. R. Bregani, via Venini 1, 20127 Milano, Italy; e-mail rinobregani@yahoo.it

dominal moving mass sensation but there was no rele- vant physical examination findings. Inspection of the left eye fundus revealed no change.

The patient was then treated with mebendazole 100 mg twice a day for 14 d, without significant clinical and haematological change, and with a further 14 d of mebendazole at the same dosage. At the end of this treatment visual impairment with reduction in visual acuity of the left eye persisted as the only residual symptom. Analysis of the fundus of the left eye showed fragmentation of the previously observed narrow white line. There was a small further decrease in mf concen- tration and the eosinophil count was 3 %.

After a week, with no tirther treatment, visual im- pairment improved and complete recovery was progres- sively achieved. Visual acuity increased to 8/10 in the left eye, with no variation in visual acuity of the right eye. The fundus of the left eye showed almost total resorption of the white line and patient follow-up was discontinued.

Ocular symptoms occur quite frequently in sympto- matic carriers of M. perstans (E. R. Bregani, personal observation), but intraocular localization has never been described. Analysis of retinal lesion morphology, the presence of M. perstans mf in the blood, and the modification of the ocular pattern with antifilarial treat- ment coinciding with blood mf reduction strongly sug- gest the possibility of intraocular localization of an M. perstans adult worm, possibly male, causing subretinal protrusion. The visual impairment was probably due to perilesional inflammatory oedema surrounding the worm, since the patient complained of generalized ocular pruritus. Given that the macular region was not affected, visual acuity was restored as perilesional oede- ma improved. A focal night vision deficit would be expected in the scarred ret&al area.

Mansonella aerstans filariasis is a difficult infection to treat. Treatment with DEC is often ineffective, but mebendazole has proved effective in eliminating the mf in long-lasting treatment (HOEGAERDEN et al., 1987). In our patient, a 3-week course of DEC reduced blood mf concentration, and further treatment with meben- dazole for 4 weeks increased microfilarial destruction; the 2 drugs possibly cooperated in killing the adult intraocular worm, and visual acuity increased when the worm was destroyed and perilesional oedema abated.

References Baird, J. I<., Neafie, R. C. & Connor, D. H. (1988). Nodules

in the conjunctiva, bung-eye, and bulge-eye in Africa caused bv Mansonella berstans. American 7o’oumal of TroPical Medicine andHygiene, 3& 553-557. 1 - -

Hoegaerden, M. V., Ivanoff, B., Flocard, F., Salle, A. & Chabaud, B. (1987). The use of mebendazole in the treat- ment of filariases due to Loa loa and Mansonella perstuns. Annals of Tropical Medicine and Parasitology, 81, 275-282.

Received 11 Februay 2002; revised 10 June 2002; accepted for publication 18 June 2002