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Address correspondence to Jaber Aslanzadeh, Ph.D.,Department of Pathology, Hartford Hospital, 80 SeymourStreet, Hartford, CT 06102-5037, USA; tel 860 545 4128;fax 860 545 2726; e-mail jaslanz@harthosp.org.

Case Report and Brief Commentary:Wuchereria bancrofti and Onchocerca volvulusCo-infection in a Refugee from Sierra Leone

Michael J. Rajkumar,1 Stephanie Wright,2 and Jaber Aslanzadeh 1Departments of 1Pathology and 2Medicine, Hartford Hospital, Hartford, Connecticut

Abstract. Filarial infection is endemic in the tropics and is a public health problem in Africa, Asia, Southand Central America, and the Pacific Islands. Co-infection with filarial nematodes, if unrecognized, canresult in untoward therapeutic consequences. We report a case of co-infection of Wuchereria bancrofti andOnchocerca volvulus that was diagnosed by direct blood smear (W. bancrofti ) and serology (O. volvulus) in anative of Sierra Leone. We comment briefly on the therapeutic implications of the co-infection. (received 24September 2004; accepted 18 March 2005)

Keywords: filariasis, wuchereriasis, onchocerciasis, co-infection, Mazzotti’s reaction

Case Report

A 21-yr-old male refugee from Sierra Leone, whohad been living in the USA for 4 mo, received aprovisional diagnosis of malaria at a health clinicand was referred to Hartford Hospital. His maincomplaint was chronic intermittent chills and hot/cold sensations in his arms, associated with pain andheaviness in the left axillary region. He denied othersymptoms including fever, rigors, sweating, visualdisturbances, scrotal swelling, or nodules in any partof the body. Physical examination was unremarkableexcept for a grade 2 (of 6) systolic murmur.

Laboratory test results included bloodhemoglobin, 12.1 g/dl; mean corpuscular volume,75.7 fl; and leukocyte count, 7600 cells/mm3, with29% eosinophils. The absolute eosinophil countwas 2020 cells/mm3. A blood smear that was stainedfor malaria revealed sheathed micofilaria consistentwith Wuchereria bancrofti (Fig. 1), which wasconfirmed by examinations at the ParasitologyLaboratory of the Connecticut State Health Fig. 1. Wuchereria bancrofti microfilaria in a peripheral blood

smear. Thoroughly dried blood slides were stained with theThree Step Wright-Giemsa Stain (Richard-Allan Scientific,Kalamazoo, MI); the slides were air dried and examined bylow-power microscopy.

0091-7370/05/0200-0199. $0.75. © 2005 by the Association of Clinical Scientists, Inc.

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Department. The patient’s serum was sent to theLaboratory of Parasitic Diseases, National Institutesof Health, Bethesda, MD, for antifilarial antibodytest, which was positive at 80.9 µg/ml (normal <14µg/ml). A test for antibody to onchocercalrecombinant antigen ov-16 was also positive,indicating that the patient was co-infected withWuchereria and Onchocerca.

The patient was treated by a single dose ofivermectin (150 mg/kg), followed by a 12-day courseof diethylcarbamazapine (50 mg on day 1; 50 mg x3 on day 2; 100 mg x 3 on day 3; 115 mg x 3 ondays 4 to 14). It is planned to treat the patient foronchocerciasis annually with ivermectin.

Commentary

Filariasis is caused by vector-borne tissue dwellingnematodes called filariae. Transmission of humanfilariae is confined to the tropics, since high ambienttemperature is requisite for the parasites to developin their vectors [1]. Filariasis is endemic in Africa,Asia, South and Central America, and the Pacificislands [2]. The major disease forms caused byhuman filariae include lymphatic filariasis (W.bancrofti, Brugia malayi, Brugia timori),onchocerciasis (O. volvulus), and loiasis (Loa loa);their respective vectors are Mosquito sp, Similium sp(black fly), and Chrysops sp. The WHO estimatesthat 150 million persons are infected with micro-filaria worldwide, including lymphatic filariasis (120million), loasis (25 million), and onchocerciasis (17million) [2,3].

Given the current global nature of travel andtrade, physicians can encounter cases of filariasisoutside the tropics. In our particular case, filariasiswas not considered initially, but when a blood smearwas examined under low power magnification, thepresence of sheathed microfilaria was apparent.

Humans acquire W. bancrofti when the infectivelarvae gain entry into the skin by mosquito bite.They migrate to lymphatics and develop into adultworms. The female measures 80-100 x 0.25 mmand the male 40 x 0.1 mm. The life span of theadult female is about 20 yr [1]. Microfilariae areproduced from ova in the uterus of the adult femaleand enter the circulating blood. They are sheathed,

measuring 260 x 8 µm, and their life span is about 1yr [1]. The female mosquito ingests microfilariaeduring a blood meal. They ex-sheath in themosquito’s stomach and become first-stage larvae,which migrate to the insect’s thoracic muscles afterpenetrating the stomach wall. After moulting twice,the infective third-stage larvae migrate to themouthparts of the mosquito from whence they enterthe skin of the human host during a blood meal.

Microfilariae are mostly nocturnal, but theirpresence in peripheral blood has diurnal or nocturnalperiodicity, depending on the feeding pattern of thevector, the biologic rhythm of the microfilariae, andthe circadian rhythm of the host [1]. The life cycleof O. volvulus is similar to W. bancrofti except thatthe vector is Similium sp and adult worm live in theskin and subcutaneous region instead of thelymphatics.

Acute manifestations of filariasis includerepeated episodes of lympadenitis and lymphangitisassociated with fever and malaise. Chronicmanifestations include hydrocele and chroniclymphoedema, which can lead to elephantiasis ofthe legs. Rare manifestations are chyluria and tropicalpulmonary eosinophilia. Among persons exposedto W. bancrofti there are individuals who have neithermicrofilaremia nor obvious clinical manifestations,but most have subclinical lymphatic abnormalities.Clinical features of onchocerciasis range frompapules to extensive pigmentary and atrophic skinchanges, and include the formation of subcutaneousgranulomas. If untreated, the disease may involvethe eyes, causing sclerosing keratitis, optic nerveatrophy, and choroidoretinitis, leading to blindness.

Presence of fever, groin pain, swollen lymphnodes, and edematous legs in a patient who hasrecently lived in or traveled to a tropical countryshould suggest possible filarial infection [1,4]. Inaddition to routine examination of a blood smear,diagnostic tests include detection of circulatingfilarial antigens using monoclonal antibodies. Useof the ICT filarial card test has facilitated thelaboratory diagnosis of these infections [4,5].Diagnosis of onchocerciasis is based on the clinicalfeatures, plus a slit lamp examination of the eye,which may reveal live microfilariae or characteristicpunctate keratitis [1]. Confirmatory tests include

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demonstrating microfilariae in bloodless skin snips.Sensitive, specific serologic tests based on ELISA andimmunochromatography using specific recombinantantigen are available to detect antibodies to O.volvulus [5-7]. There are PCR-based tests for mostfilarial nematodes, but they have limited clinical use,owing to their high cost and the limitations oflaboratory facilities in endemic areas [8].

Lymphatic filariasis was formerly treated withdiethylcarbamazapine (DEC) in 3 doses /day for 12days, but recent data suggest that a single dose ofDEC may be equally effective. Other drugs used totreat microfilarial infection are ivermectin andalbendazole [1-3]. Current strategies are toadminister single doses of a 2-drug combination ofalbendazole with ivermectin or diethylcarbam-azapine [9,10].

Search for co-infection is advisable when oneform of microfilariasis is diagnosed. This isimportant especially if DEC is considered as atreatment option because of the severe reactions thatmay occur when DEC is administered to patientsco-infected with O volvulus. The so-called “Mazzottireaction” may be local (pruritis, skin rash, visualdisturbances) or systemic (fever, headache, jointpains, postural hypotension, collapse, and respiratorydistress)[1]. DEC can aggravate existing eye lesionsand precipitate new ones. For these reasons, DEC iseither avoided or used after steroid adminisrationto blunt inflammatory reactions. Often thetreatment of choice is the combination of ivermectinand albendazole [9].

The Wolbachia sp of bacteria may co-existsymbiotically in all filarial adult worms except L.loa [11]. Wolbachia evidently plays a significant rolein the embryogenesis of filaria. Targeting ofWolbachia using doxycycline has been reported tosterilize the adult worm, leading to the eliminationof microfilariae from the blood [12]. A 6-wk courseof doxycycline (100 mg/day for O. volvulus; 200 mg/day for W. bancrofti) may deplete the bacteria andlead to long-term filarial sterility [13].

References

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2. World Health Organization. Lymphatic filariasis. 2002.http://www.who.int/inf-fs/en/fact102.html.

3. World Health Organization. Onchocerciasis. 2002. http://www.who.int/inf-fs/en/fact095.html.

4. Weil GJ, Lammie PJ, Weiss N. The ICT filarial card test:a rapid-format antigen test for diagnosis of Bancroftianfilariasis. Parasit Today 1997;13:401-404.

5. Weil GJ, Steel C, Liftis F, Li BW, Mearns G, Lobos E,Nutman T. A rapid-format antibody card test for diagnosisof onchocerciasis. J Infect Dis 2000;182:1796-1799.

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8. Zimmerman PA, Guderian RH, Aruajo E, Elson L,Phadke P, Kubofcik J, NutmanTB. Polymerase chainreaction- based diagnosis of Onchocerca volvulus infection:improved detection of patients with onchocerciasis. JInfect Dis 1994;169:686-689.

9. Makunde WH, Kamugisha LM, Massaga JJ, MakundeRW, Savael ZX, Akida J, Salum FM, Taylor MJ. Treatmentof co-infection with Bancroftian filariasis and oncho-cerciasis: a safety and efficacy study of albendazole withivermectin compared to treatment of single infection withbancroftian filariasis. Filaria J 2003;2:15.

10. Ottesen EA. The global programme to eliminatelymphatic filariasis. Trop Med Int Health 2000;5:591-594.

11. McGarry H, Pfarr K, Egerton G, Hoerauf A, Akue OP,Eynong P, Wanji S, Klager SL, Bianco AG, Breching NJ,Taylor MJ. Evidence against Wolbachia symbiosis in Loaloa. Filaria J 2003;2:10.

12. Taylor MJ, Hoerauf A. A New approach to the treatmentof filariasis. Curr Opin Infect Dis 2001;14:727-731.

13. Hoerauf A. Control of filarial infections: not thebeginning of the end, but more research is needed. CurrOpin Infect Dis 2003;16:403-410.

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