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Loiasis (Loa loa infection)

Author
Amy D Klion, MD
Section Editor
Peter F Weller, MD, FACP
Deputy Editor
Elinor L Baron, MD, DTMH

INTRODUCTION

Loiasis, also known as African eye worm, is caused by the filarial nematode Loa loa. Loiasis is transmitted by the bite of the Chrysops fly; west and central Africa are endemic regions. Manifestations of infection include transient localized subcutaneous swellings (known as Calabar swellings) and migration of the adult worm across the subconjunctiva of the eye.

The epidemiology, clinical features, diagnosis, and treatment of L. loa will be reviewed here. Other filarial infections, including onchocerciasis, lymphatic filariasis, and Mansonella infection are discussed separately. (See "Onchocerciasis" and "Epidemiology, pathogenesis, and clinical manifestations of lymphatic filariasis" and "Diagnosis, treatment, and prevention of lymphatic filariasis".)

EPIDEMIOLOGY

Loiasis is transmitted by biting deerflies (Chrysops), which breed in the high-canopied rainforest of west and central Africa, including the coastal plains of northern Angola, southeastern Benin, Cameroon, Central African Republic, Chad, Republic of the Congo, Equatorial Guinea, Gabon, Nigeria, Sudan, the Democratic Republic of Congo, and Uganda.

It is estimated that between 3 and 13 million people are infected [1]. Infection is occult in a large proportion of patients; therefore, in many areas, the epidemiology of loiasis has not been clearly defined. In endemic regions, the probability of infection increases with age; the proportion of infected individuals varies depending on vector abundance, which in turn is dependent on local ecology [2].

Large-scale mapping of loiasis in 11 potentially endemic countries has been developed using a Rapid Assessment Procedure for Loiasis (RAPLOA), based on community questionnaires documenting the prevalence of a history of eye worm. RAPLOA surveys have helped identify specific regions in 10 African countries where loiasis is endemic, including regions where the prevalence of infection exceeds 40 percent (figure 1) [3,4]. This is important given potential complications arising from ivermectin treatment of onchocerciasis in those with concomitant loiasis.

                    

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Literature review current through: Nov 2016. | This topic last updated: Tue Jul 05 00:00:00 GMT+00:00 2016.
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References
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  1. Klion A, Nutman TB. Loiasis and Mansonella Infections. In: Tropical Infectious Diseases: Principles, Pathogens and Practice, 3rd ed, Guerrant R, Walker DH, Weller PF (Eds), Saunders Elsevier, Philadelphia 2011. p.735.
  2. Kelly-Hope LA, Bockarie MJ, Molyneux DH. Loa loa ecology in central Africa: role of the Congo River system. PLoS Negl Trop Dis 2012; 6:e1605.
  3. Zouré HG, Wanji S, Noma M, et al. The geographic distribution of Loa loa in Africa: results of large-scale implementation of the Rapid Assessment Procedure for Loiasis (RAPLOA). PLoS Negl Trop Dis 2011; 5:e1210.
  4. Wanji S, Akotshi DO, Mutro MN, et al. Validation of the rapid assessment procedure for loiasis (RAPLOA) in the Democratic Republic of Congo. Parasit Vectors 2012; 5:25.
  5. Nutman TB, Miller KD, Mulligan M, Ottesen EA. Loa loa infection in temporary residents of endemic regions: recognition of a hyperresponsive syndrome with characteristic clinical manifestations. J Infect Dis 1986; 154:10.
  6. Rakita RM, White AC Jr, Kielhofner MA. Loa loa infection as a cause of migratory angioedema: report of three cases from the Texas Medical Center. Clin Infect Dis 1993; 17:691.
  7. Richardson ET, Luo R, Fink DL, et al. Transient facial swellings in a patient with a remote African travel history. J Travel Med 2012; 19:183.
  8. Klion AD, Massougbodji A, Sadeler BC, et al. Loiasis in endemic and nonendemic populations: immunologically mediated differences in clinical presentation. J Infect Dis 1991; 163:1318.
  9. Gantois N, Rapp C, Gautret P, et al. Imported loiasis in France: a retrospective analysis of 47 cases. Travel Med Infect Dis 2013; 11:366.
  10. Gobbi F, Postiglione C, Angheben A, et al. Imported loiasis in Italy: an analysis of 100 cases. Travel Med Infect Dis 2014; 12:713.
  11. Herrick JA, Metenou S, Makiya MA, et al. Eosinophil-associated processes underlie differences in clinical presentation of loiasis between temporary residents and those indigenous to Loa-endemic areas. Clin Infect Dis 2015; 60:55.
  12. Saito M, Armstrong M, Boadi S, et al. Clinical Features of Imported Loiasis: A Case Series from the Hospital for Tropical Diseases, London. Am J Trop Med Hyg 2015; 93:607.
  13. Beaver PC. Intraocular filariasis: a brief review. Am J Trop Med Hyg 1989; 40:40.
  14. Gardon J, Gardon-Wendel N, Kamgno J, et al. Serious reactions after mass treatment of onchocerciasis with ivermectin in an area endemic for Loa loa infection. Lancet 1997; 350:18.
  15. Carme B, Boulesteix J, Boutes H, Puruehnce MF. Five cases of encephalitis during treatment of loiasis with diethylcarbamazine. Am J Trop Med Hyg 1991; 44:684.
  16. Pillay VK, Kirch E, Kurtzman NA. Glomerulopathy associated with filarial loiasis. JAMA 1973; 225:179.
  17. Dennis DT, Kean BH. Isolation of microfilariae: report of a new method. J Parasitol 1971; 57:1146.
  18. Bakajika DK, Nigo MM, Lotsima JP, et al. Filarial antigenemia and Loa loa night blood microfilaremia in an area without bancroftian filariasis in the Democratic Republic of Congo. Am J Trop Med Hyg 2014; 91:1142.
  19. Touré FS, Egwang TG, Millet P, et al. IgG4 serology of loiasis in three villages in an endemic area of south-eastern Gabon. Trop Med Int Health 1998; 3:313.
  20. Akue JP, Egwang TG, Devaney E. High levels of parasite-specific IgG4 in the absence of microfilaremia in Loa loa infection. Trop Med Parasitol 1994; 45:246.
  21. Burbelo PD, Ramanathan R, Klion AD, et al. Rapid, novel, specific, high-throughput assay for diagnosis of Loa loa infection. J Clin Microbiol 2008; 46:2298.
  22. Drame PM, Meng Z, Bennuru S, et al. Identification and Validation of Loa loa Microfilaria-Specific Biomarkers: a Rational Design Approach Using Proteomics and Novel Immunoassays. MBio 2016; 7:e02132.
  23. Fink DL, Kamgno J, Nutman TB. Rapid molecular assays for specific detection and quantitation of Loa loa microfilaremia. PLoS Negl Trop Dis 2011; 5:e1299.
  24. Drame PM, Fink DL, Kamgno J, et al. Loop-mediated isothermal amplification for rapid and semiquantitative detection of Loa loa infection. J Clin Microbiol 2014; 52:2071.
  25. Fernández-Soto P, Mvoulouga PO, Akue JP, et al. Development of a highly sensitive loop-mediated isothermal amplification (LAMP) method for the detection of Loa loa. PLoS One 2014; 9:e94664.
  26. Bennuru S, Pion SD, Kamgno J, et al. Repurposed automated handheld counter as a point-of-care tool to identify individuals 'at risk' of serious post-ivermectin encephalopathy. PLoS Negl Trop Dis 2014; 8:e3180.
  27. Wanji S, Amvongo-Adjia N, Koudou B, et al. Cross-Reactivity of Filariais ICT Cards in Areas of Contrasting Endemicity of Loa loa and Mansonella perstans in Cameroon: Implications for Shrinking of the Lymphatic Filariasis Map in the Central African Region. PLoS Negl Trop Dis 2015; 9:e0004184.
  28. Wanji S, Amvongo-Adjia N, Njouendou AJ, et al. Further evidence of the cross-reactivity of the Binax NOW® Filariasis ICT cards to non-Wuchereria bancrofti filariae: experimental studies with Loa loa and Onchocerca ochengi. Parasit Vectors 2016; 9:267.
  29. Vanhaecke C, Perignon A, Monsel G, et al. Aetiologies of creeping eruption: 78 cases. Br J Dermatol 2014; 170:1166.
  30. Gardner A, Hardy L, Bell SK. Eosinophilia in a returned traveler. Clin Infect Dis 2010; 50:745.
  31. Klion AD, Massougbodji A, Horton J, et al. Albendazole in human loiasis: results of a double-blind, placebo-controlled trial. J Infect Dis 1993; 168:202.
  32. Grobusch MP, Kombila M, Autenrieth I, et al. No evidence of Wolbachia endosymbiosis with Loa loa and Mansonella perstans. Parasitol Res 2003; 90:405.
  33. Brouqui P, Fournier PE, Raoult D. Doxycycline and eradication of microfilaremia in patients with loiasis. Emerg Infect Dis 2001; 7:604.
  34. Norões J, Dreyer G, Santos A, et al. Assessment of the efficacy of diethylcarbamazine on adult Wuchereria bancrofti in vivo. Trans R Soc Trop Med Hyg 1997; 91:78.
  35. Bockarie MJ, Alexander ND, Hyun P, et al. Randomised community-based trial of annual single-dose diethylcarbamazine with or without ivermectin against Wuchereria bancrofti infection in human beings and mosquitoes. Lancet 1998; 351:162.
  36. Nicolas L, Plichart C, Nguyen LN, Moulia-Pelat JP. Reduction of Wuchereria bancrofti adult worm circulating antigen after annual treatments of diethylcarbamazine combined with ivermectin in French Polynesia. J Infect Dis 1997; 175:489.
  37. Ottesen EA. Efficacy of diethylcarbamazine in eradicating infection with lymphatic-dwelling filariae in humans. Rev Infect Dis 1985; 7:341.
  38. Wahl G, Georges AJ. Current knowledge on the epidemiology, diagnosis, immunology, and treatment of loiasis. Trop Med Parasitol 1995; 46:287.
  39. Drugs for Parasitic Infections, 3rd Ed, The Medical Letter, New Rochelle, NY 2013.
  40. Klion AD, Ottesen EA, Nutman TB. Effectiveness of diethylcarbamazine in treating loiasis acquired by expatriate visitors to endemic regions: long-term follow-up. J Infect Dis 1994; 169:604.
  41. Awadzi K, Hero M, Opoku O, et al. The chemotherapy of onchocerciasis. XV. Studies with albendazole. Trop Med Parasitol 1991; 42:356.
  42. Kamgno J, Boussinesq M. Effect of a single dose (600 mg) of albendazole on Loa loa microfilaraemia. Parasite 2002; 9:59.
  43. Martin-Prevel Y, Cosnefroy JY, Ngari P, Pinder M. Reduction of microfilaraemia with single high-dose of ivermectin in loiasis. Lancet 1993; 342:442.
  44. Martin-Prevel Y, Cosnefroy JY, Tshipamba P, et al. Tolerance and efficacy of single high-dose ivermectin for the treatment of loiasis. Am J Trop Med Hyg 1993; 48:186.
  45. Chippaux JP, Bouchité B, Boussinesq M, et al. Impact of repeated large scale ivermectin treatments on the transmission of Loa loa. Trans R Soc Trop Med Hyg 1998; 92:454.
  46. Kombila M, Duong TH, Ferrer A, et al. Short- and long-term action of multiple doses of ivermectin on loiasis microfilaremia. Am J Trop Med Hyg 1998; 58:458.
  47. Boussinesq M, Gardon J, Gardon-Wendel N, et al. Three probable cases of Loa loa encephalopathy following ivermectin treatment for onchocerciasis. Am J Trop Med Hyg 1998; 58:461.
  48. Nutman TB, Miller KD, Mulligan M, et al. Diethylcarbamazine prophylaxis for human loiasis. Results of a double-blind study. N Engl J Med 1988; 319:752.