µg/kg in patients with a low microfilaria load (with densities less than 8000 mf/ml). in patients with high microfilaria load and/or the possibility of an onchocerciasis coinfection, treatment with dec and/or ivermectin may be contraindicated or require a substantially lower initial dose, as the rapid microfilaricidal actions of the drugs can provoke encephalopathy. in these cases, initial albendazole administration has proved helpful (and is superior to ivermectin, which can also be risky despite its slower-acting microfilaricidal effects over dec). the cdc recommended dosage for albendazole is 200 mg taken twice a day for 21 days. also, in cases where two or more dec treatments have failed to provide a cure, subsequent albendazole treatment can be administered. management of loa loa infection in some instances can involve surgery, though the timeframe during which surgical removal of the worm must be carried out is very short. a detailed surgical strategy to remove an adult worm is as follows (from a real case in new york city). the 2007 procedure to remove an adult worm from a male gabonian immigrant employed proparacaine and povidone-iodine drops, a wire eyelid speculum, and 0.5 ml 2% lidocaine with epinephrine 1:100,000, injected superiorly. a 2-mm incision was made and the immobile worm was removed with forceps. gatifloxacin drops and an eye-patch over ointment were utilized post surgery and there were no complications (unfortunately, the patient did not return for dec therapy to manage the additional worm—and microfilariae—present in his body). epidemiology as of 2009, loiasis is endemic to 11 countries, all in western or central africa, and an estimated 12–13 million people have the disease. the highest incidence is seen in cameroon, republic of the congo, democratic republic of congo, central african republic, nigeria, gabon, and equatorial guinea. the rates of loa loa infection are lower but it is still present in and angola, benin, chad and uganda. the disease was once endemic to the western african countries of ghana, guinea, guinea bissau, ivory coast and mali but has since disappeared. throughout loa loa-endemic regions, infection rates vary from 9 to 70 percent of the population. areas at high risk of severe adverse reactions to mass treatment (with ivermectin) are at present determined by the prevalence in a population of >20% microfilaremia, which has been recently shown in eastern cameroon (2007 study), for example, among other locales in the region. endemicity is closely linked to the habitats of the two known human loiasis vectors, chrysops dimidiata and c. silicea. cases have been reported on occasion in the united states but are restricted to travelers who have returned from endemic regions. in the 1990s, the only method of determining loa loa intensity was with microscopic examination of standardized blood smears, which is not practical in endemic regions. because mass diagnostic methods were not available, complications started to surface once mass ivermectin treatment programs started being carried out for onchocerciasis, another filariasis. ivermectin, a microfilaricidal drug, may be contraindicated in patients who are co-infected with loiasis and have associated high microfilarial loads. the theory is that the killing of massive numbers of microfilaria, some of which may be near the ocular and brain region, can lead to encephalopathy. indeed, cases of this have been documented so frequently over the last decade that a term has been given for this set of complication: neurologic serious adverse events (saes). advanced diagnostic methods have been developed since the appearance the saes, but more specific diagnostic tests that have been or are currently being development (see: diagnostics) must to be supported and distributed if adequate loiasis surveillance is to be achieved. there is much overlap between the endemicity of the two distinct filariases, which complicates mass treatment programs for onchocerciasis and necessitates the development of greater diagnostics for loiasis. in central and west africa, initiatives to control onchocerciasis involve mass treatment with ivermectin. however, these regions typically have high rates of co-infection with both l. loa and o. volvulus, and mass treatment with ivermectin can have sae. these include hemorrhage of the conjunctiva and retina, heamaturia, and other encephalopathies that are all attributed to the initial l. loa microfilarial load in the patient prior to treatment. studies have sought to delineate the sequence of events following ivermectin treatment that lead to neurologic sae and sometimes death, while also trying to understand the mechanisms of adverse reactions to develop more appropriate treatments. in a study looking at mass ivermectin treatment in cameroon, one of the greatest endemic regions for both onchocerciasis and loiasis, a sequence of events in the clinical manifestation of adverse effects was outlined. it was noted that the patients used in this study had a l. loa microfilarial load of greater than 3,000 per ml of blood. within 12–24 hours post-ivermectin treatment (d1), individuals complained of fatigue, anorexia, and headache, joint and lumbar pain—a bent forward walk was characteristic during this initial stage accompanied by fever. stomach pain and diarrhea were also reported in several individuals. by day 2 (d2), many patients experienced confusion, agitation, dysarthria, mutism and incontinence. some cases of coma were reported as early as d2. the severity of adverse effects increased with higher microfilarial loads. hemorrhaging of the eye, particularly the retinal and conjunctiva regions, is another common sign associated with sae of ivermectin treatment in patients with l. loa infections and is observed between d2 and d5 post-treatment. this can be visible for up to 5 weeks following treatment and has increased severity with higher microfilarial loads. haematuria and proteinuria have also been observed following ivermectin treatment, but this is common when using ivermectin to treat onchocerciasis. the effect is exacerbated when there are high l. loa microfilarial loads however, and microfilariae can be observed in the urine occasionally. generally, patients recovered from sae within 6–7 months post-ivermectin treatment; however, when their complications were unmanaged and patients were left bed-ridden, death resulted due to gastrointestinal bleeding, septic shock, and large abscesses. mechanisms for sae have been proposed. though microfilarial load is a major risk factor to post-ivermectin sae, three main hypotheses have been proposed for the mechanisms. the first mechanism suggests that ivermectin causes immobility in microfilariae, which then obstructs microcirculation in cerebral regions. this is supported by the retinal hemorrhaging seen in some patients, and is possibly responsible for the neurologic sae reported. the second hypothesis suggests that microfilariae may try to escape drug treatment by migrating to brain capillaries and further into brain tissue; this is supported by pathology reports demonstrating a microfilarial presence in brain tissue post-ivermectin treatment. lastly, the third hypothesis attributes hypersensitivity and inflammation at the cerebral level to post-ivermectin treatment complications, and perhaps the release of bacteria from l. loa after treatment to sae. this has been observed with the bacteria wolbachia that live with o. volvulus. more research into the mechanisms of post-ivermectin treatment sae is needed to develop drugs that are appropriate for individuals with multiple parasitic infections. one drug that has been proposed for the treatment of onchocerciasis is doxycycline. this drug has been shown to be effective in killing both the adult worm of o. volvulus and wolbachia, the bacteria believed to play a major role in the onset of onchocerciasis, while having no effect on the microfilariae of l. loa. in a study done at five different co-endemic regions for onchocerciasis and loiasis, doxycycline was shown to be effective in treating over 12,000 individuals infected with both parasites with minimal complications. drawbacks to using doxycycline include bacterial resistance and patient compliance because of a longer treatment regimen and emergence of doxycycline-resistant wolbachia. however, in the study over 97% of the patients complied with treatment, so it does pose as a promising treatment for onchocerciasis, while avoiding complications associated with l. loa co-infections. human loiasis geographical distribution is restricted to the rain forest and swamp forest areas of west africa, being especially common in cameroon and on the ogooué river. humans are the only known natural reservoir. it is estimated that over 10 million humans are infected with loa loa larvae. an area of tremendous concern regarding loiasis is its co-endemicity with onchocerciasis in certain areas of west and central africa, as mass ivermectin treatment of onchocerciasis can lead to saes in patients who have high loa loa microfilarial densities, or loads. this fact necessitates the development of more specific diagnostics tests for loa loa so that areas and individuals at a higher risk for neurologic consequences can be identified prior to microfilaricidal treatment. additionally, the treatment of choice for loiasis, diethylcarbamazine, can lead to serious complications in and of itself when administered in standard doses to patients with high loa loa microfilarial loads. history the first case of loa loa infection was noted in the caribbean (santo domingo) in 1770. a french surgeon named mongin tried but failed to remove a worm passing across a woman's eye. a few years later, in 1778, the surgeon françois guyot noted worms in the eyes of west african slaves on a french ship to america; he successfully removed a worm from one man's eye. the identification of microfilariae was made in 1890 by the ophthalmologist stephen mckenzie. localized angioedema, a common clinical presentation of loiasis, was observed in 1895 in the coastal nigerian town of calabar—hence the name "calabar" swellings. this observation was made by a scottish ophthalmologist named douglas argyll-robertson, but the association between loa loa and calabar swellings was not realized until 1910 (by patrick manson). the determination of vector—chrysops spp.—was made in 1912 by the british parasitologist robert thomson leiper. synonyms synonyms for the disease include african eye worm, loaiasis, loaina, loa loa filariasis, filaria loa, filaria lacrimalis, filaria subconjunctivalis, calabar swellings, fugitive swellings, and microfilaria diurnal. loa loa, the scientific name for the infectious agent, is an indigenous term itself and it is likely that there are many other terms used from region to region.