The disease is treated with the drug diethylcarbamazine (DEC), and when appropriate, surgical methods may be employed to remove adult worms from the conjunctiva.

When chronic, they can form cyst-like enlargements of the connective tissue around the sheaths of muscle tendons, becoming very painful when moved.

The cycle of infection continues when a non-infected mango or deer fly takes a blood meal from a microfilaremic human host, and this stage of the transmission is possible because of the combination of the diurnal periodicity of microfilariae and the day-biting tendencies of the Chrysops spp.

Other minor potential reservoirs have been indicated in various fly-biting habit studies, such as hippopotamuses, wild ruminants (e.g. buffalo), rodents, and lizards.

A simian type of loiasis exists in monkeys and apes which is transmitted by the deer fly vector Chrysops langi.

They are hematophagous and typically live in forested and muddy habitats like swamps, streams, reservoirs, and rotting vegetation.

The larvae mature in water or soil,[5] where they feed on organic material such as decaying animal and vegetable products.

The flies are attracted to smoke from wood fires and they use visual cues and sensation of carbon dioxide plumes to find their preferred host, humans.

Adults live in the subcutaneous tissues of humans, where they mate and produce wormlike eggs called microfilariae.

[4] During a blood meal, an infected Chrysops fly introduces third-stage filarial larvae onto the skin of the human host, where they penetrate the bite wound.

These include centrifugation of the blood sample lyzed in 2% formalin (Knott's technique), or filtration through a nucleopore membrane.

This is even though many recently developed methods of antibody detection are of limited value because substantial antigenic cross-reactivity exists between filaria and other parasitic worms (helminths), and a positive serologic test does not necessarily distinguish among infections.

The new tests have not reached the point-of-care level yet, but show promise for highlighting high-risk areas and individuals with co-endemic loiasis and onchocerciasis.

Specifically, Thomas Nutman and colleagues at the National Institutes of Health have described the a luciferase immunoprecipitation assay (LIPS) and the related QLIPS (quick version).

[10] No report on the distribution status of LIPS or QLIPS testing is available, but these tests would help to limit complications derived from mass ivermectin treatment for onchocerciasis or dangerous strong doses of diethylcarbamazine for loiasis alone (as pertains to individual with high Loa loa microfilarial loads).

[citation needed] In the past, healthcare providers used a provocative injection of Dirofilaria immitis as a skin-test antigen for filariasis diagnosis.

[citation needed] 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.

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.

[4] 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, among other locales in the region.

[citation needed] Cases have been reported on occasion in the United States but are restricted to travelers who have returned from endemic regions.

[citation needed] 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.

[citation needed] In Central and West Africa, initiatives to control onchocerciasis involve mass treatment with ivermectin.

These include hemorrhage of the conjunctiva and retina, hematuria, and other encephalopathies that are all attributed to the initial L. loa microfilarial load in the patient before treatment.

[citation needed] 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.

[citation needed] Within 12–24 hours post-ivermectin treatment (D1), individuals complained of fatigue, anorexia, headache, joint, and lumbar pain—a bent forward walk was characteristic during this initial stage accompanied by fever.

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.

[citation needed] The first hypothesis suggests that ivermectin causes immobility in microfilariae, which then obstructs microcirculation in cerebral regions.

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 the emergence of doxycycline-resistant Wolbachia.

Localized angioedema, a common clinical presentation of loiasis, was observed in 1895 in the coastal Nigerian town of Calabar—hence the name "Calabar" swellings.