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Loaza is a painful swelling that occurs and disappears quickly under the skin and around the joints, which is a symptom of infection with a parasite called Loa Loa.
Loaza – epidemiology
Loaose, the infestation of the Loa loa parasite, is found in Central and West Africa, in the rainforest zone. The geographical range of this infection is related to the presence of carriers of this disease – Chrysops blind worms. These insects feed during the day and then the amount of microfilariae in the blood is the highest. A particular risk of loaosis occurs during the rainy season – the mud on the shaded banks of the streams is the place where blind birds breed – vectors of this disease.
Loa loa is a worm 50-70 mm in length and 0,5 mm in diameter for females and 25-35 mm in length and 0,25 mm in diameter (for males). Sheathed microfilariae 7-9 mm in diameter and 250-300 mm long; they appear in the blood most often in the number of 10-14. The adult lifetime is 4-17 years.
Loaza – symptoms
In contrast to lymphatic filariasis and onchocercosis, in Loa loa infection, most clinical signs are due to the mature parasite and not to microfilariae. Calabrian edema is believed to be the result of hypersensitivity to the parasite’s antigens as it travels under the skin. Treatment-induced breakdown of microfilariae appears to be responsible for the most serious complication of loaosis: encephalitis. Glomerulonephritis is associated with the build-up of immune complexes.
Clinical symptoms
The clinical picture in people living in endemic areas differs from that in people who became infected during a short stay. Among the inhabitants of endemic areas, the clinical symptoms are less pronounced, and the asymptomatic course is more common.
A typical symptom of Loa loa infection is the so-called Calabrian swelling. This is limited, usually painless angioedema, accompanied by itching and erythematous changes. This swelling lasts from a few days to several or even several weeks, resolves spontaneously, but there are relapses. Subconjunctival migration of the parasite visible to the naked eye causes eyelid edema and intense conjunctivitis of the affected eye.
Moreover, loaosis causes sometimes nonspecific skin symptoms, such as:
- hives
- maculo-papular rash accompanied by itchy skin.
In additional tests, high eosinophilia and elevated IgE levels are noteworthy.
Loase diagnostics
Both the detection of microfilariae in the blood and the removal of a mature worm from the subcutaneous tissue or from under the conjunctiva confirm the diagnosis of loase. Blood for microfilariae testing should be collected around noon. In the diagnosis of loase, serological tests are used only in the diagnosis of people returning from the endemic zone, while specific antibodies are detected in virtually all people permanently residing in endemic areas.
How to cure a loase?
In lazy therapy, the drug of choice is dietylkarbamazyna (DEC) at a dose of 6 mg / kg bw / day, in 3 divided doses for 14-21 days. Treatment of people with high microfilariaemia can provoke a rapid inflammatory reaction with itching and hives; sometimes there are proteinuria, renal failure and encephalitis, in extreme cases leading to coma and life-threatening.
Similar symptoms may occur after administration iwermektyny. Attempt to administer initially small and then gradually increasing doses, as well as parallel use corticosteroids do not prevent side effects. Administration is recommended albendazolu at a dose of twice 2 mg for 400 days prior to appropriate treatment to reduce microfilariaemia, but the efficacy of this treatment has not been definitively evaluated.
What’s the prognosis?
Loaosis is rarely life-threatening, but treatment is difficult and not always effective.
What are the complications of loazy?
The complications of loaosis include:
- inflammation of the meninges and the brain,
- kidney damage with proteinuria and hematuria,
- endocardial and myocardial fibrosis.
Central nervous system symptoms usually occur in response to an antiparasitic drug. After the implementation of the massive ivermectin onchocercosis treatment program, the number of patients with this complication increased. In addition, cases of CNS inflammation in the course of loaosis have also been described without relation to the therapy used.
Source: J. Cianciara, J. Juszczyk, Infectious and parasitic diseases; Czelej Publishing House