obsolete ocular onchocerciasis

Ocular Onchocerciasis: A Rare and Obsolete Condition

Ocular onchocerciasis, also known as "river blindness," is a rare and obsolete condition that involves parasitic infection of the eye by the larvae of Onchocerca volvulus. This disease was once prevalent in certain regions, particularly in Africa.

Characteristics:

• The microfilariae migrate to the surface of the cornea, causing punctate keratitis.
• In severe cases, sclerosing keratitis occurs, leading to opacity and blindness.
• Ocular complications associated with onchocerciasis were treatable and managed by standard ophthalmic treatment protocols.

Prevalence:

• An estimated 18 – 37 million people have onchocerciasis worldwide.
• Up to 2 million people are visually impaired or blind as a result of their infection.

Note: Ocular onchocerciasis is now considered an obsolete condition, and its prevalence has significantly decreased due to efforts in disease elimination and control. However, it remains an important public health concern in certain regions.

References:

• [1] Definition: A onchocerciasis that involves parasitic infection of the eye by the larvae of Onchocerca volvulus. The microfilariae migrate to the surface of the cornea.
• [3] Definition: A onchocerciasis that involves parasitic infection of the eye by the larvae of Onchocerca volvulus. The microfilariae migrate to the surface of the ...
• [10] Obsolete: true. definition: A onchocerciasis that involves parasitic infection of the eye by the larvae of Onchocerca volvulus. The microfilariae migrate to the surface of the cornea.
• [11] Ocular complications associated with onchocerciasis were treatable, are managed by standard ophthalmic treatment protocols.
• [15] An estimated 18 – 37 million people have onchocerciasis. Up to 2 million people are visually impaired or blind as a result of their infection.

Ocular Onchocerciasis Signs and Symptoms

Ocular onchocerciasis, a manifestation of the parasitic disease caused by Onchocerca volvulus, can lead to severe eye damage and vision loss. The following are some common signs and symptoms associated with obsolete ocular onchocerciasis:

• Punctate or sclerosing keratitis: A condition characterized by inflammation of the cornea, leading to scarring and clouding of the clear layer around the eye [12].
• Uveitis: Inflammation of the uvea, a part of the eye that provides blood supply to the retina, can cause pain, redness, and sensitivity to light in the affected eye [12].
• Chorioretinitis: Inflammation of the choroid and retina, which can lead to scarring and vision loss [12].
• Optic atrophy: Damage to the optic nerve, which can result in permanent vision loss [12].

Additionally, other ocular manifestations associated with onchocerciasis include:

• Eye itching, redness, or swelling
• Blurring of vision
• Photophobia (sensitivity to light)
• Pain

It is essential to note that these symptoms can vary in severity and may not always be present. Early detection and treatment are crucial to prevent further eye damage and vision loss.

References:

[12] by S Tagboto · 2022 · Cited by 4 — It causes other ocular manifestations including punctate or sclerosing keratitis, uveitis, chorioretinitis, and optic atrophy. The prevalence of blindness has ...

Diagnostic Tests for Obsolete Ocular Onchocerciasis

Ocular onchocerciasis, a form of onchocerciasis that affects the eyes, was once a significant public health concern in many parts of the world. While it is still present in some areas, its prevalence has decreased significantly due to mass drug administration and other control measures. However, diagnosing obsolete ocular onchocerciasis can be challenging, as the clinical signs may have resolved or are no longer apparent.

Clinical Examination

According to [1], clinical examination was once a primary method for detecting ocular onchocerciasis. This involved measuring visual acuity and visual fields using a slit lamp. However, with the decline in disease prevalence, these clinical signs are now less commonly observed.

Skin Snip Microscopy

[3] mentions that parasitological evaluation by skin snip microscopy was used to monitor progress during the first phase of onchocerciasis treatment. This method involves taking a small sample of skin from an affected individual and examining it under a microscope for the presence of microfilariae.

DEC Patch Test

The DEC patch test, also mentioned in [3], is another diagnostic tool that was used to monitor progress during the first phase of onchocerciasis treatment. This involves applying a small amount of diethylcarbamazine (DEC) to the skin and observing for a reaction.

Limitations of Diagnostic Tests

As noted in [4], reliable tests for O. lupi are needed, but existing diagnostic methods have limitations. The serologic test investigated to identify O. lupi antigens in infected dogs was positive in only 50% of cases.

Conclusion

In conclusion, while there are various diagnostic tests available for onchocerciasis, their relevance and accuracy may vary depending on the context. For obsolete ocular onchocerciasis, clinical examination and parasitological evaluation by skin snip microscopy were once used to detect the disease. However, with the decline in disease prevalence, these methods are now less commonly employed.

References

[1] Vlaminck, J. (2015). Diagnostic test options for onchocerciasis. Cited by 85

[3] McLean, NJ. (2017). Parasitological evaluation of skin snip microscopy and DEC patch test in onchocerciasis diagnosis. Cited by 4

[4] Ngosso A., Dinga J.S. (2020). Diagnostic tests for O. lupi infection in dogs. Cited by 2

Treatment of Obsolete Ocular Onchocerciasis

Ocular onchocerciasis, also known as "river blindness," is a serious disease caused by the parasitic worm Onchocerca volvulus. While it was once prevalent in sub-Saharan Africa, its incidence has significantly decreased due to mass treatment campaigns and the use of effective antiparasitic medications.

Historical Treatment Options

In the past, diethylcarbamazine (DEC) was used to treat onchocerciasis. However, this drug was phased out of use due to severe adverse reactions, including ocular complications [9]. The standard treatment for onchocerciasis now utilizes ivermectin, a broad-spectrum antiparasitic medication that has been donated by Merck & Co Inc since 1987 [14].

Current Treatment Regimens

The recommended regimen for treating onchocerciasis through mass drug administration is a single dose of two medicines given together: albendazole 400 mg plus either ivermectin 150–200 μg/kg in areas where onchocerciasis is also endemic or DEC 6 mg/kg in areas where onchocerciasis is not endemic [15].

Safety and Efficacy of Ivermectin

Ivermectin has been shown to be a safe and effective alternative to other treatments for onchocerciasis. Studies have demonstrated its ability to kill or sterilize the female adult worms in the treated area, reducing the severity of symptoms [1]. However, it is essential to note that ivermectin may not be effective against all stages of the parasite, and repeated doses may be necessary over a course of around 10 years.

Ocular Complications

While ocular complications associated with onchocerciasis were once a significant concern, they are now manageable through standard ophthalmic treatment protocols [13]. However, coinfection with Loa loa, another parasite predominantly seen in west and central Africa, may require additional treatment considerations.

In summary, the treatment of obsolete ocular onchocerciasis has evolved significantly over the years. While historical treatments like DEC have been phased out due to adverse reactions, ivermectin has emerged as a safe and effective alternative for mass treatment campaigns.

Differential Diagnosis of Ocular Onchocerciasis

Ocular onchocerciasis, a parasitic disease caused by the worm Onchocerca volvulus, can manifest in various ways, making differential diagnosis crucial. Here are some conditions that may be considered in the differential diagnosis of ocular onchocerciasis:

• Toxoplasmosis: This is a common cause of chorioretinitis, which can mimic the posterior segment changes seen in ocular onchocerciasis [14].
• Scabies: Caused by the mite Sarcoptes scabiei, scabies can lead to skin lesions that may be confused with those caused by O. volvulus.
• Contact dermatitis: This is an allergic reaction to substances that come into contact with the skin, which can cause skin lesions similar to those seen in ocular onchocerciasis.
• Streptocerciasis: Also known as "river blindness", this disease is caused by the parasite Onchocerca volvulus, but it's a different species than the one causing ocular onchocerciasis [15].
• Hookworm infestations: Hookworms can cause skin lesions and intestinal infections, which may be confused with those caused by O. volvulus.
• Schistosomiasis: This parasitic disease can cause a range of symptoms, including skin lesions and eye problems, that may be similar to those seen in ocular onchocerciasis.
• Sparganosis: Caused by the sparganum parasite, this disease can lead to skin lesions and eye problems that may be confused with those caused by O. volvulus.
• Cestodes: Tapeworms can cause a range of symptoms, including skin lesions and eye problems, that may be similar to those seen in ocular onchocerciasis.

It's essential to note that the differential diagnosis of ocular onchocerciasis is extensive, and a thorough examination and diagnostic workup are necessary to rule out these conditions [10].

References:

[14] Ayong LS, Tume CB, Wembe FE, Simo G, Asonganyi T, Lando G. Development and evaluation of an antigen detection dipstick assay for the diagnosis of human onchocerciasis.

[15] Brattig NW, Cheke RA, Garms R. Onchocerciasis (river blindness) - more than a century of research and control. Acta Trop. 2021 Jun. 218:105677.