Clinical responses in human onchocerciasis: parasitological and immunological implications
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Abstract:
Onchocerciasis can cause severe dermal and ocular disease due, it is thought, to the events surrounding the destruction of the microfilarial stage. The evolution of papular pruritic dermatitis and punctate keratitis is clearly related to the killing of microfilariae. Other more chronic changes such as dermal and epidermal atrophy are probably due to repeated episodes of microfilarial killing. It is common to find that not all patients are, at any one time, mounting clinically obvious destructive host responses against the microfilariae, and such individuals can carry very high loads of parasites without any apparent adverse effects. The immunological basis of the differences between these types of patients forms one of the most important questions in the pathogenesis of onchocerciasis today. Various explanations are now emerging. These include immunosuppressive factors and variation in the form of Onchocerca volvulus antigens presented to the host. Clinical presentations of this disease appear to reflect variations in host responses and can be used to provide information concerning the protective immune responses an individual can mount against this parasite.
Insights
Onchocerciasis causes severe skin and eye disease linked to microfilariae destruction. Patient immune responses vary, influencing disease severity and parasite load, offering insights into protective immunity.
Area of Science:
- Immunology
- Parasitology
- Dermatology
Background:
- Onchocerciasis, a parasitic disease, leads to significant dermal and ocular pathology.
- Disease manifestations are primarily attributed to host responses against microfilariae.
- Patient responses to Onchocerca volvulus infection vary, impacting disease progression.
Purpose of the Study:
- To explore the immunological basis for varied patient responses in onchocerciasis.
- To understand the relationship between host immune responses and clinical presentations.
- To identify factors contributing to protective immunity against Onchocerca volvulus.
Main Methods:
- Clinical observation of dermal and ocular manifestations.
- Assessment of host immune responses to microfilarial destruction.
- Analysis of Onchocerca volvulus antigens and their presentation.
Main Results:
- Papular pruritic dermatitis and punctate keratitis correlate with microfilariae killing.
- Chronic changes like atrophy result from repeated microfilarial killing episodes.
- Asymptomatic individuals carry high parasite loads, suggesting immune tolerance or evasion.
Conclusions:
- Host immune response variability is central to onchocerciasis pathogenesis.
- Immunosuppressive factors and antigen variation may explain differential patient outcomes.
- Clinical presentation provides insights into protective immune mechanisms against onchocerciasis.