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Anti-Onchocerca volvulus immunoglobulin subclass response in children from Sierra Leone
A A Gbakima1, M S Ibrahim, A L Scott
1Department of Biological Sciences, Njala University College, University of Sierra Leone.
Insights
Researchers studied immune responses in children in Sierra Leone to improve diagnosis of onchocerciasis (river blindness). Elevated IgG4 antibodies may indicate early-stage infections in children, aiding serodiagnosis.
Area of Science:
- Immunology
- Tropical Medicine
- Parasitology
Background:
- Onchocerciasis, caused by Onchocerca volvulus, is a significant public health concern, particularly in endemic regions like Sierra Leone.
- Accurate diagnosis of early-stage and prepatent onchocerciasis in children is challenging but crucial for effective control strategies.
- Humoral immune responses, specifically antibody levels, are key indicators of parasitic infection.
Purpose of the Study:
- To investigate antigen-specific IgG and IgG4 antibody levels in a paediatric population in an onchocerciasis-endemic area.
- To evaluate the utility of these antibody levels in the serodiagnosis of prepatent and low-level Onchocerca volvulus infections.
- To correlate immune responses with parasitological status in children.
Main Methods:
- Studied 224 children aged 2-15 years in Sierra Leone.
- Measured antigen-specific IgG and IgG4 antibody levels against O. volvulus.
- Assessed parasitological status through microfilariae detection in skin snips.
Main Results:
- Over 87% of microfilaria-negative children showed significant levels of O. volvulus-specific antibodies, suggesting high prevalence of subclinical infections.
- Elevated O. volvulus-specific IgG4 was found in over 60% of children with detectable microfilariae.
- Only 23% of microfilaria-negative children had detectable IgG4 responses, highlighting its specificity for active infection.
Conclusions:
- O. volvulus-specific IgG4 levels may serve as a valuable biomarker for identifying children with early-stage onchocerciasis.
- Serological markers like IgG4 can aid in the diagnosis of prepatent and low-level infections, improving disease surveillance.
- Understanding humoral immune responses in paediatric populations is essential for targeted onchocerciasis interventions.
Abstract:
The humoral immune responses of a paediatric population of 224 children, 2-15 years of age, residing in an onchocerciasis endemic area of Sierra Leone, were studied to gain information that may be useful in the serodiagnosis of prepatent and low-level infections with Onchocerca volvulus. The antigen-specific levels of IgG and IgG4 were determined and evaluated in the context of the parasitological status of the child. Over 87% of the microfilaria-negative children had significant levels of antigen-specific antibodies against O. volvulus, suggesting that a large percentage of this paediatric population were harbouring prepatent or low-level infections. Over 60% of the children in the group that had detectable numbers of microfilariae in skin snips had elevated levels of O. volvulus-specific IgG4. In contrast, only 23% of the microfilaria-negative children had detectable IgG4 responses. The results presented here indicate that measures of O. volvulus-specific IgG4 may be a useful indicator of the parasitological status of children during the very early stages of onchocerciasis.