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The circumoval precipitin reaction in Fasciola. Detection of shell pores by scanning electron microscopy
M H el-Sayad1, A F Allam, A Y Shehab
1Department of Parasitology, Medical Research Institute, Alexandria University, Alexandria, Egypt.
Abstract:
Precipitation reaction was detected around Fasciola eggs containing mature miracidia when they were incubated for 20 minutes with the sera of acute and chronic fasciolosis patients. The reaction was of the bleb type. The amount of blebs formed around the eggs was greater in case of acute than chronic fasciolosis. Scanning electron microscopy illustrated pores in the shell of Fasciola eggs. It is probable that the metabolic antigen passes through these pores leading to the positive circumoval precipitin reaction in cases of Fasciola infection. Antibodies specific to Fasciola excretory/secretory (E/S) egg antigens were not detected in the sera of Schistosoma cases.
Insights
Precipitation reactions around Fasciola eggs indicate infection. More blebs formed in acute fasciolosis, suggesting metabolic antigens exit through eggshell pores, aiding diagnosis.
Area of Science:
- Immunoparasitology
- Helminthology
- Diagnostic immunology
Background:
- Fasciolosis is a significant parasitic disease.
- Accurate diagnosis of Fasciola infection is crucial.
- Understanding host-parasite interactions aids diagnostic development.
Purpose of the Study:
- To investigate the circumoval precipitin reaction (COPR) in Fasciola infections.
- To characterize the nature of the precipitation reaction around Fasciola eggs.
- To explore the potential role of eggshell pores in antigen release.
Main Methods:
- Incubation of Fasciola eggs with sera from acute and chronic fasciolosis patients.
- Observation of precipitation reactions using light microscopy.
- Scanning electron microscopy (SEM) of Fasciola eggshells.
Main Results:
- A bleb-type precipitation reaction was observed around Fasciola eggs.
- The reaction was more pronounced in sera from acute fasciolosis cases compared to chronic cases.
- SEM revealed pores in the Fasciola eggshell.
- Antibodies against Fasciola excretory/secretory (E/S) egg antigens were absent in Schistosoma patient sera.
Conclusions:
- The circumoval precipitin reaction is a potential indicator of Fasciola infection.
- Metabolic antigens likely pass through eggshell pores, eliciting the COPR.
- The intensity of the reaction may correlate with disease stage (acute vs. chronic).
- Cross-reactivity with Schistosoma infections regarding these specific egg antigens is unlikely.