Parasite-Driven Brain Changes May Explain Epilepsy in Neurocysticercosis

Neurocysticercosis, a central nervous system infection caused by the larval stage of the pork tapeworm Taenia solium, remains a leading cause of acquired epilepsy in endemic regions, and a new narrative mini-review argues that seizures in this disease arise from far more than simple inflammation. Published in Acta Epileptologica, the review synthesizes experimental and clinical evidence to portray epileptogenesis as an active, multilevel dialogue between parasite, host, and neuron, in which the larvae actively reshape the cerebral microenvironment rather than passively irritating brain tissue.

The disease burden is substantial. NCC affects millions globally, with the highest burden in low- and middle-income regions of Latin America, sub-Saharan Africa, and Asia. In these endemic settings, the review notes, NCC accounts for up to one-third of epilepsy cases, making it a predominant cause of acquired epilepsy worldwide. Yet it is often underrecognized and inadequately managed, compounded by limited access to neuroimaging, laboratory diagnostics, and specialized neurological care in resource-limited areas.

The life cycle explains how the parasite reaches the brain. Humans harbor the adult tapeworm in the intestine as the definitive host, while pigs are the typical intermediate hosts, developing cysticerci preferentially in striated muscles such as the tongue, masseter, and limb muscles. Humans become accidental intermediate hosts through fecal-oral contamination via tainted food, water, or poor hand hygiene. After ingestion of eggs, the oncosphere penetrates the intestinal mucosa, enters the circulation, and disseminates to tissues including the CNS. Blood-brain barrier penetration is hypothesized to involve transient disruption of endothelial tight junctions and interactions with adhesion molecules, although precise mechanisms remain under investigation.

Once inside the brain, larvae typically enter a vesicular stage characterized by minimal inflammation. The review describes how the parasite maintains this quiet state by secreting immunomodulatory molecules such as prostaglandin E2 and transforming growth factor-beta, and by shedding tegumental antigens that aid immune evasion. Clinical symptoms, particularly seizures, most commonly emerge during cyst degeneration, when exposed parasitic antigens provoke a robust host inflammatory response that damages surrounding neural tissue. In concert with cyst location, developmental stage, and the host’s immune status, this cascade disrupts neuronal networks via mechanical pressure, gliosis, and synaptic reorganization.

The inflammatory cascade is detailed at the molecular level. Exposure to parasitic antigens rapidly activates resident microglia and astrocytes, prompting a surge of pro-inflammatory cytokines including interleukin-1β, tumor necrosis factor-alpha, and interferon-gamma. Elevated levels of these mediators are consistently found in the cerebrospinal fluid and perilesional brain tissue of patients with active NCC. Although counter-regulatory cytokines such as interleukin-10 and TGF-β are also upregulated, especially in later infection stages, this anti-inflammatory response often proves insufficient to quell sustained pro-inflammatory signaling within epileptogenic niches.

These cytokines exacerbate blood-brain barrier disruption, promoting vasogenic edema and facilitating the influx of peripheral immune cells like macrophages and lymphocytes. The ensuing inflammatory milieu elevates extracellular glutamate concentrations while impairing GABAergic inhibition, effectively lowering the seizure threshold. Interleukin-1β plays a central role by potentiating NMDA receptor activity, enhancing calcium influx, and amplifying neuronal excitability. Astrocytic gliosis further worsens hyperexcitability by impairing potassium buffering and glutamate uptake, prolonging excitatory neurotransmission and promoting enduring synaptic reorganization.

Beyond immune-mediated mechanisms, the review highlights direct neuroexcitatory effects of parasite products. In vitro studies using rodent hippocampal organotypic slices and acute human cortical brain slices demonstrated that excretory-secretory products from Taenia larvae can induce epileptiform activity via glutamate receptor activation. These products are rich in excitatory amino acids like glutamate and aspartate, and the parasite likely expresses specific excitatory amino acid transporters, actively releasing these neurotransmitters into the immediate neural environment to drive sustained neuronal depolarization and network hyperexcitability. Upon cyst degeneration, stored products are released into the parenchyma, and disrupted barrier function facilitates their diffusion into surrounding tissue, while exposed antigens engage glial pattern recognition receptors including Toll-like receptors TLR2 and TLR4 and NOD-like receptors.

Structural remodeling cements the epileptogenic process. Histopathological studies consistently show neuronal loss, reactive gliosis, and aberrant synaptic rewiring in tissue enveloping cysts, with axonal sprouting and new excitatory synapse formation particularly pronounced around parenchymal and cortical cysts and calcified lesions. Neuroimaging corroborates these findings, revealing region-specific alterations in perfusion, metabolism, and functional connectivity adjacent to cysts and calcifications that frequently correlate with seizure recurrence and pharmacoresistance. Lesion location matters: cortical regions, especially frontal, temporal, and parietal lobes, and subcortical white matter are highly susceptible to generating recurrent seizures, whereas ventricular or subarachnoid cysts tend to be less epileptogenic. Multiple cysts and higher cumulative inflammatory burden increase seizure risk. Notably, calcified lesions once dismissed as inactive scars are now recognized as common sites of intermittent perilesional edema and recurrent seizures, suggesting smoldering low-grade inflammation persists long after the parasite has degenerated.

The review also points to host genetics and translational implications. Polymorphisms in immune-regulatory genes such as IL1B and TNFA can amplify and prolong pro-inflammatory cytokine release during cyst degeneration, lowering seizure thresholds, while variants in GRIN2A and GABRA1, genes governing excitatory and inhibitory neurotransmission, have been linked to altered cortical excitability in focal and acquired epilepsies, though direct genetic studies in NCC populations are sparse. On the biomarker front, cerebrospinal fluid levels of IL-1β and TNF-α correlate with active disease and seizure occurrence, elevated glutamate associates with seizure frequency though it lacks disease specificity, and parasite-specific antigens like Ts8B2 offer etiological specificity for monitoring disease activity. Pediatric studies suggest combination therapy with albendazole plus praziquantel achieves superior cysticidal efficacy compared to albendazole monotherapy, which may reduce long-term epileptogenic potential.

The authors frame control of NCC-associated epilepsy, especially in children, as requiring a One Health approach integrating human, animal, and environmental health, including pig vaccination and anthelmintic treatment, improved meat inspection, community education, and environmental sanitation, aligned with World Health Organization advocacy for linking neglected tropical disease programs with epilepsy surveillance. The review acknowledges limitations: it focused on parenchymal NCC, which constitutes the majority of epilepsy-related cases, leaving rarer intraventricular or subarachnoid forms and emerging anti-inflammatory therapies outside its scope, and constrained surveillance data with systematic underreporting of infectious epilepsy etiologies, particularly in sub-Saharan Africa, continue to limit both mechanistic understanding and public health response.

Subject of Research: Mechanistic pathways linking Taenia solium infection to epileptogenesis in neurocysticercosis

Article Title: Taenia solium development and host interactions in neurocysticercosis: a narrative mini review on mechanistic pathways to epileptogenesis

Article References: Sikakulya, F. K., Lekuya, H. M., Kamabu, L. K., Manzekele, M. K., Ochen, E., Sonia, F. D., Baanitse, J. M., Pascal, F. N. B., Shah, R. A., Balarabe, S. H., Kavulikirwa, O. K., Kitya, D., & Jones, M. K. (2026). Taenia solium development and host interactions in neurocysticercosis: a narrative mini review on mechanistic pathways to epileptogenesis. Acta Epileptologica, 8(1), Article 23. https://doi.org/10.1186/s42494-026-00261-7

Image Credits: AI Generated

DOI: 10.1186/s42494-026-00261-7

Keywords: neurocysticercosis, Taenia solium, epileptogenesis, neuroinflammation, blood-brain barrier, glutamate, calcified lesions, gliosis, biomarkers, One Health, cytokines, seizures