Parasitic infection of the CNS
Most common parasitic infection of the CNS
[A] Malaria
[B] Cysticercosis
[C] Schistosomiasis
[D] Angiostrongyliasis
Most common presentation of Neurocysticercosis is
[A] Focal deficits
[B] Intracranial hypertension
[C] Seizures
[D] Cognitive decline
Katayama syndrome is produced by
[A] Malaria
[B] Cysticercosis
[C] Schistosomiasis
[D] Angiostrongyliasis
Swimmer’s itch caused by
[A] Acanthamoeba Infection
[B] Dracunculiasis
[C] Schistosomiasis
[D] Angiostrongyliasis
Neuroschistosomiasis most commonly caused by
[A] Schistosoma japonicum
[B] Schistosoma haematobium
[C] Schistosoma mekongi
[D] Schistosoma mansoni
| Feature | Schistosoma mansoni | Schistosoma haematobium |
|---|---|---|
| Primary habitat | Mesenteric venous plexus (draining large intestine) | Venous plexus of bladder and pelvic organs |
| Main organ involvement | Intestines, liver (periportal fibrosis) | Urinary tract (bladder, ureters, kidneys) |
| Neurological complications | Common – spinal cord involvement via Batson’s venous plexus | Rare – CNS involvement unusual |
| Typical CNS site | Spinal cord (especially lower thoracic, lumbar) | Brain (very rarely) |
| Mechanism of spinal involvement | Egg embolization → granulomatous inflammation → transverse myelitis/radiculopathy | Uncommon egg migration to CNS |
| Clinical presentation | Paraparesis, sensory loss, bladder/bowel dysfunction | Usually no spinal signs; hematuria is dominant symptom |
| Epidemiology | Widespread in Africa, South America, Middle East | Widespread in Africa, Middle East |
| Diagnosis | Stool microscopy (eggs with lateral spine) | Urine microscopy (eggs with terminal spine) |
| Treatment | Praziquantel | Praziquantel |
1. The most common cause of neurocysticercosis is:
Taenia solium larvae (cysticerci) are the leading parasitic cause of seizures worldwide in endemic areas.
2. A cyst with an eccentric scolex on MRI (\”dot-in-hole\”) is diagnostic of:
The scolex is a classic sign of viable cysticerci (Taenia solium) on neuroimaging.
3. In HIV patients with focal ring-enhancing lesions, the two most important differentials are:
Multiple ring-enhancing lesions suggest toxoplasmosis; solitary lesion raises concern for lymphoma. Serology, empiric therapy response, or biopsy help distinguish.
4. Cerebral malaria is caused by which plasmodium species?
P. falciparum causes severe cerebral disease via microvascular sequestration of infected erythrocytes.
5. Primary amoebic meningoencephalitis after freshwater swimming is due to:
Naegleria invades via the cribriform plate following nasal exposure, causing fulminant disease.
6. Granulomatous amebic encephalitis is most commonly caused by:
Acanthamoeba and Balamuthia produce subacute–chronic granulomatous encephalitis, often in immunocompromised hosts.
7. Spinal cord schistosomiasis is most commonly linked to:
Egg embolization via the Batson plexus leads to granulomatous inflammation in the spinal cord—S. mansoni is most commonly implicated.
8. Standard therapy for cerebral toxoplasmosis includes:
This combination is the standard; alternative regimens exist for sulfa allergy (e.g., pyrimethamine + clindamycin).
9. A solitary large cystic intracranial lesion with mass effect suggests:
Hydatid cysts are often single, large, and space-occupying—neurosurgical management is frequently required.
10. The inflammatory peak in neurocysticercosis occurs during which stage?
When cysts degenerate they release antigens that provoke maximal host inflammation and symptomatic disease.
11. Rapid diagnosis of Naegleria fowleri infection is best achieved by:
A fresh CSF wet mount can rapidly show motile trophozoites; PCR/culture can confirm later.
12. First-line antiparasitic agent for neurocysticercosis is:
Albendazole (often with steroids for inflammation) is the mainstay; praziquantel is also used and sometimes combined.
13. Subacute–chronic granulomatous encephalitis in both immunocompetent and -compromised is caused by:
Balamuthia and Acanthamoeba produce granulomatous brain infections that can be indolent and difficult to treat.
14. Diagnosis of cerebral toxoplasmosis typically relies on:
Imaging, serology, and empirical therapeutic response are central to diagnosis; CSF tests have limited sensitivity.
15. Eosinophilic meningitis is classically caused by:
Angiostrongylus infection often presents with CSF eosinophilia after ingestion of raw intermediate hosts (snails, prawns).
16. Empiric therapy for suspected toxoplasmosis in an HIV patient includes:
Standard empiric regimen while awaiting response; improvement supports toxoplasmosis diagnosis.
17. The best public-health measure to prevent neurocysticercosis is:
Breaking the fecal–oral transmission (human eggs contaminating pig food/water) reduces human cysticercosis risk.
18. Diagnosis of cerebral hydatid disease relies primarily on:
Hydatid cysts have characteristic imaging appearances; serology supports the diagnosis. Surgery is often required.
19. Which parasite is known to reactivate or be donor-derived after organ transplantation causing CNS disease?
Toxoplasma can reactivate in immunosuppressed transplant recipients or be transmitted from seropositive donors.
20. Which CNS parasitic lesion commonly requires neurosurgical removal due to mass effect?
Hydatid cysts produce significant mass effect and often need careful surgical excision (with precautions to avoid spillage).
1. The most common parasitic cause of seizures worldwide is:
Neurocysticercosis, caused by Taenia solium larval cysts in the brain, is the leading parasitic cause of epilepsy worldwide, especially in endemic areas.
2. Toxoplasma gondii infection is most severe in:
Toxoplasma gondii can cause life-threatening encephalitis in immunocompromised individuals, especially those with advanced HIV/AIDS.
3. Cerebral malaria is most often caused by:
Plasmodium falciparum infection can cause cerebral malaria due to sequestration of parasitized RBCs in brain capillaries.
4. The definitive host of Taenia solium is:
Humans are the definitive hosts for Taenia solium, harboring the adult tapeworm in the intestine. Pigs act as intermediate hosts.
5. A classic MRI finding in neurocysticercosis is:
A cyst with an eccentric scolex (“dot-in-hole” sign) is characteristic of viable neurocysticercosis on MRI.
| No. | Parasitic infection of the CNS – Key Points |
|---|---|
| 1 | Neurocysticercosis is the most common parasitic infection of the CNS worldwide, caused by Taenia solium larvae. |
| 2 | Cerebral malaria is caused mainly by Plasmodium falciparum and can rapidly progress to coma and death. |
| 3 | Toxoplasmosis is a common opportunistic CNS infection in immunocompromised patients, especially with HIV/AIDS. |
| 4 | Echinococcosis of the CNS is rare but causes cystic brain lesions with mass effect. |
| 5 | Acanthamoeba and Naegleria fowleri cause fatal CNS infections through contaminated water exposure. |
| 6 | Schistosoma species can cause granulomatous inflammation in the spinal cord or brain. |
| 7 | Imaging (CT/MRI) is critical for diagnosing CNS parasitic infections, showing cystic or ring-enhancing lesions. |
| 8 | Serological tests like ELISA can detect parasite-specific antibodies or antigens. |
| 9 | CSF analysis may reveal eosinophilia in helminthic CNS infections. |
| 10 | Albendazole and praziquantel are mainstays of therapy for helminthic CNS infections. |
| 11 | Corticosteroids are often co-administered to reduce inflammation and edema. |
| 12 | Surgical removal may be required for large or symptomatic parasitic cysts. |
| 13 | Preventive measures include proper meat cooking, water sanitation, and vector control. |
| 14 | In endemic areas, routine deworming can reduce CNS helminth infection rates. |
| 15 | Seizures are the most common presenting symptom in neurocysticercosis. |
| 16 | Hydrocephalus may occur in CNS parasitic infections due to CSF flow obstruction. |
| 17 | Brain biopsy is rarely required but may be necessary in unclear cases. |
| 18 | Differential diagnosis includes tuberculosis, fungal infections, and neoplasms. |
| 19 | Travel history is crucial in diagnosing parasitic CNS infections in non-endemic countries. |
| 20 | Early diagnosis and treatment improve prognosis and reduce neurological sequelae. |
Short Questions and Answers — Parasitic Infections of the CNS
- Q: What is the most common parasitic infection of the CNS worldwide?
A: Neurocysticercosis caused by Taenia solium. - Q: Which parasite causes cerebral malaria?
A: Plasmodium falciparum. - Q: Which parasitic CNS infection is associated with seizures as the most common symptom?
A: Neurocysticercosis. - Q: How does Toxoplasma gondii typically present in immunocompromised patients?
A: Multiple brain abscesses with ring-enhancing lesions on MRI. - Q: Which diagnostic test is gold standard for cerebral malaria?
A: Thick and thin peripheral blood smear. - Q: Which CNS parasite is linked with hydatid cyst formation?
A: Echinococcus granulosus. - Q: Name a parasite that causes spinal cord compression due to granulomas.
A: Schistosoma mansoni. - Q: What is the mode of transmission for Naegleria fowleri?
A: Entry through the nasal passages during water exposure. - Q: What is the mainstay of diagnosis for Toxoplasma gondii encephalitis?
A: Serology for IgG and MRI brain findings. - Q: Which CNS parasite is associated with racemose cysts in the subarachnoid space?
A: Taenia solium (racemose neurocysticercosis). - Q: What drug combination is used in treating neurocysticercosis?
A: Albendazole + corticosteroids. - Q: How does Onchocerca volvulus affect the CNS?
A: Can cause epilepsy and “nodding syndrome”. - Q: Which parasite causes eosinophilic meningitis?
A: Angiostrongylus cantonensis. - Q: What is the usual MRI appearance of cerebral hydatid cysts?
A: Well-defined, thin-walled, spherical cyst without perilesional edema. - Q: How is Schistosoma haematobium CNS infection different from S. mansoni?
A: S. haematobium more commonly affects spinal cord; S. mansoni affects both spinal cord and brain. - Q: What is the most fatal form of amoebic CNS infection?
A: Primary amoebic meningoencephalitis (PAM) by Naegleria fowleri. - Q: Which parasite causes granulomatous amoebic encephalitis (GAE)?
A: Acanthamoeba species. - Q: How does cerebral malaria cause coma?
A: Sequestration of infected red cells in cerebral microvasculature leading to hypoxia. - Q: What is the treatment for Toxoplasma gondii CNS infection in HIV patients?
A: Pyrimethamine + sulfadiazine + leucovorin. - Q: Which parasite can cause both brain and spinal cord involvement leading to transverse myelitis?
A: Schistosoma mansoni.
Parasitic Infections of the Central Nervous System — 20 High-Yield Points
Quick reference: causes, imaging clues, diagnosis, treatment and prevention for neuroparasitic diseases (neurocysticercosis, toxoplasmosis, cerebral malaria, schistosomiasis, hydatid disease, amoebic encephalitis).
| No. | Key point |
|---|---|
| 1 | Neurocysticercosis (Taenia solium) is the worldwide leading parasitic cause of adult-onset seizures. |
| 2 | Cerebral malaria is caused by Plasmodium falciparum and presents with coma, seizures and high mortality if untreated. |
| 3 | Toxoplasma gondii causes ring-enhancing lesions in immunocompromised patients; serology + MRI + therapeutic response guide diagnosis. |
| 4 | Echinococcus granulosus (hydatid disease) can produce large solitary cerebral cysts requiring neurosurgical removal. |
| 5 | Naegleria fowleri causes fulminant primary amoebic meningoencephalitis after nasal freshwater exposure — rapid diagnosis (CSF wet mount) is critical. |
| 6 | Acanthamoeba and Balamuthia cause chronic granulomatous encephalitis, often in immunocompromised patients; diagnosis may require brain biopsy or PCR. |
| 7 | Schistosoma species (especially S. mansoni & S. haematobium) can cause spinal cord granulomas and transverse myelitis via egg embolization. |
| 8 | Imaging is central: neurocysticercosis shows cysts ± scolex; toxoplasmosis shows multiple ring-enhancing lesions; hydatid shows large unilocular cysts. |
| 9 | CSF eosinophilia suggests helminthic infection (e.g., Angiostrongylus, Gnathostoma); eosinophilic meningitis is a red flag for parasites. |
| 10 | Albendazole and praziquantel are first-line antiparasitic agents for many helminthic CNS infections; use steroids to manage inflammation when cysts degenerate. |
| 11 | Corticosteroids reduce symptomatic edema in degenerating parasitic cysts but should be used carefully with antiparasitic therapy. |
| 12 | Surgical intervention is often needed for large hydatid cysts or cysts producing raised intracranial pressure or focal mass effect. |
| 13 | Toxoplasma encephalitis standard therapy: pyrimethamine + sulfadiazine + leucovorin; alternatives for sulfa-allergic patients include pyrimethamine + clindamycin. |
| 14 | Diagnosis often combines epidemiology (travel/exposure), imaging, serology, CSF testing, and sometimes biopsy or PCR confirmation. |
| 15 | Prevention: cook meat thoroughly, improve sanitation (to prevent Taenia transmission), safe water, vector control, and public-health measures in endemic regions. |
| 16 | Travel history and exposure questions (undercooked pork, freshwater swimming, contact with dogs/sheep) are essential in evaluation. |
| 17 | Eosinophilia in blood or CSF supports helminthic etiology but is often absent in protozoal CNS infections. |
| 18 | Rapid, aggressive support (antiparasitic drugs, ICP control, antimicrobials where mixed infection suspected) improves outcomes in severe cases like PAM or cerebral malaria. |
| 19 | Definitive diagnosis sometimes requires tissue PCR/biopsy (Acanthamoeba, Balamuthia) or direct visualization (Naegleria trophozoites in CSF). |
| 20 | Early recognition and prompt therapy reduce neurological sequelae; coordinate infectious disease, neurology and neurosurgery for complex cases. |
Image alt-text suggestions
- “Infographic: MRI features of neurocysticercosis showing cyst with scolex”
- “Flowchart: diagnosis and treatment of cerebral toxoplasmosis in HIV patients”
- “Diagram: life cycle of Taenia solium and routes to human CNS infection”
- “Illustration: Naegleria fowleri entry via olfactory nerve after freshwater exposure”
Quick FAQs
What is the top parasitic cause of seizures?
Neurocysticercosis (Taenia solium) — cysts and perilesional inflammation provoke seizures.
How is cerebral hydatid disease treated?
Surgical excision is often required; albendazole may be used adjunctively.
When should I suspect Naegleria infection?
Rapidly progressive meningoencephalitis after freshwater nasal exposure — examine fresh CSF for motile trophozoites urgently.
