Which Parasitic Infections Require Surgical Treatment?

Most parasitic infections are treated with anti-parasitic medications alone, but a significant number can cause complications that only a surgeon can fix. The parasites that most frequently land patients in an operating room include the hydatid tapeworm (Echinococcus), the pork tapeworm when it reaches the brain (neurocysticercosis), Chagas disease when it permanently stretches the esophagus or colon, and filarial worms that cause massive swelling in the legs or genitals. Beyond these well-known examples, roundworms that physically block bile ducts, flukes that obstruct the lungs or spinal cord, and larvae that wander into the eye all have scenarios where medications alone fall short and a procedural intervention becomes necessary.

Hydatid Disease and Echinococcosis

Hydatid disease, caused by the tapeworm Echinococcus granulosus, is probably the single parasitic infection most associated with surgery worldwide. The parasite forms fluid-filled cysts, most often in the liver and lungs, that can grow for years before causing symptoms. These cysts are encased in a tough, layered wall that anti-parasitic drugs struggle to penetrate fully. For uncomplicated liver cysts, a less invasive option exists: percutaneous drainage combined with albendazole therapy, which has been shown to be effective and safe while requiring a shorter hospital stay than open surgery.¹ That approach works well for simpler cyst types, but more complex cysts, those with internal divisions or connections to bile ducts, are best managed surgically. Complete excision of the cyst along with its surrounding membrane is the preferred operation because it reduces the risk of recurrence and cavity-related complications.²

When cysts sit close to major blood vessels or bile channels inside the liver, complete excision becomes risky, and surgeons may opt for a drainage-style operation instead. One unusual but real danger of hydatid surgery is anaphylactic shock, which can occur if cyst fluid leaks into the patient’s bloodstream during the procedure.³ The heart is another site where hydatid cysts occasionally develop, and cardiac involvement typically requires open-heart surgery to remove the cyst safely.⁴

A closely related but far more aggressive parasite, Echinococcus multilocularis, causes alveolar echinococcosis. Unlike its cousin’s neat cysts, this species grows in an infiltrating, tumor-like pattern through the liver, often invading surrounding tissue for years before diagnosis. Radical surgery remains the only curative option. Because patients tend to present late, by the time the disease is found a complete resection that preserves enough functional liver tissue is often impossible. In end-stage cases, liver transplantation has been performed as palliative treatment for life-threatening complications.⁵ Transplantation for alveolar echinococcosis is technically difficult, but experience has shown it is feasible and worth considering in very symptomatic patients with no other options.⁶

Neurocysticercosis

When a person accidentally ingests eggs of the pork tapeworm Taenia solium, the larvae can migrate to the brain and form cysts there. This condition, neurocysticercosis, is the most common parasitic infection of the central nervous system and a leading cause of acquired epilepsy in many parts of the world. Many patients are managed with anti-parasitic drugs and steroids, but surgery enters the picture in two main scenarios: when cysts block the flow of cerebrospinal fluid inside the brain’s ventricles, and when cysts are located in positions where drugs work too slowly or not at all.

Ventricular neurocysticercosis is particularly dangerous because a cyst sitting in one of the brain’s fluid-filled chambers can obstruct drainage and cause hydrocephalus, a buildup of pressure. In a U.S. referral center series, the fourth ventricle was involved in about two-thirds of patients with ventricular disease, and nearly three-quarters developed hydrocephalus. Surgeons performed cyst removal (cystectomy) in about 60% of cases, typically through a suboccipital craniotomy, and placed a shunt to drain fluid in roughly 44% of patients.⁷ A larger systematic review found similar patterns, with about 45% of patients who had hydrocephalus receiving a shunt.⁸ Shunts can fail or become infected, so when direct cyst removal is feasible, surgeons prefer to take the cyst out rather than just manage the downstream pressure.

Anti-parasitic treatment after surgery matters, too. Among patients who had a single ventricular cyst removed, those who received post-operative anti-helminthic therapy had a substantially lower risk of developing delayed hydrocephalus compared with those who did not receive it.⁹ Surgery for neurocysticercosis, in other words, rarely stands alone; it is usually part of a combined approach with medications.

Chagas Disease and the Digestive Tract

Chagas disease, caused by the protozoan Trypanosoma cruzi and transmitted by triatomine bugs (sometimes called “kissing bugs”), is best known for its heart complications. But in its chronic phase it can also destroy the nerve cells that control the muscles of the esophagus and colon, causing these organs to dilate massively. The resulting conditions, megaesophagus and megacolon, can become severe enough that surgery is the primary treatment.

For megaesophagus in earlier stages, surgeons typically perform a procedure that widens the lower esophageal opening and adds a valve to prevent acid reflux. In advanced disease, the esophagus is so stretched and non-functional that it needs to be removed and replaced with a tube fashioned from the stomach.¹⁰ Surgical treatment is considered the first choice in these advanced stages.¹¹ Esophageal resection in Chagas disease carries real risks, with early reports noting notable rates of pleural effusion and fistula formation at the surgical connection site, though most patients adapted well afterward and regained weight.¹² For megacolon, the standard operation involves removing the dilated portion of the sigmoid colon and reconnecting the remaining bowel.

Amebic Liver Abscess

Entamoeba histolytica, the parasite behind amoebic dysentery, can travel from the gut to the liver and form large abscesses. Most amebic liver abscesses respond well to metronidazole without any need for drainage. Surgery or percutaneous drainage enters the picture in specific circumstances: when doctors cannot tell whether an abscess is amebic or bacterial, when the patient is deteriorating despite drug therapy, when the abscess appears about to rupture, or when it sits in the left lobe of the liver (which has a higher risk of rupturing into the heart’s surrounding sac).¹³

When an abscess has already ruptured and caused widespread peritonitis, percutaneous drainage can be a lifesaving alternative to open surgery, since operating on these patients carries a high mortality risk.¹⁴ Open surgery is reserved for the most severe cases, such as when there is uncontrolled bleeding or when percutaneous drainage fails.

Roundworms in the Bile Duct

Ascaris lumbricoides, the large human roundworm, is one of the most common parasitic infections globally. Normally the worms live in the small intestine and are treated with a single dose of anti-parasitic medication. Problems arise when a worm physically migrates into the bile duct or pancreatic duct, causing intense pain, jaundice, or pancreatitis. The management of biliary ascariasis follows a stepwise approach: medical treatment first, endoscopic removal if medications fail, and surgery only in selected cases when both of those approaches are not feasible.¹⁵

Endoscopic removal is often the definitive fix. In a reported case, a worm was directly visualized during an endoscopic procedure, pulled out of the bile duct, and the patient’s pain resolved immediately.¹⁶ Surgery for biliary ascariasis is genuinely rare today, reserved for situations like bowel perforation or complete intestinal obstruction from a mass of worms, which occasionally occurs in children with heavy worm burdens.

Liver Flukes and Lung Flukes

Fasciola hepatica, the liver fluke acquired from eating contaminated watercress or other aquatic plants, goes through an early phase of migrating through liver tissue and a later phase of living inside the bile ducts. In its chronic phase, the adult flukes can physically obstruct the bile duct and cause jaundice. Endoscopic extraction during a procedure similar to gallstone removal has proven effective for pulling the flukes directly out of the duct.¹⁷ In some cases, flukes are discovered incidentally during endoscopy performed for other reasons.¹⁸

Paragonimus, the lung fluke, usually responds to praziquantel, but it can cause serious lung complications that require surgical cleanup. When the infection leads to a thick, infected fluid collection around the lung (empyema), the drug alone may not be enough. In one adolescent case, praziquantel was given but the lung remained trapped by a peel of inflammatory tissue, requiring video-assisted thoracic surgery to free it.¹⁹

Schistosomiasis of the Spinal Cord

Schistosomiasis is more commonly associated with liver damage and bladder disease, but the parasite’s eggs can occasionally lodge in the spinal cord, causing a rare and frightening complication: progressive weakness or paralysis in the legs along with loss of bladder control. Treatment typically involves praziquantel to kill the worms, corticosteroids to reduce inflammation around the eggs, and in some cases surgical intervention.²⁰ Surgical excision combined with praziquantel has been reported to improve neurological deficits in patients with intramedullary (within the spinal cord itself) disease.²¹ Surgery for spinal schistosomiasis is not standard for every patient; it tends to be reserved for those whose neurological function is worsening despite medical treatment or where the diagnosis is uncertain and a biopsy is needed.

Lymphatic Filariasis

Lymphatic filariasis, caused by thread-like worms transmitted by mosquitoes, damages the lymphatic system over years of repeated infection, leading to chronic swelling. The most recognized surgical complication is hydrocele, a fluid collection around the testicle that is the most common clinical manifestation of the disease in men. Hydrocele surgery is the recommended treatment for this condition.²² The operation itself is straightforward enough to be performed in resource-limited settings, with complication rates ranging from about 3% to 7% depending on technique, and recurrence rates in a similar range.²³

In more severe cases, chronic lymphatic damage causes elephantiasis of the genitals, with massive tissue overgrowth that anti-parasitic drugs cannot reverse. These cases require more complex reconstruction, combining removal of the excess tissue with soft tissue coverage and sometimes lymphatic reconstruction.²⁴ Complication rates increase with the complexity of the reconstruction. The fundamental issue is that anti-filarial drugs can kill the worms and prevent further damage, but they cannot undo the structural damage already done to the lymphatic system, so surgery addresses the consequences rather than the infection itself.

Parasites Inside the Eye

Few parasitic scenarios are as unsettling as a living organism inside the eye, and these cases almost always require surgical removal. The eyeball is a closed, delicate space where a worm or larva can cause inflammation, traction on the retina, and permanent vision loss if left alone. Anti-parasitic drugs are often ineffective or even dangerous here, because killing a parasite inside the eye can trigger a severe inflammatory reaction that damages surrounding tissue.

Pars plana vitrectomy, a microsurgical technique that accesses the back of the eye through small incisions, is the workhorse procedure for intraocular parasites. It has been used to remove Toxocara canis organisms (a roundworm acquired from dogs), clear the vitreous inflammation they cause, and relieve traction that threatens retinal detachment.²⁵ The same technique has been applied to cases of diffuse unilateral subacute neuroretinitis, where a live parasite is identified moving within the eye and successfully extracted.²⁶ Ophthalmomyiasis, caused by fly larvae that penetrate the eye, follows the same principle: vitrectomy allows the surgeon to remove the larva and repair any structural damage it caused.²⁷

Sparganosis

Sparganosis is an uncommon infection caused by the larval stage of Spirometra tapeworms, typically acquired by drinking contaminated water, eating undercooked frogs or snakes, or through traditional poultices made from animal flesh. The larvae can migrate to virtually any part of the body, forming nodules under the skin, in muscle, or occasionally in the brain. There is no reliably effective drug treatment for sparganosis, making surgical removal the standard approach.

When the parasite lodges under the skin, excision is often curative. In one case, a worm was surgically removed from a thigh nodule, and follow-up blood tests confirmed that the infection was cleared.²⁸ When sparganosis develops in the colon, endoscopic removal has been performed successfully.²⁹ The most challenging cases involve the brain, where the larvae can survive for years and cause seizures or progressive neurological symptoms. Surgery guided by modern navigation technology is the preferred treatment for cerebral sparganosis.³⁰ In that brain case report, a patient had lived with a live parasite for 17 years before it was finally found and removed.

Strongyloides and Bowel Emergencies

Strongyloides stercoralis is a soil-transmitted roundworm that can persist silently in a person’s gut for decades through a cycle of self-reinfection. In people with suppressed immune systems, the worm can multiply explosively in what is called hyperinfection syndrome. This can lead to genuine surgical emergencies: the overwhelming worm burden damages the intestinal wall, sometimes causing obstruction, gangrene, or perforation.

In one reported case, a patient arrived at the emergency department with signs of bowel obstruction, and at surgery the team found adhesions and a necrotic segment of small intestine with a tiny perforation.³¹ Another patient with hyperinfection was found to have gangrenous small bowel at surgery, requiring removal of the dead segment and reconnection of the healthy ends.³² These cases are thankfully rare, but they underscore why screening for Strongyloides before starting immunosuppressive therapy (such as high-dose steroids or chemotherapy) is so important. The surgery itself is not treating the parasite; it is rescuing a patient from the catastrophic tissue damage the parasite has already caused.

When Anti-Parasitic Drugs and Surgery Work Together

For several of the infections above, the best outcomes come from combining surgery with medications rather than relying on either alone. In pulmonary hydatid disease, giving a course of anti-helminthic drugs before surgery helps kill the tiny infectious particles (protoscoleces) inside the cyst. A minimum four-week course of combination therapy with albendazole and praziquantel before lung cyst surgery appears to provide enough parasite-killing activity to reduce the risk of recurrence from accidental spillage during the operation.³³

Post-operative drug therapy is equally important in some settings. After surgical removal of a single brain ventricle cyst in neurocysticercosis, patients who received anti-helminthic drugs afterward had a much lower rate of developing delayed hydrocephalus than those who did not.⁹ These findings reflect a broader principle: surgery handles the mechanical problem the parasite has created, while drugs mop up any remaining organisms and reduce the chance of the problem recurring.

Parasitic Infections Mimicking Cancer

One scenario where knowing about parasitic surgery matters is the opposite one: avoiding unnecessary surgery altogether. Parasitic infections in the lungs can produce masses on imaging that look remarkably similar to lung cancer. A review has stressed the importance of considering parasitic infection in the differential diagnosis of lung masses, particularly in patients from endemic areas, to prevent misdiagnosis and unnecessary surgical procedures.³⁴ Hydatid cysts, paragonimiasis nodules, and even amoebic abscesses have all been mistaken for tumors. A thorough travel and exposure history, combined with serological testing, can sometimes spare a patient a major operation that was never needed in the first place. On the flip side, in some cases the parasitic lesion genuinely does need to come out, and the cancer scare is what finally leads to its discovery.