Cysticercosis

Cysticercosis is a tissue infection caused by the young form of the pork tapeworm. People may have few or no symptoms for years. In some cases, particularly in Asia, solid lumps of between one and two centimetres may develop under the skin. After months or years these lumps can become painful and swollen and then resolve. A specific form called neurocysticercosis, which affects the brain, can cause neurological symptoms. In developing countries this is one of the most common causes of seizures. Cysticercosis is a tissue infection caused by the young form of the pork tapeworm. People may have few or no symptoms for years. In some cases, particularly in Asia, solid lumps of between one and two centimetres may develop under the skin. After months or years these lumps can become painful and swollen and then resolve. A specific form called neurocysticercosis, which affects the brain, can cause neurological symptoms. In developing countries this is one of the most common causes of seizures. Cysticercosis is usually acquired by eating food or drinking water contaminated by tapeworm eggs from human feces. Among foods, uncooked vegetables are the major source. The tapeworm eggs are present in the feces of a person infected with the adult worms, a condition known as taeniasis. Taeniasis, in the strict sense, is a different disease and is due to eating cysts in poorly cooked pork. People who live with someone with the pork tapeworm have a greater risk of getting cysticercosis. The diagnosis can be made by aspiration of a cyst. Taking pictures of the brain with computer tomography (CT) or magnetic resonance imaging (MRI) are most useful for the diagnosis of disease in the brain. An increased number of a type of white blood cell, called eosinophils, in the cerebral spinal fluid and blood is also an indicator. Infection can be effectively prevented by personal hygiene and sanitation: this includes cooking pork well, proper toilets and sanitary practices, and improved access to clean water. Treating those with taeniasis is important to prevent spread. Treating the disease when it does not involve the nervous system may not be required. Treatment of those with neurocysticercosis may be with the medications praziquantel or albendazole. These may be required for long periods of time. Steroids, for anti-inflammation during treatment, and anti-seizure medications may also be required. Surgery is sometimes done to remove the cysts. The pork tapeworm is particularly common in Asia, Sub-Saharan Africa, and Latin America. In some areas it is believed that up to 25% of people are affected. In the developed world it is very uncommon. Worldwide in 2015 it caused about 400 deaths. Cysticercosis also affects pigs and cows but rarely causes symptoms as most do not live long enough. The disease has occurred in humans throughout history. It is one of the neglected tropical diseases. Cysticerci can develop in any voluntary muscles in humans. Invasion of muscle by cysticerci can cause myositis, with fever, eosinophilia, and muscular pseudohypertrophy, which initiates with muscle swelling and later progress to atrophy and fibrosis. In most cases, it is asymptomatic since the cysticerci die and become calcified. The term neurocysticercosis is generally accepted to refer to cysts in the parenchyma of the brain. It presents with seizures and, less commonly, headaches. Cysticerca in brain parenchyma are usually 5–20 mm in diameter. In subarachnoid space and fissures, lesions may be as large as 6 cm in diameter and lobulated. They may be numerous and life-threatening. Cysts located within the ventricles of the brain can block the outflow of cerebrospinal fluid and present with symptoms of increased intracranial pressure. Racemose neurocysticercosis refers to cysts in the subarachnoid space. These can occasionally grow into large lobulated masses causing pressure on surrounding structures. Spinal cord neurocysticercosis most commonly presents symptoms such as back pain and radiculopathy.