Cryptosporidium infection of human intestinal epithelial cells increases expression of osteoprotegerin: a novel mechanism for evasion of host defenses.

Cryptosporidium parasites are pathogens of human intestinal epithelial cells. To determine which genes are regulated during early infection, human ileal mucosa cultured as explants was infected with C. parvum or C. hominis, and gene expression was analyzed by microarray. The gene for osteoprotegerin (OPG) was up-regulated by both parasites. OPG mRNA was also significantly increased in biopsy specimens obtained from a volunteer experimentally infected with C. meleagridis, compared with levels in a prechallenge biopsy specimen. After in vitro infection of HCT-8 cells, there was an early peak in production of OPG mRNA protein. Treatment of infected cells with the OPG ligand tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) induced epithelial cell apoptosis and reduced parasite numbers, and recombinant OPG blocked these effects. These results suggest a novel TRAIL-mediated pathway for elimination of Cryptosporidium infection and a role for OPG in modulating this host response.

Advances in the diagnosis and management of neurocysticercosis.

Neurocysticercosis is the most common cause of late-onset epilepsy in developing countries. The larval stage of Taenia solium is the causative agent of the disease. Recent advances in neuroimaging and serologic diagnostic techniques have led to increased recognition of its importance, but its pathogenesis is just beginning to be clarified. Experts now agree that the clinical manifestations, pathogenic mechanisms and optimal treatment vary with the number of parasites, their location and the degree of host inflammation. Symptomatic therapy (i.e., antiepileptic medications and, when indicated, surgery) is critically important but there are also important roles for antiparasitic and anti-inflammatory drugs. Neurocysticercosis is a potentially eradicable disease but this is probably unlikely to be achieved in the short term.

Cysticercosis: Recent Advances in Diagnosis and Management of Neurocysticercosis.

Neurocysticercosis, caused by infection with the pork tapeworm Taenia solium, is increasingly recognized as a cause of neurologic disease worldwide. Because the clinical presentation is nonspecific, diagnosis has been difficult. Advances in imaging studies and serodiagnostic techniques are facilitating the diagnosis of neurocysticercosis and tapeworm carriers. Neurocysticercosis represents a spectrum of disease. Seizures are the main clinical manifestation in parenchymal neurocysticercosis. Recent studies emphasize that such seizures are the result of the host inflammatory response, even in patients who only have calcifications with no viable cysticerci. Controlled clinical trials have demonstrated that antiparasitic drugs can decrease the number of generalized seizures, although the benefit is small and confined to a subgroup of patients. Corticosteroids can also decrease seizure frequency. Case studies have demonstrated that endoscopic surgery appears to be the optimal approach to ventricular cysts. Recombinant vaccines are being developed and may prove important in disease control.