Medical management of neurocysticercosis

Update on the diagnosis and management of neurocysticercosis

ABSTRACT Background: Neurocysticercosis (NCC) is a serious public health problem in several developing countries, including those in Latin America, Asia, and Africa. NCC is considered to be the main cause of late-onset epilepsy in endemic areas. Objective: This review summarizes recent advances in diagnosis and therapy of NCC. Methods: Relevant articles and books were reviewed and used as a source of information for this review. Results: The diagnosis of NCC is based upon neuroimaging studies (MRI and computed tomography) and laboratory analysis of the cerebrospinal fluid (CSF). Praziquantel and albendazole are considered parasiticidal drugs against NCC, but there is an intense debate over the value and safety of these drugs. Conclusion: Given the relative scarcity of clinical trials, more comparative interventional studies, especially randomized controlled trials in long-term clinical evolution, are required in order to clarify the controversy over the validity of parasitic therapy in patients with NCC.

Neurocysticercosis in a Japanese woman with lung cancer who repeatedly visited endemic countries

BACKGROUND

Taenia solium, present in most developing countries, infects many individuals and may result in their death. Neurocysticercosis (NCC) develops after invasion of the brain by parasitic larvae. It is the most common parasitic disease of the human central nervous system. On imaging scans it can be similar to brain tumors. We report a patient with a metastatic brain tumor and NCC. The co-presence of NCC was diagnosed based on specific neuroimaging- and epidemiologic findings.

CASE PRESENTATION

A 36-year-old non-smoking Japanese woman with a history of non-small-cell lung cancer had undergone resection of the lower lobe followed by cytotoxic chemotherapy 2 years before apparently suffering recurrence. A positron emission computed tomography (PET) scan incidentally revealed multiple intracranial cold spots exhibiting differences in their shape and size. On brain magnetic resonance imaging (MRI) scans we observed many different patterns of peripheral edema and gadolinium-enhancing effects. As she had often visited Latin America and Southeast Asia and had eaten raw pork and Kimchi, we suspected that the brain lesions were due to NCC rather than metastatic brain tumors. However, serum immunoblotting assay and DNA analysis were negative for T. solium. Rather than performing resection, we administered albendazole (ABZ) and dexamethasone because her earlier cytotoxic chemotherapy had elicited severe pancytopenia. Except for a single large lesion in the left frontal lobe, this treatment resulted in a significant reduction in the size of these lesions and a decrease in perilesional edema. She underwent resection of the residual lesion 10 months later. Histology revealed it to be a metastatic tumor. Polymerase chain reaction (PCR) assay for NCC was negative. In the course of 11-months follow-up there has been no recurrence.

CONCLUSION

This is the first presentation of NCC in a Japanese woman with a metastatic brain tumor. NCC was incidentally discovered on PET scans and, based on her travel history and epidemiological findings; it was diagnosed and successfully treated with ABZ. NCC is endemic in most developing countries and as visits to such countries have increased, NCC must be ruled out in patients with multiple cystic nodular brain lesions.

Albendazole and Mebendazole as Anti-Parasitic and Anti-Cancer Agents: an Update

The use of albendazole and mebendazole, i.e., benzimidazole broad-spectrum anthelmintics, in treatment of parasitic infections, as well as cancers, is briefly reviewed. These drugs are known to block the microtubule systems of parasites and mammalian cells leading to inhibition of glucose uptake and transport and finally cell death. Eventually they exhibit ovicidal, larvicidal, and vermicidal effects on parasites, and tumoricidal effects on hosts. Albendazole and mebendazole are most frequently prescribed for treatment of intestinal nematode infections (ascariasis, hookworm infections, trichuriasis, strongyloidiasis, and enterobiasis) and can also be used for intestinal tapeworm infections (taeniases and hymenolepiasis). However, these drugs also exhibit considerable therapeutic effects against tissue nematode/cestode infections (visceral, ocular, neural, and cutaneous larva migrans, anisakiasis, trichinosis, hepatic and intestinal capillariasis, angiostrongyliasis, gnathostomiasis, gongylonemiasis, thelaziasis, dracunculiasis, cerebral and subcutaneous cysticercosis, and echinococcosis). Albendazole is also used for treatment of filarial infections (lymphatic filariasis, onchocerciasis, loiasis, mansonellosis, and dirofilariasis) alone or in combination with other drugs, such as ivermectin or diethylcarbamazine. Albendazole was tried even for treatment of trematode (fascioliasis, clonorchiasis, opisthorchiasis, and intestinal fluke infections) and protozoan infections (giardiasis, vaginal trichomoniasis, cryptosporidiosis, and microsporidiosis). These drugs are generally safe with few side effects; however, when they are used for prolonged time (>14-28 days) or even only 1 time, liver toxicity and other side reactions may occur. In hookworms, Trichuris trichiura, possibly Ascaris lumbricoides, Wuchereria bancrofti, and Giardia sp., there are emerging issues of drug resistance. It is of particular note that albendazole and mebendazole have been repositioned as promising anti-cancer drugs. These drugs have been shown to be active in vitro and in vivo (animals) against liver, lung, ovary, prostate, colorectal, breast, head and neck cancers, and melanoma. Two clinical reports for albendazole and 2 case reports for mebendazole have revealed promising effects of these drugs in human patients having variable types of cancers. However, because of the toxicity of albendazole, for example, neutropenia due to myelosuppression, if high doses are used for a prolonged time, mebendazole is currently more popularly used than albendazole in anti-cancer clinical trials.

Follow-up study of high-dose praziquantel therapy for cerebral sparganosis

Background

Cerebral sparganosis is the most serious complication of human sparganosis. Currently, there is no standard for the treatment of inoperable patients. Conventional-dose praziquantel therapy is the most reported treatment. However, the therapeutic outcomes are not very effective. High-dose praziquantel therapy is a useful therapeutic choice for many parasitic diseases that is well tolerated by patients, but it has not been sufficiently evaluated for cerebral sparganosis. This study aims to observe the prognoses following high-dose praziquantel therapy in inoperable patients and the roles of MRI and peripheral eosinophil absolute counts during follow-up.

Methodology

Baseline and follow-up epidemiological, clinical, radiological and therapeutic data related to 10 inoperable patients with cerebral sparganosis that were treated with repeated courses of high-dose praziquantel therapy, with each course consisting of 25 mg/kg thrice daily for 10 days were assessed, followed by analyses of the prognoses, MRI findings and peripheral eosinophil absolute counts.

Principal findings

Baseline clinical data: the clinical symptoms recorded included seizures, hemiparesis, headache, vomiting and altered mental status. Peripheral blood eosinophilia was found in 3 patients. The baseline radiological findings were as follows. Motile lesions were observed in 10 patients, including aggregated ring-like enhancements, tunnel signs, serpiginous and irregular enhancements. Nine of the 10 patients had varying degrees of white matter degeneration, cortical atrophy and ipsilateral ventricle dilation. The follow-up clinical data were as follows. Clinical symptom relief was found in 8 patients, symptoms were eliminated in 1 patient, and symptoms showed no change from baseline in 1 patient. Peripheral blood eosinophilia was found in 2 patients. The follow-up radiological findings were as follows. Motile lesions that were transformed into stable, chronic lesions were found in 8 patients, and motile lesions that were eliminated completely were found in 2 patients.

Conclusions

High-dose praziquantel therapy for cerebral sparganosis is effective. The radiological outcomes of motile lesions are an important indicator during the treatment process, especially during follow-ups after clinical symptoms have improved. Peripheral eosinophil absolute counts cannot be used as an effective prognostic indicator.

Sparganosis is a rare parasitic disease with a high prevalence in East Asia. Because of limited radiological technology and clinical experience, the prevalence of cerebral sparganosis is likely underestimated in developing countries. Cerebral sparganosis is the most serious complication of human sparganosis. Currently, it is generally believed that the most effective treatment for cerebral sparganosis is surgical treatment. However, the choice of treatment is a challenge for inoperable patients, including those with multifocal lesions or lesions in deep structures or important functional areas and those refusing invasive treatment due to personal willingness. Currently, there is no standard for the treatment of inoperable patients. In addition, anthelmintic treatment for sparganosis has rarely been reported in the literature. High-dose praziquantel therapy is a useful therapeutic choice for many cerebral parasitic diseases, including neurocysticercosis, and is well tolerated for patients, but it has not been sufficiently evaluated for the treatment of cerebral sparganosis. This study aims to describe the clinical, radiological and therapeutic data following high-dose praziquantel therapy for ten inoperable patients. All patients reached clinical cure after one to five courses. These results suggest that high-dose praziquantel therapy for cerebral sparganosis could achieve favorable outcomes and that MRI plays an important role in follow-up, especially when clinical symptoms have improved.

Human taeniasis/cysticercosis: a potentially emerging parasitic disease in Europe

Taenia saginata (T. saginata)/Taenia solium (T. solium) taeniasis/cysticercosis disease complexes remain a significant challenge for food safety and public health. Human taeniasis is an infectious disease caused by the ingestion of the metacestode larval stage, the cysticerci of T. saginata in beef or T. solium in pork. Humans can also become infected via the ingestion of T. solium eggs. In this case, the cysticerci can establish in the central nervous system, causing the infection called neurocysticercosis. T. solium is of higher importance than T. saginata because the former species can cause neurocysticercosis in humans, a major cause of neurological morbidity in the world. The taeniasis/cysticercosis complex is included in the list of neglected zoonotic diseases by the World Health Organization and Food and Agriculture Organization, with T. solium being the number one foodborne parasite; it occurs mostly in developing countries, such as regions of Asia, Africa and Latin America, where the disease remains endemic. Long absent in Western Europe and other developed countries, cysticercosis has been recently re-emerged as a result of immigration, travel and commerce. In this review, cysticercosis is presented with special emphasis on some aspects of this neglected disease: the main clinical manifestations, risk factors and epidemiology. In addition, any recent advances in diagnostic approaches and treatment are discussed. Finally, the complexities involved in the control of the disease and the need to revise current management strategies are highlighted.

Cysticercosis/taeniasis endemicity in Southeast Asia: Current status and control measures

The parasitic zoonoses cysticercosis/taeniasis is among the 17 major Neglected Tropical Diseases (NTDs) identified by the WHO as a focus for research and control. It is caused by a larval stage (cysticercus) infection of Taenia solium tapeworm in both humans and pigs. Cysticercosis occurs in many resource-poor countries, especially those with warm and mild climates in the regions of Latin America (LA), Asia and Sub-Saharan Africa (SSA). The prevalence of human cysticercosis is marked in those areas where individuals are traditionally keen to consume raw or insufficiently cooked pork and/or where the husbandry of pigs is improper. The worldwide burden of cysticercosis is unclear and notably, large-scale control initiatives are lacking in all regions. This review focuses on the current endemic status of cysticercosis caused by T. solium infection in both humans and pigs living in 13 Southeast Asian countries. We will also emphasize epidemiological data as well as prevention and control of human neurocysticercosis.

Neurocysticercosis with Diplopia Responds Well to Albendazole

We report a case of neurocysticercosis concurrent with taeniasis in a 31-year-old woman. The patient presented with a headache and diplopia. Oculomotor disturbances with a left adduction deficit were observed. Fundoscopy revealed papilledema. Additionally, computed tomography of the brain revealed more than 20 small cysts within the parenchyma, most of which were associated with ring enhancement. Moreover, serum antibody testing (Western blotting) for Taenia solium-cysticerci was positive. The patient received albendazole and corticosteroids, and progressive resolution of the neurological symptoms and papilledema was observed starting approximately three days after administration. This patient has been asymptomatic for more than one year.

An Unusual Presentation of Neurocysticercosis: A Space-Occupying Lesion in the Fourth Ventricle Associated with Progressive Cognitive Decline

We communicate a case of a middle-aged Brazilian patient with an unusual presentation of fourth ventricular neurocysticercosis: occurrence of two intraventricular cysts at different locations in the brain within 2 years and cognitive decline as the only neurological symptom. Neurocysticercosis was confirmed by magnetic resonance imaging, serology, histology, and genetic analysis. Neurocysticercosis should be considered as a differential diagnosis in cases with atypical neurologic or psychiatric symptoms, atypical neuroimaging and travel history. Especially, fourth ventricular cysts carry the risk of obstructive hydrocephalus and brainstem compression and therefore should be extirpated completely. If complete removal of the cystic structures cannot be proven in cases with surgically treated neurocysticercosis, anthelminthic therapy and thorough follow-up examinations should be conducted.

Managing neurocysticercosis: challenges and solutions

Taenia solium neurocysticercosis (NCC) is a major cause of neurological morbidity in the world. Variability in the neuropathology and clinical presentation of NCC often make it difficult to diagnose and manage. Diagnosis of NCC can be challenging especially in endemic and resource-limited countries where laboratory and imaging techniques are often lacking. NCC management can also be challenging as current treatment options are limited and involve symptomatic agents, antiparasitic agents, or surgery. Although antiparasitic treatment probably reduces the number of active lesions and long-term seizure frequency, its efficacy is limited and strategies to improve treatment regimens are warranted. Treatment decisions should be individualized in relation to the type of NCC. Initial measures should focus on symptomatic management, with antiparasitic therapy only to be considered later on, when appropriate. Symptomatic treatment remains the cornerstone in NCC management which should not only focuses on epilepsy, but also on other manifestations that cause considerable burden (recurrent headaches, cognitive decline). Accurate patients’ categorization, better antiparasitic regimens, and definition of new clinical outcomes for trials on NCC could improve management quality and prognosis of NCC. Prevention strategies targeting tapeworm carriers and infected pigs are yielding good results in local models. If local elimination of transmission is confirmed and replicated, this will open the door to cysticercosis eradication efforts worldwide.

Neurocysticercosis

Cysticercosis is one of the most common parasitic diseases of the nervous system in humans, and constitutes a major public health problem for most of the developing world. The clinical manifestations of neurocysticercosis (NCC) largely depend on the the host immune response against the parasite. NCC diagnosis is based upon neuroimaging studies (computerized tomography, magnetic resonance imaging) and antibody/antigen detection in the serum and the cerebrospinal fluid. Anticysticercal therapy has been marked by an intense controversy. Randomized controlled trials evaluating the clinical benefit of treatment have yield conflicting data with some studies indicating a benefit and others failing to show a difference. Prevention strategies must rely on multiple approaches, tailoring each to the special features of the particular endemic area.

Nothing is perfect! Trouble-shooting in immunological and molecular studies of cestode infections

This personal review focuses on ways to approach and overcome some of the more common issues encountered while studying cestode zoonoses. The information presented here is based on the author's own experiences with immunological and molecular approaches for the detection of these parasites. There are many incongruities between immunological and molecular studies due to biased work. Nothing is perfect. Indirect approaches using either immunological, or even molecular tools, are limited without confirmation from direct evidence of infection. The dilemma of whether developing countries should develop their own diagnostic tests or rely on commercially available kits is also discussed.

Praziquantel treatment in trematode and cestode infections: an update

Status and emerging issues in the use of praziquantel for treatment of human trematode and cestode infections are briefly reviewed. Since praziquantel was first introduced as a broadspectrum anthelmintic in 1975, innumerable articles describing its successful use in the treatment of the majority of human-infecting trematodes and cestodes have been published. The target trematode and cestode diseases include schistosomiasis, clonorchiasis and opisthorchiasis, paragonimiasis, heterophyidiasis, echinostomiasis, fasciolopsiasis, neodiplostomiasis, gymnophalloidiasis, taeniases, diphyllobothriasis, hymenolepiasis, and cysticercosis. However, Fasciola hepatica and Fasciola gigantica infections are refractory to praziquantel, for which triclabendazole, an alternative drug, is necessary. In addition, larval cestode infections, particularly hydatid disease and sparganosis, are not successfully treated by praziquantel. The precise mechanism of action of praziquantel is still poorly understood. There are also emerging problems with praziquantel treatment, which include the appearance of drug resistance in the treatment of Schistosoma mansoni and possibly Schistosoma japonicum, along with allergic or hypersensitivity reactions against praziquantel treatment. To cope with and overcome these problems, combined use of drugs, i.e., praziquantel and other newly introduced compounds such as triclabendazole, artemisinins, and tribendimidine, is being tried.

A research agenda for helminth diseases of humans: the problem of helminthiases

A disproportionate burden of helminthiases in human populations occurs in marginalised, low-income, and resource-constrained regions of the world, with over 1 billion people in developing areas of sub-Saharan Africa, Asia, and the Americas infected with one or more helminth species. The morbidity caused by such infections imposes a substantial burden of disease, contributing to a vicious circle of infection, poverty, decreased productivity, and inadequate socioeconomic development. Furthermore, helminth infection accentuates the morbidity of malaria and HIV/AIDS, and impairs vaccine efficacy. Polyparasitism is the norm in these populations, and infections tend to be persistent. Hence, there is a great need to reduce morbidity caused by helminth infections. However, major deficiencies exist in diagnostics and interventions, including vector control, drugs, and vaccines. Overcoming these deficiencies is hampered by major gaps in knowledge of helminth biology and transmission dynamics, platforms from which to help develop such tools. The Disease Reference Group on Helminths Infections (DRG4), established in 2009 by the Special Programme for Research and Training in Tropical Diseases (TDR), was given the mandate to review helminthiases research and identify research priorities and gaps. In this review, we provide an overview of the forces driving the persistence of helminthiases as a public health problem despite the many control initiatives that have been put in place; identify the main obstacles that impede progress towards their control and elimination; and discuss recent advances, opportunities, and challenges for the understanding of the biology, epidemiology, and control of these infections. The helminth infections that will be discussed include: onchocerciasis, lymphatic filariasis, soil-transmitted helminthiases, schistosomiasis, food-borne trematodiases, and taeniasis/cysticercosis.

Parasitic infections in HIV infected individuals: diagnostic & therapeutic challenges

After 30 years of the human immunodeficiency virus (HIV) epidemic, parasites have been one of the most common opportunistic infections (OIs) and one of the most frequent causes of morbidity and mortality associated with HIV-infected patients. Due to severe immunosuppression, enteric parasitic pathogens in general are emerging and are OIs capable of causing diarrhoeal disease associated with HIV. Of these, Cryptosporidium parvum and Isospora belli are the two most common intestinal protozoan parasites and pose a public health problem in acquired immunodeficiency syndrome (AIDS) patients. These are the only two enteric protozoan parasites that remain in the case definition of AIDS till today. Leishmaniasis, strongyloidiasis and toxoplasmosis are the three main opportunistic causes of systemic involvements reported in HIV-infected patients. Of these, toxoplasmosis is the most important parasitic infection associated with the central nervous system. Due to its complexity in nature, toxoplasmosis is the only parasitic disease capable of not only causing focal but also disseminated forms and it has been included in AIDS-defining illnesses (ADI) ever since. With the introduction of highly active anti-retroviral therapy (HAART), cryptosporidiosis, leishmaniasis, schistosomiasis, strongyloidiasis, and toxoplasmosis are among parasitic diseases reported in association with immune reconstitution inflammatory syndrome (IRIS). This review addresses various aspects of parasitic infections in term of clinical, diagnostic and therapeutic challenges associated with HIV-infection.