Historical perspective: The British contribution to the understanding of neurocysticercosis

Neurocysticercosis: The duration of its preclinical phase relies on the parasite location

OBJECTIVES

Neurocysticercosis (NC) is a heterogeneous disease particularly in terms of response to treatment and prognosis. Parasite localization is one of the main factors involved in this heterogeneity. In this study we aim to determine whether differences in the duration of the preclinical phase associated with parasite location, could contribute to said heterogeneity.

METHODS

Ninety-nine patients were included, 24 with parasites in the parenchyma (PAR), 56 in the subarachnoid (SA) space and 19 in the ventricular system (IV). A questionnaire designed to assess exposure to classic NC risk factors 5, 10, 15, 20 and more than 20 years prior to diagnosis was applied. The results were compared between the three groups. Also, asymptomatic relatives of patients who had shared their living conditions in childhood or more recently were included and underwent brain scan and blood testing for specific antibodies.

RESULTS

Over the course of their lives, exposure to risk factors decreased significantly for all patients, although the decrease was more evident in patients with parasites in the SA space (p < 0.001) compared to patients with PAR (p = 0.011) or IV cysts (p = 0.020). Five years prior to diagnosis, exposure to risk factors was significantly higher in patients with PAR or IV NC than in patients with SA NC (p = 0.04). Furthermore, individuals in close contact with PAR or IV patients in the years preceding diagnosis were more likely to have asymptomatic NC, specific antibodies in sera, particularly IgM, compared to individuals in close contact with SA patients during the same period.

CONCLUSIONS

All these findings are highly suggestive of the possibility of a more recent infection of patients affected by parenchymal and ventricular NC than of patients with subarachnoid NC. Consequently, subarachnoid disease could be considered a chronic disease, which, probably contributes to the severity of the disease as well as the minimal response to medical treatment.

Standardizing an Experimental Murine Model of Extraparenchymal Neurocysticercosis That Immunologically Resembles Human Infection

BACKGROUND

Neurocysticercosis (NCC) is endemic in non-developed regions of the world. Two forms of NCC have been described, for which neurological morbidity depends on the location of the lesion, which can be either within the cerebral parenchyma or in extraparenchymal spaces. The extraparenchymal form (EXP-NCC) is considered the most severe form of NCC. EXP-NCC often requires several cycles of cysticidal treatment and the concomitant use of glucocorticoids to prevent increased inflammation, which could lead to intracranial hypertension and, in rare cases, to death. Thus, the improvement of EXP-NCC treatment is greatly needed.

METHODS

An experimental murine model of EXP-NCC, as an adequate model to evaluate new therapeutic approaches, and the parameters that support it are described. EXP-NCC was established by injecting 30 Taenia crassiceps cysticerci, which are less than 0.5 mm in diameter, into the cisterna magna of male and female Wistar rats.

RESULTS

Cyst implantation and infection progression were monitored by detecting the HP10 antigen and anti-cysticercal antibodies in the serum and cerebral spinal fluid (CSF) of infected rats and by magnetic resonance imaging. Higher HP10 levels were observed in CSF than in the sera, as in the case of human EXP-NCC. Low cell recruitment levels were observed surrounding established cysticerci in histological analysis, with a modest increase in GFAP and Iba1 expression in the parenchyma of female animals. Low cellularity in CSF and low levels of C-reactive protein are consistent with a weak inflammatory response to this infection. After 150 days of infection, EXP-NCC is accompanied by reduced levels of mononuclear cell proliferation, resembling the human disease. EXP-NCC does not affect the behavior or general status of the rats.

CONCLUSIONS

This model will allow the evaluation of new approaches to control neuroinflammation and immunomodulatory treatments to restore and improve the specific anti-cysticercal immunity in EXP-NCC.

Mortality associated with cysticercosis in a historical cohort from Britain

ABSTRACT Background: The burden of premature mortality associated with human cysticercosis is largely ignored mainly due to poor record-keeping in Taenia solium endemic regions. Objective: To document mortality and survival characteristics of an historical cohort with cysticercosis. Methods: The years of onset of symptoms and death untill 1957 were extracted from published reports of a British military cohort (n=450) examined in London in the early twentieth century. Data were entered into a Kaplan Meier survival analysis with the presence (or absence) of clinical manifestations as independent variables, which were then fitted into a Cox proportional hazards model to determine their significance. Results: Cysticercosis was responsible for 24 (52.2%) of 46 deaths in the first 15 years of follow-up in comparison to 7 (19.4%) of 36 deaths in the 20-40 years of follow-up period. In the univariate and Cox analyses, intracranial hypertension (hazard ratio [HR]: 8.26; CI: 4.71, 14.49), ocular cysticercosis (HR: 6.60; CI: 3.04, 14.33), and mental disorder (HR: 3.98; CI: 2.22, 7.13) but not epilepsy (HR: 0.66; CI: 0.20, 2.18) were associated with mortality. Over half of all deaths in the first 15 years of follow-up were attributed to cysticercosis. Conclusions: Several deaths occurred early after acquiring cysticercotic infection. Intracranial hypertension, ocular cysticercosis, and mental disorder but not epilepsy were predictors of mortality in this cohort.

Neurocysticercosis and movement disorders: A literature review

Neurocysticercosis (NCC) is a specific form of cysticercosis that affects the central nervous system. It is caused by the tapeworm Taenia solium, which is often found in pigs. NCC is considered one of the “great simulator/mimickers” of other diseases. In this context, movement disorders (MDs) can occur in a small percentage of individuals with NCC. This review aims to evaluate the clinicoepidemiological profile, pathological mechanisms, and historical features of NCC-associated MD. Relevant reports in six databases were identified and assessed by two reviewers without language restriction. A total of 71 reports containing 148 individuals who developed an MD related to NCC were identified. NCC-associated MD included parkinsonism (n = 47), ataxia (n = 32), chorea (n = 18), dystonia (n = 13), tremor (n = 8), myokymia (n = 6), myoclonus (n = 4), ballism (n = 1), tics (n = 1), and others (n = 18). The mean and median ages were 36.58 (standard deviation: 20.51) and 35 years (age range: 1–88 years), respectively. There was a slight predominance of female sex (52.17%). On follow-up, 58.90% of the individuals had a full recovery; two deaths were reported. We believe that the majority of cases reported were only diagnosed because patients had classical clinical manifestations generally investigated by neuroimaging, resulting in incidental findings suggestive of NCC, which were later supported by laboratory examinations. Therefore, the association between NCC and MD is probably underreported. Clinicians should be wary of this association, mainly in endemic areas for cysticercosis.