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Seizures
Seizures are usually the first sign of NCC. According to Schantz et al. (1998), Vasquez et al. (1992) and Zenteno-Alanis, (1982), it is estimated that in an endemic area NCC may be the cause of epilepsy in 30 to 50% of cases.
Patients with NCC usually have partial-onset seizures with or without secondary generalization (Carabin et al., 2011). When the first seizure occurs, most patients show an active cyst on CT scan of the brain – either a vesicular cyst or a colloidal cyst – as reported by Medina et al. (1990) and Del Brutto et al. (1992). Newonset seizures are commonly associated with an active cyst rather than a calcified cyst. Carpio et al. (2002) reported that chronic epilepsy is usually associated with calcified cysts.
Epileptogenesis in patients with NCC is related to several different factors:
inflammation, gliosis and predilection for the cysts to travel to the frontal and temporal lobes, as reported by Sanchez et al. (1999) and Stringer et al., (2003). Sotelo (1995) contributed to this discussion by reporting that the host response to degenerating cysts plays an important role in the associated epileptogenesis. Children and young women tend to present a more intense host reaction to a parasitic infection of the brain while adults usually have a variable response (Sotelo, 1995).
Antibody detection methods
Different techniques have been described to detect antibodies to T. solium infections in humans and pigs, such as the complement fixation test, hemagglutination, radioimmunoassay, enzyme-linked immunosorbent assay (ELISA), dipstick-ELISA, latex agglutination and immunoblot techniques (Ferreira et al., 1997; Garcia and Sotelo, 1991; Ito et al., 1998; Miller et al., 1984; Rocha et al., 2002 and Tsang et al., 1989). According to Tsang et al. (1989) the most specific test developed is the enzymelinked immunoelectrotransfer blot (EITB), which is widely used for the diagnosis of cysticercosis in human and pig serum samples. This test is an immunoblot of seven cysticercus glycoproteins, purified by lentil lectin-purified chromatography, which gives close to 100% specificity and a sensitivity varying from 70 to 90%.
However, Wilson et al. (1991) reported a sensitivity of only 28% in cases with single cysts in the brain.
Because of issues related to availability, simplicity and cost, ELISA testing is often preferred to immunoblot tests. Rosas et al. (1986) reported that this is the choice made by most developing countries since the test may provide a suitable alternative and may also provide a tool for serological monitoring of anti-parasitic therapy. Ito et al. (1998) reported also that the purification of glycoproteins from cyst fluid by single-step preparative isoelectric focusing produced very specific antigens which can be applied in both immunoblot and ELISA with comparable specificity and sensitivity. The specificity and sensitivity of ELISA matched those of immunoblot methods in Ito’s study.
There are two major problems related to antibody detection in clinical settings: (i) as reported by Garcia et al. (2001), antibodies indicate the exposure to infection but not the presence of an active infection, and (ii) as reported by Harrison et al. (1989) and Garcia et al. (1997), antibodies may persist long after the parasite has been eliminated by immune mechanisms or drug therapy.
Thus antibody testing does not necessarily reflect the true prevalence of cysticercosis and may lead to unnecessary use of antiparasitic therapy in cases where no active infection exists (Bern et al., 1999; Garcia et al., 2000).
Antigen detection methods
Antigen detection may provide a suitable alternative to antibody detection. It may also provide a tool for serological monitoring of anti-parasitic therapy. Several assays as reported by Correa et al. (1989); Wang et al. (1992) and Erhart et al. (2002) have been developed to detect parasite antigens, but only the monoclonal antibody-based tests directed at defined parasite antigens were able to ensure sensitivity, specificity and reproducibility.
Antigen detection may be performed on serum as well as on CSF according to Choromanski et al. (1990) and Garcia et al. (1998, 2000). Because of the localization of the cysts in the brain, antigen detection in CSF may be more appropriate for diagnosis than in the serum; however, sampling of CSF is more demanding and with higher risk of complications than blood sampling.
The sensitivity of the antigen detecting ELISA test is reported to be high. Garcia et al. (2000) found a sensitivity of 85%, however, in their study only patients who were seropositive on EITB were examined with ELISA. The sensitivity in patients with a single viable cyst was 65% as reported by Garcia et al. (2000). Erhart et al. (2002) found a very high agreement between an ELISA for detecting circulating antigen, computerized tomography scanning and biopsy examination of subcutaneous cysticerci.
CHAPTER ONE
INTRODUCTION
CHAPTER TWO
THE CURRENT STATUS OF HUMAN CYSTICERCOSIS IN THE WORLD
CHAPTER THREE
TAENIA SOLIUM / CYSTICERCOSIS / NEUROCYSTICERCOSIS
3.1. TAENIA SOLIUM AND CYSTICERCUS CELLULOSAE
3.2. TAENIA SOLIUM LIFE CYCLE
3.3. NEUROCYSTICERCOSIS
3.4. POPULATION AT RISK
3.5. DIAGNOSIS OF CYSTICERCOSIS / NEUROCYSTICERCOSIS
3.6 MANAGEMENT AND TREATMENT OF CYSTICERCOSIS
3.7 PROGNOSIS
3.8 CONTROL OF TAENIA SOLIUM
3.9 RATIONALE FOR THE STUDY
3.10 OBJECTIVE
CHAPTER FOUR
METHODOLOGY
4.1 STUDY AREA AND POPULATION
4.2 STUDY DESIGN
4.3 SAMPLING AND SAMPLE SIZE CALCULATION
4.4 METHODS
4.5 DATA MANAGEMENT AND ANALYSIS
4.6 ETHICAL CONSIDERATIONS
CHAPTER FIVE
RESULTS
5.1. SOCIO DEMOGRAPHIC CHARACTERISTICS
5.2. DRINKING WATER AND SANITATION INFORMATION
5.3. PORK CONSUMPTION AND MANAGEMENT INFORMATION
5.4. HUMAN CYSTICERCOSIS / TAENIOSIS INFORMATION
5.5. EPIDEMIOLOGY OF EPILEPSY IN THE STUDY AREA
5.6. SEROLOGICAL DIAGNOSIS OF CYSTICERCOSIS
5.7. HISTORY OF EPILEPSY AND POSITIVE SEROLOGY
5.8. ENVIRONMENTAL FACTORS AND SEROLOGY
5.9. RISK FACTORS FOR NCC
5.10. SEROPOSITIVITY, BRAIN CT SCAN AND EEG EXAM
5.11. EEG RESULTS
CHAPTER SIX
DISCUSSION
6.1. SOCIO DEMOGRAPHIC CHARACTERISTICS
6.2. DRINKING WATER AND SANITATION INFORMATION
6.3. PORK CONSUMPTION AND PORK MANAGEMENT
6.4. HUMAN NEUROCYSTICERCOSIS \ TAENIOSIS
6.5. EPILEPSY PREVALENCE
6.6. EPIDEMIOLOGY OF CYSTICERCOSIS
6.7. BRAIN CT SCAN EXAM
6.8. EEG EXAM
6.9. NCC TREATMENT
6.10. DISEASE BURDEN DUE TO T. SOLIUM
6.11. CONTROL STRATEGY
CHAPTER SEVEN
CONCLUSIONS AND RECOMMENDATIONS
REFERENCES
