**3. Other helminth parasitic infections to be considered**

The capacity of climatic conditions to modulate the extent and intensity of parasitism is well known since long ago. Concerning helminths, among the numerous environmental modifications giving rise to changes in infections, climate variables appear as those showing a greater influence, so that climate change may be expected to have an important impact on the diseases they cause. However, the confirmation of the impact of climate change on helminthiases has been reached very recently. Only shortly before, helminthiases were still noted as infectious diseases scarcely affected by climate change, when compared to diseases caused by microorganisms in general: viruses, bacteria, and protozoans (Mas-Coma et al., 2009). In this group we have: neurocysticercosis as a leading cause of epilepsy in developing coutries and some developed places. (Foyaca-Sibat, 2011), and also sparganosis and toxocariasis among others.

#### **3.1 Neurosparganosis**

Sparganosis is a rare parasitic infection caused by the larval cestode of *Spirometra* that results from ingesting the plerocercoid harbored in frogs, snakes, and chickens. Reported worldwide, sparganosis is most prevalent in Southeast and Eastern Asia. The diagnosis is suggested by a wandering lesion, especially in endemic areas; the tunnel sign on a post contrast MRI is characteristic. The preferred treatment is the surgical removal of live worm.( Shirakawa et al., 2010) In the endemic area of sparganosis, where other neurological parasitic infestations (*e.g.* cysticercosis and gnathostomiasis) are also common, the clinical usefulness of MR imaging is very limited in providing a definitive diagnosis of cerebral sparganosis. A history of risky behaviour (*e.g.* drinking impure water, eating frog or snake meat, or using frog or snake meat as a poultice) might be a clue and offers supporting evidence for a presumptive diagnosis in cases of abnormal brain MR imaging results ( Song et al., 2007; Chiu et al., 2010; Wiwanitkit, 2010). 4 cases had a history of eating raw frogs or snakes. 5 showed eosinophilia in peripheral blood, all with positive anti-Sparganum mansoni antibody in serum and cerebrospinal fluid. Cerebral MRI showed placeholder in all patients. Diagnosis was confirmed by pathological examination of operations and species identification. All patients were cured by operation removal and praziquantel treatment. (Chen & Shi, 2010).

#### **3.2 Neurofilariasis**

324 Novel Aspects on Epilepsy

(suramin, pentamidine, and melarsoprol), only melarsoprol penetrates the blood-brain barrier to be effective in CNS disease. Its use is complicated by an up to 18% incidence of severe, reactive arsenic encephalopathy, which can result in permanent neurologic damage or death. Consequently, melarsoprol should be used only in patients with CNS involvement. In a study of melarsoprol effects on patients with T. gambiense in the meningoencephalitic stage, EEG tracings before treatment showed marked abnormalities in the form of periodic

American trypanosomiasis, also known as Chagas' disease, is an acute or chronic infection caused by *Trypanosoma cruzi* and occurs only in the western hemisphere. Chagas disease is the third most common parasitic infection worldwide after malaria and schistosomiasis. (WHO 2005). Seizures sometimes occur at stroke onset, and epilepsy is quite a frequent complication after chagasic stroke. Chronic vascular epilepsy, characterized by secondary generalised seizures, have been reported in around 20% of patients surviving chagasic stroke, whereas around 10% of stroke patients without the Chagas disease have seizures (Carod-Artal et al., 2005).The effect of uncontrolled seizures on cognition and disability in Chagas disease is unknown. No prospective epidemiological studies have addressed the risk of acute seizures and their recurrence in acute chagasic stroke (Carod-Artal & Gascon,

The capacity of climatic conditions to modulate the extent and intensity of parasitism is well known since long ago. Concerning helminths, among the numerous environmental modifications giving rise to changes in infections, climate variables appear as those showing a greater influence, so that climate change may be expected to have an important impact on the diseases they cause. However, the confirmation of the impact of climate change on helminthiases has been reached very recently. Only shortly before, helminthiases were still noted as infectious diseases scarcely affected by climate change, when compared to diseases caused by microorganisms in general: viruses, bacteria, and protozoans (Mas-Coma et al., 2009). In this group we have: neurocysticercosis as a leading cause of epilepsy in developing coutries and some developed places. (Foyaca-Sibat, 2011), and also sparganosis and

Sparganosis is a rare parasitic infection caused by the larval cestode of *Spirometra* that results from ingesting the plerocercoid harbored in frogs, snakes, and chickens. Reported worldwide, sparganosis is most prevalent in Southeast and Eastern Asia. The diagnosis is suggested by a wandering lesion, especially in endemic areas; the tunnel sign on a post contrast MRI is characteristic. The preferred treatment is the surgical removal of live worm.( Shirakawa et al., 2010) In the endemic area of sparganosis, where other neurological parasitic infestations (*e.g.* cysticercosis and gnathostomiasis) are also common, the clinical usefulness of MR imaging is very limited in providing a definitive diagnosis of cerebral sparganosis. A history of risky behaviour (*e.g.* drinking impure water, eating frog or snake

delta outbursts. (Hamon & Camara, 1991)

**3. Other helminth parasitic infections to be considered** 

**2.8 American trypanosomiasis** 

toxocariasis among others.

**3.1 Neurosparganosis** 

2010)

Filariasis and onchocerciasis are parasitic helminth diseases that constitute a serious public health issue in tropical regions. The filarial nematodes that cause these diseases are transmitted by blood-feeding insects and produce chronic and long-term infection through suppression of host immunity. Disease pathogenesis is linked to host inflammation invoked by the death of the parasite, causing hydrocoele, lymphoedema, and elephantiasis in lymphatic filariasis, and skin disease and blindness in onchocerciasis. (Taylor et al., 2011) As far we know, epilepsy secondary to filariasis has not been reported.

This capability, coupled with an integrated, multidisciplinary and ecological approach, makes possible the identification of parasitic infections and diseases likely to be particularly susceptible to climate change and, with adjustments for regional variations, the exploration of some of the possible consequences of accelerating climate change of the occurrence ofthese diseases and for animal and human health. This is a very urgent need, and without such an attempt to anticipate the possible, society is likely to be a more or less impotent spectator to the certainty of continual ecological calamities. (Polley, 2010).

#### **3.3 Neurocysticercosis**

Neurocisticercosis (NC) is a parasitic infection of central nervous system (CNS) caused by the larval stage (Cysticercus cellulosae) of the pig tapeworm Taenia solium. This is the most common helminth to produce CNS infection in human being. The occurrence of acquired epilepsy or the syndrome of raised intracranial pressure in a person living in or visiting a region where taeniasis is endemic or even in one living in close contact with people who have taeniasis should suggest a diagnosis of cysticercosis; the NC may remain asymptomatic for months to years and sometimes its diagnosis is made incidentally when neuroimaging is performed. Symptoms and signs are related both to the parasite which can show a different biological behavior from one place to another, and to the inflammatoryinmunological response of the host. NC is the most common cause of acquired epilepsy worldwide and most of the patients taking phenytoin or carbamazepine for a proper control of their seizures, respond very well NC is also an important cause of ischemic stroke secondary to infectious vasculitis (Foyaca-Sibat & Ibañez-Valdés, 2003). The most common cause of epilepsy due to NC is calcified lesion with or without evidence of perilesional edema. The prognosis of this situation is worse when there is an associated intraventricular cyst (Figure 2) that usually does not respond well to praziquantel and albendazole should be prescribe (Foyaca-Sibat & Ibañez-Valdés, 2003). More information about NC can be found in this book.

Epilepsy Secondary to Parasitic Zoonoses of the Brain 327

Three recent case-control studies conducted in rural Bolivia, Burundi and Italy (Nicoletti et al., 2002, 2007, 2008) reported a significant association between seropositivity to *T. canis* and epilepsy. The adjusted odds ratios (OR) in these three studies were 2.70 (95%CI=1.41-5.19), 2.13 (95%CI: 1.18-3.83) and 3.90 (95%CI: 1.91-7.98), in Bolivia, Burundi and Italy, respectively. Of particular interest, in 2 of the 3 studies, the OR of epilepsy associated with seropositivity to *Toxocara* spp. was higher among persons with partial seizures (OR=4.70, 95%CI=1.47-15.1 and OR=4.69, 95%CI: 2.24-9.80, respectively). The opposite was true in Burundi where the association was stronger among persons with generalized seizures (OR=2.52; 95%:1.01-6.26). Toxocariasis has also been associated with epilepsy in a study of children in Italy (Alpino et al., 1990)*.* In this study, prevalence of antibody to *T. canis* was compared in 91 children with epilepsy younger than 18 years and 214 controls. The OR for seropositivity was estimated to 2.0 (95% CI=1.0-4.0). The association was present primarily in children less than 5 years of age. Whether exposure precedes the onset of seizures or is a result of behaviors such as geophagy in children with epilepsy is uncertain. However, there was no association between pica and seropositivity in the study by Alpino et al. (1990) and Nicoletti et al. (2002), the association between seropositivity and epilepsy was stronger for adults than for children and for those with partial seizures than for those with generalized seizures. These findings argue against exposure being a consequence of seizures rather than an antecedent. Pica had a protective effect in the most recent study of Nicoletti et al.

Recall bias is unlikely since an overestimation of the association rather than an underestimation was observed. Persons with early onset seizures (<15 years old) showed a stronger association between toxocariasis and epilepsy, which tends to support the hypothesis that young children are at higher risk of infection. The prevalence of infection with *Toxocara* spp. was 50.8% among the control group in Burundi, suggesting that the

We were unable to find a well-designed studies from countries where parasitic zoonoses are endemic that assessed the association between HIV infection, NC and cerebral toxocariasis. While it is possible that HIV infection may modify the association between known risk factors and parasitic zoonotic infections of the brain, to our knowledge, this has never been addressed (personal communication by Carabin H, 2010). More information about parasitic zoonoses of the brain and epilepsy can be found in our book entitled Epilepsy. Clinical

In 2004 and 2005, we conducted a pilot study at the St-Elisabeth hospital in Lusikisiki (ECP) which included 296 consecutive patients consulting the medical clinic for suspected newonset seizures or existing epilepsy cases. Each week, four (4) randomly selected, consenting patients with confirmed seizure disorder were transported to Mthatha for CT scan of the brain. The prevalence of seropositivity to antigens of *T. solium* was 8% (95%CI: 4.5%-13%). A total of 92 patients with recurrent seizures and who also completed a questionnaire were referred to Mthatha for a CT-scan. Of these, 34 (37.0%, 95%CI: 27.1%-47.7%) had a definite diagnosis of neurocysticercosis (NCC), 14 of whom had active lesions visible on CT, 39 (42%) had no CT abnormality, and 19 (21%) had other, undefined non-NCC calcifications. Our results showed that serology alone cannot be used to diagnose NCC in this population

HIV status was available from 50 patients with confirmed seizures or epilepsy. Among the 47 patients with antibody ELISA results available, the antibody seroprevalence of *T. solium*

exposure to this zoonotic parasite in SSA is very high (Nicoletti et al., 2002).

conducted in Sicily (2008).

manifestations. ISBN 978-953-307-1341-2

(Foyaca-Sibat et al., 2009)

Fig. 2. Shows multiple intraparenchymal calcified NC with and without perilesional edema and hydrocephalus secondary to intraventricular NC.
