**3.3 Risk factors for human cysticercosis in West Africa**

Out of the selected articles reviewed, 16 identified risk factors associated with the prevalence of *Taenia solium* cysticercosis, taeniasis, epilepsy and porcine cysticercosis. Lack of proper meat inspection, clandestine slaughtering of pigs and illegal sales of meat leading to poor sanitary control were all risk factors that were associated with an increased prevalence of cysticercosis in Benin Republic [30] as it will promote sale of infected pork carcass to unsuspecting consumers (since condemnation cannot be carried out) and predispose them to infection by these parasites (taeniasis) which increases transmission of infection in the community while increase age, stigma and lack of medical facilities were associated with increase prevalence of epilepsy, people with epilepsy may hide their true identity due to fear of marginalization and may not get proper health care [31]. In Burkina Faso, being a male, pig farming including percentage of soil in sand, residing in poor homes, lack of latrine. Males may have poor hygiene compared with females as they are likely to eat improperly washed fruits or vegetables after purchase and may eat food from food vendors prepared outside the home who might be carriers of the adult tapeworm. The authors also thought the acidic nature of the gastrointestinal tract might have made the eggs tolerate slightly more acidic soil. The higher soil (sandy) percentage might have favored spread of taenid eggs unto vegetation and water by wind. Carabin et al. [32] and living in communities with higher percentage of traditional pig husbandry [32, 36] were risk factors associated with the seroprevalence of cysticercosis [32]. Other factors include pig ownership, preparation method of pork by mothers, access to latrine [33] and pork consumption, pork consumption is associated with cysticercosis either by self-infection or through ingestion of contaminated food and water [32, 37]. Interestingly, previous consumption of pork, being a paid worker or trader as against farmer and housewives was also associated with the seroprevalence of cysticercosis [22, 37]. It was also observed that free roaming pigs in the rainy season and knowledge of porcine

**37**

Taenia solium *Cysticercosis in Pigs and Human: A Review of Epidemiological Data…*

cysticercosis was associated with an increase prevalence of porcine cysticercosis. Free roaming pigs get exposed to infected human feces deposited in the bush or open field thereby increasing the chance of infection and spread of porcine cysticercosis. Being a residence with more than one individual having epilepsy was associated with higher prevalence of active cysticercosis. Refs. [34, 36] observed that NCC and epilepsy were observed in older people compared with people with epilepsy without NCC. In addition, NCC was associated with epilepsy in communities where pig husbandry is practised and higher prevalence of NCC was observed in people with epilepsy. In Ghana, pork consumption and consumption of measly pork and pork soups lightly cooked were risk factors for taeniasis [39], while hypertension and exposure to *Taenia solium* infection were risk factors responsible for adult onset of epilepsy [40]. In Nigeria, pork preparation method and history of epilepsy was associated with seroprevalence of cysticercosis. Heat generated from boiling or frying is likely to kill the metacestode compared with heat from roasting or barbecuing [48]. Others include type and availability of toilets, open defecation, lack of personal hygiene after toilet use, pork consumption and traditional system of pig management [47]. One of the risk factors for epilepsy was history of febrile convulsions [70], purchasing home slaughtered pigs, lack of toilet facilities [64], sourcing pig from the northern part of the country and local breed of pigs [26]. It was observed in Senegal that the risk factor for seropositivity to cysticercosis was

Majority of studies on epilepsy use various combination of screening question-

naires, clinical confirmation by neurologists, general practitioners or medical students to identify cases of epilepsy with screening questionnaires developed by World Health Organization (WHO) [72] and Limoges Institute of Epidemiology and Tropical Neurology IENT questionnaire [69]. Epileptic seizures, which are the most common presentation of neurocysticercosis, have been documented in developing countries, which is three to six times higher than those in developed countries [68]. Causes of epilepsy are highly variable across different regions of sub-Saharan Africa and depend on geographical, climatic, political, social and hygienic conditions [73]. The main and most important causes of epilepsy seem to be very similar throughout sub-Saharan Africa showing that hypertension [40]. A genetic predisposition, a past history of febrile convulsions, perinatal neurological disorders, head injuries, cerebrovascular accidents and infections of the central nervous system account for most cases of epilepsy [73] Other presumed causes include witch craft/spiritual [43, 74], brain tumor [75], blood transmission and birth trauma due to self-delivery. Also included are protozoon and helminthic infections, including admission to hospital with malaria, exposure to *T. canis*, *T. gondii*, *O. volvulus* and *T. solium* [40] of which *Taenia solium* has received attention in sub-Saharan Africa over the past few years. Neurocysticercosis is a common cause of epilepsy in pig breeding area [76], however the wide variation in the frequency of epilepsy in the continent could be due to different definitions and type of epilepsy including the population studied and type of sample [44]. Some studies in the region showed the association between epilepsy and cysticercosis using different diagnostic criteria both for epilepsy and cysticercosis. These include three studies in Burkina Faso, of which some researchers [34] showed a seropositivity between cysticercal antigens and active epilepsy with a prevalence odds ratio (POR) of 2.40 (95%). A second study [36] showed 68 of the subjects

*DOI: http://dx.doi.org/10.5772/intechopen.89559*

older age group and lack of latrine [42].

**4. Discussion**

Taenia solium *Cysticercosis in Pigs and Human: A Review of Epidemiological Data… DOI: http://dx.doi.org/10.5772/intechopen.89559*

cysticercosis was associated with an increase prevalence of porcine cysticercosis. Free roaming pigs get exposed to infected human feces deposited in the bush or open field thereby increasing the chance of infection and spread of porcine cysticercosis. Being a residence with more than one individual having epilepsy was associated with higher prevalence of active cysticercosis. Refs. [34, 36] observed that NCC and epilepsy were observed in older people compared with people with epilepsy without NCC. In addition, NCC was associated with epilepsy in communities where pig husbandry is practised and higher prevalence of NCC was observed in people with epilepsy. In Ghana, pork consumption and consumption of measly pork and pork soups lightly cooked were risk factors for taeniasis [39], while hypertension and exposure to *Taenia solium* infection were risk factors responsible for adult onset of epilepsy [40]. In Nigeria, pork preparation method and history of epilepsy was associated with seroprevalence of cysticercosis. Heat generated from boiling or frying is likely to kill the metacestode compared with heat from roasting or barbecuing [48]. Others include type and availability of toilets, open defecation, lack of personal hygiene after toilet use, pork consumption and traditional system of pig management [47]. One of the risk factors for epilepsy was history of febrile convulsions [70], purchasing home slaughtered pigs, lack of toilet facilities [64], sourcing pig from the northern part of the country and local breed of pigs [26]. It was observed in Senegal that the risk factor for seropositivity to cysticercosis was older age group and lack of latrine [42].

## **4. Discussion**

*Overview on Echinococcosis*

each study is given in **Table 2**.

**3.3 Risk factors for human cysticercosis in West Africa**

Out of the selected articles reviewed, 16 identified risk factors associated with

the prevalence of *Taenia solium* cysticercosis, taeniasis, epilepsy and porcine cysticercosis. Lack of proper meat inspection, clandestine slaughtering of pigs and illegal sales of meat leading to poor sanitary control were all risk factors that were associated with an increased prevalence of cysticercosis in Benin Republic [30] as it will promote sale of infected pork carcass to unsuspecting consumers (since condemnation cannot be carried out) and predispose them to infection by these parasites (taeniasis) which increases transmission of infection in the community while increase age, stigma and lack of medical facilities were associated with increase prevalence of epilepsy, people with epilepsy may hide their true identity due to fear of marginalization and may not get proper health care [31]. In Burkina Faso, being a male, pig farming including percentage of soil in sand, residing in poor homes, lack of latrine. Males may have poor hygiene compared with females as they are likely to eat improperly washed fruits or vegetables after purchase and may eat food from food vendors prepared outside the home who might be carriers of the adult tapeworm. The authors also thought the acidic nature of the gastrointestinal tract might have made the eggs tolerate slightly more acidic soil. The higher soil (sandy) percentage might have favored spread of taenid eggs unto vegetation and water by wind. Carabin et al. [32] and living in communities with higher percentage of traditional pig husbandry [32, 36] were risk factors associated with the seroprevalence of cysticercosis [32]. Other factors include pig ownership, preparation method of pork by mothers, access to latrine [33] and pork consumption, pork consumption is associated with cysticercosis either by self-infection or through ingestion of contaminated food and water [32, 37]. Interestingly, previous consumption of pork, being a paid worker or trader as against farmer and housewives was also associated with the seroprevalence of cysticercosis [22, 37]. It was also observed that free roaming pigs in the rainy season and knowledge of porcine

Human cysticercosis from Nigeria was obtained from two studies [47, 48] by using Ab ELISA with prevalence of cysticercosis ranging from 9.6 to 14.3% in a total of 425 individuals. There were five studies selected for epilepsy [43, 44, 51, 70] with prevalence ranging from 4.3/1000 to 20.8/1000 in a total of 64,979 individuals for the epilepsy study. Five studies in the region were case report of cysticercosis [45, 49, 50, 71] involving the ocular and breast cysticercosis. Human taeniasis was obtained from two studies by stool microscopy [25, 46] with a prevalence ranging from 8.6 to 40% among a total of 1953 individuals in the region. Human cysticercosis in Senegal was obtained from one study performing antigen and antibody ELISA [42]. The total number of individuals in the study were 403, and prevalence of both antigen and antibody was 7.6%.The prevalence of epilepsy in the country was obtained from two selected studies [52, 53] and the prevalence of epilepsy ranged from 8.3/1000 to 14.2/1000 in a total of 12,182 individuals. Prevalence of epilepsy from Liberia was obtained from two studies [41, 54] and the prevalence of epilepsy across the region ranged from 28.0/1000 to 43.0/1000 among a total of 7169. Prevalence of epilepsy from Mauritania was obtained in one study [55] with a prevalence of 34.7/1000 in a total of 236 individuals. Human cysticercosis was obtained from two sero-epidemiological studies from Togo by antibody ELISA and gave a prevalence of 23.3 [57] and cysticercosis 38/1000 [56] among a total of 14,419 individuals. The two studies also estimated the prevalence of epilepsy and obtained 16/1000 and 18.6/1000 [56, 57] among a total of 6607. A detailed description of

**36**

Majority of studies on epilepsy use various combination of screening questionnaires, clinical confirmation by neurologists, general practitioners or medical students to identify cases of epilepsy with screening questionnaires developed by World Health Organization (WHO) [72] and Limoges Institute of Epidemiology and Tropical Neurology IENT questionnaire [69]. Epileptic seizures, which are the most common presentation of neurocysticercosis, have been documented in developing countries, which is three to six times higher than those in developed countries [68]. Causes of epilepsy are highly variable across different regions of sub-Saharan Africa and depend on geographical, climatic, political, social and hygienic conditions [73]. The main and most important causes of epilepsy seem to be very similar throughout sub-Saharan Africa showing that hypertension [40]. A genetic predisposition, a past history of febrile convulsions, perinatal neurological disorders, head injuries, cerebrovascular accidents and infections of the central nervous system account for most cases of epilepsy [73] Other presumed causes include witch craft/spiritual [43, 74], brain tumor [75], blood transmission and birth trauma due to self-delivery. Also included are protozoon and helminthic infections, including admission to hospital with malaria, exposure to *T. canis*, *T. gondii*, *O. volvulus* and *T. solium* [40] of which *Taenia solium* has received attention in sub-Saharan Africa over the past few years. Neurocysticercosis is a common cause of epilepsy in pig breeding area [76], however the wide variation in the frequency of epilepsy in the continent could be due to different definitions and type of epilepsy including the population studied and type of sample [44]. Some studies in the region showed the association between epilepsy and cysticercosis using different diagnostic criteria both for epilepsy and cysticercosis. These include three studies in Burkina Faso, of which some researchers [34] showed a seropositivity between cysticercal antigens and active epilepsy with a prevalence odds ratio (POR) of 2.40 (95%). A second study [36] showed 68 of the subjects

confirmed with epilepsy by CT scan and 20 were diagnosed with definitive NCC (for a proportion of 45.5–46.9% in two of the study villages). The third study [37] showed that 39 of 70 positive were confirmed with epilepsy for a lifetime prevalence of 4.5% and epilepsy was associated with cysticercosis by Ag-ELISA (POR = 3.1, 95% BCI = 1.0; 8.3). All three studies confirmed epilepsy by ILAE definition/physician. In Senegal, a study [42] showed that one of 10 CT-scan positives individual by Ag-ELISA and EITB was reported to have epileptic seizures, and cerebral CT-scans showed that 23.3% of the seropositive were affected by neurocysticercosis. In Togo, a previous study [57] showed that cysticercosis (confirmed by ELISA, anatomopathological examination, cranial or muscle X-ray) caused 29.5% epilepsy in sufferers. A study by [40] in five Health and Demographic Surveillance System centeres in Kintampo Ghana and four other countries (Kenya, South Africa, Uganda and Tanzania) showed that epilepsy was significantly associated with exposure to *T. solium* (odds ratios 7·03, *P* = 0·002), in adults epilepsy confirmed by questionnaire/clinician and cysticercosis was confirmed by detection antibody by Western Blot, while active convulsive epilepsy in the study was defined as two or more unprovoked convulsive seizures (occurring at least 24 h apart, with at least one seizure in the preceding 12 months).

The stigmatization and marginalization of epilepsy is also enormous *n* many African countries, epileptic patients are cast out because it is considered a contagious or shameful disease [28, 43, 69, 77]. Those affected go through social seclusion and people will not marry PWE unless both parties have epilepsy. For example, consanguineous marriage is forbidden by culture in South East Nigeria [43], and may potentially force them to intermarry thereby promoting genetic transmission of epilepsy [43, 44]. Other beliefs include that inheriting properties from PWE will get one infected but if a medicine man performs burial rites for the dead person and takes away their properties and burn it then it stops. Burial of PWE far away from home prevents people from getting epilepsy. Eating, sleeping together or wearing same clothes with PWE is said to be a source of infection [43, 44]. Eating of pork by someone with epilepsy promotes cysticercosis and corroborates with a study that found a significant link between cysticercosis occurrence and epilepsy [78]. In West Africa, *T. solium* cysticercosis in pigs and man has been reported and reports have shown the prevalence's of porcine cysticercosis across the west African countries varies from 0.05 to 46% for both carcass inspection and serological studies and prevalence of taeniid eggs were found to be between 8.6 and 40% based on stool microscopy while copro-antigen ELISA gave a prevalence of 30% [65] as shown in **Tables 1** and **2**. Difference in severity of infection caused by *T. solium* could also explain the differences in prevalence of epilepsy. In addition, the extent of the presence of other environmental factors such as use of bad hygiene practices, close contact of humans and pigs and consumption of inadequately cooked pork affects the differences in prevalence of epilepsy [31] including free roaming pigs [43]. Abattoirs and approved slabs are the only approved places for slaughter and inspection of pork meat for consumption, however most carcasses are sold uninspected hence, lack of inspection and large scale clandestine slaughter of pigs promote spread of cysticercosis [32, 34]. The poor knowledge of *T. solium*, poor hand washing practices, not treating drinking water and handling of raw pork with bare hands promote spread of cysticercosis [65]. Reports in the region indicate that home slaughter conditions were normally substandard because they are makeshift and not constructed to actually meet the requirements of ideal slaughter premises [48]. There was also strong association between knowledge of cysticercosis and occupation and could be attributed to the fact that people in certain occupations are considered to be more knowledgeable about the disease than others [48].

**39**

Taenia solium *Cysticercosis in Pigs and Human: A Review of Epidemiological Data…*

the menace caused by the parasite and how it could be prevented.

The high prevalence of porcine and human cysticercosis and epilepsy in the region indicates that there is a need to get more updated prevalence data of cysticercosis in rural areas where epilepsy is suspected to be more prevalent, compared to urban regions due to parasitic infection. Studies determining the association between epilepsy and cysticercosis should be carried out in countries where it has not been done. The conditions necessary for the parasite to thrive and be transmitted in the region is present in West Africa. Interventions studies including Health education has only been done recently in Burkina Faso, such intervention measures should be carried out in other parts of the region so as to enlighten the populace on

The present study has some limitations as the criteria for inclusion and exclusion of articles might have increased or reduced the number of studies used in the region and not all risk factor s and causes of epilepsy were discussed. The study did not determine the prevalence of epilepsy and both porcine and human cysticercosis, in the region as the aim of the study was to show data on studies done by other

The authorship criteria are listed in our Authorship Policy: https://www.intecho-

This section of your manuscript may also include funding information.

We wish to thank the management of National Veterinary Research Institute

Vom for assistance rendered during the preparation of the manuscript.

*DOI: http://dx.doi.org/10.5772/intechopen.89559*

**5. Conclusions**

**6. Limitations**

researchers in the region.

**Acknowledgements**

**Conflict of interest**

pen.com/page/authorship-policy.

**Notes/thanks/other declarations**

**Acronyms and abbreviations**

PWE people with epilepsy HCC human cysticercosis Ag-ELISA antigen ELISA Ab-ELISA antibody ELISA ND not done

GP general population

HB hospital based

CR cross sectional survey CT computed tomography

VL villagers

The authors declare no conflict of interest.

Taenia solium *Cysticercosis in Pigs and Human: A Review of Epidemiological Data… DOI: http://dx.doi.org/10.5772/intechopen.89559*
