**2. Life cycle**

### **2.1 Life cycle and pathogenesis**

*Taenia solium* life cycle is sustained where free roaming pigs, have access to contaminated feces of tapeworm carriers. *T. solium* has a complex two host life cycle and is cyclically transmitted between pigs and man. Humans are the only definitive host and harbor the adult stages of these cestodes following ingestion of insufficiently cooked pork meat infested with cysticerci. Infection with the adult stage is relatively innocuous and carries mild clinical manifestations leading to taeniasis [1–11]. Pigs are the natural intermediate host, while human's acts as the accidental dead-end intermediate host and are both infected with *T. solium* by ingestion of embryonated eggs from feces of tapeworm carriers from contaminated soil, water, vegetation/foods to form cysticerci. Infection with the cysticerci leads to more severe symptoms including headache and neurocysticercosis when the pathology occurs in the CNS [11].

#### **2.2 Epidemiology**

Neurocysticercosis has been considered to be the most common parasitic infestation of the central nervous system and the single most common cause of preventable acquired epilepsy and mortality in developing countries [12–14], and a strong correlation was reported between the prevalence of epilepsy and seropositivity against *T. solium* cysticercosis [15]. The association between cysticercosis and epilepsy has been documented as a leading neurological condition worldwide including West Africa. Epilepsy is a frequent chronic neurologic disorder that affects approximately 70 million people of all ages worldwide [15] Studies of [10] in 2010 reported that the median prevalence of active epilepsy was 4.9/1000 (2.3–10.3) for developed countries, 12.7/1000 (3.5–45.5) and 5.9/1000 (3.4–10.2) in rural and urban studies in developing countries. Neurocysticercosis has been associated with 30% of adult onset epilepsy in endemic regions where 10–20% of the general population can have brain lesions consistent with neurocysticercosis on CT scans [16]. Neurocysticercosis creates a tremendous economic burden in endemic areas incurring significant costs due to diagnosis, treatment and disability [17]. Poor sanitary conditions, traditional pig farming, lack of awareness of the disease and poverty play an important role in the perpetuation of the *Taenia solium*/cysticercosis, and are present in West Africa [18]. Research in the region on *Taenia solium* cysticercosis and taeniasis in both human and pigs has been limited. Prevalence information of the disease in some countries within the region has been scanty leading to underestimation of the prevalence, epidemiology and clinical impacts of the disease which has made it difficult to make definitive recommendations on control strategies. Data on porcine and human cysticercosis are available from several countries. However, there is no recent information on *T. solium* taeniasiscysticercosis complex in some countries including Guinea Bissau, Liberia, Ivory

**29**

**Table 1.**

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

coast and Sierra-Leone [19] as shown in **Tables 1** and **2**. The aim of this study is to review scientific and gray literature and to identify the empirical data on *T. solium* taeniasis/human/porcine cysticercosis/neurocysticercosis/epilepsy in West Africa and the risk factors responsible for the epidemiology of *T. solium* cysticercosis in order to understand the differences in exposure to the parasite in endemic areas around the world. This will give an update and compile the current knowledge on *T. solium* in Western Africa, including risk factors for infections in pigs and humans

**Author Country/location Diagnosis Total Prevalence Type of** 

[20] Benin, Southern Benin Meat inspection 118.073 0.06–0.69% Abattoir

[22] Burkina Faso B158/B60 Ag-ELISA 336 32.5–39.6% Cross

mortem

mortem

[67] Gambia, Western region Lingual, Ag-ELISA 1705 4.8% Cross

[67] Senegal Lingual, Ag-ELISA 1705 6.4–13.2% Cross

[66] Nigeria, Jos Antibody ELISA 115 46%

[58] Burkina Faso Meat inspection 117,026 0.57%

Meat inspection 62,311 0.22

Meat inspection 593 1.01%

Post mortem 323 4.95%

Post mortem 250 4.4%

Lingual/post mortem 2358 20%

Lingual, post mortem 4208 5.85%

**study**

Abattoir

sectional

Abattoir

Cross sectional

sectional

Abattoir

sectional

sectional

Cross sectional

Cross sectional

Cross sectional

Cross sectional

Cross sectional

sectional

Cross sectional

sectional

sectional

(*n* = 139)

(*n* = 673)

(*n* = 95)

(*n* = 6)

(*n* = 16)

(*n* = 205) 14.4% (*n* = 118)

(*n* = 11)

(*n* = 274)

(*n* = 483)

(*n* = 29)

4380 6.25%

Post mortem 379 2.4% (*n* = 9) Cross

4121 2.31%

Post mortem 60 11.70% Cross

Post mortem 247 3.2% (*n* = 8) Cross

Post mortem 43 9.3% (*n* = 4) Cross

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

[21] Burkina Faso,

[60] Ghana, Upper East

[61] Nigeria, Bodija, Ibadan,

[62] Nigeria, Michika,

[65] Nigeria, Nasarawa and

[63] Nigeria, Jalingo, Taraba

[23] Nigeria, Zuru, Kebbi

[25] Nigeria, Nsukka Enugu

[26] Nigeria, Enugu State

[64] Nigeria,

Ouagadougou

Region

Oyo State

Adamawa State,

Gonin Gora,Chikun, Kaduna

State

State

Bodija, Ibadan,

State

Udenu, Igbo-Eze South Nsukka Enugu State

*Selected studies of porcine cysticercosis in West Africa 1980–2019.*

[24] Nigeria, Ibi Taraba State Antemortem/post

[59] Ghana, Kumasi Ante mortem/post

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

coast and Sierra-Leone [19] as shown in **Tables 1** and **2**. The aim of this study is to review scientific and gray literature and to identify the empirical data on *T. solium* taeniasis/human/porcine cysticercosis/neurocysticercosis/epilepsy in West Africa and the risk factors responsible for the epidemiology of *T. solium* cysticercosis in order to understand the differences in exposure to the parasite in endemic areas around the world. This will give an update and compile the current knowledge on *T. solium* in Western Africa, including risk factors for infections in pigs and humans


#### **Table 1.**

*Selected studies of porcine cysticercosis in West Africa 1980–2019.*

*Overview on Echinococcosis*

farming community [8, 9].

**2.1 Life cycle and pathogenesis**

occurs in the CNS [11].

**2.2 Epidemiology**

**2. Life cycle**

travel and immigration [6, 7]. Hence cysticercosis/neurocysticercosis/teaniosis complex caused by the larval stage of *T. solium* in both pigs and humans remains a significant cause of human morbidity and mortality in many parts of the world. It is seriously affecting pig production and also considered as a public health and economic problem in many developing countries affecting food security and negatively impacts the nutritional and economic well-being of the small holder

*Taenia solium* life cycle is sustained where free roaming pigs, have access to contaminated feces of tapeworm carriers. *T. solium* has a complex two host life cycle and is cyclically transmitted between pigs and man. Humans are the only definitive host and harbor the adult stages of these cestodes following ingestion of insufficiently cooked pork meat infested with cysticerci. Infection with the adult stage is relatively innocuous and carries mild clinical manifestations leading to taeniasis [1–11]. Pigs are the natural intermediate host, while human's acts as the accidental dead-end intermediate host and are both infected with *T. solium* by ingestion of embryonated eggs from feces of tapeworm carriers from contaminated soil, water, vegetation/foods to form cysticerci. Infection with the cysticerci leads to more severe symptoms including headache and neurocysticercosis when the pathology

Neurocysticercosis has been considered to be the most common parasitic infestation of the central nervous system and the single most common cause of preventable acquired epilepsy and mortality in developing countries [12–14], and a strong correlation was reported between the prevalence of epilepsy and seropositivity against *T. solium* cysticercosis [15]. The association between cysticercosis and epilepsy has been documented as a leading neurological condition worldwide including West Africa. Epilepsy is a frequent chronic neurologic disorder that affects approximately 70 million people of all ages worldwide [15] Studies of [10] in 2010 reported that the median prevalence of active epilepsy was 4.9/1000 (2.3–10.3) for developed countries, 12.7/1000 (3.5–45.5) and 5.9/1000 (3.4–10.2) in rural and urban studies in developing countries. Neurocysticercosis has been associated with 30% of adult onset epilepsy in endemic regions where 10–20% of the general population can have brain lesions consistent with neurocysticercosis on CT scans [16]. Neurocysticercosis creates a tremendous economic burden in endemic areas incurring significant costs due to diagnosis, treatment and disability [17]. Poor sanitary conditions, traditional pig farming, lack of awareness of the disease and poverty play an important role in the perpetuation of the *Taenia solium*/cysticercosis, and are present in West Africa [18]. Research in the region on *Taenia solium* cysticercosis and taeniasis in both human and pigs has been limited. Prevalence information of the disease in some countries within the region has been scanty leading to underestimation of the prevalence, epidemiology and clinical impacts of the disease which has made it difficult to make definitive recommendations on control strategies. Data on porcine and human cysticercosis are available from several countries. However, there is no recent information on *T. solium* taeniasiscysticercosis complex in some countries including Guinea Bissau, Liberia, Ivory

**28**


**31**

**Author**

[40] [41] [42] [42] [43] [44] [48] [45] [70]

Nigeria

Door to door Questionnaire,

6800

4.3/1000 (*n* = 29)

ND

neurologist

Ukpo,Dunukofia

Anambra state,

[46] [25] [47] [48] [49]

Nigeria Ile-Ife

Nigeria Nasarawa

Nigeria Jos

Ab-ELISA Copro Ag ELISA, questionnaire

Surgeon/histopathological, biopsy

10

125

Nigeria Nsukka

Enugu State,

Nigeria Odeda,

Sodium acetate acetic acid

428

ND

40%

(*n* = 175)

formalin concentration method

(SAF-Ether)

Stool microscopy

1525

ND ND

9.6% (*n* = 12)

ND

30 (*n* = 3)

Cysticercosis of

ND

breast

ND

8·6%

(*n* = 131)

Ogun State,

Nigeria Abuja

Nigeria Kaduna

Ab-ELISA An 8000 B-Scan Scanmate

300

Nigeria Agu-Abor/

Enugu

Questionnaire, medical

8228

0.6%/1000 (*n* = 49)

ND

ND 14.3% (*n* = 43)

Ocular

cysticercosis

ND

ND

ND

Nigeria ebonyi/

benue state

Questionnaire

2500 and 6000

(*n* = 52) 20.8/1000 and (28) 4.7/1000, PB

ND

ND

ND

Senegal

GhanaKintampo

Questionnairesclinicians/western blot

Direct fecal examination

Fecal egg count

Worm expulsion/amorphological identification

ND

**Country/location**

**Diagnosis**

**Total** 586,607

**Epilepsy (***n***)**

10.1/1000

ND ND ND

ND ND ND

ND ND ND

1/43\*\*\*2.33

4/43\*\* 9.30

2/43\* 4.65

**Neurocysticercosis**

ND

**Cysticercosis**

0.01

ND

**Taeniasis**

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

ND

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

#### *Overview on Echinococcosis*


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

*Overview on Echinococcosis*

**30**

**Author**

[27] [28] [29] [29] [29] [30] [31] [32] [33] [34] [35] [36] [37] [34] [38] [39]

Ghana Bunkpuru

Kato-Katz technique

Burkina-Faso

Burkina Faso

Questionnaire neurologist

4768 16,627

494

669 (14.0%), VL

10.6 per 1000, CB

Burkina Faso

Burkina Faso

Burkina Faso

Burkina Faso´ a

B158/B60 Ag-ELISA

B158/B60 Ag-ELISA

questionnaire/neurologist

AgELISA/CT scan/neurologist

Ag-ELISA, physician

888 888

4.4\$(39) epi, VLVL

4.5% (39) of 70 VL

29% (20/68) 5/39 epileptics (12.8%),

3.4% (28/814)

0.6% (29)

ND ND

ND ND ND

13.15%

(*n* = 65)

ND

ND

ND ND

ND

ND

763 3696

GP 3.9% (*n* = 145), GP

ND

Burkina Faso

Burkina Faso

B158/B60 AG-ELISA

Ag B158/B60 ELISA

3609 1729/1719

Benin

Benin

Benin

Benin, Vekky

Benin, Savolou

Benin

**Country/location**

Benin

**Diagnosis** Capture recapture/Neurlogist

Capture recapture/Neurlogist

Ab-ELISA, skull/muscle X-ray and

pathol. of cysts

Ab-ELISA, skull/muscle X-ray and

319

pathol. of cysts

Ab-ELISA, skull/muscle X-ray and

2625

GP

1.6% (*n* = 41)

ND

ND

pathol. of cysts

AB,ELISA/(EITB)

Questionnaire,clinical/neurologist

13,046

2625

41/1.3% (35) GP

8.05/1000 (*n* = 105),

GP

GP GP

ND ND

0–11.5% (*n* = 120)

3·8% (*n* = 65)

ND

CC 2.7% (*n* = 47)

(2.7%)

6.29% (*n* = 48)

3.4% (*n* = 129)

ND

ND

ND

ND ND

ND ND

ND

ND

11,668

1443

3134

**Total**

**Epilepsy (***n***)** 20.1/1000 (*n* = 66) GP

12.7/1000 (148) GP

1.5 (22/1443), 17/186

GP

GP

3.5% (319)

**Neurocysticercosis**

ND ND 4.0% (*n* = 57)

**Cysticercosis**

ND ND 1% (*n* = 14 skin

ND

nodules)

ND

ND

ND

ND

**Taeniasis**


**Table 2.**

**33**

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

cysticercosis (HCC) from endemic communities. The objective of the study will be to review and document data on the prevalence of human cysticercosis/neurocysti

A systematic literature search was done on studies carried out on cysticercosis in humans and pigs, seroprevalence of cysticercosis in humans and pigs, neurocys

ticercosis/taeniasis, risk factors for transmission of cysticercosis and epilepsy in West Africa published between 1980 and 2019. This search focused on the articles in which data was obtained using the following techniques and protocols: (1) enzymelinked immunoelectrotransfer blot (EITB), (2) enzyme-linked immunosorbent assay (B158/B60 Ag-ELISA or HP10 Ag-ELISA), (3) copro-antigen ELISA and real-time polymerase chain reaction assay (copro-PCR). Language restriction was applied, the considered languages were English and French. The selected databases for this study were: PubMed (http://www.ncbi.nlm.nih.gov/pubmed/), Google scholar and others. The search was performed from May 22 to August 22, 2019.

The following data were included in this study (1) peer-reviewed studies of *T. solium* taeniasis/cysticercosis/neurocysticercosis, porcine cysticercosis and epilepsy in West Africa. (2) "Gray literature" on *T. solium* taeniasis/cysticercosis, neurocys

ticercosis presence in West Africa which consisted of informally published written materials including reports. We performed a literature search using PubMed (http:// www.ncbi.nlm.nih.gov/pubmed/) with date restriction from January 1, 1980 to January 5, 2019 using the following search term: (solium OR Tapeworm OR Taeniasis OR Taeni\* OR Taeniosis OR Neurocysticercosis OR Cysticerc\* OR epilepsy) AND West Africa (Benin OR Burkina Faso OR Ivory Coast OR Cape Verde OR Gambia OR Ghana OR Guinea OR Guinea Bissau OR Liberia OR Libya OR Malawi OR Mali OR Mauritania OR Niger OR Nigeria OR Senegal OR Sierra Leone OR Togo). We also searched other databases such as Google Scholar (http://scholar.google.com), Cab Direct (http://www.cab direct.org) and African Journals Online (http://www.ajol. info) using the following keywords: "*Taenia solium*," "porcine cysticercosis," "neuro

cysticercosis," "human cysticercosis" and "taeniasis" Epilepsy, West Africa.

Presence of *T. solium* in this study was defined as a documented case of disease related to the tapeworm, whether it was diagnosed and documented as human cys

**Figure 1** describes the review process and the number of articles selected at each stage of the review. From an initial number of 550 articles, only 121 were eventually used. The search selected by removal of duplicate studies from the title selection and studies performed before 1980. Secondly, another set of articles were excluded due to: (1) parasites other than *T. solium*; (2) studies performed in non-west African

ticercosis, neurocysticercosis, porcine cysticercosis, taeniasis or epilepsy. Initially, we reviewed all titles and abstracts, if accessible, and excluded studies outside West Africa, and studies with no specified diagnostic technique, studies written in languages other than English and French, and studies not having full paper, that is,






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

**2.3 Methods**

**2.4 Literature search**

**2.5 Data extraction and collection**

**2.6 Study selection**

abstracts only experimental studies were also excluded.

cercosis in the region with emphasis on epilepsy.

 *Selected prevalence of human cysticersosis and epilepsy in west African countries.* cysticercosis (HCC) from endemic communities. The objective of the study will be to review and document data on the prevalence of human cysticercosis/neurocysticercosis in the region with emphasis on epilepsy.
