Pig population estimates of North African countries in 2010 and the current status of porcine cysticercosis (PCC) caused by
This chapter reviews the status of pig production and porcine cysticercosis caused by
Porcine cysticercosis refers to as an infection of pigs with the larval form of
Although a number of animal species including dogs  can be infected with
In response to the WHO’s effort to estimate the global burden of neurocysticercosis, four comprehensive studies have reported estimates of burdens of
In Africa, pig keeping is popular in many countries. However, there has been no study that has clearly described the pattern of pig production and the overall status of porcine cysticercosis on the continent. This is important in order to understand the importance of the pig enterprise in the region as well as the potential for porcine cysticercosis to constrain the industry. Africa is one of the regions where the full cycle of
In this chapter, we review the pig production and agricultural impact of porcine cysticercosis on the African continent based on available literature. Data on the pig population in Africa is based on the most current global pig population estimates . For the prevalence of porcine cysticercosis, the most recent information is included, with a priority for prevalence estimated using antigen ELISA, where available, in order to reflect active infections. However, prevalence based on a less accurate diagnostic method is used if that is the only information available. Note that, the purpose of the review is to describe the current status of porcine cysticercosis in the African region rather than presenting all that has been done in the region with regard to porcine cysticercosis. For simplicity, the African continent is divided into five major regions as classified by the United Nations. That is northern Africa, southern Africa, western Africa, central Africa, and eastern Africa [Figure 2]. Only the 54 countries fully recognised by the United Nations are included. These consists of seven, five, 16, nine and 17 countries of the northern, southern, western, central and eastern Africa, respectively.
It is possible that porcine cysticercosis poses more economic losses than those only related to condemnation or reduced value of infected pigs. For example, studies have established possible reduced fertility of pigs naturally infected with cysticercosis, which would reduce the productive performance of the pigs . Similar findings have been reported in human infected with neurocysticercosis . In both the pig and human studies, cysticercosis was found to significantly reduce serum level of testosterone while increasing significantly the level of follicle stimulating hormones in males [12,13]. On the other hand, cysticercosis significantly reduced the level of progesterone in females . These endocrinological changes are thought to exert significant inhibitory action in the reproduction function of the infected individuals. However, it has been observed that the effect is more intense in male than female hosts. Although the study of pigs included males only, there is strong evidence from laboratory trials, which suggests that the effect of the parasite in female pigs will most likely resemble that observed in female humans [12,13].
Disability in persons infected with neurocysticercosis is another potential factor that is likely to contribute to further economic losses in the agricultural sector through reduced manpower, some of which would be used in pig production in the countries. This can be supported by studies in Eastern Cape Province of South Africa and Cameroon, which show that the majority of people in Africa are not employed in salaried jobs [4,5]. This significant proportion of the population is likely to engage in small-scale businesses, including pig farming. Those suffering from neurocysticercosis in this category of the population are likely to contribute significantly to agricultural losses in the pig industry.
Because of the current lack of information on the actual reduction of pigs’ reproductivity as a result of cysticercosis and specific contribution of unemployed populations to pig production in endemic countries, the analysis of the agricultural impact of
4.1. Study area and duration
This study was carried out between April and June, 2012 and included the 54 African countries that were fully recognised by the United Nations as of 2012 
Collection of data on country pig populations and status of porcine cysticercosis
Pig population data for each of the 54 countries were downloaded from the FAO statistical database . The most recent pig population estimates (those of 2010) were used. Thereafter, several Google searches were performed for each country name and key English phrases and words such as “porcine cysticercosis”,
Estimation of agricultural impact of porcine cysticercosis
This was the main focus of the study. Therefore, more attention was given to this aspect. A total of 200 articles were retrieved following several Google searches using the following four phrases in that order: (i) Burden-of Taenia-solium cysticercosis, (ii) Impact-of Taenia-solium, (iii) Economic-impact Taenia-solium, and (iv) Financial-impact Taenia-solium. For each search phrase, 50 first articles we retrieved from which the relevant ones were downloaded from their publishers for further analysis. This first screening was based on a quick assessment of information given in the abstracts. Following the first screening, a total of 18 articles were considered relevant and different from each other, and hence, were included. Out of the 18 articles, 10 were obtained from the first search, seven new articles from the second search, one form the third, and none new from the fourth search phrase. In the second screening, only those articles that included information for Africa were sub-selected from the 18 articles. Five were obtained at this sub-sampling stage. Finally, only those articles that included information on the economic burden of porcine cysticercosis in Africa were selected. Four articles met this criterion and were included for further analysis. The four articles were all peer-reviewed journal papers [4,5,16,17]. A flow diagram to illustrate the sampling procedure described above is given in Figure 3.
The information collected was recorded as reported by the author(s) of the article. If there was different information regarding the cost of porcine cysticercosis in a country, a range of values was given and data sources cited.
5.1. General results
The study area consisted of 54 countries. The total population of pigs estimated in the study area in 2010 amounted 29,606,438. This was approximately 3.1% of the world pig population estimate (N = 965,855,414) of 2010. Out of the Africa regional pig population, approximately 0.2% was reared in the northern countries, while 6.1%, 43.3%, 16,4%, and 34.0% were reared in the southern, western, central, and eastern Africa, respectively. Overall, 19 (35.2%) of the 54 study countries reported prevalence of cysticercosis in pigs. While no data were available in the northern region, the remaining regions provided prevalence data, with more reporting frequency observed in the eastern followed by central Africa.
Porcine cysticercosis in northern Africa
Countries of northern Africa comprise Algeria, Egypt, Libya, Morocco, Sudan, Southern Sudan, and Tunisia. Pig rearing in this region is minimal (Table 1). While there were no pigs reported for Libya, Sudan, and Southern Sudan, indicating possibly absence of or insignificant pig rearing in the countries, pig populations in the remaining four countries ranged from 5,700-38,000 in 2010, making an overall regional pig population of 58,200 pigs. The small number of pigs reared in the northern Africa region is likely to be due to drought and the fact that most of the inhabitants in the region are Muslims. Generally, there was no report available with regard to porcine cysticercosis in the northern Africa. While there is an indication of Egypt providing the most ancient known case of
Porcine cysticercosis in southern Africa
Table 2 presents the pig population estimates and status of porcine cysticercosis in southern Africa. South Africa is the only country in the region, which has reported prevalence of porcine cysticercosis. A number of studies have been conducted in several parts of the country for various periods of time. It is apparent that porcine cysticercosis is hyperendemic in some parts of the country. The possibility of the other countries in the region being free from porcine cysticercosis is yet to be scientifically proven. Such studies would be very valuable in guiding potential control measures for
|South Africa||1,594,490||54.8 – 57||Ag-ELISA|||
Porcine cysticercosis in western Africa
Western Africa has the largest pig population in the region (Table 3). Six of the 16 countries of the region have reported presence of porcine cysticercosis. Burkina Faso seems to have high prevalence of porcine cysticercosis in some region, probably because of variations in pig management practices. Apart from Burkina Faso, Gambia and Senegal, data from the other countries are rather old. This suggests that research on porcine cysticercosis in these countries has been inactive for quite some time.
|Gambia||28,500||4.8 (n = 371)||Ag-ELISA|||
Porcine cysticercosis in central Africa
Four out of the ten countries of central Africa have reported prevalence of porcine cysticercosis. Extensive studies have been conducted in Cameroon, ranging from epidemiological, intervention trials and disease burden analysis. Porcine cysticercosis prevalence in Cameroon seems to resemble that in the Democratic Republic of Congo. Central Africa also indicates high infection rates of porcine cysticercosis.
|Central Afr Rep||1,087,000||ND|
|DR Congo||967,000||41.2 (n=153)||Ag-ELISA|||
|Sao Tomé & Pr||2,620||ND|
Porcine cysticercosis in eastern Africa
The eastern Africa region consists of 17 countries and approximately 10 million pigs were reared in the region in 2010 (Table 5). The region includes ten out of 13 countries that belong to the CWGESA, an international non-governmental scientific organisation that was founded in 2002 with the overall objective of combating taeniasis/cysticercosis on a regional effort, considering that the disease has no border. As shown in the table below, a number of countries have reported prevalence of porcine cysticercosis, also suggesting high infection pressure in some countries. In Tanzania, an incidence rate of 69 per 100 pig-yeas was estimated in sentinel pigs based on antigen ELISA .
Economic impact of porcine cysticercosis in Africa
Quite a good amount of information regarding the monetary burden of porcine cysticercosis has been reported in the southern, western, central, and eastern Africa regions. Extensive and most recent studies are those conducted in South Africa and Cameroon [4,5]. These studies were also able to establish the disease burden in humans. Overall, the available information provides enough evidence of the agricultural impact of porcine cysticercosis in Africa, especially most of sub-Saharan Africa. Table 6 summarises the information on the monetary burden of porcine cysticercosis in Africa.
|Zambia||500,000||8.2-23.3 (n=98-1691)||Ag-ELISA||[28, 29]|
|Southern Africa||S. Africa 04||US $18.6 - 34.2 M||US $5.0 M||ND|||
|Western Africa||B/ Faso||€ 52,830|||
|Nigeria||€ 17,442, 000|||
|Central Africa||Cameroon||€ 10,255,202||€ 478,844||€ 45,838.4|||
|D R Congo||€ 2,141,700|||
|Eastern Africa||Burundi||€ 218,325|||
This extensive literature survey has established the agricultural impact of porcine cysticercosis in Africa. The results indicate a high disease burden and its economic impact to affected countries due to monetary losses in the agricultural sector, human health related costs and reduced manpower as a result of disabilities in neurocysticercotic patients. Most of the previous studies have focused on financial losses due to reduced value of infected pigs. This can grossly underestimate the burden of
Authors for the various studies and data sources used in the compilation of the information presented in this chapter are highly acknowledged.