Characterization of the Environmental Risk of Cysticercosis Induced Epilepsy in the City of Abidjan

  

    
Commune
    
Districts
  
  

    
Abobo
    
Anokoua-Kouté
  
  

    
Anador
  
  

    
Avocatier
  
  

    
Abobo-Centre
  
  

    
Abobo-Té
  
  

    
Cocody
    
Anono
  
  

    
Cocody-Centre
  
  

    
Plateau-Dokui
  
  

    
Koumassi
    
SOPIM
  
  

    
Embankments
  
  

    
Marcory
    
Hibiscus
  
  

    
Yopougon
    
Gesco-Handling
  
  

    
Old Sicogi District
  

Table 5: List of neighbourhoods with CYSTICERCOSIS SE-positive patients.

Discussion

The methodological approach implemented during the present study is based on a process of spatial analysis simplicity to characterize the state of the environment near the place of life of epileptic patients. Indeed, the environmental and anthropogenic data collected have not been hierarchically codified because there is not, to our knowledge, a predominance of one factor over another in the infestation by the larva of Tænia solium. The various studies devoted to this disease show that it occurs in spaces “where hygienic conditions are defective, sanitary facilities are rare, meat consumption or pork preparations are frequent and where human-animal promiscuity is very important” [10-12] Several studies have revealed that cysticercosis is due to an unhealthy environment and a lack of hygiene, both reservoir of the larva of Tænia solium and vector of diffusion of the latter, without however determining the supremacy of one element of the environment over another [13,14]. It is therefore this idea that motivated the choice of the synthetic indicator used in this study. In addition, the index developed materializes the sufficient presence or not of the environmental parameters identified as close as possible to the area of residence of the patients.

The idea of characterizing the environment but also the risk incurred only in the patient’s living space led to the choice of the mapping technique by carroyage. The latter makes it possible to carry out our analysis in a regular and homogeneous spatial mesh over the entire territory studied. This makes it possible to overcome administrative geographical boundaries avoiding any extrapolation of the phenomenon to areas not concerned or influenced. This aspect is also highlighted by CERTU [15] when it states that cartographic representation by carroyage ensures ‘independence from the administrative and statistical perimeters to which cartographers and users of Geographic Information Systems (GIS) are accustomed’. In the same spirit Darriau [16] suggests using the assembly of tilesx (carroyage) in urban areas to overcome the imprecision of municipal divisions in the analysis of demographic and socioeconomic phenomena. According to Darriau [16], the mapping system by carroyage is very suitable for the study of variables related to the environment. Indeed, for this author the analysis of the spatial distribution of a fact escapes any partition of space therefore cannot be circumscribed within an administrative limit.

The fine-scale spatial analysis of data offered by carroyage maping is already used in various fields of activity. Various applications have been developed especially for plants, i.e. in botany in relation to the census of plant species, or in rural geography in Brazilian cerrados [17]. More recently, this technique has been used by regional urban planning agencies in France to carry out territorial diagnoses. National Institute of Statistics and Economic Studies (INSEE) has also developed this mapping technique to analyze both the distribution of the population and certain other socio-demographic and socioeconomic indicators.

The analysis of the data collected during the study both on spatialization of the synthetic index and on cysticercosis cases reveal degradation of the environment. Indeed, 98% of the data collected are marks of insalubrity of the environment. These are stagnant water points, litter dumps, gutters clogged by garbage or enforceable septic tanks. They are supposed to be poqitive environment for contamination by Tænia solium eggs. The concentration of these elements in the vicinity of the living place of epileptics supports their role in the contamination.

Moreover, these environmental parameters are perceived as sources of contamination of populations and disease vectors because their presence increases the exposure of local residents. Authors (Sy I et al, Dongo K et al) in their study on the analysis of the health environment situation of disadvantaged neighborhoods of Yopougon obtained results similar to ours [5]. Indeed, they were able to observe a deficit of the sanitation and garbage management system in these precarious neighborhoods that underpins the use of public spaces and alleys as places of sewage disposal and garbage dump. This situation is also highlighted by Sy et al. [4] when they stated that the growth of the city of Nouakchott has led to many environmental changes linked to the difficulties of sewage disposal, household waste collection and access to drinking water [4]. The state of the sanitary environment of these neighborhoods explodes the populations who live there to different diseases of fecal peril including cysticercosis. Indeed, the presence in the streets of wastewater but also those of sewers that overflow or are open in case of rain on the one hand and defecation in the open air or in wild deposits of garbage on the other hand multiply the chances of individual’s tobe in contact with seals containing larvae of Taenia solium. In accordance with the data collection centered only in the residence areas of epileptics and the recommended mapping method by carroyage, the environmental risk related to cysticercosis could be characterized in the living space of the latter. The results obtained show that only 20% of this territory has a sanitary environment conducive to the emergence of cysticercosis. In addition, at the general scale of the city of Abidjan the measurement of the level of environmental risk observed is moderate with some pockets of high or very high risk.

The districts of Gonzagueville and Adjouffou in the municipality of Port-Bouët, which show the highest proportion of very high risk (5.3%) correspond to urban areas of spontaneous habitats. In the latter, the lack of sewerage network favors the use of vacant streets and spaces as garbage dumps and sewage dumps, and even as places of defecation. In addition, the sandy appearance of the soil promotes the retention of rainwater hence the proliferation of stagnant water. Ultimately, both the physical environment and the urban structure of these neighborhoods contribute to the degradation of their health environment, exposing residents to significant health risks.

The spatial distribution of epileptic patients with positive seroprevalence of cysticercosis is not always consistent with the level of degradation of their living environment. Indeed, the majority of neighborhoods with cysticercosis-positive patients have a low or medium risk level. Only the districts of SOPIM and Anokoua-Kouté located respectively in the communes of Koumassi and Abobo have a high environmental and anthropogenic risk.

However, it is initially observed that not all the neighbourhoods surveyed despite the state of environmental degradation they present do not harbour positive cases. Secondly, the district of Adjouffou in the commune of Port-Bouët, which has the highest level of risk in the city of Abidjan with 5.3%, has no positive cases of cysticercosis.

Conclusion

The mapping of the environmental and anthropogenic risk related to cysticercosis in the Abidjan agglomeration operated from the gridding technique has allowed an efficient spatialization of this phenomenon in the living environment close to the epileptics identified in the neurology departments of the city.

The findings reveal firstly that only 20% of the total area represented by the patients’ neighbourhood of residence is submitted to a moderate environmental risk. Secondly, the sectors where the level of risk is high and/or very high are observed in Gonzagueville and Jean Folly neighbourhoods in the Port-Bouët commune and in Niangon Nord in Yopougon commune.

Methodologically, the development of a composite index to measure the level of exposure of neighbourhoods to environmental and anthropogenic risk appears to be an important decision-making tool. Because it enables the detection of unhealthy areas in urban environments that are potential reservoirs of pathogens, it can guide health authorities in epidemiological surveillance and the implementation of measures to contain diseases.

Following the present study, during which only the immediate environment to epileptic patients was investigated, it would be appropriate to consider the collection of environmental and anthropogenic data in all the neighbourhoods composing the urban space of Abidjan. This would indicate the level of degradation of the urban environment at the scale of Abidjan while also assessing the risk of exposure to faecal peril diseases for the entire city.

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