Geographic Distribution of the Prevalence of Neurocysticercosis in the Municipality of Piedade, São Paulo

1. INTRODUCTION

Neurocysticercosis (NCC) is a term used to define the involvement of the central nervous system (CNS) by the larval form of Taenia solium. This disease is the leading cause of epilepsy in adults worldwide and one of the main parasitosis associated with chronic morbidity on all continents. Other clinical manifestations observed are dementia, intracranial hypertension, headache and meningitis, among others. In its vesicular form, the cysticercus can persist for many years in the CNS without the patient developing symptoms [1-4].

Despite its importance and global morbidity, unfamiliarity of the population with NCC makes it an underestimated disease. The lack of investment in scientific research prevents the advances in the treatment and prevention of this neuroinfection that are necessary in order to help millions of patients with epilepsy. It is estimated that 50 million people in the world have NCC, with 50,000 annual deaths [3-8]. However, new research is necessary to update this number.

Brazil is a country that is greatly affected by the taeni- asis/cysticercosis complex. The lack of basic sanitation and precarious hygiene habits, including food hygiene, among other factors, contribute to the occurrence of this disease. Although one of the richest states in the country, São Paulo has the same problem in all regions, regardless of the socioeco- nomic situation. One of the few studies on the topic available in Brazil reports an incidence of 54 NCC cases per 100,000 inhabitants in Ribeirão Preto, located in the northeastern region of the state [1, 3, 5]. Within this context, the aim of this study was to analyze the geographic distribution of the prevalence of NCC in the municipality of Piedade, São Paulo.

2. MATERIALS AND METHODS

3. RESULTS

The questionnaire was applied to 136 patients, including 54 (39.71%) men and 82 (60.29%) women ranging from 13 to 86 years. All patients with NCC, 24 (17.65%), had the calcified cerebral form of the disease. In this group in which the parasite was detected by imaging examinations, 29.2% lived in the urban area and 70.8% in the rural area. There were 29.2% men and 70.8% women.

All respondents, 136 (100%), reported to have heard, at some point, comments about “pork disease”. The participants knew that, in this disease, the parasite can lodge in the human brain and that after the death of the parasite, also based on the information of medical professionals, the disease will cease without causing future problems for the organism.

As can be seen in Table 1, there was a significant difference in age and NCC+ in the urban area due to the higher prevalence among older adults. A higher prevalence of the open sewer category was observed in rural area. Comparison of the urban and rural areas showed a lower prevalence of NCC+ in the rural area for public sewer/septic tank, for water-/urban untreated, urban treated but not filtered, and for fruits-/washed (filter water or boiled or chlorinated or vinegar). In addition, analysis of the total sample in the rural area revealed a lower prevalence of NCC+ when compared to the urban area (p<0.01).

Table 2 shows a significantly higher prevalence of NCC+, regardless of the other factors of the table, for older adults in the urban area and total sample; for the open sewer category in the total sample, and for unwashed fruits in the urban area and total sample. When adjusted for the other variables, the prevalence of NCC did not differ significantly between the rural and urban areas (p=0.06).

Fig. (1) illustrates the concentration of NCC+ cases in the urban area.

4. DISCUSSION

The prevalence of NCC in the sample was 17.65%, which was strongly associated with age above 60 years in both areas, the presence of open sewers, especially in the rural area, the lack of drinking water treatment, particularly in the urban area, treated water but without adequate filtration in the urban area, and inappropriate washing of fruits and vegetables before consumption in both areas.

Analysis of the geospatial distribution of NCC showed a larger proportion of cases in the urban area; however, there was no significant difference between the rural and urban areas. The hypotheses to explain this result include the natural history of the disease, rural-urban immigration, and the site of exposure differing from the place of residence, among others. Within this context, the following factors are very important for the eradication of the taeniasis/cysticercosis complex: personal hygiene habits, care with the preparation and washing of foods before consumption, appropriate drinking water treatment including filtration, investment in basic sanitation, adequate preparation of pork products, and rigorous monitoring of pig farm facilities and commercialization by health surveillance authorities.

The results found in this study make a valuable contribution since the prevalence of NCC in Brazil is unknown because of the absence of compulsory notification in many states and the difficulty of access of the majority of the population to diagnostic methods. The calcified forms of the parasite found in the patients studied may pose a serious health threat because they can cause irreversible changes in the individual and require lifelong treatment and medications. The diagnosis of NCC is made by a combination of immunological methods and neuroimaging [6, 8-13]. The false notion evidenced in the population studied, similar to that observed in the world population, that the calcified form of the parasite does not cause health damage in affected individuals must be urgently revised and corrected [3, 4, 8, 9, 11-14]. According to Camargo et al [3, 4, 15, 18-20], the expressions cerebral calcification, inactive cyst, dead parasite, cysticercotic calcification and dead cysticercus, which are all very common in popular language, must be revised and adequately explained to the population and health professionals who are unaware of the disease. In the area studied, other asymptomatic individuals may be contaminated with different forms of the parasite, which can lodge in the CNS and persist for many years without causing symptoms [1, 2, 8, 9, 16, 17].

As mentioned earlier, the factors that contribute to the endemic appearance of the taeniasis/cysticercosis complex are numerous and closely related to personal and family hygiene habits and environmental factors. Within this context, government investment in health and educational programs is needed, advising the population on the importance of controlling and preventing this disease in view of its severe consequences for public health and the lack of access of the majority of the population to diagnostic methods [21-25].

CONCLUSION

Considering the parasite’s biological cycle, avoiding the deposition of human feces in septic tanks may be an important start for disease control. Raising the awareness of the population and of the competent authorities about the disease and methods for its prevention is an urgent measure, not only for the area studied but for the world population living in urban and rural regions.

REFERENCES