In this blog we take a look at the economic impact of a parasitic worm infection responsible for a large proportion of epilepsy cases in the developing world. The disabling nature of the disease translates into a huge economic burden on both a personal scale for the sufferer and for the countries where the disease is prevalent. By demonstrating the value to be gained from disease elimination we hope to demonstrate the importance of investment in appropriately funded and designed control and eradication programmes.
Cysticercosis is an example of a neglected tropical disease (NTD) identified by the WHO and is caused by the larval stages of the tapeworm species Taenia solium, which affects both man and pigs. [1, 2] The disease remains a big issue in many developing countries, mostly affecting the health and livelihoods of the poorest populations within a country. The fact that the disease is entirely preventable, makes its impact on health and economy even more devastating. Epileptic seizures, chronic headaches and memory loss are all common symptoms of infection that contribute to the morbidity of the disease. The disabling nature of these symptoms translates into a huge economic burden to the sufferer in the form of expenses needed for treatment and productivity losses, making disease control essential yet desperately lacking.
For people living in developing countries around the world, one of their only economic productivity assets is often their body. The economic shock of a debilitating illness, like cysticercosis, can drive a sufferer into abject poverty. Although data on the global disease burden of cysticercosis is limited, it is estimated that there are approximately 50 million people in the world living with the infection and that epileptic seizures occur in 50-70% of all symptomatic cysticercosis cases.
To begin to develop a better picture of the economic burden of cysticercosis across the globe, we searched key repositories of health-related publications including PubMed, the World Health Organisation (WHO) and Cochrane websites combining a variety of disease-related search terms with a selection of economic-related terms. Disease-related search terms included all of the 17 NTDs as defined by the WHO, and economic-related search terms included words such as burden, cost and employment. Diseases, like cysticercosis, with inexpensive treatments that affect the largest populations were prioritised. A total of 282 articles met our inclusion criteria, which we then subdivided by disease area giving a total of  articles for cysticercosis. Of these, we were able to access 8 articles for our review. The locations of these studies included East Asia, South Africa, West Cameroon, Mexico and Peru.
Table 1 shows annual economic losses arising from cysticercosis according to different developing countries across the globe. These estimates are always in the tens of millions and suggest that T. solium cysticercosis results in considerable costs for regions that are already economically constrained. We hope that these figures:
Table 1. A comparison of annual economic losses arising due to human/pig cysticercosis according to country.
At this point, it is also important to note that T. solium does not only produce a severe disease in humans but also causes widespread economic losses to the pig industry. In Mexico, for example, porcine cysticercosis caused loss of more than half the national investment in swine production, and the losses that arise as a result of the destruction of meat are estimated at $43 million per year. In less developed countries, pigs are an important source of money for farmers due to them being cheap and more easily marketable than other animals such as cows. T. solium transmission is maintained in rural areas where pigs have access to untreated human sewage or faeces. By simply improving sanitation and controlling domestic pig farming, many developed countries have eradicated cysticercosis. So why has this not occurred in developing countries? A lack of socioeconomic development impedes a country's chance of control and elimination and unfortunately the near future holds limited hope for further socioeconomic advancement. As a result, investment in intervention measures to control and eradicate cysticercosis are desperately needed and should be appropriately targeted to the places that need them most.
While the annual costs presented in this blog are eye wateringly high enough, they are only estimates, and unfortunately it is likely that the majority are underestimates. This could be for a number of reasons, for example, Praet et al (2009) make estimations based on epilepsy as the only symptom of cysticercosis and Rajkotia et al (2007) do not discriminate between leisure time and idle time due to job loss; thus productivity losses have probably been underestimated. Also, the study by Rajkotia et al (2007) does not estimate the losses arising from the reduced future potential earnings among cysticercosis patients who cannot return to work after infection with the parasite; a figure that stands at approximately two-thirds of wage-earners. Of these sufferers, only 61% were then able to re-engage in wage-earning activities.
To further increase the chance of eradication, future work should attempt to estimate the burden of cysticercosis on a global level and identify priority areas for action. This early attempt at collating country specific costs revealed that the cost of inactivity due to disease, influenced by salaries, plays the largest role in the monetary burden of T. solium cysticercosis. If we could gain access to accurate country-wide salary levels and disease prevelance this would certainly improve our chances of gaining a more accurate indication of the total economic burden of T. solium cysticercosis that could be summed across the globe. These accurate global estimates are essential for highlighting the gains that could be made, not only in terms of people's health but also in terms of money saving, by eliminating these diseases.