Designing interventions to control cysticercosis

Porcine cysticercosis is a parasitic condition of pigs caused by the larval stage of the human tapeworm Taenia solium. People become infected with an adult tapeworm by eating undercooked pork containing cysts. Pigs and people become infected with the larval stage by ingesting the eggs which are passed in the faeces of an infected tapeworm carrier.

In pigs, the parasite does not cause significant disease. However, in people the disease has two forms.

Neurocysticercosis is the leading cause of acquired epilepsy worldwide. Unfortunately, the vast majority of affected people live in low-and-middle income countries and do not have access to appropriate health care services and treatment. There is a large treatment gap in the management of epilepsy in these regions and combined with the social stigma associated with the condition people living with epilepsy often do not have the same opportunities as other members of the community.

Control options for cysticercosis may be focused on preventing or treating the infection in people or can be animal focused. Human interventions include improved sanitation, targeted deworming of tapeworm carriers and education programmes regarding the life cycle of the parasite. Animal control options include improved meat inspection, deworming and vaccination of pigs.

We have been conducting research on the epidemiology of cysticercosis in Kenya since 2010. We have identified risk factors associated with exposure to the parasite and have modelled the success of various control options. As we move forward with our research we aim to use the information we have collected to develop a culturally appropriate intervention for the control of porcine cysticercosis in the region.

Research questions and methods

The next phase of our research is divided into two parts. During phase one we will continue to collect baseline data in order to guide the design of the most effective and appropriate control options and phase 2 will be the implementation of these interventions.

Diagnostic test development (2019-2020)

One of the limitations when developing a control programme for porcine cysticercosis is the ability to rapidly and accurately diagnose infections in pigs. We are collaborating with partners, the Technical University of Munich and Arista Biologicals to trial pen side tests (Image 1) that can be used to detect infected pigs at the point of slaughter and hence reduce the number of infected carcasses entering the food chain.

Risk mapping (2019-2020)

We are currently collecting slaughterhouse data (Image 2) regarding porcine cysticercosis and household level data regarding risk factors to identify geographical areas at high risk of porcine cysticercosis.

Review of current control methods (2019-2020)

There are various control methods for porcine cysticercosis. We are conducting a review of the published literature to assess the success of these methods. We are also conducting key informant interviews with veterinary and public health officials in Kenya to evaluate the existing policy, strategy and programs for the control of cysticercosis in the country.

Burden of epilepsy (2021)

Interviews with people living with epilepsy will help us to understand the burden and stigma associated with this condition. We will also interview healthcare workers to better understand the available resources for diagnosing and treating epilepsy and the existing gaps. Matching cases of acquired epilepsy with control patients will give us a better understanding of the risks and benefits of animal ownership to people living with epilepsy

Intervention baseline (2021)

A cross sectional study of pig keeping households (Image 3) in a region identified as being at high risk for porcine cysticercosis will be conducted as a baseline for the proposed control intervention.

Expected results

The results of Phase 1 will help us the design an intervention strategy for porcine cysticercosis that will be appropriate to the region. This will be trialled in Phase 2 of the project. Phase two will be implemented as a randomised control trial to quantify the impact of the control methods on the prevalence of porcine cysticercosis. The intervention will likely be a combination of previously trialled methods. We will use multimedia tools to educate pig keepers about porcine cysticercosis and measure the uptake of affordable interventions as well as the impact on the prevalence of the disease

The control of porcine cysticercosis will require collaboration with the veterinary, public health and human medicine partners since the lifecycle involves both pigs, people and the environment but we will also need to understand the human element that predisposes certain people to higher risk. Understanding the risk behaviours and animal husbandry practices that increase the transmission of this disease will guide the design of our intervention package.

Pork meat with Taenia solium cysts