Surveillance, prevention and control
While infections with T. saginata can be managed through an individual clinical approach due to its low pathogenicity, those due to T. solium require proper public health interventions aimed at their prevention, control and possibly elimination.
Such interventions should in principle require strict meat inspection regimens, health education, thorough cooking of pork, sound hygiene, adequate water and sanitation, improved pig husbandry practices and easy access to treatment for both infected individuals and people who are in close contact with them. Difficulties linked to the implementation of such measures are increased by the fact that reliable epidemiological data on geographical distribution of T. solium taeniasis/cysticercosis in people and pigs is often missing.
Appropriate surveillance mechanisms should enable new cases of human or porcine cysticercosis to be reported to national authorities in order to facilitate the identification of communities at high risk and focus prevention and control measures in such areas.
Identification of T. solium endemic areas relies on a number of tools which detect taeniasis and cysticercosis in humans or cysticercosis in pigs.
As epidemiological studies have demonstrated that cases of human and porcine cysticercosis tend to cluster around persons infected with T. solium tapeworms, who act as sources of transmission, identification of human tapeworm carriers might help focus the public health interventions. Methods available include detection of eggs in human faeces or in the peri-anal region, or detection of tapeworm antigens in human stool samples.
Options available for detecting human cysticercosis include biopsy of subcutaneous cysts (a common manifestation of cysticercosis in Asia), immunodiagnosis (detection of antibodies or parasite antigens in serum samples) and imaging (radiography, computed tomography and magnetic resonance imaging).
Methods for detecting cysticercosis in pigs include the rapid, inexpensive method of detecting lingual cysts, but this has low sensitivity, or more sensitive immunodiagnostic tests and postmortem inspection. One dose of the drug oxfendazole has been found to cure porcine cysticercosis though it may take several months for the cysts to disappear.
In 2009, all aspects of controlling T. solium infection and disease were discussed during an expert consultation on foodborne trematodiasis and taeniasis/cysticercosis held in Vientiane, Lao People’s Democratic Republic. The meeting issued guidance that focused on an integrated approach that targets both taeniasis and cysticercosis and includes large-scale preventive chemotherapy in humans, and treatment and vaccination of pigs. These tools should be ready for use in the field within 2–3 years.
The consultation group further acknowledged that community-led total sanitation (that is, the provision of adequate water and sanitation organized by the community itself) is a novel approach to behavioural change and has the potential to be scaled up with minimal investment. Its potential role in control of helminth infections is being investigated.
The hope is that the combined implementation of all these interventions will produce such an impact on transmission of T. solium that elimination of taeniasis/cysticercosis will be an achievable goal in the foreseeable future.