Diseases

Cysticercosis

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Control Tools

  • Diagnostics availability

  • Commercial diagnostic kits available worldwide

    None in pigs. A number of assays for antibodies to T. solium in humans are now available commercially (E.g Cysticercosis RIDASREEN, Cysticercosis MERLO TEST, MAGIWEL , Immunetics QualiCode cysticercose kit). These use ELISA or western blot technology.

    GAPS:

    • Kits are not available worldwide. The few available are Antibody based ELISA or Western blot. Performances (se/sp)
    • Antigen, antibody ELISA’s are available, however not commercialized.
    • Large scale validation studies should be carried out.
  • Commercial diagnostic kits available in Europe

    None in animals.

    GAPS:

    • The kits not available worldwide. The few available are Antibody based ELISA or Western blot. Performances (se/sp)
    • Antigen, antibody ELISA’s are available, however not commercialized. Large scale validation studies should be carried out.
  • Diagnostic kits validated by International, European or National Standards

    None for pigs but some have been internationally validated for humans, e.g Immunetics QualiCode cysticercose kit.

    GAPS:

    • Need for appropriate (geographic) validation.
    • Need to establish reference serum banks and laboratories (quality control)
  • Diagnostic method(s) described by International, European or National standards

    Methods are described in the OIE Manual of Diagnostic Tests and Vaccines for Terrestrial Animals 2009 Chapter 2.9.5.–Cysticercosis.

    These include:

    • Identification of the agent
    • Serological tests (Ag and Ab detection)
    • Molecular confirmation

    WHO FAO OIE guidelines for surveillance and prevention and control of taeniosis/ cysticercosis(2005): chapter 4, pp45-56.

  • Commercial potential for diagnostic kits in Europe

    Yes. The potential for commercial is there for human cysticercosis, not for porcine cysticercosis.

    GAP: There is limited production thus affecting distribution and availability in Africa, Latin America and Asia.

  • DIVA tests required and/or available

    Not required (antibodies from natural infection can be easily distinguished from antibodies against TSOL18 (recombinant oncosphere protein) or S3Pvac (synthetic peptides).

  • Opportunities for new developments

    The development of an automated sensitive and specific diagnostic test would greatly reduce the costs of damage to the carcass and also the costs of labour.

    Ag-ELISAs do have a use in field-based epidemiological studies for indicating transmission. For example, the detection of viable infections in pigs could indicate point sources of infection, season of transmission and age of animals at risk.

    GAPS:

    • Serum bank needed with well documented serum and cerebrospinal fluid samples in order to study sensitivity, specificity, reproducibility of serological tests.
    • User friendly, cheap, rapid, pen- side test needed: lateral flow to automated ELISA ( no need of cold chain, robust…)
    • Better diagnostic tests for taeniosis
    • Diagnostic test for detection of eggs in the environment
    • Multi-testing
  • Vaccines availability

  • Commercial vaccines availability (globally)

    None but a T. ovis recombinant vaccine was registered in 1994 by the New Zealand Animal Remedies Board. However, due to market changes in New Zealand, the vaccine is not available commercially.

    GAP: Full development and availability for routine use.

  • Commercial vaccines authorised in Europe

    None.

  • Marker vaccines available worldwide

    None.

  • Marker vaccines authorised in Europe

    None.

  • Effectiveness of vaccines / Main shortcomings of current vaccines

    TSOL18 >99% effective in repeated controlled experimental trials and a field trial in Cameroon (Two to 3 vaccinations in combination with treatment were needed to provide high vaccine protection). S3Pvac attained statistically significant reduction in porcine cysticercosis in field trials.

    GAPS: More field trials with TSOL18. Controlled experimental infection trials with S3Pvac. Duration of immunity. Interference by maternal antibody.

  • Commercial potential for vaccines in Europe

    None in Europe. The importance of cysticercosis due to T. solium in humans increases the costs of the disease, but it remains to be seen whether the significance of the disease in endemic countries will be sufficient to push commercial production of the vaccine for use in pigs to prevent cysticercosis and to break the chain. Tapeworm vaccines have, in general, not been economically feasible or practical in their implementation.

  • Regulatory and/or policy challenges to approval

    No specific challenges linked to vaccines other than the need to obtain licences or authorisation. No likely regulatory issues for TSOL18.

    GAPS: The safety and efficacy of the potential vaccine candidate may have to be tested in GLP studies in the pig, where 5-10 times the clinical dose is tested, before regulatory approval. Contact to regulatory authorities is recommended.

  • Commercial feasibility (e.g manufacturing)

    Feasible to manufacture but will depend on the demand and potential markets. This in turn will be linked to cost especially for the developing countries. Lack of commercial incentives for use of cysticercosis vaccine by poor farmers.

  • Opportunity for barrier protection

    Limited but could be used in a region or zone as part of a control programme.

    GAPS: Costs currently unknown. No large scale production undertaken at present. Combination with commercially valuable porcine vaccine to improve vaccine uptake.

  • Opportunity for new developments

    TSOL18 vaccine would be no barrier to trade.

    GAP: Combination with commercially valuable porcine vaccine.

  • Pharmaceutical availability

  • Current therapy (curative and preventive)

    Possible use of oxfendazole in pigs but would need to be specially linked to safety and withdrawal periods as the main reason for use would be to kill the cysticerci to ensure no infection of humans eating the meat.

    Human cysticercosis is currently treated using albendazole, praziquantel or a combination. There is evidence that albendazole is cheaper and more effective than PZQ (Del Brutto et al, 2006. Ann Int Med 145: 43-51). Albendazole has an efficacy of 85 % whereas that of PZQ is even much lower.

    Treatment of NCC requires a range of treatments from anti-epileptic drugs to placement of a shunt in the case of hydrocephaly.

  • Future therapy

    Development of new drugs to treat the cysticerci.

    GAPS:

    • In vitro techniques for drug screening
    • Drug which kills cysticerci both in muscles and in brain of the pigs.
    • Neurocysticercosis: more effective drugs or drug combinations needed.
  • Commercial potential for pharmaceuticals in Europe

    Very low.

  • Regulatory and/or policy challenges to approval

    No specific challenge.

  • Commercial feasibility (e.g manufacturing)

    With praziquantel, albendazole and oxfendazole already on the market it is unlikely that big pharma will endeavor into the costly development of new products.

  • Opportunities for new developments

    None at present.

  • New developments for diagnostic tests

  • Requirements for diagnostics development

    1. The development of an automated sensitive and specific diagnostic test would greatly reduce the costs of damage to the carcass and also the costs of labour.

    2. Ag-ELISAs do have a use in field-based epidemiological studies for indicating transmission. For example, the detection of viable infections in pigs could indicate point sources of infection, season of transmission and age of animals at risk.

  • Time to develop new or improved diagnostics

    From development through validation to commercial availability will be time consuming (5 to 10 years).

  • Cost of developing new or improved diagnostics and their validation

    The development of an improved diagnostic test is expensive. It is questionable if a potential market is available.

    GAP: funding.

  • Research requirements for new or improved diagnostics

    1. The development of an automated sensitive and specific diagnostic test would greatly reduce the costs of damage to the carcass and also the costs of labour.

    2. Ag-ELISAs do have a use in field-based epidemiological studies for indicating transmission. For example, the detection of viable infections in pigs could indicate point sources of infection, season of transmission and age of animals at risk.

    GAPS:

    • multi-testing
    • Serological test which is able to detect living cysts in the brain
  • New developments for vaccines

  • Requirements for vaccines development / main characteristics for improved vaccines

    The TSOL18 which is currently the best available vaccine should be further improved. The ideal vaccine should provide 100% of protection after one dose. Preferably it should be possible to combine the TSOL18 vaccine with other vaccines, e.g. against classical swine fever or in future against African swine fever.

  • Time to develop new or improved vaccines

    Depending on when a candidate vaccine could be identified the timescale will be 5-10 years. Potential vaccines are under trial at present and depending on the outcome will depend the time to commercial availability.

  • Cost of developing new or improved vaccines and their validation

    Expensive with the need to develop and undertake all the relevant tests to provide data to enable the product to be authorised. The safety and efficacy of the potential vaccine candidate may have to be tested in GLP studies in pigs, where 5-10 times the clinical dose is tested, before regulatory approval.

  • Research requirements for new or improved vaccines

    A single shot vaccine might be achieved by pulse-release vaccine formulations or by live recombinant vaccine vectors such as Salmonella which may give a long-lasting immunity after one immunisation.

    GAP: Protection level when a combined vaccine is administered.

  • New developments for pharmaceuticals

  • Requirements for pharmaceuticals development

    GAPS:

    • In vitro techniques for drug screening
    • Drug which kills cysticerci both in muscles and in brain of the pigs.
    • Neurocysticercosis: more effective drugs or drug combinations needed
  • Time to develop new or improved pharmaceuticals

    Time to develop would depend on the product and the trials necessary to validate the efficacy and safety. Commercial production would then take further time.

  • Cost of developing new or improved pharmaceuticals and their validation

    Costly. With praziquantel, albendazole and oxfendazole already on the market it is unlikely that big pharma will endeavor into the costly development of new products.

Disease details

  • Description and characteristics

  • Pathogen

    Humans are the definitive host of the tapeworm (Taenia solium) which causes taeniosis. Cysticercosis occurs when humans and pigs become infected with the larval (metacestodes) stages.

    GAPS:

    • Life-span of the adult tapeworm
    • Multiple tapeworm infections
    • Co-infection with multiple species
  • Variability of the disease

    The adult stages of T. solium occur in the intestine of humans. The cysticerci of the human tapeworm T. solium cause porcine cysticercosis and occur mainly in muscles and the central nervous system. In heavy infections the liver and other organs of the pig may also be infected. Usually only one adult worm in man, single or multiple larval infections in humans and pigs.

    GAPS:

    • Strain differences;
    • human host parasite relationship
    • Parasite-parasite interactions including concomitant immunity.
    • Morphology and localization of cysts in different tissues at different times.
  • Stability of the agent/pathogen in the environment

    The eggs are generally shed inside a proglottid, which remains in the faecal bolus and disintegrates in the environment. The eggs may be disseminated by rain wind and invertebrates and can contaminate vegetation and water. T. solium eggs can survive in the environment for a few weeks or months.

    GAPS:

    • Length of persistence of eggs in the environment under various pH, moisture and temperature conditions
    • Difference of survival in water vs ground vs surfaces Density of egg contamination
  • Species involved

  • Animal infected/carrier/disease

    Cysticercosis is an infection of pigs with the larval stages of the parasitic cestode, Taenia solium.

    GAP: Possible involvement of wild pigs, warthogs, non-human primates.

  • Human infected/disease

    Cysticercosis is an infection caused by the human tapeworm, Taenia solium. Infection occurs when the tapeworm oncospheres enter the body and form cysticerci. The most serious form is neurocysticercosis when cysticerci are found in the central nervous system.

  • Vector cyclical/non-cyclical

    Mechanical vectors only.

    GAP: Role of dung beetles and flies – tracing of faecal contamination.

  • Reservoir (animal, environment)

    Only humans, pigs, sometimes dogs.

    GAP: other reservoirs?

  • Description of infection & disease in natural hosts

  • Transmissibility

    Human-pig-human, human-human (mechanical, auto-infection).

    GAPS:

    • The ways of horizontal and vertical transmission
    • Role of dogs in transmission; The role of pig-to-pig transmission via faeces
    • The role of pigs as transport hosts
    • The role of food borne transmission of larvae (through bad hand hygiene) vs water-borne transmission of larvae
    • The routes of human auto-infection
  • Pathogenic life cycle stages

    Eggs are shed from infected humans, ingested by pigs, after which the oncospheres penetrate the intestine and migrate to muscle tissue and develop into cysticerci. The parasite life cycle is completed, when humans ingest undercooked pork containing cysticerci. Cysticerci evaginate and attach to the small intestine by their scolex resulting in human tapeworm infection.

    GAPS:

    • Release of oncospheres from segments in intestinal tract
    • Duration of infection with adult T. solium in humans (no study available)
    • Possibility of cysticercal infection from taeniosis infection (auto-infection)
  • Signs/Morbidity

    Usually asymptomatic. The type and severity of the clinical signs depend on the number and location of the larvae.

    GAPS:

    • Pathogenesis of porcine cysticercosis and clinical symptoms
    • Studies on pigs could be helpful to better understand natural history of CNS infections in man
  • Incubation period

    In theory, cysts can be visualised in pigs or felt in tissues such as the tongue of heavily infected animals as early as 2 weeks after infection. Cysticerci are readily visible by 6 weeks and fully developed between 60 to 70 days.

  • Mortality

    None.

  • Shedding kinetic patterns

    Adult tapeworms which develop in humans reside in the small intestine for years. Sporadic shedding pattern in humans (short intervals) and production of less than 1000 proglottids. Usually, one to two proglottids are excreted per day, each with approximately 50,000 eggs part of which are immediately infective to pigs and humans when passed.

    GAP: Proportion of infective eggs of the total number excreted.

  • Mechanism of pathogenicity

    Development of cysticerci in different tissues in pigs and humans.

    GAPS:

    • Immunological responses to the cysticerci in the brain
    • Immunological responses to the larval stages in humans (cellular vs humoral)
  • Zoonotic potential

  • Reported incidence in humans

    Worldwide, taeniasis and cysticercosis are common parasitic infections. Cysticercosis and taeniosis are rare in the U.S. and most parts of Europe.

    GAPS:

    • Not enough information about prevalence and incidence. There has been only one cohort study on incidence rate of NCC-associated epilepsy (recent).
    • Need more cohort studies to estimate the incidence rate
  • Risk of occurence in humans, populations at risk, specific risk factors

    Linkages with pigs, lack of meat inspection, undercooked meat and poor sanitation/personal hygiene have been identified. Human cysticercosis can occur in local populations even though pork is not eaten and the environment is not shared with pigs if there is a human excreting T. solium eggs in the locality. Auto-infection may occur when tapeworm eggs from a infected individual pass from the intestine back into the stomach, but this has never been proven.

    GAPS:

    • Specific risk factors for neurocysticercosis and auto-infection need to be investigated. Is true intestinal auto-infection possible and taking place or is auto-infection a result of faecal-oral route only?
    • Risk factors for sero-conversion in a cohort study in pigs and humans.
    • Risk factors for taeniosis infection and possible re-infection. Human susceptibility and immunity to T. solium taeniosis.
  • Symptoms described in humans

    Cysticercosis often becomes symptomatic only when cysticerci are developing, disintegrating, dying or become large enough to interfere with blood flow. In the muscles cysticerci do not generally cause symptoms. Sub-cutaneous nodules in humans is common in parts of Latin America and Asia. Although rare in the eyes cysticerci may cause blurry or disturbed vision and may also cause swelling or detachment of the retina. Symptoms of neurocysticercosis depend upon where and how many cysticerci are found in the CNS. Epileptic seizures and headaches are the most common symptoms. Confusion, lack of attention to people and surroundings, difficulty with balance, hydrocephalus may also occur. Death can occur suddenly with heavy infections or in case of low infections when hydrocephalus is created.

    GAPS:

    • Variation in manifestations and reasons for this variation (host or parasite related, genetic variations)
    • Do strains exist which have a predilection to develop in the brain and others to develop subcutaneously or in the muscles?
    • Cohort studies of NCC and associated symptoms needed
    • Duration of the symptoms linked to NCC is unknown
    • Distribution of symptoms among people with NCC is unknown (including people who may remain asymptomatic)
    • Standard definitions of symptoms possibly linked to NCC lacking
    • Possible link with severe headaches / cognition / stroke / dementia / haematological brain disease / psychiatric problem / vision loss etc require more research
    • Several case series report % cases dying, often from hydrocephalus, but no specific studies on this
  • Estimated level of under-reporting in humans

    High. This is classified as a neglected zoonosis. NCC is not a notifiable disease. NCC requires imaging for diagnosis which leads to an underestimation in areas where such facilities are lacking.

    GAPS: A major gap. The real prevalence and incidence of taeniosis, cysticercosis and in particular neurocysticercosis need to be assessed. Regional mapping and co-endemicity with other NTD.

  • Likelihood of spread in humans

    T. solium eggs spread from human to human, through contaminated food and drinking water or by direct contact.

    GAPS:

    • Transmission dynamics models.
    • Risk factors for human to human transmission.
    • Relative transmission via contamination of food vs water borne vs auto-infection.
    • Indirect transmission through fomites unknown.
  • Impact on animal welfare and biodiversity

  • Both disease and prevention/control measures related

    Confinement of the pigs for control.

  • Endangered wild species affected or not (estimation for Europe / worldwide)

    None.

    GAP: More information needed re wild pigs and non-human primates.

  • Slaughter necessity according to EU rules or other regions

    None.

  • Geographical distribution and spread

  • Current occurence/distribution

    Taenia solium is found principally in Mexico, Central and South America, sub-Saharan Africa, non-Islamic countries of Asia, including India and China where there are free ranging, scavenging pigs and where sanitation is lacking.

    GAPS:

    • Much more studies required to delineate areas of high prevalence.
    • GIS analysis in areas where information on pig population, pig rearing methods, sanitation, and prevalence of infection is available.
  • Epizootic/endemic- if epidemic frequency of outbreaks

    Endemic; unlikely to occur as an epidemic, but outbreaks have been reported in isolated populations (For example, Orthodox Jews in New York).

  • Seasonality

    No, except in pigs where the infection is linked to the period of harvesting – pigs are allowed to roam after harvesting.

  • Speed of spatial spread during an outbreak

    Depends on the level of infection in humans and the contamination of the environment.

    GAPS:

    • This has never been scientifically assessed.
    • Movement of pigs within villages and between villages.
    • The importance of human migration.
  • Transboundary potential of the disease

    Spread by people and infected pig meat sold across borders.

  • Seasonal cycle linked to climate

    No.

    GAPS:

    • Seasonality in relation to free-roaming of pigs.
    • Seasonality in relation to the survival of eggs in the environment.
  • Distribution of disease or vector linked to climate

    No.

  • Outbreaks linked to extreme weather

    No.

    GAP: Effects of flooding on dissemination of eggs?

  • Sensitivity of disease or vectors to the effects of global climate change (climate/environment/land use)

    No.

  • Route of Transmission

  • Usual mode of transmission (introduction, means of spread)

    Animals acquire infection from ingestion of segments and eggs contained in human faeces that contaminate herbage, water, vegetation etc...

    GAPS:

    • Contamination of water has not been well documented.
    • Measurement of environmental contamination with eggs has not been done.
  • Occasional mode of transmission

    None clearly defined.

    GAPS:

    • Dog role in transmission, horizontal and vertical transmission need further investigation.
    • The role of birds and coprophagic insects as transport hosts.
  • Conditions that favour spread

    Clinically normal humans infected with T. solium excreting high levels of tapeworm eggs in their faeces with little or no sanitation. Poor pig rearing. Poor hand hygiene in humans.

    GAP: Transmission dynamics models needed.

  • Detection and Immune response to infection

  • Mechanism of host response

    Humoral, cellular and non-specific host responses to cysticerci. A strong protective immunity occurs after natural infection. High levels of protective immunity are induced by antigens in oncospheral extracts. Immunity is largely antibody mediated as evidenced by passive and maternal transfer of immunity.

    GAPS:

    • Effectiveness and longevity of immune response.
    • Role of specific cellular immunity and markers.
    • Inadequate knowledge regarding the most efficacious vaccination protocol (age of onset, number of boosters etc).
    • Characterisation of humoral response to vaccine.
    • Characterisation of host-parasite dynamics depending upon age of first exposure.
  • Immunological basis of diagnosis

    Antibody and antigen detection.

    GAPS:

    • Serum bank needed with well documented serum and cerebrospinal fluid samples in order to study sensitivity, specificity, reproducibility of serological tests.
    • User friendly, cheap, rapid, pen- side test needed: lateral flow to automated ELISA ( no need of cold chain, robust…).
    • Better diagnostic tests for taeniosis.
    • Diagnostic test for detection of eggs in the environment.
  • Main means of prevention, detection and control

  • Sanitary measures

    • Educate and ensure community participation.
    • Prevent contact between pigs and human faeces or food, water, environments contaminated with infected human faeces.
    • Treat humans against tapeworms.
    • Introduce sanitation for the disposal of human faeces.

    GAPS:

    • Implementation and sustainability;
    • egg persistence in night soil, in different sanitation systems;
    • more information needed on effectiveness of interventions in both humans and pigs. Only 1 large scale randomised community trial in pigs available.
  • Diagnostic tools

    Diagnosis in animals is usually based on the detection of the cysticerci at meat inspection or necropsy. In many endemic countries farmers and pig traders look at the tongue to detect cysts. Light infections are often missed. Tests for antibodies or antigens in serum are not used currently for the diagnosis of cysticercosis in animals except for epidemiological purposes.

    GAPS:

    • Serum bank needed with well documented serum and cerebrospinal fluid samples in order to study sensitivity, specificity, reproducibility of serological tests.
    • User friendly, cheap, rapid, pen- side test needed: lateral flow to automated ELISA ( no need of cold chain, robust…)
    • Better diagnostic tests for taeniosis
    • Diagnostic test for detection of eggs in the environment
  • Vaccines

    There is no commercial vaccine available.

    Two vaccines under development, a recombinant protein vaccine TSOL18 (University of Melbourne) and a synthetic peptide vaccine S3Pvac (Institute Biomedicas, Mexico). Other vaccine candidates described but yet to be confirmed.

    GAPS:

    • More research needed under field conditions (duration of immunity, transfer of maternal antibodies, etc). The S3Pvac has never been tested under experimental conditions (challenge of pigs with T. solium eggs).
    • Market studies, Cost-effectiveness studies
  • Therapeutics

    30mg/kg oxfendazole kills 100% muscle cysts within 4 weeks of dosing; does not kill brain cysts. Dead cysts leave lesions that potentially make the carcase inedible for as long as 6 months.

    GAPS:

    • Study needs to be repeated under field conditions.
    • Residue data in pork at the 30mg/kg dose of oxfendazole.
    • Alternative treatments for pigs e.g. ivermectin/ praziquantel, albendazole or flubendazole (in feed) with pig and farmer friendly formulations.
  • Biosecurity measures effective as a preventive measure

    Prevention of contact between pigs or humans with infective tapeworm eggs.

    GAPS:

    • Implementation and sustainability;
    • acceptability and socio-economic impact of any biosecurity measures.
  • Border/trade/movement control sufficient for control

    Information exists regarding cross-border trade of pigs and introduction of T. solium infection via immigrants.

    GAPS:

    • Effective implementation of border controls.
    • Trade implications of future vaccination programs.
  • Prevention tools

    Cysticercosis in pigs can be decreased by preventing or treating T. solium in humans. To prevent infections with T. solium, animals should not be exposed to human faeces.

    GAP: Effectiveness of alternative control strategies on the incidence rates of infection in humans and pigs in large scale randomised field trials.

  • Surveillance

    Generally through meat inspection in abattoirs. Serological tests may be used for epidemiological studies. Large numbers of pigs are home slaughtered and carcases are not controlled.

    GAPS:

    • Making NCC a notifiable disease.
    • Molecular confirmation of lesions.
    • Fate of infected meat.
    • Adequate surveillance throughout the food-chain (e.g. at butchers shops etc).
  • Past experiences on success (and failures) of prevention, control, eradication in regions outside Europe

    Control of T.solium in humans, combined treatment of tapeworm carriers and of pigs, health education can reduce the levels of infection in pigs and humans. Vaccine trials are underway in pigs in a number of areas worldwide. Combined vaccination with TSOL18 and OXF treatment of pigs was able to eliminate transmission in a hyperendemic area in Cameroon (Assana et al., 2010. Int J Parasitol 40: 515-519).

    Eradication of T. solium in Europe was possible by a combination of improved pig husbandry (confinement of pigs), meat inspection and better sanitation.

    GAPS:

    • Is eradication possible if pigs are kept free-ranging?
    • Evidence-based studies to estimate the effectiveness of alternative control strategies.
    • Assessment of the efficacy of integrated control ( being integration of many control policies and also integration for control of different diseases).
    • Effect of Community Led Total Sanitation.
  • Costs of above measures

    Potentially high relative costs for developing countries. Sanitation and restriction of pig movement is the most promising approach in terms of costs and sustainability

    A pig management educational program was shown to be cost-beneficial for pig infection in Tanzania.

    GAPS:

    • Individual studies required for each situation.
    • Cost-effectiveness and cost-benefit of various control options.
  • Disease information from the OIE

  • OIE disease card available

    No.

  • OIE Terrestrial Animal Health Code

    No reference.

  • Socio-economic impact

  • Zoonosis: impact on affected individuals and/or aggregated DALY figures

    Infection is found most often in rural, developing countries with poor hygiene and sanitation where pigs are allowed to roam freely and eat human faeces. This allows the tapeworm lifecycle to be completed and the cycle to continue. Taeniosis and cysticercosis are rare in Muslim countries where eating pork is forbidden. NCC can have very important monetary impact in humans.

    Review underway to identify costs and case studies under the ICONZ project to assess burdens in selected sites in sub-Saharan Africa + WHO/FERG initiative (global burden). Data available for Cameroon and South Africa.

    GAPS:

    • Only NCC-associated epilepsy has been included in the estimates so far. Data on the prevalence / incidence of NCC and the distribution of symptoms is not known enough to obtain a fair estimate of DALYs.
    • Monetary burden of NCC in different areas
    • Stigma associated with NCC in different areas
    • Productivity losses associated with NCC 
  • Zoonosis: cost of treatment and control of the disease in humans

    Drugs for epilepsy are cheap, but the treatment has usually to be continued for the whole life.

    Control should be focused on sanitation, hygiene and better pig management. Building and maintenance of latrines, building pig pens and especially buying feed for pigs is quite expensive although there are also better returns. Treatment of taeniosis cases would be very expensive due to the cost of diagnosis and the low prevalence of infection in humans. Diagnosis and treatment of neurocysticercosis are expensive (CT or MRI scans needed).

    GAPS:

    • Cost-effectiveness and cost-benefit analyses of alternative control strategies.
    • Cost-effectiveness studies on diagnosis + treatment versus mass treatment.
  • Direct impact (a) on production

    Probably none.

    GAP: Impact of infection on pig fertility and growth?

  • Direct impact (b) cost of private and public control measures

    None.

  • Indirect impact

    Cysticercosis causes economic loss through condemnation of infected meat and offal. In Africa, there are reports of losses related to a lower commercial value (reduction of 30 to 50%) of infected live pigs detected on the basis of the tongue test.

    GAP: Economic loss in pigs in Latin America and Asia?

  • Trade implications

  • Impact on international trade/exports from the EU

    None as there are currently no rules re trade apart from the need to ensure meat is subject to meat inspection and certified fit for human consumption. The OIE Terrestrial Animal Health Code 2009 does not currently include a chapter on cysticercosis.

  • Impact on EU intra-community trade

    None as there are no rules re trade apart from the need to ensure meat is subject to meat inspection and certified fit for human consumption and can be placed on the market.

  • Impact on national trade

    None as there are no rules re trade apart from the need to ensure meat is subject to meat inspection and certified fit for human consumption.

  • Main perceived obstacles for effective prevention and control

    • Poor development and sanitation
    • Behavioural change is needed
    • Breaking the cycle of infection and preventing pigs having access to Taenia solium eggs.
    • Lack of availability of simple tests to detect T. solium infections in humans, of pen-side diagnostic tests for individual pigs and for detection of infected carcasses in the abattoir
    • Anthelmintics to treat taeniosis not everywhere available

    GAP: Need for randomized controlled field trials to test the effectiveness of such control measures.

  • Main perceived facilitators for effective prevention and control

    The following facilitators can play a role:

    • Agricultural extension officers
    • Public health extension officers
    • Health staff in dispensaries
    • Traditional healers
    • Community leaders for sanitation aspects
    • Schools, media

Risk

  • Main risk from animals is infection of humans and the difficulty in breaking the cycle.

    Development and increase of NCC cases in Europe through immigration of tapeworm carriers from endemic countries.

Main critical gaps

Conclusion

  • Cysticercosis is of major importance in the developing world where it is a neglected zoonoses and where the neural form is grossly under diagnosed. The natural history of NCC remains unknown. Very little is known about the symptoms and burden of NCC. The frequency of cysticercosis and NCC worldwide is unknown. Control of the tapeworm in humans is important, but treatment is challenging due to the difficulty in finding the very few cases that exist. Hence, the most sustainable and cost-effective method may be (this has not been tested, but is suggested by transmission dynamics models) good sanitation and to prevent contact between pigs and tapeworm eggs excreted by people. Condemnation or thorough cooking of infected meat is important but in poor areas the presence of meat inspection is unlikely and the discarding of infected meat is impossible to achieve. Control of infection in pigs either by vaccination or pre slaughter treatment with a compound which kills the cysticerci is possible although their costs and application may be too high to enable implementation in developing countries.

Sources of information

  • Expert group composition

    Expert group members are included where permission has been given

    Pierre Dorny Institute of Tropical Medicine, Belgium. [Leader]

    Maria Vang Johansen, Centre for Health Research and Development, DenmarkHelene Carabin, The University of Oklahoma Health Sciences Center, USA

  • Reviewed by

    Project Management Board.

  • Date of submission by expert group

    31st August, 2011.

  • References

    30th September, 2011.