Lecture 9: T. Solium Elimination vs. Control: Field Experience in Zambia Flashcards
Why does Taenia solium have the highest burden on DALY’s of the foodborne parasites?
It can cause neurocysticercosis.
Where can the cysticerci localise in humans?
Subcutaneous (skin), muscles, CNS, other (e.g. eyes).
What are the symptoms of cysticercosis in humans?
It is asymptomatic in 50-70% of the cases. Whether people are and remain asymptomatic depends on the number of cysts, their location and the stage of the cysts. The viable cysts have a hiding mechanism to ensure you don’t build an inflammatory reaction. When the cysts start generating, it is recognised by the body. This starts an inflammatory reaction that causes the symptoms.
What are the symptoms of Neurocysticercosis (NCC)?
Main cause of acquired epilepsy in acquired areas (up to 60%!), headache, etc.
What are the symptoms of Taenia solium infection in pigs?
It was long thought to be asymptomatic, but recent research has shown that it causes seizures and behavioural changes.
What can be done to interfere in the cycle of the Taenia solium infection?
Look at the different points of the life cycle and decide at which points a viable and cost-effective intervention can be implemented. E.g.: mass drug administration in humans and/or pigs, properly cook meat, increase the use of good latrines, don’t use faeces to fertilize food for the pigs, vaccinate pigs, don’t give pigs access to human faeces, hand washing
Why is telling people to throw away meat not very effective?
People in endemic areas are very poor and don’t have access to meat every day.
What is important to consider when designing interventions for neurocysticercosis?
It is important to prevent, but this does not stop the life cycle of the parasite and thus does not stop transmission.
What are barriers for latrine use?
The building of latrines is often not finished, a deep hole in the latrines might be scary for kids, stones for toilets are often used for something else
What is community-led total sanitation?
A methodology for mobilising communities to completely eliminate open defecation (OD). Communities are facilitated to conduct their own appraisal and analysis of OD and take their own action to become ODF (open defecation free). The focus lies on behavioural change. It is based on a shock system.
How does community-led total sanitation work?
- Build rapport in community meetings
- Open defecation mapping: visualise the sanitation problem.
- Transect walk. It uses the shock system here, you walk around the village and point out and describe every shit you see (“oh whose is this one? It’s still a bit warm, it’s a fresh one!”)
- Shit calculation. Calculate how much shit is produced by the village every day. This number is expressed in numbers of bags of maize as this is easy to visualize.
- Food-shit exercise: eating shit demonstration. Put a bottle of water or soda next to a shit sample and watch the flies go back and forth. Afterwards this bottle is presented to the people with the question if they want to drink from it
- Medical expense calculation: cost of poor sanitation
- Plan of action to become a open defecation free village
How well does community-led total sanitation work?
A lot of latrine construction started, but the impact on Taenia solium infections was minimal at best, but this could have been because the end-point was to early at 22 months and some environmental contamination still remained. There was however, evidence that CLTS markedly increased latrine ownership and latrine quality. However, none of the villages reached universal latrine coverage (one latrine per household).
What were constraints for latrines discovered during the community-led total sanitation intervention?
Latrines are not being built properly and may not last long, materials and money for latrines are hard to find, women with no husbands found it hard to build and logs hard to find (men’s responsibility), field work slowed progress, use of latrines is not a habit, lack of follow-up during the intervention, men do not build the latrines (lazy, drunk), not enough education on how to build and the advantages.q
What is a striking reason why people don’t use latrines as much?
There is a lot of taboo around defaecating to the point where men pretend to go chop wood and instead go into the bush to defaecate. There is also the belief upheld that older people don’t go to the toilet (and children do).
What are the different treatments for humans infected with T. solium?
Niclosamide, praziquantel and albendazole. Niclosamide is 65% effective with a single dose of 2g for adults. It has minimal side effects.
Praziquantel is 95% effective with a single dose of 5-10 mg/kg. It is also very cheap However, there are some concerns, because it has some effects on the cysts. This could cause bursting cysts in neurocysticercosis patients, causing seizures. How high this risk is, is unknown. Therefore, you have to be very careful using praziquantel. However, praziquantel is also used for schistosomiasis treatment.
A big disadvantage of albendazole is that it needs to be given in three consecutive doses of 400 mg/day. In addition it is less effective, but the exact efficacy is unknown. This makes it less effective and less practical in interventions.
