one health lecture 6- eradication Flashcards
what is one health?
‘One Health recognizes that the health of humans, animals and ecosystems are interconnected.’
what are zoonotic diseases?
Zoonoses are diseases and infections where the agents are transmitted between vertebrate animals and humans.
what are details about zoonotic diseases?
-Interactions of agent, host, and the environment they share determines whether or not transmission of the agent will be successful.
-Carrier hosts are important in the persistence of many zoonotic agents.
-Vertebrate animals are the reservoirs of zoonoses and the agents may be transmitted directly or indirectly by fomites or vectors.
-Zoonoses cover broad range of diseases with different clinical and epidemiological features and control measures.
-Fungi, bacteria, viruses, protozoa, helminths, arthropods all include some zoonotic agents.
what are the stages of eradication?
Control of an infection at which transmission ceased within a specified area.
Elimination of the occurrence in the absence of all preventive measures.
Reduction or Eradication of the worldwide incidence of a disease to zero as a result of deliberate efforts.
Extinction of disease pathogen.
what is control of a disease?
The reduction of:
-Disease incidence.
-Prevalence.
-Morbidity.
-Mortality.
To a locally acceptable level.
As a result of: Deliberate efforts and Continued intervention measures.
eg diarrhoea diseases
what is the elimination of disease stage?
Reduction to zero of:
-The incidence of a disease.
-In a defined geographical area.
As a result of:
-Deliberate efforts.
-Continued intervention measures.
eg Neonatal Tetanus
what is the elimination of infections stage?
Reduction to zero of:
-The incidence of a disease.
-infection caused by a specific agent.
-In a defined geographical area.
As a result of: Deliberate efforts and Continued measures to prevent re-establishment.
eg measles
what is reduction or eradication?
Permanent reduction to zero of:
-The worldwide incidence.
-Infection caused by a specific agent.
As a result of:
-Deliberate efforts.
-Intervention methods are no longer needed.
eg smallpox - hard but manageable
what is extinction?
The specific infectious agent no longer exists:
-In nature
-In the laboratory
eg none yet
what are the ways to eradicate?
1- Effective intervention to interrupt transmission of the agent.
2- Practical tools with sufficient sensitivity and specificity.
3- Humans are essential for the life cycle of the agent, which has no other vertebrate reservoirs and does not amplify in the environment.
what are the different approaches to tackling one health across countries?
-Health investment doesn’t relate to health equality.
-Prevention is better than a cure but not easy, especially on a global effort.
what is toxocara ssp?
-First discovered in humans in 1950.
-Toxocara larvae detected in ocular granulomata in children with suspected retinoblastoma .
-Further clinical symptoms have been described in humans.
-However, the significance of human toxocariasis as a disease entity remains enigmatic as symptoms can be generalised, multifaceted and cryptic.
what are the problems to controlling toxocara?
-Complex mode of transmission
-Multiple sources of infection
-Variation in exposure levels
-Complex symptoms that are multifaceted, general and diverse
what are the scolex in tapeworms?
Attachment organ with hooks and suckers
how is the eradication of taenias achievable?
-Mass drug administration (treatment).
-Identification and treatment of cases.
-Health education.
-Improved sanitation.
-improved livestock husbandry.
-Vaccination of livestock.
-Improved meat inspection.
why has the eradication of taenias been a failure?
-Disconnect between medical and veterinary responsibilities – not the best example of One Health.
-Lack of funding.
-Mapping of Taenias 1985-2014.
-Only 141 reports from 476 districts in 29 countries = neglected.
Strong links as a socially determined disease.
Sub-Saharan Africa is heavily affected
what are the facts about the eradication of guinea worms?
-No drugs or vaccines available to cure or prevent infections.
-No wild animal reservoirs known, is a zoonoses, wildlife hosts of dogs and baboons.
-Slow painful extraction (up to two weeks).
-Damaged worms can lead to secondary infections.
what has happened to the incidence of guinea worms?
-Since eradication efforts started the incidence of Guinea worm has reduced by 99.99%
- in 2023 there were 14 cases eg
Chad = 9
Ethiopia = 0
Mali = 1
South Sudan = 2
Cameroon = 1 - by Jan 1st – 10th Oct 2024 = 7 cases
why as the eradication of guinea worms been successful so far?
-First example of human parasitic disease to be eradicated without the use of vaccines or medicines.
-Smallpox was first success, certified as eradicated in 1980.
1981 = WHO Drinking Water Supply & Sanitation Decade
1986 = Carter Centre, WHO & UNICEF partnership
2011 = Interruption of transmission and enforce nation-wide WHO surveillance-call to member states
what is the certification process? led by WHO?
1- Interruption of transmission – zero indigenous cases over a complete calendar month – move to 2.
2- Pre-certification – zero indigenous cases via active surveillance for at least 3 consecutive years – move to 3.
3- Certification – Internation Certification Team (ICT) visti the country to verify the national report.
what are the eradication measures for guinea worms?
-Mapping, using community-based surveillance systems.
-Effective case containment measures.
-Safe water, health education, community mobilization, filters, and control of vector.
-Regular reporting.
-Management of certification process for eradication (country-by-country).
As of 2019, the WHO goal for eradication is 2030.
Previously targets have been set at 1991, 2009, 2015, and 2020…
-Soaring and unexplained infections among dogs in Chad
-Unexplained infections in baboons in Ethiopia
-Conflicts in Mali, Sudan and South Sudan
why has animal reservoir caused doubt for the eradication measures taken?
-Finding the remaining cases are the most difficult and expensive
-Lack of assess to areas and the security of them
-Canine infections with D. medinensis is a big challenge – 2020 Chad reported 1508 infected dogs and 63 infected cats, Ethiopia reported 3 infected dogs, a8 infected cats and 4 infected baboons
-The detection, prevention and containment of canine cases is a priority
-This means that the current methods of surveillance need to be increased to incorporate animal reservoirs
- Should not underestimate the importance of a communities based approach
