Parasitic Neglected Tropical Diseases Flashcards
List some Parasitic NTDs
Chagas
Dracunculiasis
Echinococcosis
Foodborne trematodiases
Human African trypanosomiasis
Leishmaniasis
Lymphatic filariasis
Onchocerciasis
Schistosomiasis
Soil
-transmitted helminthiases
Taeniasis/cysticercosis
Define Eradication
Permanent reduction to zero of the worldwide incidence of infection
caused by a specific agent as a result of deliberate efforts.
Define Elimination of Infection
Reduction to zero of the incidence of infection caused by a specific agent
in a defined geographical area, with minimal risk of reintroduction, as a
result of deliberate efforts
Define Elimination of disease
Reduction to zero of the incidence of a specified disease in a defined
geographical area as a result of deliberate efforts
Define Control
The reduction of disease incidence, prevalence, morbidity and/or
mortality to a locally acceptable level as a result of deliberate efforts
Define Elimination of a disease as a public health problem
a term related to both infection and disease, defined by
achievement of measurable targets set by WHO in relation to a specific
disease. When reached, continued action is required to maintain the
targets and/or to advance interruption of transmission
Soil-Transmitted Heminthiases?
What impact of infections?
- Abdominal symptoms
- Allergic reactions to worm metabolites
- Anaemia
- Malnutrition, wasting, stunted growth in children
- Cognitive function & school performance?
Tx against these helminths?
Albendazole 400mg
Mebendazole 500mg
although evidence that Trichuris does not response so well - need multiple MBZ treatments
What preventative chemotherapy for preschool and school aged children?
albendazole or mebendazole against A. lumbricoides, T. trichiura and hookworms:
o twice per year where STH prevalence ≥50%
o once per year where STH prevalence ≥20%
ivermectin added where S. stercoralis >10% prevalence and
if high prevalence of T. trichiura
Who else to give preventative deworming to?
women of child-bearing age in antenatal care
Who are the reservoirs of helminths?
- Ascaris suum and Trichuris suis in pigs
- Ancylostoma caninum and Ancylostoma ceylanicum in dogs
- Strongyloides stercoralis – dogs & primates
- Strongyloides fulleborni – apes & monkeys
What causes human African trypanosomiasis (HAT) -> ‘SLEEPING SICKNESS’ ?
Trypanosoma brucei gambiense
Trypanosoma brucei rhodesiense
Lifecycle of trypanosomiasis?
Compare the two types of sleeping sickness
Approach to disease control ?
Case finding and treatment
o Mobile screening teams
o Much more effective for T. b. gambiense
o Reduce human reservoir of infection,
prevent morbidity & mortality
Vector control
Control in animal reservoirs
Continued surveillance is very important
What vector control options?
- Tsetse trapping
- Aerial spraying
- Sterile insect technique
Describe public-private partnerships
- WHO established public-private partnerships with Aventis
Pharma (now Sanofi) & Bayer HealthCare in early 2000s - Led to creation of a WHO-led control and surveillance
programme - Provides support to endemic countries in their control
activities - Medicines supplied free of charge
- Other private partners now involved, sustain until 2030
What causes Dracunculiasis (Guinea Worm Disease)
Guinea worm -> Dracunculus medinensis
Describe guinea worm
- Nematode worm
- Largest tissue parasite affecting humans
- Adult females up to 80 cm in length
- Female carries up to 3 million embryos
- Indirect lifecycle involving copepods
(water flea)
Lifecycle of Guinea worm?
Describe the disease from guinea worm
- Severe pain as parasite migrates through subcutaneous tissues
- Worm eventually emerges (mainly from feet) → painful oedema, blister and ulcer
(fever, nausea and vomiting) - Patients try to relieve burning sensation by immersing infected body part in local
water sources e.g. ponds - Induces contraction of female worm → expulsion of 100 000s larvae
- Many patients bed-bound for a month during/after worm emergence
- Extraction of worm by winding around a stick
– can take several weeks
Control /eradication of guinea worm
- Diagnosis is easy, unambiguous
- Intermediate host of restricted to stagnant water bodies
- Control interventions are simple, cost effective and easy to implement
- Limited geographical distribution and transmission is seasonal
- Political commitment from governments is available
What recent article foudn novel transmission pathway in emerging animal reservoir of guinea worm?
SEASONAL FISHERIES & dogs eating fish likely contributing to disease persistence
