Intro to NTD Flashcards
Define NTDs
Poverty promoting chronic infectious diseases occurring primarily in low and middle income countries (LMICs).
Neglected as there is disparity between funding received and impact in terms of DALYs
Types of NTD
Parasite
- Guinea worm (copepod host)
- Schistosomiasis (snail host)
Zoonotic:
- Rabies
Vector borne
- Chagas (triatomine bug)
- Dengue (mosquito)
non-infectious like snake bite
5 Interventions to combat NTDs
- Preventative chemotherapy and transmission control, PCT
- Control through periodic administration of efficacious, safe and inexpensive (usually donated) drugs to entire at-risk populations (large-scale preventative therapy) e.g lymphatic filariasis, onchocerciasis, schistosomiasis
- Innovative and intensified disease management (IDM)
- Vector ecology and management
- Methods of targeting mosquitoes, flies, ticks, bugs and other vectors that transmit pathogens - Safe water, sanitation and hygiene (WASH)
- Veterinary public health service
WHO has classified NTDs into 2 groups
- Preventive chemotherapy and transmission control (PCT)
- Innovative and intensified disease management (IDM) - NTDs that lack appropriate tules for large scale use e.g Buruli ulcer, chagas, HAT, lesihmaniasis
What is the WHO criteria for classifying NTDs?
- Disproportionately affect populations living in poverty and cause important morbidity and mortality – including stigma and discrimination
- Primarily affect populations living in tropical and sub-tropical areas
- Are immediately amenable to broad control, elimination or eradication
- Are relatively neglected by research
What are some diseases not on the NTD list?
Endomyocardial fibrosis
Noma
Rheumatic heart disease
Podoconiosis
Strongyloides
What is the burden of disease?
Combined premature death and disability into single measure
Disability adjusted life years
- Quantifies burden of disease from mortalty and morbidity
- Used to asses and compare the relative impact of a number of diseases locally and globally
Equations for DALYs
1 DALY = 1 year lof of healthy life
Burden of disease = sum of DALYs
- Measures gap between current health status and an ideal health situation
DALYs for a disease = years of life lost/YLL due to premature mortality in population + years lost due to disability for people with health condition / YLD
DALY = YLL + YLD
Equations for YLL and YLD
YLL = number of deaths (n) x standard life expectancy at age of death in years (L)
YLL = N x L
YLD = number of incident cases in a particular period (I) x average duration of disease (L) x weight factor that relates to severity of disease on scale from 0 (perfect health) to dead (DW)
YLD = I x DW x L
Critisim of DALYs
Simplification of a complex reality giving only a crude indication of
environmental health impact
Measure only direct health loss and does not consider the economic
impact from detrimental effects on school attendance, child development,
agriculture (especially from zoonotic NTDs), and overall economic
productivity
Do not account for direct costs of treatment, surveillance, and
prevention measures, elements of social stigma, spillover effects to family
and community members, loss of tourism
Aid is most often directed at diseases with the highest DALYs,
ignoring the fact that other diseases, despite having lower DALYs, are still
major contributors to disease burden - less-publicized diseases thus have
little or no funding for health efforts
Challenges in NTD control, geopolitical links
Several NTDs with enormous regional importance but low impact globally so not high disease burden and ignored by global community
- Buruli ulcer in West Africa, podoconiosis in East Africa
Political destabilisation in the ‘Old World’: Next to poverty, conflict may be the biggest social determinant of NTDs
- Leishmaniasis outbreaks arising from horrific battles and collapsed health system infrastructures in Syria, Iraq, Afghanistan, DRC, Sudan and south sudan
- Lethal epidemic of Cholera in Yemen
Political destabilisation in the New world: Venezuela’s health system slowly collapses resurgence of malaria and NTDs: Dengue and other arthropod-borne virus- Chagas, Schistosomiasis
Challenges in NTD control, climate change
Impact on vector-borne and zoonotic NTDs
- Rapid introduction of dengue, chikungunya, yellow fever, and Zika virus infection in the
Western Hemisphere
- Mosquito-transmitted and snail-borne diseases in parts of Europe (arbovirus infections
and schistosomiasis)
Challenges in NTD control blue marble health
New paradoxical findings that the poor living in wealthy group of 20 (G20) nations and Nigeria (richer than the bottom three or four G20 nations) account for a majority of the world’s disease burden for the poverty-related neglected diseases and NTDs
Pockets of poverty in wealthy nations
