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MITIGATING INFECTIOUS DISEASEOPPORTUNITIES AND AWARENESS FOR PERMACULTURE DESIGNERS
Susan V. Cousineau, MSc. [email protected]
OVERVIEW
Disease Overview: What & WhyDefinitions and Pathogen Types
Thinking FrameworksHow can we use good design to mitigate risks and impacts?
Illustrative Examples
Conclusions & Wrap-Up
Conclusions&
Wrap-Up
ThinkingFrameworks
IllustrativeExamples
Pathogen Types
ROADMAP
DiseaseOverview:
What & Why
Conclusions&
Wrap-Up
ThinkingFrameworks
IllustrativeExamples
Pathogen Types
Pathogen Types
ROADMAP
DiseaseOverview:
What & Why
WHAT ARE WE TALKING ABOUT?
Infectious diseases that spread between human and animalsRelationships between agriculture, poverty and disease, and our capacity to help at a grassroots level
We won’t be covering…crop diseases (per se)non-infectious diseases
DEFINITIONSinfectious disease: a disease that spread between hosts via a pathogen
pathogen ( = parasite): an organism that causes illnesse.g. bacterium, virus, fungi, protozoan, helminth worm
host: an organism that becomes infected by a pathogen; may or not show illness
e.g. insects, rodents, birds, humans
vector: an organism that transmits a pathogen between hostsoften invertebrates, including ticks, mosquitoes, flies, and snails
WHY ARE WE TALKING ABOUT THIS?
>1400 infectious diseases that affect humans, more emerging
We are in the third major disease era known to humankind
Between 1995 and 2008, global economic impact >$120 billion USD
KEY DRIVERS
Socio-economics
Environmental change
Nutrition
Water management
INFLUENCERISK MAGNITUDE
WHO 2013
CURRENT GLOBAL OUTLOOK
Many known diseases expanding their ranges; new ones emerging
Novel populations and driving factorsintensified farming; elderly and immunosuppressed; marginalized and extremely poor; global travelenvironmental degradation, habitat encroachment
Divestment in public health infrastructurepolitical unrest, economic disparity and declining social conditions
Conclusions&
Wrap-Up
ThinkingFrameworks
IllustrativeExamples
DiseaseOverview:
What & Why
Pathogen Types
Pathogen Types
Water-borne
Vector-borne
Vertebrate Hosts
Bacteria Protozoa
Water
Hosts(Humans, Livestock,Wildlife)
Vectors
Animals
Viruses Helminths
WATER-BORNE PATHOGENS
Transmitted through water via
aquatic vegetationcontaminated soilsinadequate sanitation
Many are bacterial infectionsEscherichia coliShigella spp.
and protozoans… SchistosomaFasciola trypanosomesGiardiaCryptosporidia
VECTOR DISEASES>17% of all infectious diseases
>1 million deaths/year
Flying insects: mosquitoes (malaria, dengue, yellow fever), sandflies (leishmaniasis) and blackflies (river blindness)
Ticks (Lyme disease, encephalitises, tularaemia), snails and triatomine bugs (Chagas disease)
“ANIMAL” DISEASES
Pathogens associated with a vertebrate, non-human host
Lyme diseaseHantavirus (e.g. Sin Nombre)
Diseases of wildlife-livestock interface
Rinderpest, blue tongue, foot-and-mouth
Diseases of farmed livestockAvian influenzaFasciolosis (liver flukes)
WATER-BORNE VECTOR-BORNE VERTEBRATE
SOCIOECONOMICS
• Housing• Sanitation• Storage
• Access to treatment
• Vector control
• Housing• Control (e.g.
fencing)
NUTRITION • Sanitation• Immunity
• Sanitation• Immunity
• Biodiversity loss
• Habitat change
ENVIRONMENT • Exposure to new pathogens
• Available vector habitat
• New pathogens• Livestock and
wildlife• Water accessWATER
MANAGEMENT
• Water sanitation
• Exposure
Conclusions&
Wrap-Up
IllustrativeExamples
DiseaseOverview:
What & Why
Pathogen Types
ThinkingFrameworks
Sanitation
ThinkingFrameworks
Health & Nutrition
Prevention
Holistic Management
8 Forms/RegenerativeEnterprise
Permaculture&
SystemsDesign
RegenerativeAgriculture
LearningModels
CulturalDialogue
This work is licensed under the Creative Commons Attribution-Noncommercial-No Derivative Works 2.5 Australia License. To view a copy of this license, visit http://creativecommons.org/licenses/by-nc-nd/2.5/au/ or send a letter to Creative Commons, 171 Second Street, Suite 300, San Francisco, California, 94105, USA. The ‘design principles’ have been adapted from David Holmgren’s book ‘Permaculture: Principles & Pathways Beyond Sustainability’. Permaculture Principles Poster 2.0
Ask relevant questions, gather information
Focus on health building
nutrition, soil, diversity
Design for minimum intervention
Close waste loops
DESIGN STRATEGIES
Zones, Sector and Element Analyses
Stacking functions, patterns and scales
Scales of permanence
Appropriate technology
Local resources and knowledge
CULTURAL
FINANCIAL
PERSONAL
SOCIAL ECOLOGICAL
EXPERIENTIAL
INTELLECTUAL
MATERIAL
WWW.8FORMS.ORG
Regrarians Platform
1. Climate 2. Geography 3. Water 4. Access 5. Forestry 6. Buildings 7. Fences 8. Soils 9. Economy 10. Energy
INFLUENCERISK MAGNITUDE
RISK MANAGEMENT
idiosyncratic risky events affect individual farms or firms e.g. infections of individuals; illness of the owner or labourers; single-farm outbreaks
covariate risky events affect many locations simultaneously e.g. major droughts, floods; fluctuating temperatures; epidemics either community level (meso) or entire region (macro) arise from war, natural disasters, price instability, financial crises
difficult to manage locally require a coordinated response
HOME GARDENSDRIP IRRIGATION
SANITATION
AGROFORESTRYEARTHWORKS
COMMUNITY TRAININGHOUSING & INFRASTRUCTURE
POLICY CHANGEMUNICIPAL GOVERNANCE
Frameworks for addressing social, economic, ecological needs
Pre-determined collaborative interdisciplinary “toolbox” approach
May require further integration with public health and organizational capacity
Seek to build knowledge, awareness and conduct thorough assessments
PERMACULTURE
PERMACULTURE
Frameworks for addressing social, economic, ecological needs
Pre-determined collaborative interdisciplinary “toolbox” approach
May require further integration with public health and organizational capacity
Seek to build knowledge, awareness and conduct thorough assessments
Conclusions&
Wrap-Up
ThinkingFrameworks
DiseaseOverview:
What & Why
Pathogen Types
IllustrativeExamples
WATER-BORNE VECTOR-BORNE VERTEBRATE
SOCIOECONOMICS
• Housing• Sanitation• Storage
• Access to treatment
• Vector control
• Housing• Control (e.g.
fencing)
NUTRITION • Sanitation• Immunity
• Sanitation• Immunity
• Biodiversity loss
• Habitat change
ENVIRONMENT • Exposure to new pathogens
• Available vector habitat
• New pathogens• Livestock and
wildlife• Water accessWATER
MANAGEMENT
• Water sanitation
• Exposure
WATER-BORNE VECTOR-BORNE VERTEBRATE
SOCIOECONOMICS Nicaraguan immigrants in
Costa RicaChagas Disease &
Palm Oil
Swine & Avian Influenzas
NUTRITION Old & New World Hantaviruses
ENVIRONMENT
SchistosomiasisMosquito
Diseases (Malaria & Dengue)
Nipah Virus in Malaysia
WATER MANAGEMENT
Fasciolosis in Livestock
NICARAGUANS IN COSTA RICA
Lind, J. (2009). The political ecology of intestinal parasites among Nicaraguan immigrants in Monteverde, Costa Rica.
Nicaraguan immigrants in Costa Rica suffer from . . .
higher intestinal parasitespoor housing infrastructurelack of access to health care
INTESTINAL PARASITES & NUTRITION
IPs result in chronic undernutritionstunting from poor nutrition and persistent infectionslong-term effects on growth, earning potential, immunity and cognition
people need more calories to grow and maintain activityinfected conditions amplify and reinforce poverty
micronutrient insufficiency: especially Vitamin A, zinc, iron, iodine~1 billion people suffer from insufficient food overall (“hunger”)far more from micronutrient deficiencies (often overlooked)
~15% of the global population; 1 billion considered “food insecure” (2009)
POLITICAL ECOLOGY OF DISEASE
political change; public health policy
industrialization, marginalization of communities
forced or voluntary immigration
HOUSEHOLD ECOLOGY
general sources of infection insufficient counter spacewashing and toilet facilities (dirty, absent, inadequate)storage (food, wastes, water)insufficient protection (rodents, mosquitoes, other insects)
cockroaches and flies carrying intestinal parasites
common sources of co-infection by Giardia, Toxoplasma gondii, Entamoeba histolytica, roundworms and hookworms
NICARAGUANS IN COSTA RICA
intestinal parasite prevalence higher in Nicaraguan immigrants than Costa Rican residents
protozoan infections (~15%) >> helminth worms (2%)prevailing medical treatments for helminths; routine rather than specific to cases
elders in communities familiar with plant and home remedies
younger members accustomed to taking pills from health care centres (e.g. Albendazole, Sentel)
Crowding = more parasites
Unsanitary kitchens = more vectors
Nicaraguans 8.7x more likely to have inadequate bathroom facilities than Costa Ricans
REMEDIES & SOLUTIONS
18 home remedies identified by both Costa Ricans and Nicaraguans
Apazote: Dysphania ambrosioidesGarlicGuara/o (“Costa Rican vodka”)Padra, yerba buena, coconut milk
kitchen, bathroom infrastructuregreywater systemsadequate access to health care, home ownership
SCHISTOSOMIASIS (“BILHARZIA”)
• Water-borne flatworms (Schistosoma) transmitted by freshwater snails
• Causes liver and intestinal damage
• Associated with overfishing, flood irrigation and ponds/dams
• Eggs are shed in faeces; enter waterways
SCHISTOSOMIASIS (“BILHARZIA”)
• Trematodes develop in freshwater Bulinus snails• free-swimming larval stage (“cercariae”) are
infectious to humans through skin contact
• ~200 million people infected worldwide; risks affect ~780 million
• Greatly increased with overfishing• use of fine-mesh seines• re-introduction in Kenya, Cameroon ineffective
IRRIGATION
A potentially major infectious disease risk
creates vector habitatdirect transmission of water-borne diseases
Flood irrigation an important source of emerging zoonoses
repeating contact between humans, wildlife and livestock
Better optionsdripline irrigationearthworks catchment and soil storage
CHEMICAL UV BIOSAND FILTERS BOILING
+ ineffective for protozoans
+ effective for all organisms
+ effective for most organisms
+ effective for most organisms
+ scaleable+ requires minimal training
+ community-scale
+ no training required
+ resistant to re-infection + non-toxic + appropriate
technology
- chlorine and chloramines
toxic
- technologically
expensive
- take 2-4+ weeks to “ripen”
- inefficient, energy
intensive- reliant on
ongoing inputs- limited access
for rural- dependent on proper building
- can be reinfected
- requires pre-filtration
- temperature and use sensitive
WATER SANITATION
BIOSAND WATER FILTERS
SOLUTIONScurrent treatment: Praziquantel
broad-spectrum anti-helminth given annually or as neededWHO’s list of most needed world medicines
improve sanitationplaying in and use of contaminated waterprovide clean drinking, washing water
reduce snail populationspredatory fish (multiple species)native African river prawn
CHAGAS DISEASE & PALM OIL
African oil palms planted throughout South America for biodiesel
habitat for bug vectors of Chagas disease (Trypanosoma cruzi)
Primarily agricultural workers affected
~150 million people at risk~18 million infected
PALM OIL PLANTATIONS & BIOFUELS
Extensive planting of African oil palm (Elaeis guineensis) for oil and biodiesel production throughout South America
habitat for triatomine bugs; estimated ~65% infection in some areas
Brazil’s Ministry of Agriculture estimates area of palm cultivation could expand from 60 000 ha today to >6 million by 2025
Political/socioeconomic goal to decrease dependency on coca
increased exposure of working poor (13% of the population)
CHAGAS DISEASEbugs pierce the skin, then defecate
parasite contained in faecesitching breaks the skin for infection
long-term cardiac damagedeath occurs 10-30 years later
found in crevices of dwellingsthatch roofs, behind furniture, in animal shelters, cracks, wood piles
>150 species, 24 families of animals carry the parasite, making re-infestation frequent
SOLUTIONSPyrethroid pesticides
bugs are often resistant
Eliminating packrat middensanecdotal, but seems to be effective
Sealing cracks, walls, entries
Opportunity for design and site hygiene that reduces hiding locations
NIPAH VIRUS
loss of forest habitats, agricultural expansion
changes in size, location and structure of bat colonies
bats forage in fruit trees around urban and residential areas
spread to humans, livestock
NIPAH VIRUS MALAYSIA
Swine infected through feeding on dropped fruit contaminated with bat droppings and urine
A result of environmental encroachment, possibly climate changes, and food-animal production into wildlife habitat
Outbreaks in 1997-1998 spread from fruit bats to domestic pigsdisease and mortality in livestock and agricultural workers1999: high human mortality created widespread panic and had catastrophic effects on the Malaysian swine industry
WILDLIFE & LIVESTOCK
Major contribution of zoonotic disease (~75%)
Livestock and pets have disease risks for wildlife
Even if not symptomatic, can act as reservoirs and “amplifiers”
Increasingly important with environmental and social changes
PIGS, BIRDS & INFLUENZAS
Intensive pig and poultry systems increasing
short turn-around compared to ruminantsfewer workers per animal, but more infections
Pigs are “viral mixing grounds”highly varied, omnivorous diet creates pathogen opportunitiesknown infections from wild birds and domestic poultry
Intensified conditions create disease “playgrounds”crowding, low genetic diversity, unsanitary conditions
INDIRECT TRANSMISSION
INDIRECT TRANSMISSION
CONSUMPTION/INFECTION
SOLUTIONSPrevention is the best cure
separate wildlife and livestockfencing, guardian dogs most effective
Avoid free-range foraging by livestock, e.g. where fruit bats occur
Keep animal husbandry standards highHealth, nutrition, space, shelter
Build and maintain good soil healthfiltration of viruses, other pathogens shed in wasteroots and soil structure sequester pathogens deep in soil stratamicrobial and macrofaunal diversity consume pathogens
MOSQUITO-VECTORED DISEASESMajor mosquito-borne diseases of the tropics and subtropics
Malaria: Plasmodium spp. protozoans; Anopheles mosquitoesDengue (“breakbone fever”): dengue virus; Aedes aegypti mosquitoes
Climate change impactsincreasing range, reproduction
Deforestation, land use change clearing creates sunlit pools
Malaria in 2015: 440k dead, 214 million sickDengue: 100 to 400 million cases: 500k hospitalized, ~25k deaths (mostly children)
ENVIRONMENTAL CHANGE & DISEASE RISKS
Climatic effects on water- and vector-borne diseaseslengthen transmission season; speed reproductiontends to increase geographic range (altitude, latitude)
Natural disasters affect sanitation, exposure, socioeconomics
Habitat change and degradationloss of biodiversityhomogenizationdense vegetation; stagnant secondary forest undergrowth
CLIMATE CHANGE
In the US: costs $2-4 billion/year in direct public health costs
Between 2030 and 2050, will cause ~250k additional deaths/yearmalaria, diarrhea, malnutrition
Key impacts for mosquito-vectored diseasesincreasingly variable rainfall patternsmore frequent and severe flooding and droughtincreasing minimum temperatures
CHOLERA
Bangladesh: outbreaks predicted by sea surface temperature and heightchlorophyll levels (phytoplankton/algal blooms)
DEFORESTATION
Creates mosquito-friendly habitatalso for other insect vectors (sandflies, ticks)
Creates mosaics of fragmented habitat support diversity and abundance of vectors, but few predatorsmore human-adapted species
Road construction increases access, exposure
Plus - muddy, rutted tracks fill with rain
Community-led trainings for prevention of dengue
Developed by Sustainable Sciences Institute
founded by Eva Harris, UC Berkeley
Basically the only method shown to be effective
DENGUECurrent strategy: spraying with larvicides, pesticides
organophosphate temephos for day-to-daymunicipalities spray malathion during outbreaks, but ineffectiveresistance common
BiocontrolsWolbachia bacteriaMesocyclops copepods
Bed nets ineffective (day feeders)
MALARIA
Current treatmentsinsectide-impregnated bed netsintermittent treatment for pregnant womenindoor spraying
Potential biological control agentse.g. fungi, nematodes: parasitize and kill larval mosquitoesinefficient for control; not widely usedmosquito fish largely been ineffective except in a few cases
For mosquito-vectored diseases, reducing habitat is key
spraying ineffective at bestmany mosquito (and other insect) species resistant
Community-led training most effective so faremptying, cleaning, covering containerslocally developed trainingreduced pesticide use
ThinkingFrameworks
DiseaseOverview:
What & Why
Pathogen Types
IllustrativeExamples
Conclusions&
Wrap-Up
FINDING SOLUTIONS. . .
Global agreementSolutions must be interdisciplinary, collaborative, holistic, etc.
Proven success with community-led solutions
Accounting for multiple factorshabitat and biodiversity lossclimate changewildlife presencesanitation needsetc.
– World Health Organization, 2013, xii
“A much broader-based response to the evolving patterns of infectious disease risk is needed — one that entails integrative strategies and that is environmentally sustainable, socio-ecologically sensitive and adaptive to changing conditions. [This will require] stronger and
harmonized strategic alliances between all organizations, sectors and institutions concerned with development, environment and social justice,
including public health.”
FINDING SOLUTIONS. . .
Global agreementSolutions must be interdisciplinary, collaborative, holistic, etc.
Do we wait for organizations to cooperate, or begin at a grassroots level?
Institutional bickering, territoriality and domain specialization endemicCoordination of funding, political regime change, international trade…
Sanitation
ThinkingFrameworks
Health & Nutrition
Prevention
Holistic Management
8 Forms/RegenerativeEnterprise
Permaculture&
SystemsDesign
RegenerativeAgriculture
LearningModels
CulturalDialogue
APPROACHES WITH BROAD APPLICATIONS
Each problem has multiple solutionsEach solution may be able to address multiple problemsDesign from patterns to details; follow the 12 principlesGather information, relevant knowledge, and community support
APPROACHES WITH BROAD APPLICATIONS
Preventionreduce or eliminate vector habitatencourage biodiversity in contiguous land areasreduce contact between wildlife and livestock
Sanitationprioritize multi-step processes for creating clean water (e.g. BSFs)close waste loops (composting, vermicompost)build soil health and vegetation to absorb waste
Health & Nutritionintricately linked to poverty through immunity, earning potential, cognition, physical capacity: rebuild nutrient-dense food and habitatssocioeconomics begins with household ecology, prevention & sanitation
REFERENCES
• Cascio, A., Bosilkovski, M., Rodriguez-Morales, a. J., & Pappas, G. (2011). The socio-ecology of zoonotic infections. Clinical Microbiology and Infection, 17, 336–342. http://doi.org/10.1111/j.1469-0691.2010.03451.x
• Jones, B. A., Grace, D., Kock, R., Alonso, S., Rushton, J., Said, M. Y., … Pfeiffer, D. U. (2013). Zoonosis emergence linked to agricultural intensification and environmental change. Proceedings of the National Academy of Sciences, 110(21), 8399–8404. http://doi.org/10.1073/pnas.1208059110
• Lambin, E. F., Tran, A., Vanwambeke, S. O., Linard, C., & Soti, V. (2010). Pathogenic landscapes: interactions between land, people, disease vectors, and their animal hosts. International Journal of Health Geographics, 9(1), 54. http://doi.org/10.1186/1476-072X-9-54
• Mawdsley, J. L., Bardgett, R. D., Merry, R. J., Pain, B. F., & Theodorou, M. K. (1995). Pathogens in livestock waste, their potential for movement through soil and environmental pollution. Applied Soil Ecology, 2(1), 1–15. http://doi.org/10.1016/0929-1393(94)00039-A
• Pongsiri, M. J., Roman, J. O. E., Ezenwa, V. O., Goldberg, T. L., Koren, H. S., Newbold, S. C., … Salkeld, D. J. (2009). Biodiversity Loss Affects Global Disease Ecology. BioScience, 59(11), 945–954. http://doi.org/10.1525/bio.2009.59.11.6
• Genevieve V. Weaver, Joseph Domenech, Alex R. Thiermann, and W. B. K. (2013). Wildlife Disease Association - FOOT AND MOUTH DISEASE A LOOK FROM THE WILD SIDE, 49(4), 759–785. http://doi.org/http://dx.doi.org/10.7589/2012-11-276
• Wilcox, B. A., & Colwell, R. R. (2005). Emerging and Reemerging Infectious Diseases : Biocomplexity as an Interdisciplinary Paradigm, 244–257. http://doi.org/10.1007/s10393-005-8961-3
• World Health Organization. (2013). Research priorities for the environment, agriculture and infectious diseases of poverty. World Health Organization technical report series.
HELPFUL RESOURCES
DIARRHEAL DISEASES
Symptom of other diseases usually caused by bacteria (e.g. cholera, shigellosis, typhoid) may also be caused by viruses or protozoa (e.g. amoeba, cryptosporidium and giardia)
Amoebic dysentery is the most commonaffects ~500 million people each year
Diarrhea overall the most common cause of illness and mortalitykills 1.8 million out of ~4 billion cases of illness annually
CRYPTOSPORIDIUM
• 7 species, one (c. parvum) focused as cause of clinical zoonotic disease in humans, livestock and other mammals (Robertson and Smith 1992); implicated in a large proportion of diarrhoeal outbreaks in pigs, sheep and cattle (Reynolds et al., 1986; Angus, 1990; Robert et al., 1991; Villacorta et al., 1991). In cattle and sheep cryptosporidiosis and the associated diarrhoea is almost exclusive to young animals and thus peaks of disease outbreaks occur around lambing and calving times (Fig. 2). Infection with Cryptosporidium often occurs in conjunction with other enteropathogens such as rota- virus, enteropathogenic E.coli and Salmonella spp., and such multiple infections increase both morbidity and mortality rates (Angus, 1990); animals ingest transmissive cysts that are excreted in large numbers in infected animals (Smith 1992); as few as 10 can result in disease; severity governed by immunological status of host (Ungar 1990); can be deadly in severely immunocompromised, esp. HIV, patients (Current 1987) due to excessive watery diarrhoea and dehydration; otherwise, 7-14 days of acute infection (nausea, anorexia, vomiting, abdominal pain, fever, diarrhoea) with general malaise and cramps up to a month; start 5-10 days after oocyst ingestion; excretion of oocysts can continue long after disease symptoms have ceased (Ungar 1990); water course contamination potentially a problem because oocysts are not removed by current water treatment practices (resistent to standard chlorine levels, West 1991); sand-bed filtration currently only effective method of removal (Smith 1992)
GIARDIA
• binucleate flagellates; three species on basis of host range and morphology; focused on G. lamblia (or G. intestinalis or G. duodenalis); causes disease in mammals, birds and reptiles; only two stage life-cycle: infective cyst and vegetative trophozoite; after cyst ingestation, excystation occurs in small intestine and two trophozoites are released; divide binary fission in small intestine and cause symptoms of giardiasis; some encyst, are shed in faeces and cycle continues; waterborne transmission via the infective cyst is major factor in spread; one of the most common waterborne epidemic diarrhoea in US (Deng and Cliver 1992); severity of disease varies greatly from asymptomatic to chronic diarrhoea. In addition to diar- rhoea, common symptoms which may persist for up to 6 weeks include abdominal cramps, nausea, loss of appetite, malaise and weight loss; sand filtration effective as for Cryptosporidium (Rose et al 1989)
SHIGELLA
• Four species: Shigella sonnei (the most common species in the United States) S. flexneri, S. boydii; S. dysenteriae Type 1 causes deadly epidemics; symptoms start 1-2 days post infection, with diarrhea (often bloody); tenesmus (feeling like having to make a bowel movement but is empty; fever; abdominal pain; typically last 5-7 days, although bowel activity may take several weeks to return to normal. Normally resistant to re-infection by the same species, but susceptible to others. Can be treated with antibiotics, but often resistant: usually left untreated will subside; keep well hydrated. Avoid drugs that slow the digestive system, e.g. Imodium
• long-term complications include arthritis (~2%), blood stream infections, seizures and hemolytic-ureic syndrome
RISK FACTORS: WATER-BORNE DISEASES
poor sanitation (household infrastructure: up next)
infected livestock around water
infected vegetation, e.g. manure applications
CHAGAS DISEASE (“KISSING BUG DISEASE”)• serious health problem in many parts of South and Central America; wide
distribution of host species; In the natural cycle, triatomine bugs commonly occur in native palms found in the Amazon and elsewhere in northern South America. Several studies have reported high rates of Chagas infection in these insects, sometimes exceeding 65% (WHO 2013 379).
• - mainly transmitted by faecal contamination of skin or conjunctivae that have been broken by the bite of many Reduviid bugs, especially Triatoma and Rhodnius spp.
• - originated in forest environments but have adapted well to domestic ones; some effective control of T. infestans in Brazil, Chile and Uruguay, but still present
• - difficult to eradicate due to re-infestation from forest habitat; >150 species from 24 families of sylvatic and domestic animals infected with etiological agent, Trypanosoma cruzi
• - ~25% of the 600 million in Latin America, specifically the poor (13% of total population) are at risk
• - most countries of Central America, and Colombia, Venezuela, species is Rhodnius prolixus; and in Gran Chaco region (Argentina, Bolivia, SW Brazil, Paraguay), T. infestans: re-infestations likely due in part to resistance to pyrethroid insecticides
• - Associated with biofuel plantations in Brazil
RISK FACTORS: VECTOR-BORNE DISEASES
standing water, dense vegetation (larval habitat)
monoculture plantations
lack of control methods, e.g. mosquito nets
FASCIOLOSIS
• two species of parasitic flatworms (trematodes) that mainly affect the liver• Fasciola hepatica and F. gigantica• are leaf-shaped worms; visible to the naked eye; can hybridize
• until recently, human cases occurred occasionally • increasingly reported from Europe, the Americas and Oceania (F.
hepatica only) and from Africa and Asia (both species)
• ~2.4 million people are infected in more than 70 countries worldwide, with several million at risk
• infection rates 80-100% in some countries
• large economic losses to sheep and cattle industries• e.g. £23 million in the UK
HANTAVIRUS PULMONARY/RENAL SYNDROME
• Hantaviruses found in Asia, Europe and Americas; all rodent hosts• North America: deer mouse + Sin Nombre virus (~35-50% mortality)• Central America: rice rat + Choclo virus• Europe: bank voles + Puumula virus (0.5% mortality)
• Transmitted through biting and scratching• humans infected through aerosolized faeces or urine
• Climatic events and human activities that reduce biodiversity associated with outbreaks
RISK FACTORS: VERTEBRATE DISEASES
loss of biodiversity; increases in host species
climatic variability
infected livestock; poor husbandry