Zika, Dengue, ChikungunyaZika, Dengue, Chikungunya after Irma, Maria and Harvey Pascal Bittel...
Transcript of Zika, Dengue, ChikungunyaZika, Dengue, Chikungunya after Irma, Maria and Harvey Pascal Bittel...
Zika, Dengue, Chikungunya after Irma, Maria and Harvey
Pascal Bittel Institute for Infectious Diseases Universität Bern 08.03.2018, Molecular Diagnostics Symposium Zurich
Actors:
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Pathogens Climate
Vectors Impact & Disease
Dengue
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A potentially lethal disease affecting >50 mio pp/y Lead Syptoms High Fever Mild rash
Mild muscle pain
Moderate joint pain
Moderate headache
Moderate bleeding
Shock (DHF)
DENV; ssRNA Flavivirus (Flaviviridae), 4 genotypes
Transmission via mosquitos
Exposure gives immunity to the same strain, but not others.
Secondary infection with different strain can lead to DHF
(2.5% of DHF are lethal)
Incubation period 3-7 days
Vaccine available (Dengvaxia)
Guzman, MG et al. The Lancet , Volume 385 , Issue 9966 , 453 - 465 Dengue
Zika
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Lead Symptoms Low/Moderate Fever
Strong rash Conjunctivitis Moderate joint pain
Mild muscle pain
Mild headache
The emerging arboviral pathogen of 2016
ZIKV; ssRNA Flavivirus (Flaviviridae)
WHO 2016 International Public Health Emergency
Transmission via mosquitos, sexual and intrauterine
Linked to birth defects (Microcephaly)
Linked to Guillain-Barré-Syndrome
Incubation period 3–12 days
Chikungunya
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Lead Symptoms High Fever Mild Rash
Mild conjuctivitis
Strong joint pain & swelling Mild muscle pain
Moderate headache
The painful third
CHIKV; ssRNA Alphavirus (Togaviridae)
Transmission via mosquitos
Some patients with persistent joint pains for months to
years
Incubation period 3–7 days
Clinical Manifestation Summary
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Symptom Dengue Chikungunya Zika (80% asymptomatic)
Fever ++++ ++++ ++
Headache +++ ++ +
Rash ++ ++ +++
Conjunctivitis + ++ ++
retro orbital pain ++ + +
muscle pain ++ + ++
joint pain/swelling + +++ ++
gastrointestinal symptoms + ++ +
Pruritus/dysaesthesia ++ + ++
Petechiae + - -
spontaneous bleeding + (+) -
Modified from Blum & Hatz, 2009; Neumayr & Hatz, 2016
…but also other mosquito-borne viruses
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West Nile Virus
Japanese Encephalitis Virus
La Crosse Virus
(Yellow Fever Virus)
St.Louis Encephalitis Virus
Diagnostic Techniques
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Serology Antigen Dengue rapidtests available (NS1Ag)
Molecular
IgM/G Crossreactions among flaviviruses
Only in acute phase (RT-PCR)
Cel. Virology Plaque Reduction Neutralization Test (Zika, Dengue; CDC)
https://www.swisstph.ch/en/travelclinic Information and recommendations of the Swiss Expert Committee of Travel Medicine (ECTM)
Main Vectors
9 Kraemer, M. et al. Elife. 2015 Jun 30;4:e08347 The global distribution of the arbovirus vectors Aedes aegypti and Ae. albopictus
Ae. albopictus
Ae. aegypti
Aedes Biology
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● Adult life span: 14-21 days
● Female lays eggs 3-4 times in her life
● ca. 100-200 eggs per oviposition Egg → Larva: 2-3 days Larva → Pupa: 4-5 days Pupa → Adult: 1-2 days ● Blood meal required to develop eggs
● Vertical virus transmission possible
aquatic, container breeder
Mosquitoborne-disease Season = Rainsaison
11 Wiwanitkit V. J Vector Borne Dis. 2006 Jun;43(2):73-6. An observation on correlation between rainfall and the prevalence of clinical cases of dengue in Thailand
Den
gue
inci
denc
e
Average rainfall
98%
3.5%
5.-13.2.2016
5.-21.8.2016
Risk to be stung by an Aedes mosquito
Chr
isto
ph H
atz,
TPH
, 201
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Worldwide tropical storm paths
12 NASA Earth Observatory
«Dengue-belt» Tracks and intensities of tropical storms 1951-2007
Climate
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HARVEY 215km/h 17.8.17-3.9.17
US National Hurricane Center; https://www.nhc.noaa.gov
IRMA 298km/h 30.8.17-14.9.17
MARIA 282km/h 16.9.17-30.9.17
Climate
Atlantic Hurricane Season: June – November ↑Sept Pacific Hurricane Season: May – September ↑Sept Pacific Typhoon Season: June – October ↑Aug Australian / Southern Cyclone Season: November – April ↑Feb
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Impact and Aftermath
15 Zorilla CD, N Engl J Med 2017; 377:1801-1803 The View from Puerto Rico — Hurricane Maria and Its Aftermath
San Juan, Puerto Rico; Maria
“As of 16 days after the hurricane, 25 of 69 hospitals were working, only 9.2% of people had power, 54% had water, 45% had cell phone service”
St. Maarten; Irma
Arboviral diseases are not a 1. line priority
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► Flood water contaminated by fecal material: Typhoid fever and cholera
► Safety concerns including potential crime and violence
► Caring for those directly injured during the storm
► Inadequate food and water supplies
► Rebuilding of a basic functional infrastructure
The question
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Hurricane events increase the incidence of cases of mosquito-arboviral diseases. or Hurricane events have little or no effect on the incidence of cases of mosquito-arboviral diseases.
Facts pro
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Hurricane events increase incidence of cases • Increased rainfall and flooding • Accumulation of water puddles: New breeding grounds for mosquitoes Mosquito populations may increase • Suspended vector control measures • Displacement of large numbers of people into crowded shelters / camps (3. world, global south)
Facts contra
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Hurricane events have little or no effect on the incidence of cases • Strong winds, salt water surge, downpours: Displace or kill mosquitoes, «flush-out effects» Adult Mosquitos don’t survive hurricane level storms • Altered ecology past event: Disruption of vertical transmission: New freshly hatched mosquitoes are virus-free Weeks for recovery of virus in population • Mass-evacuation of people to less affected (e.g. dry) inland-areas: Reduction of active reservoires (1. world)
Post-Hurricane arboviral outbreaks?
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Available data say NO, (but…)
Post-Hurricane arboviral outbreaks?
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Available data say NO, (but…) Joe Posid, CDC
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● 11 cases within 3 weeks past-event ● only 1 out of 150 WNF-patients develops neuroinvasive disease
Post-Hurricane arboviral outbreaks?
The CDC's and ECDC’s opinion
23 https://www.cdc.gov/zika/vector/mosquitoes-and-hurricanes.html
“Although flooding caused by hurricanes can be severe and an increase in mosquito populations is expected in the coming weeks, CDC does not generally expect to see a substantial increase in the incidence of mosquito-borne diseases.”
But why is the topic so much discussed then?
Public awareness vs. empirical evidence
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Hurricane events increase incidence of cases
Hurricane events have little or no effect on incidence of cases, but…
If, then late…
Mosquito-borne diseases are hurricane late-consequences: ● Mosquito population has to rebuild: weeks (most adults are dead) ● Virus has to reestablish in the mosquito population
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Affected areas have time to react (but also lots of other problems)
A complex network…
► Data must be integrated into multidisciplinary studies of pathogen dynamics and transmission risk
Mar
ian
Kam
ensk
y
Main Influencing Factors: Uncontrollable
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Early in rainseason = risk of transmission may rise
Late in rainseason = risk may even decrease
Time and location of the hurricane event is important:
Main Influencing Factors: Uncontrollable
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Early in rainseason = risk of transmission may rise
Late in rainseason = risk may even decrease
Manmade Influencing Factors
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Basic needs have to be fullfilled before affected areas can «switch back from disaster survival mentality» Mosquito control is not a 1st priority action after a major hurricane event.
Governmental/Social efficiency for disaster control
Vector Surveillance / Mosquito control
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Recommendations of WHO Vector Control Advisory Group (VCAG)
http://www.who.int/neglected_diseases/news/mosquito_vector_control_response/en
● Vector traps ● Targeted residual spraying ● Space spraying ● Larval control (source reduction / larviciding) ● Personal protection measures (repellents)
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Advanced Mosquito control techniques
● Microbial control of human pathogens in adult vectors using Wolbachia and Incompatible insect technique (IIT)
Terradas G, McGraw EA.; Curr Opin Insect Sci. 2017 Aug;22:37-44. Wolbachia-mediated virus blocking in the mosquito vector Aedes aegypti
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Advanced Mosquito control techniques
Ritchie SA et al.; Trends Parasitol. 2018 Mar;34(3):217-226 Mission Accomplished? We Need a Guide to the 'Post Release' World of Wolbachia for Aedes-borne Disease Control
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Advanced Mosquito control techniques
● Microbial control of human pathogens in adult vectors using Wolbachia and Incompatible insect technique (IIT) ● Sterile insect technique (SIT), Ae. aegypti OX513A
Terradas G, McGraw EA.; Curr Opin Insect Sci. 2017 Aug;22:37-44. Wolbachia-mediated virus blocking in the mosquito vector Aedes aegypti
Ritchie SA, Johnson BJ.; J Infect Dis. 2017 Mar 1;215 Advances in Vector Control Science: Rear-and-Release Strategies Show Promise
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Advanced Mosquito control techniques
● Microbial control of human pathogens in adult vectors using Wolbachia and Incompatible insect technique (IIT) ● Sterile insect technique (SIT), Ae. aegypti OX513A Hurricane events as chances?
Terradas G, McGraw EA.; Curr Opin Insect Sci. 2017 Aug;22:37-44. Wolbachia-mediated virus blocking in the mosquito vector Aedes aegypti
Ritchie SA, Johnson BJ.; J Infect Dis. 2017 Mar 1;215 Advances in Vector Control Science: Rear-and-Release Strategies Show Promise
Disease Surveillance
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CDC Arbonet: US national arboviral surveillance system Operational since 2000. Passive surveillance system. Clinicians/scientists obtaining the appropriate diagnostic tests, reporting the diagnosis of arboviral diseases, laboratory-analysis and vector surveillance data. Can be combined with climate data. Actively curated and can be used as a modelling instrument.
National surveillance and detection systems In non-industrialized countries often incomplete or non-existent. Little predictive value.
Multidisciplinary Surveillance
https://wwwn.cdc.gov/arbonet/
Virus surveillance?
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Isothermal amplification methods? A tool for field virus surveillance..?
Low-tech molecular diagnostics:
Summary
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● Hurricane events can create new mosquito breeding sites.
● Recovery of mosquito population typically takes some weeks.
● Adult mosquitos generally do not survive hurricane level storms.
● The dangers of post-hurricane arboviral outbreaks are often exaggerated in mass media.
● No major post-hurricane arboviral outbreaks have been reported However, if conditions are right, post-hurricane arboviral outbreaks can’t be excluded
Arboviral outbreak after hurricane-event?
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time of year
location
disaster response
situation before event
Outbreak
Thank you for you attention
Questions?
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