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Mosquito-borne virus prevention and

control: a global perspective

Chikungunya 2017, Sapienza Universita di Roma

10 November 2017

Erika Garcia

Mathematical Epidemiologist

World Health Organization

Geneva, Switzerland

garciaer@who.int

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To provide a summary of the global strategies for prevention and control of mosquito-borne diseases

Objective

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Outline

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1. Current situation

2. Surveillance and early detection, lab, clinical

management

3. Vector control strategy

4. Challenges

5. Next steps

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1. Current Situation

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- Emergence & Re-emergence

- Dengue causing extensive human disease

- Chikungunya - Geographic expansion and changes

in pattern of illness

- 2015/2016 Zika virus outbreak was unexpected

- YF Outbreaks in areas previously not at risk (urban)

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Malaria1 DengueWHO RECENT 2

Population at risk 3.2 billion 2.5 billion 4 billion

Endemic countries 96 >100 128

Infections /year 214 million 50 million 70- 500

million

Severe Cases 3 million 2.1

million

Deaths/ year 438,000 20,000 40,000

1) Global Malaria Report 2015

2) http://www.pdvi.org/about_dengue/GBD.asp and Brady et.al. PLoS Negl Trop Dis 2012; 6: e1760

Dengue – Burden estimation

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0

500000

1000000

1500000

2000000

2500000

3000000

3500000 EMR

AMR

WPR

SEAR

Trends in cases reported to WHO

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Spread of Aedes-borne Disease

• Estimated dengue age-standardized cases from 1990-2013 increased nearly 450%

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Americas

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Chikungunya and Dengue, Pakistan 2017

2 Outbreaks

• Karachi Started Nov 2016 and continues. Health authorities estimate the total number of patients to be more than 30 000. The National Institutes of Health, Pakistan, and Armed Forces Institute of Pathology, Pakistan, confirmed 4000+ cases through qualitative RT-PCR.

• Dengue in Peshawar (Jul to Sept) also detected CHIKV. 50,000 cases

Chikungunya virus was found circulating in rodents in Pakistan as early as 1983. A few patients with chikungunya were also reported in Lahore during the 2011 dengue outbreak.

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Yellow fever, Angola, 2016

Location No. of cases Population

(million)

March Lo-Hi

Temp (°C)

Past reports

of Dengue

Beijing 4 11.51 -1 to 11 -

Fuzhou 2 2.124 9 to 19 2015

Shanghai 3 14.35 5 to 13 -

Source: MoH, China Meteorological Admnistration

• Dec '15 – Oct '16, 4347

susp cases, 377 deaths

• Spread to DRC, 2987

cases and 121 deaths

• Btwn 18 Mar - 4 Apr

2016, a total of 9

imported cases of YF

from Angola were

reported by NFP China.

Unvaccinated workers.

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The context

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2. Surveillance and early detection

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- Early detection of Aedes-

borne outbreaks

- Integrated surveillance

(humans, animals, vectors)

- At-risk populations i.e,

pregnant women, elderly

- Utilize existing systems, i.e.,

AFP surveillance, Congenital

Rubella Surveillance,

Sentinel

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Laboratory

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- Laboratory techniques: RT-PCR, ELISA or IF, PRNT

- Collection of patient samples: urine, saliva not just sera

- Challenges for Zika, et al: expertise about flaviviruses since

interpretation is complex. No WHO prequalified test

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Clinical management

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• All arboviral diseases transmitted

by Ae. spp. (DENV, CHIKV, and

ZIKV) currently have no specific

treatment.

• But clinical management for each

is very important

• Studies needed to see the

severity of CHIKV

• No vaccine

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“

… above all, the spread of Zika, the resurgence of dengue, and the emerging threat of Chikungunya are the price being paid for a massive policy failure that dropped the ball on

mosquito control in the 1970s.

Margaret ChanFormer Director-General, World Health Organization

Opening Address at World Health Assembly 69th sessionMay 2016

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3. Global Vector Control Response 2017-

2030

REDUCE THE BURDEN AND

THREAT OF VECTOR-BORNE

DISEASES THAT AFFECT

HUMANS

ENABLING FACTORS

Country leadership

Advocacy, resource

mobilization and partner

coordination

Regulatory, policy

and normative support

Reduce incidence by 60%Reduce mortality by 75%By 2030

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Aedes control is linked to many SDGs Each goal

is important in itself…

And they are all

connected

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Vector Control Objectives

• To reduce human-vector contact

• To reduce longevity and abundance of disease

vectors

• To reduce vector breeding sites, where and when

possible

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Involvement of Communities

• Vector control methods applied in a community will depend on the local situation and preferences of the population.

• Suitable methods should be:– Effective

– Affordable

– Simple to understand and easy to apply

– Acceptable and compatible with local customs, attitudes and beliefs

– Safe to the user and the environment.

• Methods used in one place may not work in another place

• Social mobilization to eliminate breeding sites (targeting mothers, educating children through games), health promoters going to door to door for visits educating how to prevent disease, removing water containers.

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Larval Control• Chemical control

– Organophosphates

– Pyrethroids

– Spinosad

– Insect Growth Regulators

• Biological control– Fishes

– Copepods

• Biocides –Bacillus thuringiensis var israelensis

• Environmental Control

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Conditions for space spraying

• Precise location to be sprayed

• Distribution of case house(s)

• The case history [when is the first case (index case), movement pattern of cases, probable source of infection]

• Type of vector (Aedes aegypti vs Aedes albopictus or both)

• Major breeding sites

• Adequate trained supervisors

• Number of trained spray people available for mobilization

• Availability of protective cloth and accessories

• Health information and communication back up

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Entomological indicators disease incidence

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The actual entomological indicators are all based on densities: Larvae (HI, BI, LI), Pupae (PI) and Adults (HI).

Larvae and Pupae densities are far away from the transmission. These indicators are linked to climatic and social conditions, but cannot be related to diseases incidence.

Adults females densities are more close to transmission, however, the fluctuations of the females abundances is not always directly related to transmission since factors such as duration of life (survival) and immunological status of human population can have more significance.

?

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Preparedness plans

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• National preparedness plans in

collaboration with local levels

– Identify human resources needed,

training required

– Entomol/Epi surveillance integrated

– Multi sectoral approach

– Increasing awareness of physicians

(malaria case earlier this year)

• Development of Regional plan

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4. Challenges

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• Rapid development of insecticide resistance in mosquitoes

• Educating the public of reduction of sources of standing

water

• Major commercial investment is needed for vaccine

development for Zika and Chikungunya.

• Difficulty in predicting future outbreaks making it difficult to

do efficacy trials and future markets.

• Improved surveillance and Point-of-care diagnostics

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5. Next Steps

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• Conceptual framework is needed for Aedes-borne diseases

– Change from disease specific programs to comprehensive approach

– End points differ, specific treatments and vaccines. Upstream is same.

– More efficient than developing specific antiviral drugs, vaccines

• Further research on: animal reservoirs, natural history of disease,

global burden

• Innovative methods, tools for vector control

• Development of laboratory diagnostics urgently needed

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Acknowledgements

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• Sergio Yactayo – IHM/WHO

• Kyohei Nishino – IHM/WHO

• Florence Fouque – TDR/WHO

• Raman Velayudhan – NTD/WHO

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Thank you!