Dengue - A Virus Without Borders

Department of Pathology

Center for Biodefense and Emerging Infectious Diseases

Institute for Human Infections and Immunity

Center for Tropical Diseases

Nikos Vasilakis, PhD

Rural settlement near Ngari, Senegal

Brazil - UTMB : A Long Relationship

Adapted from: Morens, Folkers & Fauci. Nature 2004

H1N1

influenza

Global Pathogen Emergence

Global Aviation Network

Hufnagel L et al. PNAS 2004;101:15124-15129

©2004 by National Academy of Sciences

Dengue Emergence

Spillover in sylvatic habitats

e.g. eastern Senegal

Urban dengue

Ae. aegypti

Ae. albopictus

Throughout

the tropics

and

subtropics

Malaysia,

West Africa

Arboreal Aedes spp.

Dengue Emergence

Urban dengue

Ae. aegypti

Ae. albopictus

Throughout

the tropics

and

subtropics

Spillover in sylvatic habitats

e.g. eastern Senegal,

Nigeria, peninsular Malaysia

Malaysia,

West Africa

Arboreal Aedes spp.

DomRep1981 Thai/734/00

Th0/348/91 Thai/0485/01

Thai/87/77 Thai/476/97 Thai/179/97

Mal/P75-215/75 BFaso/1349/82

Austral/TSV01/93 China/FJ11/99 Thai/1974 Thai/38/1974

Thai/NH73/93 Thai/NH36/93

Thai/NH55/93 Thai/17/98 Thai/78/01 Thai/C0167/96

Thai/263/95 Thai/K10/94 Thai/55/99

Thai/26/88 Thai/433/85

Thai/NHp14/93 Thai/168/79 Thai/498/84

Thai/16681/64 NGuinea/NGC/44

Braz/64022/98 Ven/Mara4/90 Mart/1998

Jam/N1409/83 Chin/04/85

Thai/284/90 Peru/1950/95 Peru/291396

Peru/1797/95 Ven/131/92

Ven/2/87 PRico/1328/77

Bfaso/2039/80 ICoast/A1247/80 Bfaso/A2022/80 ICoast/A510/80 ICoast/578/80 Guin/PM33974/81

Sen/319/99 Sen/320/99

Sen/5505/91 Nig/1208/66 Nig/11664//66 Nig/11234/66 Sen/20761/74 Sen/A10674/70

Mal/P81407/70

Mal/P72-1244/72 Thai/0673/80 Thai/0442/80

FrGuiana/89 Braz/90

Braz/111/97 Braz/233/97 Braz/MR/01 Parag/259/00

Argen/297/00 Argen/293/00

ICoast/Abidjan/98 Thai/0488/94 Thai/0097/94

Sing/S275/90 Thai/0102/91 Thai0049/01

Thai/0336/91 Thai/0323/91

Djibouti/98 Chin/Guangzhou/80 Thai/0081/82 Thai/0008/81

Jap/Mochizuki/43 Indon/A88/88

Thai/1687/98 Thai/1283/98

Thai/0104/93 Thai/0055/93

Thai/0007/87 Thai/0010/87

Martin/99

Phil/H87/56

DENV-1

Sylvatic

Human

Sylvatic

Human DENV-3

Sylvatic

Human

DENV-2

Sylvatic

Human DENV-4

5% nucleotide

Sequence divergence

MRCA≤1000

years ago

MRCA≤600

years ago

MRCA≤200

years ago

SriL/00

94

100

97

97

97

94

94

90

Ancestral

Sylvatic DENV

in Asia

Chen & Vasilakis (2011) Viruses 3:1562-1608

Global Dengue Virus Distribution - 1960

DENV-1 DENV-2 DENV-3 DENV-4

DENV-1 DENV-2

DENV-1 DENV-2

Global Dengue Virus Distribution - 2010

DENV-1 DENV-2 DENV-3 DENV-4

DENV-1 DENV-2 DENV-3 DENV-4

DENV-1 DENV-2 DENV-3 DENV-4

DENV-1 DENV-2 DENV-3 DENV-4

DENV-1 DENV-2 DENV-3 DENV-4

DENV-1 DENV-2 DENV-3

Dengue in Brazil : 1986 -2010

Range of Dengue Disease DENV inoculation

asymptomatic infection symptomatic infection

fever, myalgia, arthralgia, nausea,

vomiting, headache, rash

hemorrhagic manifestations

skin hemorrhages, gingival bleeding and epistaxis,

gastrointestinal bleeding, menorrhagia

dengue fever

without hemorrhage

DF

undifferentiated fever

dengue fever with hemorrhage

DF severe hemorrhagic disease

plasma leakage, liver enlargement, circulatory failure

dengue hemorrhagic fever

DHF

grades I and II

Shock

dengue shock syndrome

circulatory failure, shock

DSS

grades III and IV

Dengue in Brazil : Epidemic of 2008

Ernesto Marques, MD/PhD, FIOCRUZ, Recife

Ernesto Marques, MD/PhD, FIOCRUZ, Recife

Dengue Incidence Rate in Brazil

Dengue Transmission Cycle

Vasilakis etal. (2011), Nature Reviews Microbiology 9:532-541

Was human dengue emergence

mediated by adaptation to the

peridomestic mosquito vectors,

Aedes aegypti and Ae. albopictus,

and/or human reservoir host ?

Dengue Emergence in Peridomestic

Mosquitoes

Sylvatic versus Endemic: t-test; P > 0.5

% m

osq

uit

oes w

ith

dete

cta

ble

vir

us i

n s

ali

va

Hanley et al. PLoS Negl. Trop. Dis. (in peer review)

DE

N2

IC

DA

K

DE

N2

-P8 1

40

7

DE

N2

-PM

33

9

DE

N2

SE

N D

AK

DE

N2

DO

O-0

13

7

DE

N2

IQ

T 2

91

3

DE

N2

NG

C

DE

N2

To

nga

0

20

40

60

80

100

a Groups of SCID-Huh-7 mice were inoculated into the tumor with 4.0 – 4.2 log10 ffu of the indicated virus. Serum was collected on day 7 and virus titer was determined on C6/36 cells b Indicates the country and year that virus strain was isolated c ‘Endemic’ denotes human or Ae. aegypti isolates or strains that are associated with peridomestic transmission d Virus titer in serum was determined by focus forming immunoassay (FFA) in C6/36 cells e The limit of detection of the assay is 0.5 ffu/ml f Mean peak titers were assigned to statistical groups using one-way ANOVA, df = 5; F=25.6; P<0.0001 and the Tukey-Kramer post hoc test (P < 0.05). Groups with the same letter designation

are not significantly different; all means not sharing a letter are significantly different.

Vasilakis et al. (2007). Virology 358:402-412

n = 7

n =

7 n = 6

n = 6

n = 6

n = 6

A

B, C

D

C, E

A, B

D, E

Dengue Emergence in Vertebrate Hosts :

in vivo

a moDCs (2.5 x 105 per sample) from two healthy human volunteers were infected with an MOI = 2 of the indicated virus. Supernatants were collected 48 hrs p.i. and viral output was

determined on C6/36 cells b Indicates the country and year that virus strain was isolated c ‘Endemic’ denotes human or Ae. aegypti isolates or strains that are associated with peridomestic transmission d Virus titer in serum was determined by focus forming immunoassay (FFA) in C6/36 cells e The limit of detection of the assay is 0.5 log10 ffu/ml f Mean peak titers were assigned to statistical groups using the Tukey-Kramer post hoc test (P < 0.05). Groups with the same letter designation arenot significantly different; all means not

sharing a letter aresignificantly different. Unpaired t-test endemic versus sylvatic using mean values from 4 endemic and 6 sylvatic: df = 8; t = 1.35; P = 0.21

Vasilakis et al. (2007). Virology 358:402-412

A A

B

B

B

B B

B

C C

Dengue Emergence in Vertebrate Host :

ex vivo

Human dengue emergence was

NOT mediated by adaptation to

the peridomestic mosquito vectors,

Aedes aegypti and Ae. albopictus,

or human reservoir host !!

Do Evolutionary Processes among

Sylvatic DENV-2 Facilitate Emergence?

Adapted from: Vasilakis et al. (2007). J. Virol. 81:9591-9595

Can Sylvatic Dengue Re-emerge ??

Sylvatic Dengue in West Africa

Only DENV-2 has a sylvatic focus in West Africa Cornet, etal. (1979, 1984). Saluzzo etal. (1986)

Oscillating periodicity of sylvatic amplification cycles

(1974, 1980-1982, 1989-1990, 1999-2000) Diallo etal (2003)

Unlike other arboviruses, rainfall amount and distribution have no correlation

with sylvatic DENV emergence Davies et al. (1985). Linthicum et al. (1999). Diallo et al. (2003)

Virus circulates in peridomestic habitats, but no recorded clinical cases:

- virus is confined to the forest, or

- if human/mosq/human transmission occurs, its levels are low and

asymptomatic

Do unrecognized,

spillover epidemics are caused by sylvatic DENV-2 strains in

West Africa??

Vasilakis, Tesh and Weaver (2008). EID 14:502-504

DENGUE VIRUSES FROM FEBRILE PATIENTS IN NIGERIA,

1964-1968 D.E. CAREY, O.R. CAUSEY, S. REDDY AND A.R. COOKE LANCET 1971 1(7690);105-106

Can Sylvatic Dengue Re-emerge ??

Documented Human Sylvatic Cases in Africa

1970: 6 yr old girl living in Bandia prefecture, Senegal. (Robin etal. ‘Isolement du virus dela dengue au Senegal’. Ann. Virol. 1980 131:149-154)

1983: Caucasian scientist while investigating the 1983 amplification

cycle in SE Senegal. Severe clinical presentation.

1983: Caucasian tourist returning from Casamance. Classic DF clinical

presentation. (Saluzzo etal. ‘Isolation of dengue 2 and dengue 4 viruses from patients in Senegal’. TRSTMH 1986 80:5)

1990: 31 yr old Caucasian returning from military manoeuvres in

eastern Senegal. (Monlun etal. ‘Caracteres cliniques et epidemiologiques de la dengue 2 au Senegal’. Med. Mal.

Infect. 1992 22:718-721)

1990: 15 yr old Senegalese boy living in the vicinity of Kedougou presented with malaria-like disease & arthralgia lasting one month (Monlun etal. ‘Caracteres cliniques et epidemiologiques de la dengue 2 au Senegal’. Med. Mal. Infect. 1992 22:718-721)

2009: 27 yr old Guinea Bissau native returning to Spain via Dakar. First documented DHF case in Africa due to sylvatic DENV infection. (Franco etal. ‘First report of sylvatic DENV-2 associated with dengue hemorrhagic fever in West Africa’. PLoS NTD 2011 accepted for publication)

Can Sylvatic Dengue Re-emerge in Africa??

Human Prevalence

Vasilakis, Hanley, and Weaver (2010) In: Frontiers in Dengue Virus Research. Caister Academic Press (Hanley & Weaver, Eds).

Can Sylvatic Dengue Re-emerge in Africa??

Geographic Range of Vector and NHP

Vasilakis etal. (2011), Nature Reviews Microbiology 9:532-541

Can Sylvatic Dengue Re-emerge in Asia??

Human Exposure

Vasilakis, Hanley, and Weaver (2010). In: Frontiers in Dengue Virus Research. Caister Academic Press (Hanley & Weaver, Eds).

Can Sylvatic Dengue Re-emerge in Asia??

Geographic Range of Vector and NHP

Vasilakis etal. (2011), Nature Reviews Microbiology 9:532-541

Does the presence of pre-existing

antibodies to endemic DENV in the

human population could influence

the re-emergence of sylvatic DENV ??

Homotypic and Heterotypic Sylvatic Neutralization

of DENV-2 Sera at Day 42 Post Vaccination

Vasilakis et al. (2008). Am. J. Trop. Med. Hyg. 79:128 - 132

Homotypic and Heterotypic Sylvatic DENV-4

Neutralization of Convalescent Patient Sera

Durbin etal. In peer review, EID

Strong homotypic neutralization of sylvatic strains

Strong homotypic neutralization could explain the periodicity of sylvatic

amplification cycles and absence of epidemics in the human population

Should a licensed vaccine lead to the eradication of the endemic

transmission cycle in the future, re-emergence of sylvatic strains into

the endemic cycle would be limited by sterilizing homotypic immunity

Role of Pre-existing DENV Abs in Emergence

of DENV

Re-emergence Potential and Implications

for Public Health

Re-emergence of current sylvatic DENV can pose a major public health

problem

Success of programs to reduce or eradicate dengue from human

populations utilizing vector control programs or vaccination may be

short-lived

Success of such programs would hinge on sustainable vaccination AND

vector control programs to reduce the endemic vector mosquitoes

If endemic transmission cycle is eradicated, cessation of anti-dengue

measures for a sufficiently long time could lead to the rise of susceptible

human populations, as well as, the establishment of adequate

populations of endemic vector mosquitoes

Sylvatic DENV in the Americas?

Vasilakis etal. (2011), Nature Reviews Microbiology 9:532-541

Hemagogous janthinomys (S. America?)

Aedes mediovittatus (S. America?)

Assess the risk that they pose to contemporary human

populations

Ecological studies of the identity of the vertebrate hosts

of sylvatic DENV, their role in the maintenance and

amplification of these viruses

Better diagnostic assays

And Now What?

Acknowledgements

Financial Support:

Department of Pathology

DARPA PROPHECY - DARPA-BAA-10-93 NIAID/CPCIDB - HHSN272200800048C

CDC Fellowship Training Program in Vector-Borne Infectious Diseases, T01/CCT622892

Institut Pasteur de Dakar

Senegal Mawlouth Diallo, PhD

Amadou A. Sall, PhD

University of Buea

Cameroon Eric B. Fokam

CDC, PR Jorge Munoz-Jordan, PhD

NIH Brian Murphy, MD

Steve Whitehead, PhD

NMSU Kathryn A. Hanley, PhD

JHSPH Anna Durbin, MD

Duke/NUS Eng Eung Ooi, MD

Instituto Nacional de Salud

Publica, Mexico Jose Ramos-Castaneda, PhD

UNIMAS, Malaysia Mary Jane Cardosa, PhD

Weaver Lab Eleanor Deardorff, PhD

Shannan Rossi, PhD

Joan Kenney, MPH

Wenli Kang

Anonymous Blood Donors

World Reference

Center for

Emerging Viruses

and Arboviruses Bob Tesh, PhD

Hilda Guzman

PSU Eddie Holmes, PhD

Vasilakis Lab Evgeniya Volkova, MSc

Sandra Mayer, DVM

FIOCRUZ, Recife E.T. Marques, MD/PhD

Marli Tenorio, PhD

Laura Gil, PhD

FAMERP, São Jose do Rio

Preto Mauricio L. Nogueira, MD/PhD