#PAGE_PARAMS# #ADS_HEAD_SCRIPTS# #MICRODATA#

Characterizing the Epidemiology of the 2009 Influenza A/H1N1 Pandemic in Mexico


Background:
Mexico's local and national authorities initiated an intense public

health response during the early stages of the 2009 A/H1N1 pandemic. In this

study we analyzed the epidemiological patterns of the pandemic during

April–December 2009 in Mexico and evaluated the impact of nonmedical

interventions, school cycles, and demographic factors on influenza

transmission.

Methods and Findings:

We used influenza surveillance data compiled by the Mexican Institute for

Social Security, representing 40% of the population, to study

patterns in influenza-like illness (ILIs) hospitalizations, deaths, and

case-fatality rate by pandemic wave and geographical region. We also

estimated the reproduction number (R) on the basis of the growth rate of

daily cases, and used a transmission model to evaluate the effectiveness of

mitigation strategies initiated during the spring pandemic wave. A total of

117,626 ILI cases were identified during April–December 2009, of which

30.6% were tested for influenza, and 23.3% were positive for

the influenza A/H1N1 pandemic virus. A three-wave pandemic profile was

identified, with an initial wave in April–May (Mexico City area), a

second wave in June–July (southeastern states), and a geographically

widespread third wave in August–December. The median age of laboratory

confirmed ILI cases was ∼18 years overall and increased to ∼31 years

during autumn (p<0.0001). The case-fatality ratio among

ILI cases was 1.2% overall, and highest (5.5%) among people

over 60 years. The regional R estimates were 1.8–2.1, 1.6–1.9,

and 1.2–1.3 for the spring, summer, and fall waves, respectively. We

estimate that the 18-day period of mandatory school closures and other

social distancing measures implemented in the greater Mexico City area was

associated with a 29%–37% reduction in influenza

transmission in spring 2009. In addition, an increase in R was observed in

late May and early June in the southeast states, after mandatory school

suspension resumed and before summer vacation started. State-specific fall

pandemic waves began 2–5 weeks after school reopened for the fall

term, coinciding with an age shift in influenza cases.

Conclusions:
We documented three spatially heterogeneous waves of the 2009 A/H1N1 pandemic

virus in Mexico, which were characterized by a relatively young age

distribution of cases. Our study highlights the importance of school cycles

on the transmission dynamics of this pandemic influenza strain and suggests

that school closure and other mitigation measures could be useful to

mitigate future influenza pandemics.

:

Please see later in the article for the Editors' Summary


Vyšlo v časopise: Characterizing the Epidemiology of the 2009 Influenza A/H1N1 Pandemic in Mexico. PLoS Med 8(5): e32767. doi:10.1371/journal.pmed.1000436
Kategorie: Research Article
prolekare.web.journal.doi_sk: https://doi.org/10.1371/journal.pmed.1000436

Souhrn

Background:
Mexico's local and national authorities initiated an intense public

health response during the early stages of the 2009 A/H1N1 pandemic. In this

study we analyzed the epidemiological patterns of the pandemic during

April–December 2009 in Mexico and evaluated the impact of nonmedical

interventions, school cycles, and demographic factors on influenza

transmission.

Methods and Findings:

We used influenza surveillance data compiled by the Mexican Institute for

Social Security, representing 40% of the population, to study

patterns in influenza-like illness (ILIs) hospitalizations, deaths, and

case-fatality rate by pandemic wave and geographical region. We also

estimated the reproduction number (R) on the basis of the growth rate of

daily cases, and used a transmission model to evaluate the effectiveness of

mitigation strategies initiated during the spring pandemic wave. A total of

117,626 ILI cases were identified during April–December 2009, of which

30.6% were tested for influenza, and 23.3% were positive for

the influenza A/H1N1 pandemic virus. A three-wave pandemic profile was

identified, with an initial wave in April–May (Mexico City area), a

second wave in June–July (southeastern states), and a geographically

widespread third wave in August–December. The median age of laboratory

confirmed ILI cases was ∼18 years overall and increased to ∼31 years

during autumn (p<0.0001). The case-fatality ratio among

ILI cases was 1.2% overall, and highest (5.5%) among people

over 60 years. The regional R estimates were 1.8–2.1, 1.6–1.9,

and 1.2–1.3 for the spring, summer, and fall waves, respectively. We

estimate that the 18-day period of mandatory school closures and other

social distancing measures implemented in the greater Mexico City area was

associated with a 29%–37% reduction in influenza

transmission in spring 2009. In addition, an increase in R was observed in

late May and early June in the southeast states, after mandatory school

suspension resumed and before summer vacation started. State-specific fall

pandemic waves began 2–5 weeks after school reopened for the fall

term, coinciding with an age shift in influenza cases.

Conclusions:
We documented three spatially heterogeneous waves of the 2009 A/H1N1 pandemic

virus in Mexico, which were characterized by a relatively young age

distribution of cases. Our study highlights the importance of school cycles

on the transmission dynamics of this pandemic influenza strain and suggests

that school closure and other mitigation measures could be useful to

mitigate future influenza pandemics.

:

Please see later in the article for the Editors' Summary


Zdroje

1. Chowell

G

Bertozzi

SM

Colchero

MA

Lopez-Gatell

H

Alpuche-Aranda

C

2009

Severe respiratory disease concurrent with the circulation of

H1N1 influenza.

N Engl J Med

361

674

679

2. Perez-Padilla

R

de la Rosa-Zamboni

D

Ponce de Leon

S

Hernandez

M

Quinones-Falconi

F

2009

Pneumonia and respiratory failure from swine-origin influenza A

(H1N1) in Mexico.

N Engl J Med

361

680

689

3. Gomez-Gomez

A

Magana-Aquino

M

Garcia-Sepulveda

C

Ochoa-Perez

UR

Falcon-Escobedo

R

2010

Severe pneumonia associated with pandemic (H1N1) 2009 outbreak,

San Luis Potosi, Mexico.

Emerg Infect Dis

16

27

34

4. 2009

Swine influenza A (H1N1) infection in two children--Southern

California, March-April 2009.

MMWR Morb Mortal Wkly Rep

58

400

402

5. 2009

Outbreak of swine-origin influenza A (H1N1) virus infection -

Mexico, March-April 2009.

MMWR Morb Mortal Wkly Rep

58

467

470

6. Cordova-Villalobos

JA

Sarti

E

Arzoz-Padres

J

Manuell-Lee

G

Mendez

JR

2009

The influenza A(H1N1) epidemic in Mexico. Lessons

learned.

Health Res Policy Syst

7

21

7. Bootsma

MC

Ferguson

NM

2007

The effect of public health measures on the 1918 influenza

pandemic in U.S. cities.

Proc Natl Acad Sci U S A

104

7588

7593

8. Shaman

J

Kohn

M

2009

Absolute humidity modulates influenza survival, transmission, and

seasonality.

Proc Natl Acad Sci U S A

106

3243

3248

9. Shaman

J

Pitzer

VE

Viboud

C

Grenfell

BT

Lipsitch

M

2010

Absolute humidity and the seasonal onset of influenza in the

continental United States.

PLoS Biol

8

e1000316

doi:10.1371/journal.pbio.1000316

10. 2010

H1N1 Flu.

Atlanta (Georgia)

Centers for Disease Control and Prevention

11. Fraser

C

Donnelly

CA

Cauchemez

S

Hanage

WP

Van Kerkhove

MD

2009

Pandemic potential of a strain of influenza A (H1N1): early

findings.

Science

324

1557

1561

12. Ghani

AC

Baguelin

M

Griffin

J

Flasche

S

Pebody

R

2009

The early transmission dynamics of H1N1pdm influenza in the

United Kingdom.

PLoS Curr Influenza

doi:10.1371/currents.RRN1130

RRN1130

13. Yang

Y

Sugimoto

JD

Halloran

ME

Basta

NE

Chao

DL

2009

The transmissibility and control of pandemic influenza A (H1N1)

virus.

Science

326

729

733

14. Nishiura

H

Castillo-Chavez

C

Safan

M

Chowell

G

2009

Transmission potential of the new influenza A(H1N1) virus and its

age-specificity in Japan.

Euro Surveill

14

15. Laguna-Torres

VA

Gomez

J

Aguilar

PV

Ampuero

JS

Munayco

C

2010

Changes in the viral distribution pattern after the appearance of

the novel influenza A H1N1 (pH1N1) virus in influenza-like illness patients

in Peru.

PLoS One

5

e11719

doi:10.1371/journal.pone.0011719

16. Valdivia

A

Lopez-Alcalde

J

Vicente

M

Pichiule

M

Ruiz

M

2010

Monitoring influenza activity in Europe with Google Flu Trends:

comparison with the findings of sentinel physician networks - results for

2009-10.

Euro Surveill

15

17. Echevarria-Zuno

S

Mejia-Arangure

JM

Mar-Obeso

AJ

Grajales-Muniz

C

Robles-Perez

E

2009

Infection and death from influenza A H1N1 virus in Mexico: a

retrospective analysis.

Lancet

374

2072

2079

18. CONAPO

2010

Mexico City: Consejo Nacional de Poblacion, Mexico

19. 2009

Centers for Disease Control and Prevention. Serum cross-reactive

antibody response to a novel influenza A (H1N1) virus after vaccination with

seasonal influenza vaccine.

MMWR Morb Mortal Wkly Rep

58

521

524

20. Chowell

G

Bettencourt

LM

Johnson

N

Alonso

WJ

Viboud

C

2008

The 1918-1919 influenza pandemic in England and Wales: spatial

patterns in transmissibility and mortality impact.

Proc Biol Sci

275

501

509

21. Wallinga

J

Lipsitch

M

2007

How generation intervals shape the relationship between growth

rates and reproductive numbers.

Proc Biol Sci

274

599

604

22. Chowell

G

Viboud

C

Simonsen

L

Miller

MA

Acuna-Soto

R

2010

Mortality patterns associated with the 1918 influenza pandemic in

Mexico: evidence for a spring herald wave and lack of preexisting immunity

in older populations.

J Infect Dis

202

567

575

23. Chowell

G

Nishiura

H

Bettencourt

LM

2007

Comparative estimation of the reproduction number for pandemic

influenza from daily case notification data.

J R Soc Interface

4

155

166

24. Cauchemez

S

Donnelly

CA

Reed

C

Ghani

AC

Fraser

C

2009

Household transmission of 2009 pandemic influenza A (H1N1) virus

in the United States.

N Engl J Med

361

2619

2627

25. Cowling

BJ

Chan

KH

Fang

VJ

Lau

LL

So

HC

2010

Comparative epidemiology of pandemic and seasonal influenza A in

households.

N Engl J Med

362

2175

2184

26. Monto

AS

Koopman

JS

Longini

IM

Jr

1985

Tecumseh study of illness. XIII. Influenza infection and disease,

1976-1981.

Am J Epidemiol

121

811

822

27. Cauchemez

S

Ferguson

NM

Wachtel

C

Tegnell

A

Saour

G

2009

Closure of schools during an influenza pandemic.

Lancet Infect Dis

9

473

481

28. Chao

DL

Elizabeth Halloran

M

Longini

IM

Jr

2010

School opening dates predict pandemic influenza A(H1N1) outbreaks

in the United States.

J Infect Dis

202

877

880

29. Cauchemez

S

Valleron

AJ

Boelle

PY

Flahault

A

Ferguson

NM

2008

Estimating the impact of school closure on influenza transmission

from Sentinel data.

Nature

452

750

754

30. Gomez

J

Munayco

C

Arrasco

J

Suarez

L

Laguna-Torres

V

2009

Pandemic influenza in a southern hemisphere setting: the

experience in Peru from May to September, 2009.

Euro Surveill

14

31. Nishiura

H

2010

Case fatality ratio of pandemic influenza.

Lancet Infect Dis

10

443

444

32. Baker

MG

Wilson

N

Huang

QS

Paine

S

Lopez

L

2009

Pandemic influenza A(H1N1)v in New Zealand: the experience from

April to August 2009.

Euro Surveill

14

33. Wu

JT

Cowling

BJ

Lau

EH

Ip

DK

Ho

LM

2010

School closure and mitigation of pandemic (H1N1) 2009, Hong

Kong.

Emerg Infect Dis

16

538

541

34. Hens

N

Ayele

GM

Goeyvaerts

N

Aerts

M

Mossong

J

2009

Estimating the impact of school closure on social mixing

behaviour and the transmission of close contact infections in eight European

countries.

BMC Infect Dis

9

187

35. Langmuir

AD

Pizzi

M

Trotter

WY

Dunn

FL

1958

[Asian influenza surveillance.].

Public Health Rep

73

114

120

36. Dunn

FL

Carey

DE

Cohen

A

Martin

JD

1959

Epidemiologic studies of Asian influenza in a Louisiana

parish.

Am J Hyg

70

351

371

37. Pourbohloul

B

Ahued

A

Davoudi

B

Meza

R

Meyers

LA

2009

Initial human transmission dynamics of the pandemic (H1N1) 2009

virus in North America.

Influenza Other Respi Viruses

3

215

222

38. Boelle

PY

Bernillon

P

Desenclos

JC

2009

A preliminary estimation of the reproduction ratio for new

influenza A(H1N1) from the outbreak in Mexico, March-April

2009.

Euro Surveill

14

39. Nishiura

H

Chowell

G

Safan

M

Castillo-Chavez

C

2010

Pros and cons of estimating the reproduction number from early

epidemic growth rate of influenza A (H1N1) 2009.

Theor Biol Med Model

7

1

40. Paine

S

Mercer

GN

Kelly

PM

Bandaranayake

D

Baker

MG

2010

Transmissibility of 2009 pandemic influenza A(H1N1) in New

Zealand: effective reproduction number and influence of age, ethnicity and

importations.

Euro Surveill

15

41. McBryde

E

Bergeri

I

van Gemert

C

Rotty

J

Headley

E

2009

Early transmission characteristics of influenza A(H1N1)v in

Australia: Victorian state, 16 May - 3 June 2009.

Euro Surveill

14

42. Munayco

CV

Gomez

J

Laguna-Torres

VA

Arrasco

J

Kochel

TJ

2009

Epidemiological and transmissibility analysis of influenza

A(H1N1)v in a southern hemisphere setting: Peru.

Euro Surveill

14

43. Pedroni

E

Garcia

M

Espinola

V

Guerrero

A

Gonzalez

C

2010

Outbreak of 2009 pandemic influenza A(H1N1), Los Lagos, Chile,

April-June 2009.

Euro Surveill

15

44. Tuite

AR

Greer

AL

Whelan

M

Winter

AL

Lee

B

2010

Estimated epidemiologic parameters and morbidity associated with

pandemic H1N1 influenza.

CMAJ

182

131

136

45. White

LF

Wallinga

J

Finelli

L

Reed

C

Riley

S

2009

Estimation of the reproductive number and the serial interval in

early phase of the 2009 influenza A/H1N1 pandemic in the

USA.

Influenza Other Respi Viruses

3

267

276

46. Lessler

J

Reich

NG

Cummings

DA

Nair

HP

Jordan

HT

2009

Outbreak of 2009 pandemic influenza A (H1N1) at a New York City

school.

N Engl J Med

361

2628

2636

47. 2009

Current situation of the 2009 H1N1pdm influenza pandemic in

Mexico [in Spanish].

Mexico City

Secretaria de Salud

48. 2010

Situacion de influenza A(H1N1) - reporte

01/26/2010.

Santiago (Chile)

Ministerio de Salud de Chile

49. 2010

Situacion de influenza A(H1N1) - parte 87.

Buenos Aires

Ministerio de Salud de Argentina

50. Webb

SA

Pettilä

A

Seppelt

I

Bellomo

R

2009

Critical care services and 2009 H1N1 influenza in Australia and

New Zealand.

N Engl J Med

361

1925

34

51. Bishop

JF

Murnane

MP

Owen

R

2009

Australia's winter with the 2009 pandemic influenza A (H1N1)

virus.

N Engl J Med

361

2591

2594

52. Miller

MA

Viboud

C

Balinska

M

Simonsen

L

2009

The signature features of influenza pandemics--implications for

policy.

N Engl J Med

360

2595

2598

53. Chowell

G

Ammon

CE

Hengartner

NW

Hyman

JM

2006

Estimation of the reproductive number of the Spanish flu epidemic

in Geneva, Switzerland.

Vaccine

24

6747

6750

54. Andreasen

V

Viboud

C

Simonsen

L

2008

Epidemiologic characterization of the 1918 influenza pandemic

summer wave in Copenhagen: implications for pandemic control

strategies.

J Infect Dis

197

270

278

55. Ayora-Talavera

G

Gongora-Biachi

RA

Lopez-Martinez

I

Moguel-Rodriguez

W

Perez-Carrillo

H

2002

Detection of human influenza virus in Yucatan,

Mexico.

Rev Invest Clin

54

410

414

56. Shaman

J

Goldstein

E

Lipsitch

M

2011

Absolute humidity and pandemic versus epidemic

influenza.

Am J Epidemiol

173

127

135

57. Lipsitch

M

Viboud

C

2009

Influenza seasonality: lifting the fog.

Proc Natl Acad Sci U S A

106

3645

3646

58. Viboud

C

Bjornstad

ON

Smith

DL

Simonsen

L

Miller

MA

2006

Synchrony, waves, and spatial hierarchies in the spread of

influenza.

Science

312

447

451

59. Eggo RM, Cauchemez S, Ferguson NM Spatial dynamics of the 1918

influenza pandemic in England, Wales and the United States.

J R Soc Interface

8

233

243

60. Nishiura

H

Chowell

G

2008

Rurality and pandemic influenza: geographic heterogeneity in the

risks of infection and death in Kanagawa, Japan (1918-1919).

N Z Med J

121

18

27

61. Reed

C

Angulo

FJ

Swerdlow

DL

Lipsitch

M

Meltzer

MI

2009

Estimates of the prevalence of pandemic (H1N1) 2009, United

States, April-July 2009.

Emerg Infect Dis

15

2004

2007

62. Presanis

AM

De Angelis

D

Hagy

A

Reed

C

Riley

S

2009

The severity of pandemic H1N1 influenza in the United States,

from April to July 2009: a Bayesian analysis.

PLoS Med

6

e1000207

doi:10.1371/journal.pmed.1000207

63. Libster

R

Bugna

J

Coviello

S

Hijano

DR

Dunaiewsky

M

2010

Pediatric hospitalizations associated with 2009 pandemic

influenza A (H1N1) in Argentina.

N Engl J Med

362

45

55

64. Wu

JT

Ma

ES

Lee

CK

Chu

DK

Ho

PL

2010

The infection attack rate and severity of 2009 pandemic H1N1

influenza in Hong Kong.

Clin Infect Dis

51

1184

1191

65. Louie

JK

Acosta

M

Winter

K

Jean

C

Gavali

S

2009

Factors associated with death or hospitalization due to pandemic

2009 influenza A(H1N1) infection in California.

JAMA

302

1896

1902

66. Hardelid

P

Andrews

N

Hoschler

K

Stanford

E

Baguelin

M

2010

Assessment of baseline age-specific antibody prevalence and

incidence of infection to novel influenza AH1N1 2009.

Health Technol Assess

14

115

192

67. Olson

DR

Simonsen

L

Edelson

PJ

Morse

SS

2005

Epidemiological evidence of an early wave of the 1918 influenza

pandemic in New York City.

Proc Natl Acad Sci U S A

102

11059

11063

68. Valleron

AJ

Cori

A

Valtat

S

Meurisse

S

Carrat

F

2010

Transmissibility and geographic spread of the 1889 influenza

pandemic.

Proc Natl Acad Sci U S A

107

8778

8781

69. World Health Organization (WHO)

2010

Aug

10

H1N1 in post-pandemic period.

Available: http://www.who.int/mediacentre/news/statements/2010/h1n1_vpc_20100810/en/index.html.

Štítky
Interné lekárstvo

Článok vyšiel v časopise

PLOS Medicine


2011 Číslo 5
Najčítanejšie tento týždeň
Najčítanejšie v tomto čísle
Kurzy

Zvýšte si kvalifikáciu online z pohodlia domova

Aktuální možnosti diagnostiky a léčby litiáz
nový kurz
Autori: MUDr. Tomáš Ürge, PhD.

Všetky kurzy
Prihlásenie
Zabudnuté heslo

Zadajte e-mailovú adresu, s ktorou ste vytvárali účet. Budú Vám na ňu zasielané informácie k nastaveniu nového hesla.

Prihlásenie

Nemáte účet?  Registrujte sa

#ADS_BOTTOM_SCRIPTS#