Lessons from Measles outbreaks in the African Region

Lessons from Measles outbreaks in the African

Region

Annual Measles Partnership meeting

Feb 2007Washington DC

2Bureau Régional de l’OMS pour l’Afrique / WHO Regional Office for Africa


Outline

• Quality of surveillance

• Measles outbreaks in 2006

• Lessons learnt




• Lessons learnt


The AFR measles surveillance and lab network (Feb 2007)

• A total population of 668.5 million under case based surveillance for measles


Measles surveillance performance indicators in AFR. 2002 - 2006

0%10%20%30%40%50%

60%70%80%90%

100%

Districts Reporting Blood SpecimensCollected

Lab ConfirmedMeasles

2002

2003

2004

2005

2006


Measles surveillance performance & results. AFR. 2006

Indicator/ parameter Result

# suspected cases reported 21580

% investigated with blood specimens 93%

% districts reporting at least 1 suspected case

54%

% lab confirmed cases 30%

# total confirmed measles cases 7707

Incidence rate of confirmed measles 1.2 per 100,000 population


• 22 countries > 2 suspected cases investigated per 100,000 population

• 15 countries >80% districts reporting

• 24 countries > 60% districts reporting

• 25 countries < 1: 100,000 incidence of confirmed measles

Measles surveillance performance & results. AFR. 2006 (2)


Incidence of confirmed measles per 100,000 population by country. 2006




• Lessons learnt


– In 2004, 80 (5%) of a total of 1590 districts covered by the case based surveillance system reported outbreaks

– In 2005, outbreaks in 47 (3%) districts out of 1850

– In 2006, 178 (6%) of 2923 districts in 12 countries have experienced outbreaks.

NB: Tanzania database incomplete

Measles outbreaks in the African Region (2004 - 2006)


Probable causes of measles outbreaks in the African Region in 2006

• Accumulation of unvaccinated cohorts (~ over

3 -4 years) due to a combination of factors

– sub-national gaps in routine EPI coverage:

• Angola, Benin, DR Congo, Ethiopia, Mali, Tanzania,

Uganda

– delays in conducting follow up SIAs:

• Kenya, Zambia, Ghana

• cross border spread of outbreaks:• DR Congo, Rwanda


Outbreak countries. AFR. 2006

Country Average MCV

coverage

(‘03 –‘05)

Interval b/n last SIAs and

onset of outbreak (months)

# (%) districts involved

Size of largest cluster (cases/

district)

Confirmed measles

Incidence rate

Angola 57 32 13 (8%) 118 4.0

Benin 84 4 4 (5%) 17 2.3

Ghana 82 37 4 (4%) 10 0.4

Kenya 71 40 71 (90%) 162 5.0

Mali 76 14 3 (5%) 79 1.0

Rwanda 88 32 2 (5%) 468 5.5

Tanzania 94 12

Uganda 87 29 29 (52%) 126 3.2

Zambia 79 35 8 (11%) 44 1.5



Country Average MCV

coverage

(‘03 –‘05)





district)

Confirmed measles

Incidence rate

Angola 57 32 13 (8%) 118 4.0



Country Average MCV

coverage

(‘03 –‘05)





district)

Confirmed measles

Incidence rate

Ghana 82 37 4 (4%) 10 0.4



Country Average MCV

coverage

(‘03 –‘05)





district)

Confirmed measles

Incidence rate

Zambia 79 35 8 (11%) 44 1.5



Country Average MCV

coverage

(‘03 –‘05)





district)

Confirmed measles

Incidence rate

Kenya 71 40 71 (90%) 162 5.0


Trends in confirmed measles cases. Kenya. 2003 - 2006

0

50

100

150

200

250

300

350

400

2003 2004 2005 2006

num

ber

of c

onfir

med

mea

sles

cas

es

Trends of confirmed measles cases. Kenya. 2003 –2006.

F-up SIAs done July ‘06

Catch-up SIAs:

June ‘02

F-up SIAs postponed


Measles cases in Kenya. 2006


0

100

200

300

400

500

600

< 9 months 9 - 11months

1 - 4 years 5 - 14 years 15+ years

co

nfi

rme

d m

ea

sle

s c

as

es

unknown

not vaccinated

vaccinated

Confirmed measles cases by age and vaccination status. Kenya. 2006



Country Average MCV

coverage

(‘03 –‘05)





district)

Confirmed measles

Incidence rate

Uganda 87 29 29 (52%) 126 3.2


Trends in confirmed measles cases. Uganda. 2002 - 2006

0

20

40

60

80

100

120

140

160

180

2002 2003 2004 2005 2006

nu

mb

er

of

con

firm

ed

meas

les c

ase

s

Trends of confirmed measles cases. Uganda. 2002 – 2006.

Catch-up SIAs: Oct

2003

F-up SIAs: Nov 2006


Measles cases in Uganda. 2006


Confirmed measles cases by age and vaccination status. Uganda. 2006

0

50

100

150

200

250

300

350

400

< 9 months 9 - 11months

1 - 4 years 5 - 14 years 15+ years

co

nfi

rme

d m

ea

sle

s c

as

es

unknown

not vaccinated

vaccinated


Probable causes of measles outbreaks in the African Region in 2006 (2)

– Program gaps leading to a cohort of older

children (ages 6 – 7.5 years) unprotected in

some districts

• Tanzania (124 districts)

– 1999 / 2000 SIAs: all 9 – 59 months (in 91 districts)

– 2001 SIAs: 9 months – 14 years (in 31 districts)

– 2002 SIAs: 7 – 14 years (in 89 districts)

– 2005 SIAs: 9 - 59 months (nation-wide follow up)


Age distribution of measles cases. Dar es Salaam, Tanzania

July – mid Oct. 2006


Disturbing gaps in the quality of data

Country % cases with age missing

% cases with vaccination status missing/ unknown

DRC 30% 44%

Ethiopia - 55%

Kenya 4% 55%

Tanzania - 78%

Uganda - 82%

Ghana 14% 41%




• Lessons learnt


Lessons learnt

• Postponing measles follow-up SIAs beyond 36

months is risky even in “high” coverage countries

– Other platforms available for integration

– Disparities in the district level coverage

• Surveillance and outbreak investigation should

provide better quality epidemiological information

– Training and technical support for outbreak investigation


Lessons learnt (2)

• Political visibility of outbreaks;

– an opportunity to advocate for routine EPI and good quality

follow up SIAs

• Identify districts at high risk for outbreaks for extra

support to intensify immunization activities


Thank you

Lessons from Measles outbreaks in the African Region

Documents

Lessons from Measles outbreaks in the African Region