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

Documents

Lessons from Measles outbreaks in the African Region