Malawi District Level Outbreak Risk Assessment Analysis

Districts that have reported lab confirmed outbreaks as of April 20, 2010 Blantyre, Chiradzulu, Mangochi, Mulanje, Balaka, Chikwawa, Zomba, Thyolo, Mwanza (all in the Southern region), Lilongwe, Kasungu (Central Region), Mzimba (Northern region).

Criteria considered for districts at highest risk and requiring immediate response: –Districts with lab confirmed outbreaks –Districts adjacent to districts with lab confirmed outbreaks –Districts with large populations (size of birth cohort in excess of 20,000 per year) –Districts with large proportion of susceptibles accumulating in the past 5 years (> 2 thirds of the size of the birth cohort)

Cumulative percentage of reported measles cases by age group (N = 1497) NB: Data for the districts of Blantyre, Chiradzulu, Lilongwe, Mzimba, Mangochi, Machinga

Age Specific attack rates NB: Data for the districts of Blantyre, Chiradzulu, Lilongwe, Mzimba, Mangochi, Machinga

Even though the proportion of cases above 5 years of age makes up half of the case load reported, and the cases under 15 make up 80% of the case load, the age specific attack rate indicates that the attack is highest in the under ones (AR: 83 per 100,000), and then in the < 5 year olds (AR: 33 per 100,000). The information regarding vaccination status is not complete in the line list that was made available for analysis.

Recommendations Considering these specific epidemiological features and the resource constraints, we propose that the response vaccination take place in the age group 6 months to 5 years. In terms of geographic extent, an alternative scenario can be considered to target: –the districts where outbreaks have been confirmed, –the adjacent districts, –districts with large population sizes, –Districts with large population movement, migratory workers, undocumented settlers, etc –Districts known to have low routine immunisation coverage