USING MAPS IN A TB CONTROL PROGRAMME

Multi Drug Resistant Tuberculosis: Creating maps to help the control programme.

During the last month, there were 30 new cases of TB diagnosed (by ZN microscopy) in the laboratory. The samples were from three health centre in Zura district. 10 of the samples were sent to the national TB laboratory for sensitivity testing, and of these, six were MDRTB. Four were from one HC and two from an adjacent HC area. Three months earlier, there had been four cases of MDRTB from one of these areas.

Although TB is endemic in our area (despite the national TB programme), these were the first cases of MDRTB that had occurred. We thought it was time to get a clearer understanding of the pattern of TB in the district, and to look back on all the cases we had had over the last year. We hoped that this may help to improve control locally, and ensure that best use was being made of the laboratory for TB in the community, as well as for individual new cases. 

Our plan was to do two things:

a): on a spreadsheet eg Excel, list all the cases, with date of diagnosis, age, village, local HC, if they were MDRTB, if after 4 months they were still taking regular treatment.

b): put the information on a map, so that possible links between cases could be seen,  possible clusters of MDRTB identified, and village health workers could easily see the location of cases in their areas.

For mapping, there are several possibilities.  If your region has access to the WHO Healthmapper for your country, this may be the best system to use, but availability and permission for you to make local maps would depend on the MoH. Free software such as EPI-Map (from the CDC website) is useful, but not particularly flexible for unskilled users. Professional mapping systems such as ARC-Info make the most sophisticated maps, but are expensive and complicated.

If your hospital/lab has internet access, then Google maps provides a useful and simple way of creating maps for local health programmes. You need to have a Google account (eg Gmail).  Creating your own maps in Google maps requires some persistence and trial and error, but once you are used to it, they are easy to create.

The Help page for google maps is at:

https://support.google.com/mymaps/?hl=en#topic=3188329

Examples of maps we created and used are shown below:

The view above shows the boundaries of the sub-districts, the location of the health centres, and the location of each of the TB cases, and whether or not they are MDRTB.

The second view (below) is in "satellite" mode, and zoomed in to show the detailed location of cases in their village areas. Such a view can help very much in seeing links between cases, and in contact tracing.

The third view(below) again shows the location of individual cases, and in addition the data table that is automatically created in Google maps as each new point is added. It also shows the pop-up box for a case that is highlighted, so that the details on each case can easily be seen.

A Google map is an online map, not a static map on your computer. This means several things:

• You can share the map in real time with others on the internet to whom you have given the link (eg the district TB office, health workers if they have internet access on computer or smart phone, other hospitals if there are cases between districts),
• The map can be updated each time there is a new case, without having to create a new map
• You can zoom in and out of the map, to see the overall cases or concentrate on one area to see case location, and you can alternate between map and satellite view
• The map can be printed off, so that health centres without internet access can have a weekly updated map supplied

In our programme, we used the maps we created for the following ways to assist the TB control programme.

1. Looking at the overall geographical spread of TB cases in the project area to see if there are particular areas of clusters/high transmission.

2. To look at the location of MDRTB cases.  Are they sporadic or are they in clusters. Do they occur mainly in one area of the project? (eg a village where many men go as migrant workers to an industrial area).

3. Contact tracing. We can draw a eg 500m zone around a new case, on satellite view zoom in and see actual houses nearby, and arrange and mark off contact tracing.

4. As soon as a new case is diagnosed in the lab, it can be added to the map, and immediately seen by any health worker accessing the map. It can be colour coded according to normal case or MDRTB. With the "pop up" box for the new case, details such as age, village, date of diagnosis can readily be seen.

5. The case load for each HCW can easily be seen from the number of cases in their block.

6.  The data table generated in the map as each new case is added can easily be visualised to show the cases in tabular form.

7. Weekly or monthly maps, using whichever view required, can be printed off for hard copy reports, or distributed to HC's without computers/internet access.

8. Maps can be saved to a file on the computer.

We have found that using such a web based and shared map helps us to be more aware of the pattern of TB cases, and helps in the day to day running of the programme.

Further reading on disease mapping:

1. Identification of malaria hotspots in a tribal area of India. Int J Health Geog,2009;8 (This is rather complicated, but similar work could be done with Google maps).
https://ij-healthgeographics.biomedcentral.com/articles/10.1186/1476-072X-8-30

2. Mapping TB in Malawi. Malawi Med J 2005;17:33-35.
https://www.researchgate.net/publication/269103003_Not_just_pretty_pictures_Geographical_Information_Systems_in_TB_control

Two other useful sites for disease outbreak maps and lists are:

Healthmap:
http://www.healthmap.org/en/

ProMedmail:
http://www.promedmail.org/