By: Mark Leon Goldberg on June 03, 2015 Today’s map comes from the World Health Organization. It shows the number of days each district of Sierra Leone has gone since the last reported case of ebola. The magic number here is 42. This is double the 21 day incubation period of ebola. It is the standard the World Health Organization uses to declare whether or not a place is considered “ebola free.” If an entire country can go 42 days without a new ebola transmission, then that country is considered to be “ebola free.” Liberia was declared “ebola free” last month. This was a huge accomplishment. At one point, Liberia accounted for more ebola cases than Guinea or Sierra Leone. With the exception of Italy (where there is one imported case under the 42 monitoring period) most health officials believe that Sierra Leone will be the next country to kick ebola. Earlier this week, the UN’s Ebola response coordinator David Nabarro said it would be just “a matter of weeks” until Sierra Leone is declared ebola free. “The general trend lines are that increasingly, new cases are known contacts of people who’ve already got the disease, and also when cases are detected they’re brought under treatment quickly,” Nabarro told The Associated Press news agency. “And that means that we believe that it’s only a matter of weeks before the outbreak is ended in Sierra Leone,” he said, “and that’s because of strong participation of communities, a very coordinated national response, and strong leadership from Ernest (Bai) Koroma, the president.” As you can see from the map, ebola is already absent in most of the country. In all, there are just three current cases of ebola concentrated in two districts. The country is tantalizingly close to eliminating a disease that killed nearly 4,000 Sierra Leonians. UPDATE: No sooner did I hit “publish” on this piece then the WHO sent out its latest ebola data that show the number of confirmed ebola cases in Sierra Leone has increased four fold. To make matters worse, the new data shows that there are still methods of transmission that are going undetected by health workers. If these transmission trends continue, it may complicate Dr. Nabarro’s assessment that Sierra Leone may be declared ebola free in a matter of weeks. The good news, such as it is, is that the cases are still geographically concentrated. From the WHO: A total of 12 confirmed cases were reported from 3 districts in the week to 31 May, compared with 3 cases from 2 districts the previous week. The majority (8) of cases were reported from a densely populated area of the Kaffu Bullom chiefdom in Port Loko. All but one of the cases were registered contacts of previous cases within quarantined houses in the chiefdom… and are the third generation of cases in the locale that can be linked back to a single case imported from the district of Kambia, which lies just to the north of Port Loko on the border with Guinea…The additional case is from the same neighbourhood but was not on a contact list, and was living in a non-quarantined home at the time of symptom onset. Kambia reported its first case for over 2 weeks on 31 May. The case was identified after a post-mortem test of a community death and was not a known contact of a previous case. Epidemiological investigations have so far not been able to establish an epidemiological link to a previous case, and it is suspected that an active chain of transmission may have gone undetected in the community for several weeks. Community engagement has continued to be challenging in several chiefdoms in Kambia, with UNICEF reporting a large number of incidents of resistance to response measures in the district.