The most recent update posted on Madagascar's MOH website - released yesterday (October 20th) - still shows 911 plague cases, and 95 deaths, but a situation report from the World Health Organization released on the same date provides a tally more than 40% higher.
The reasons behind this discrepancy aren't immediately apparent, but - assuming the WHO's numbers are right - reports of a slowdown in cases (based on MOH reported numbers) earlier this week may have been premature.Some excerpts from the WHO SitRep #5 follow:
Madagascar has been experiencing a large outbreak of plague affecting major cities and other non-endemic areas since August 2017. Between 1 August and 19 October 2017, a total of 1 297 cases (suspected, probable and confirmed) including 102 deaths (case fatality rate 7.9%) have been reported. Of these, 846 cases (65.2%) were clinically classified as pneumonic plague, 270 (20.8%) were bubonic plague, one case was septicaemic plague, and 180 cases were unspecified (further classification of cases is in process). Of the 846 cases of pulmonary plague, 91 (10.8%) have been confirmed and 407 (48.1%) were probable.
Between 1 August and 15 October 2017, a total of 793 specimens were analysed by the Institut Pasteur de Madagascar (IPM). Of these, 126 (15.9%) have been confirmed either by polymerase chain reaction (PCR) or bacteriological culture, 242 (30.5%) were probable after testing positive on rapid diagnostic tests (RDT) and 425 (53.6%) remain suspected (additional laboratory results are in process). Eleven strains of Yersinia pestis have been isolated and were sensitive to antibiotics recommended by the National Program for the Control of Plague.
Overall, 33 out of 114 (30%) districts in 14 of 22 (63.6%) regions in the country have been affected by pulmonary plague. The district of Antananarivo Renivohitra has reported the largest number of pulmonary plague cases, accounting for 63.6% of all the cases.
On 19 October 2017, 1 621 out of 2 470 (65.6%) contacts were followed up and provided with prophylactic antibiotics. A total of 372 contacts completed the 7-day follow up without developing symptoms.
Plague is endemic on the Plateaux of Madagascar, including Ankazobe District where the current outbreak originated. There is a seasonal upsurge, predominantly of the bubonic form, which occurs every year, usually between September and April. The plague season began earlier this year and the current outbreak is predominantly pneumonic and is affecting non-endemic areas including major urban centres such as Antananarivo (the capital city) and Toamasina (the port city).
There are three forms of plague, depending on the route of infection: bubonic, septicaemic and pneumonic (for more information, see the link http://www.who.int/mediacentre/factsheets/fs267/en/).
Current risk assessment
While the current outbreak began with one large epidemiologically linked cluster, cases of pneumonic plague without apparent epidemiologic links have since been detected in regions across Madagascar, including the densely populated cities of Antananarivo and Toamasina.
Due to the increased risk of further spread and the severe nature of the disease, the overall risk at the national level is considered very high. The risk of regional spread is moderate due to the occurrence of frequent travel by air and sea to neighbouring Indian Ocean islands and other southern and east African countries, and the observation of a limited number of cases in travellers. This risk is mitigated by the short incubation period of pneumonic plague, implementation of exit screening measures in Madagascar and scaling up of preparedness and operational readiness activities in neighbouring Indian Ocean islands and other southern and east African countries. The overall global risk is considered to be low.
The risk assessment will be re-evaluated by WHO based on the evolution of the situation and the available information.