No 25 - 2018
Botulism outbreak in Southern Jutland
Botulism outbreak in Southern Jutland
As might be clear from the media coverage the outbreak has received, a major outbreak of food-borne botulism has been detected among 11 elderly persons in Southern Jutland who had shared a meal. Nine people from the group are currently ill.
Statens Serum Institut (SSI) was informed of the outbreak on Sunday morning, 17th June 2018, and secured relevant samples from the patients in the course of Sunday and throughout Sunday night. Furthermore, steps were taken to ensure that the patients could receive botulism anti-toxin.
On Monday 18th June 2018, the SSI received samples from 10 of the 11 persons. For rare diseases such as botulism, the highly specialised diagnostics are performed at the SSI only.
The SSI determines if the genetic material of the toxin is detectable in stools or spew (PCR testing). Additionally, a mouse test was performed to establish if the toxin was present in the blood. Investigators also test if Clostridium botulinum bacteria are found in the stools.
The mouse test consists in injecting a small amount of blood from the patients into mice. The mice are then followed for up to 5 days to see if they show signs of botulism symptoms. If they do, it may be established if the symptoms recede when the mice are given an antidote.
Upon reception of the sample material, the SSI performed the first mouse tests, and already 4 hours after injection of the serum from one of the sick patients, the mice showed signs of botulism, including paralysis of the respiratory muscles that presents as a so-called “hourglass figure” in the mice. This confirms that botulism toxin was present in the blood in the sample taken before administering antidote to the patient. In the course of the night, another five patients tested positive owing to the mouse test.
Today, one of the six positive mouse tests has been described as type A toxin.
On suspicion of botulism, patients must receive treatment based on the classic symptoms they have. Treatment should not await the laboratory results. The antidote will not cure the patients, but it inhibits the development of the disease.
The SSI’s main task is to provide and maintain preparedness to counter infectious diseases through monitoring of infectious diseases, handling of outbreaks, specialised diagnostics and by providing vaccines and preparedness products.
The SSI worked around the clock from Sunday morning to ensure that all patients received the antidote. The antidote was procured in part from the SSI’s local preparedness stock, in part from Norway and Sweden. The SSI forms part of a closely knit network of countries that assists each other when preparedness products are needed rapidly.
Furthermore, the SSI assists the Danish Veterinary and Food Administration in collection of detailed information about what the patients have ingested. Even so, the source of the infection remains unknown.
(T.G. Krause, S. Cowan, Department of Infectious Disease Epidemiology and Prevention, S. Skovgaard, A. Kjerulf, The Clinical Microbiology Reference Laboratory)
A total of 3,579 new MRSA cases were recorded in 2017, which is in line with the number detected in 2016 (3,550), EPI-NEWS 23/17. In 581 (16%) cases, MRSA had been acquired abroad, which is a decrease from 2016 when 712 imported cases were recorded. Minor increases were observed in the number of hospital-acquired and community-acquired cases. The increase in hospital-acquired cases was primarily due to an increased number of outbreaks in neonatal departments.
The number of livestock MRSA CC398 cases was 1,212, which is in line with the level recorded for the three preceding years. This stagnation is probably owed to the fact that a larger share than previously of persons who come into direct contact with pigs have been tested. This causes the number of persons at risk of a new infection to decrease. It should be noted that despite this levelling off, it is very likely that the number of healthy carriers will accumulate over time, particularly among carriers of livestock MRSA CC398 with contact to livestock. This is so because these carriers are not comprised by MRSA eradication programmes. The number of livestock MRSA CC398 cases in hospitals that are detected only after admission is low (10). This demonstrates that the Danish MRSA guidelines are serving their purpose.
Handling of MRSA notifications
The MRSA report is based on information that the SSI receives from the MRSA notification forms and from the characterisation of the corresponding isolates. The isolates are submitted by the diagnosing laboratory, and the MRSA notification form is submitted by the physician who obtained the sample. In practice, this means that the notifications and isolates reach the SSI at different points in time. Therefore, the SSI constantly monitors if both parts of the notification-isolate pairs have been received. A reminder is forwarded if a notification is not submitted within 2 months from the time of the diagnosis.
Among the 3,579 new MRSA cases recorded, a reminder was sent out in 685 cases according to the above-described procedure. Even after sending out reminders, information was missing for 281 persons. It was therefore necessary to contact the GP by phone in 120 cases to complete MRSA monitoring, whereas the infectious hygiene units contributed with information relating to 136 persons. Information about the remaining 25 cases was obtained by SSI in other ways.
It is clear that cases which require a reminder delay the report on the number of MRSA cases. Additionally, it is resource demanding for those who need to notify as well as for the SSI. In order to improve this, the SSI is working to establish an electronic MRSA notification procedure. Until this can be achieved, laboratories and notifying physicians are encouraged to continue forwarding isolates as well as notifications as soon as possible.
(A. Petersen, A.R. Larsen, Bacteria, Fungi and Parasites, B. Kristensen, A. Koch, C.H. Møller, T. Urth, H. Amtsbiller, Department of Infectious Disease Epidemiology and Prevention)