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| EPI-NEWS |
National surveillance of communicable diseases
Dept. of Epidemiology
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| Editor: Peter Henrik Andersen |
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Phone: +45 3268 3038 - Fax: +45 3268 3874
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| - ISSN: 1396-4798 |
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MRSA from swine, Pneumococcal vaccination in the childhood vaccination programme, Blood donor screening 2006 |
MRSA transferred from swine
Animals are not generally regarded a substantial source of Staphylococcus aureus infection, including methicillin-resistant S. aureus (MRSA), EPI-NEWS 5/07. In 2006, however, it was established that animals, particularly swine, may constitute a reservoir of infection for some subtypes, mainly MRSA ST398. This subtype has been detected in swine and in humans with swine contact, especially in the Netherlands. Furthermore, MRSA ST398 has been found in humans and production animals in other European countries and in Canada and Asia. In Denmark, a total of 32 human cases of ST398 infection have been detected since 2003, including 4 cases in 2007.
Case-control study
To identify sources of MRSA ST398 infection, a case-control study was undertaken in the spring of 2007. MRSA ST398 cases were compared with two control groups (1:2:2): one group was selected via the Central National Register, the other included persons with community-acquired MRSA of subtypes other than ST398. The groups were matched with regards to age, sex and geographical distribution. Telephone interviews were used to collect information regarding admission to hospital, other medical contact, clinical data such as skin lesions and sores, chronic diseases, use of antibiotics, travel and exposure to agriculture and animals. In cases where several MRSA ST398 infected persons were found in the same family, only the index person was included in the study.
The study comprised 21 cases and 81 controls. The median age of the cases was 29 years, 13 were females. Ten (48 %) had skin or soft tissue infections; in one case such infection was complicated by severe joint infection. Consequently, ST398 seems to present a clinical presentation identical to that of other community-acquired MRSA infections.
Compared with the CNR controls, the cases were more likely to have lived or worked on farms with livestock (odds ratio (OR) 35.4; 95% CI 2.7-469.8) and have been admitted to hospital (OR 11.4; 95% CI 1.4-94.8). Compared with the MRSA control group, cases were more likely to have lived or worked on farms with livestock (OR 14.5; 95% CI 2.7-76.7).
Thirteen (62%) cases and no controls had come into contact with swine. The owners of the farms which cases had been in contact with were contacted with a view to testing for MRSA in the current production animals. From the farms at which the owner agreed to participate, the nares of ten randomly selected animals were sampled. A total of 23 out of 50 swine from four out of five farms tested MRSA ST398 positive. The swine isolates were indistinguishable to those from the human cases. MRSA was not detected in two cattle herds examined. Samples from swine farms were taken months, and in some instances years, after MRSA ST398 had been detected in the cases. This indicates that swine remain colonised with MRSA ST398 for substantial periods of time and thus may constitute MRSA reservoirs.
Commentary
These results constitute epidemiological and microbiological evidence that humans living or working on livestock farms, particularly swine farms, are at increased risk of MRSA infection with ST398. The health care sector should therefore be aware that zoonotic MRSA occurs. MRSA introduced into the hospital setting by persons who come into contact with swine may spread further, as is the case with other staphylococci. The situation is currently being monitored closely and a revision of the guideline on Prevention of MRSA spreading, published in October 2006 (www.sst.dk/mrsa) by the National Board of Health, is being considered.
(H. Lewis, M. Selchau, K. Mølbak, Dept. of Epidemiology, R. Skov, AAS, C. Reese, Region South, F. M. Aarestrup, Danish Food Institute)
Pneumococcal vaccination in the Danish childhood vaccination programme
On 1 October 2007 vaccination against disease caused by a number of pneumococcal bacteria will be added to the Danish childhood vaccination programme.
The pneumococcal vaccine will be given as three doses when the child is 3, 5 and 12 months of age, i.e. concurrently with the DTaP-IPV/Hib vaccine. The two vaccines should be administered at separate injection sites.
During the introduction period, children who at 1 October 2007 are 4-17 months old will also be offered the vaccine:
- Children 4-11 months old (born: November 2007 – June 2007) will be offered three vaccinations
- Children 12-17 months old (born: May 2006 – October 2006) will be offered two vaccinations.
More detailed information will be published in a future EPI-NEWS.
(Department of Epidemiology)
Blood donor screening 2006
In 2006, a total of 375,768 blood units were screened and 29,377 donor candidates were examined. The number of positive donors is presented in Table 1.
Three multiple donors were HIV positive: two females and one male, aged 21 to 43 years. On subsequent retrospective investigation, no recipients were found to have been infected with HIV.
A total of six persons tested positive for HBsAg: four females and two males. The median age was 31 years (range: 20-58). Five persons were first-time donors, all born in countries with endemic hepatitis B. The sixth person was probably infected via sexual contact.
A total of six persons tested positive for anti-HCV: three females and three males. The median age was 46 years (range: 31-53). Four were first-time donors, one of which had donated blood before HCV screening was introduced in 1991. One was a multiple donor whose last unit of blood had not been used. Possible mode of transmission was stated for five donors: one had engaged in sexual contact with an intravenous drug abuser and four had piercings or tattoos.
Furthermore, all candidates for first-time donation and former donors returning to the donor pool are screened for HTLV I/II. Screening for HTLV-I/II did not reveal any positive donors.
(A.H. Christiansen, S. Cowan, Department of Epidemiology)
Weekly updates: Individually notifiable diseases and selected laboratory diagnosed infections
15 August 2007
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