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DANMAP 2015 3D
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danmap 2015 126 textbox 8.4 la-
mrsa
cc398
in people with no
livestock
contact and in various animal populations la-
mrsa
cc398
in people with no
livestock
contact danish pigs constitute a rapidly expanding reservoir of la-
mrsa
cc398
and occupational contact to pigs is known to be a major source of
mrsa
in
livestock
workers where they may also cause infections (textbox 8.5, danmap 2014). in a recent danish study, statens serum institut analyzed patient information and
mrsa
strain typing results collected between 1999 and 2011 to investigate the emergence and early epidemiology of la-
mrsa
cc398
in humans [larsen et al. 2015. euro. surveill. 20:pii=30021]. the study included 148 la-
mrsa
cc398
cases were infections were registered. the incidence increased by ca. 66% per year from the first cases in 2004 to 2011 (from 0.093 to 1.1 per 100,000 person-years). approximately one-third of the new infections per year were observed in people with no
livestock
contact, of whom the vast majority lived in rural areas with
livestock
production. figure x shows that this proportion of la-
mrsa
cc398
infections in people with no
livestock
contact has remained stable when analyzing data from 2012 to 2015 (statens serum institut, unpublished data). only seven of the 148 documented la-
mrsa
cc398
infections during 2004-2011 occurred in copenhagen. thus, the risk of acquiring a la-
mrsa
cc398
infection was higher in rural areas compared to other areas of denmark, including copenhagen. however, la-
mrsa
cc398
only accounted for a small proportion of all
mrsa
infections in the period, and the overall incidence in people without direct or indirect exposure to animals was not statistically different between urban and rural municipalities. these findings sup- port that la-
mrsa
cc398
is able to spread from animal farms into the surrounding community most likely via
livestock
workers, whereas the low number of la-
mrsa
cc398
infections in urban areas of denmark suggests that foodborne transmission does not play a major role in the la-
mrsa
cc398
epidemiology. in 2012, screening of
livestock
workers at hospital admissions was amended to the
mrsa
guidelines from the danish health authority. consequently, many
livestock
workers have been tested and found la-
mrsa
cc398
positive in the years after and non-tested persons in this subpopulation has diminished. this may explain the decrease in incidence observed in 2015, as only new
mrsa
cases are reported. since asymptomatic carriage of
cc398
mrsa
in
livestock
workers is not treated, the accumulated numbers of
mrsa
positive
livestock
workers has most likely increased during the years and thereby the potential source for secondary transmissions. despite of that, the incidence of
cc398
mrsa
among the general population has not increased in 2015, which indicates that secondary transmissions are lim- ited. this limitation could be due to constraints of the
cc398
mrsa
in the competition with other s. aureus in the environment outside the stables or in the human host, which needs to be investigated in more details. figure 1. number of new patients with la-
mrsa
cc398
infection per year. 0 20 40 60 80 100 120 140 160 180 0 0 0 0 0 0 0 0 0 0 0 0 new la-
mrsa
cc398
infections
livestock
contact no contact 0 20 40 60 80 100 120 140 160 180 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 number of cases new la-
mrsa
cc398
infections
livestock
contact no contact danmap 2015
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