Volume 2 No 4 ;25 January 2008
At this time of year, the HPA joins the Department for Environment, Food and Rural Affairs in reiterating the advice to pregnant women to avoid close contact with sheep during the lambing season.
Pregnant women who come into close contact with sheep during lambing may risk their own health and that of their unborn child, from infections that can occur in some ewes. Such infections include chlamydiosis ( Chlamydophila abortus : enzootic abortion of ewes - EAE), toxoplasmosis and listeriosis, each of which is a common cause of abortion in ewes.
Another type of infection that can be acquired following exposure during lambing (or birthing in other livestock) is Q fever (caused by Coxiella burnetii). The causative organisms may be present in birth fluids of animals which have no clinical signs of disease. Although less likely to cause harm to the unborn child , Q fever may cause acute or chronic maternal infection if acquired during pregnancy. Q fever affects a wide range of animals including cattle, goats and domestic cats, and exposure to birth products of these animals as well as sheep, should be avoided in pregnancy.
Although these infections are uncommon, and human miscarriages resulting from contact with sheep are rare, it is important that pregnant women are aware of the potential risks associated with close contact with sheep during lambing.
To avoid the possible risk of infection, pregnant women are advised that they should:
not help to lamb or to milk ewes;
avoid contact with aborted or new-born lambs or with the afterbirth, birthing fluids or materials (e.g. bedding) contaminated by such birth products ;
avoid handling clothing, boots etc which have come into contact with ewes, lambs or afterbirth
Pregnant women should seek medical advice if they experience fever or influenza-like symptoms, or if concerned that they could have acquired infection from a farm environment.
Listeriosis is a rare but life-threatening foodborne disease caused by the bacterium Listeria monocytogenes . Pregnant women, unborn or newly delivered infants, the elderly and those with weakened immunity are most commonly affected, and the disease usually presents as abortion, bacteraemia (bacterial invasion of the blood stream) or central nervous system (CNS) infection. Mortality is high in all patient groups.
The observed pattern of listeriosis in England and Wales has changed since 2001 . There has been an increase in the number of cases reported (an average of 185 cases reported annually between 2001 and 2006 compared with 109 cases between 1990 and 2000), especially in patients aged 60 years and over. The clinical presentation has also changed, with more cases presenting with bacteraemia in the absence of CNS involvement. Similar patterns have been reported in other European countries .
A provisional total of 230 cases of Listeria monocytogenes infection were reported in England and Wales in 2007, representing a 23% increase on incidence in 2006 and the second highest total since active surveillance began in 1990. Much of the increase can be explained by an unseasonably high number of cases reported between March and May 2007 , when 64 cases were reported against an average of 37 cases reported between 2004 and 2006 (figure 1).
Figure 1. Seasonal distribution of cases of L. monocytogenes infection by month. England and Wales, 2004-2007
Two thirds (152; 66%) of patients reported in 2007 were aged 60 years or over, and the incidence in this age group (13.2 cases per million population) was over seven times higher than in younger people (1.8 cases per million population; relative risk 7.2; 95% confidence interval 5.5-9.4). Disease incidence in those aged 60 or more increased with increasing age group (figure 2). The number of pregnancy-associated cases reported in 2007 (28) was comparable with the number reported in 2005 and 2006 (25 in each).
Figure 2. Age specific rates of listeriosis. England and Wales , 1990-2007
Bacteraemia in the absence of CNS involvement was the most common disease presentation (166; 73%) where the source culture was known (227; 99%) and this occurred more frequently in patients aged sixty years and over (figure 3).
Figure 3. Clinical presentation by age group for non pregnancy-associated cases of L. monocytogenes infection. England and Wales , 1990-2007 (N=1990)
The altered pattern of listeriosis, reported in England and Wales since 2001 and subsequently observed elsewhere in Europe, has continued in 2007. The Health Protection Agency (HPA) continues to collect isolates of L. monocytogenes from clinical cases of listeriosis in England and Wales and carries out a range of discriminatory tests to identify clusters of possibly related cases. A clinical questionnaire is sent to microbiologists in England and Wales and completed information is currently obtained for approximately 70% of cases. A standard detailed food and exposure history has been sought from cases since 2005 and analysis of data accrued to date (response rates of 20%, 28% and 63% in 2005, 2006 and 2007 respectively) is underway.
Laboratories in England and Wales are requested to:
refer all L. monocytogenes isolates from clinical specimens and food samples to Dr Kathie Grant , Centre for Infections, for confirmation and subtyping (telephone: 020 8327 6505; e-mail: email@example.com);
notify local Health Protection Units of cases to ensure effective routine public health follow-up.
Health Protection Units are requested to:
complete the standard HPA clinical questionnaire (available from http://www.hpa.org.uk/infections/topics_az/listeria/questionnaires.htm) and return to Iain Gillespie, Centre for Infections (telephone 020 8327 7486; e-mail Iain.Gillespie@hpa.org.uk ).
1. Gillespie IA, McLauchlin J, Grant KA, Little CL, Mithani V, Penman C, et al. Changing pattern of human listeriosis, England and Wales, 2001-2004. Emerg Infect Dis 2006 ;12(9):1361-6.
2. European Food Safety Authority. The Community Summary Report on Trends and Sources of Zoonoses, Zoonotic Agents, Antimicrobial resistance and Foodborne outbreaks in the European Union in 2006. December 2007. Available from <http://www.efsa.europa.eu/EFSA/DocumentSet/Full_report_light.pdf>.
3. Increased incidence of listeriosis in England and Wales, 2007. Health Protection Report [serial online] 2007 [accessed 25 January 2008]: 1(21): news. Available at http://www.hpa.org.uk/hpr/archives/2007/hpr2107.pdf.