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Lambing & Pregnant women


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Issued jointly with the Department for Environment, Food and Rural Affairs, and the Health and Safety Executive

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Dear little things.  But.............

Pregnant women should avoid close contact with sheep during lambing periods, the Departments of Health, the Department for Environment, Food and Rural Affairs, and the Health and Safety Executive advised today.

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. These include chlamydiosis (enzootic abortion of ewes - EAE), toxoplasmosis and listeriosis, which are common causes of abortion in ewes.

Although the number of reports of these infections and human miscarriages resulting from contact with sheep are extremely small, 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 milk ewes;

- avoid contact with aborted or new-born lambs or with the afterbirth;

- avoid handling clothing, boots etc which have come into contact with ewes or lambs.

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.

Farmers have a responsibility to minimise the risks to pregnant women, including members of their family, the public and professional staff visiting farms. Any action should be determined by their risk assessment required under the Management of Health and Safety at Work Regulations 1999. 

If a ewe aborts, farmers are advised to ask their veterinary surgeon to take a sample to their local Regional laboratory of the Veterinary Laboratories Agency to determine the cause. In the interests of hygiene, farmers should dispose of all afterbirths promptly and safely.


1. Farmers should consult their veterinary surgeon about suitable vaccination programmes and any other disease control measures in sheep.

2. The Control of Substances Hazardous to Health (COSHH) Regulations 2002 require employers to assess risks to health from harmful substances, including micro-organisms, and to take steps to prevent or control those risks, and The Management of Health and Safety at Work Regulations 1999 require employers to further assess any risks which affect pregnant women.

3. Further advice is available from Employment Medical Advisory Service offices, which are listed under the Health and Safety Executive in the telephone directory.

4. The Department of Health advisory leaflet, While you are pregnant: How to avoid infection from food and from contact with animals, is available, free of charge to general medical practitioners and midwives from:

Department of Health, Prolog, Unit 8, Sherwood Park, Annesley, Nottingham NG15 ODJ

5 Further information is also available in the 1997 publication Infection risks to new and expectant mothers in the workplace - a guide for employers, by the Advisory Committee on Dangerous Pathogens (ref: ISBN 0-7176-1360-7). Copies are available, price £10.50, from HSE Books, PO Box 1999, Sudbury, Suffolk, CO10 6FS.

Questions & Answers

Q1: What are the main infectious hazards for pregnant women in contact with sheep?
A1: Chlamydiosis (EAE), Toxoplasmosis and Listeriosis. All of these agents are zoonotic (i.e. can be transmitted from animals to humans), and cause abortion in sheep and may harm pregnant women or their unborn children.

Q2: What other organisms cause abortion in sheep?
A2: Campylobacter, Salmonella and Coxiella (Q fever). More rarely in the UK, abortion may be due to Border Disease and tick-borne fever. Abortion may also be caused by various fungi. 

Q3: Do these agents represent any risk for pregnant women?
A3: Neither salmonellosis nor campylobacteriosis are associated with specific effects upon human pregnancy, but both can cause human illness. A possible link between Q fever and an adverse outcome, in one case abortion and in another sudden infant death syndrome, has been suggested but there is as yet insufficient evidence to support this suggestion.

CHLAMYDIA (Enzootic Abortion of Ewes)(EAE)

Q1: What is Chlamydiosis?
A1: Chlamydiosis is an infection caused by Chlamydophila abortus. Chlamydiosis is thought to be transmitted by inhalation of aerosols and dusts heavily contaminated with Chlamydophila abortus (formerly called Chlamydia psittaci), which is the agent of enzootic abortion in ewes (EAE). It can cause serious disease in the unborn child, leading to stillbirth or abortion.

Q2: What effects does EAE have in human pregnancy?
A2: The main effects are severe, sometimes life-threatening, disease in the mother and stillbirth or abortion.

Q3: Is there any risk of later consequences?
A3: If the pregnancy survives the acute infection, there appears to be no risk of long term problems. There is no evidence that this infection can result in abnormalities in the baby when it is born (congenital malformation).

Q4: What are the symptoms of the disease in humans?
A4: In humans, infection may be asymptomatic, but where symptoms occur, they are commonly of a flu-like nature with headache, chills, fever, joint pains and non-productive cough. Photophobia, vomiting, sore throat and myocarditis may also occur. In pregnancy, a more severe form of the disease may occur, the majority of reported cases occurring between 24 and 36 weeks. This is characterised by systemic illness with disseminated intravascular coagulation, renal and hepatic complications. It is these cases that are most commonly associated with stillbirth or abortion, which generally occurs 3-8 days after the onset of symptoms.

Q5: Who is at risk?
A5: Only women who have close contact with ewes at the time of aborting or giving birth, with new-born lambs and with placentae or products of conception. Infection has also been associated with handling of clothing and boots contaminated by contact with infected animals. The risk appears to be limited to those actively working with sheep, including veterinary surgeons, and their immediate families. 

Although EAE is known to be present in the sheep flocks in some cases, it is often overlooked in the first year in which it is introduced to a flock. Typically, it is introduced into a flock by infected breeding females. Some of these suffer abortion in the first year and infect much of the rest of the flock but these secondary cases do not suffer abortion until the following year and a diagnosis is not made until then.

Q6: How is the infection acquired?
A6: The route of transmission to man is not known with certainty. Inhalation of aerosols and dusts heavily contaminated with Chlamydophila abortus (used to be called Chlamydia psittaci), the agent of enzootic abortion in ewes (EAE), appears to be the likely route of infection. The organism is concentrated in the uterus of pregnant sheep and the infected placenta and uterine discharges are the most potent sources of the infectious agent. Contact with aborting sheep, sheep at risk of abortion, dead lambs and placentae are thus considered to represent a risk for humans.

Q7: How common is this infection in man?
A7: Human infection with Chlamydophila abortus (Chlamydia psittaci) infection from ewes appears to be very unusual. 

Very few reports of Chlamydophila abortus (Chlamydia psittaci) in pregnant women in England and Wales are received each year by the PHLS Communicable Disease Surveillance Centre (CDSC). In one or two cases per year (maximum 5 cases in 1986), this is associated with abortion or stillbirth. Since 1980, one maternal death associated with this infection has been reported. 

In routine laboratory testing, and hence in reports to PHLS CDSC, no distinction is made between avian and mammalian (ovine) Chlamydophila abortus (Chlamydia psittaci). The avian strain is not confined to psittacine birds but is common (for example) in feral pigeons. However, with the exception of one case, the severe form of the disease associated with human abortion has been due to the mammalian strain. 

Q8: What tests are available to confirm the diagnosis?
A8: Diagnosis rests chiefly on clinical suspicion and treatment should be started on that basis.

Diagnosis is generally confirmed by serological testing but this requires testing of both acute and convalescent sera. The complement fixation test (CFT) does not distinguish between Chlamydophila abortus (Chlamydia psittaci) and C. pneumoniae, and microimmunofluorescence or whole cell inclusion immunofluorescence tests are needed to confirm the diagnosis of with Chlamydophila abortus (Chlamydia psittaci). Serological tests to distinguish avian and mammalian strains of Chlamydophila abortus (Chlamydia psittaci) may be available on a research basis.

Q9: Is there any effective treatment?
A9: Chlamydophila abortus (Chlamydia psittaci) is sensitive to macrolides and a 2 week course of erythromycin 500mg 4 times daily can be given if the patient is seen at an early stage. The effectiveness of this treatment in preventing the development of more serious disease has not been established. Azithromycin is a suitable alternative. The organism is also sensitive to tetracycline’s and these are probably the drug of choice in more severe disease despite the general reservations about use of tetracyclines during pregnancy.

Q10: Is there any vaccine?
A10: There are no effective chlamydial vaccines for human use available at present.

Q11: Are subsequent pregnancies likely to be at any risk?
A11: Following enzootic abortion, sheep generally acquire long-lasting immunity and give birth normally in subsequent seasons. Very limited data suggests that this is also the case in humans.

Q12: Is the infection common in sheep in the UK?
A12: Yes. EAE is the commonest cause of infectious abortion in sheep. DEFRA laboratories diagnosed the infection in 1551 reported incidents in 1995. This was the highest number in the 1991- 2001 period. In 2001 it was diagnosed in 421 incidents of reported abortion and accounted for 44% of the reported incidents of abortion where a diagnosis was made. Each confirmed case generally represents an outbreak and the total number of sheep affected is therefore considerably higher. Some estimate may be gained from the fact that 20-50% of abortions in sheep are thought to be due to Chlamydophila abortus (Chlamydia psittaci) and about 1 million lambs are aborted or stillborn each year.

Q13: What are the manifestations of disease in sheep?
A13: Characteristically, the production of dead or weak lambs in the last two or three weeks of pregnancy. Chlamydophila abortus (Chlamydia psittaci) is the most common cause of abortion in lowland ewes, especially under intensive farming conditions.

Q14: Is a vaccine available for use in sheep?
A14: Yes. A live vaccine is available. However, it should not be handled by pregnant women or women of child-bearing age.


Q1: What is toxoplasmosis?
A.1. Toxoplasmosis is a zoonotic infection (an infection that can be transmitted between animals and humans) caused by the parasite Toxoplasma gondii. Infection is usually asymptomatic or mild and self-limiting. When symptoms do appear, these are most commonly persistent acute fever with enlarged lymph glands. Very rarely there may be severe infection involving the brain, muscle and eye.

Q2: How is the infection acquired?
A2: Routes of infection include direct contamination of cuts and grazes or ingestion of tissue cysts. If contact with ewes at lambing time is unavoidable, open wounds (cuts, grazes etc) should be covered with waterproof dressings and hands should be thoroughly washed after handling animals to prevent the possibility of infection. Transmission of the organism can also occur from hand-to-mouth contact with the faeces of infected cats, contaminated soil, poorly washed garden produce and ingestion of cysts in undercooked meat.

Q3: Who is at risk?
A3: Pregnant women and individuals with a depressed immune system are most at risk from infection with Toxoplasma gondii.

Q4: How common is this infection in pregnant women?
A4: In the UK, toxoplasmosis is thought to affect about 2 per thousand pregnancies. Less than half of these cases are transmitted to the unborn baby. Even when transmission occurs, the majority of babies (90-95%) have no symptoms. 

Q5: What effects does toxoplasmosis have on babies when the infection has been acquired in pregnancy?
A5: Toxoplasmosis, acquired for the first time in pregnancy, may lead to infection of the foetus and this may lead to congenital malformation. Some affected babies may develop eye disease in later life. 

Q6: If one pregnancy is affected by toxoplasmosis, are subsequent pregnancies likely to be at risk?
A6: No. Chronic or recurrent infection in expectant mothers is not associated with foetal infection.

Q7: What tests are available to confirm the diagnosis?
A7: Blood tests can be carried out to detect antibodies to the organism. Since these may reflect infection in the past, confirmatory tests have to be carried out to see whether the infection is recent.

Q8: What treatment is advised for Toxoplasmosis infection?
A8: Toxoplasmosis is usually a mild, self limiting disease and does not usually require specific treatment when it occurs in normal, healthy people. 

Q9: Is there a vaccine available for humans?
A9: No.

Q10: Is the infection common in sheep in Great Britain?
A10: After chlamydia (EAE), toxoplasmosis is the second most common cause of abortion in sheep in Great Britain. The number of incidents recorded each year by DEFRA laboratories between 1991 and 2001 ranged from 197 to 1100 reported incidents. In 2001 it accounted for 21% of the incidents where a diagnosis of the cause of abortion was reached.

Q11: What are the manifestations of disease in sheep?
A11: Abortion, often in the last 4 weeks of pregnancy. Full term lambs may be born dead or alive but weak, often dying within the first 2 weeks of life. Mummified lambs, often one of a pair, may be seen.

Q12: Is a vaccine for use in sheep available?
A12: Yes. There is a live vaccine for use in sheep. However, it should not be handled by pregnant women or women of childbearing age, as it may interfere with normal foetal development.


Q1: What is Listeriosis?
A1: Listeriosis is a disease caused by the bacterium Listeria monocytogenes. This disease can cause serious disease in the unborn or newborn child. The disease may be transmitted by contact with infected animals or ingestion of contaminated food.

Q2: What effects does Listeria have in human pregnancy?
A2: Infection may cause abortion or premature birth. Infection in utero or during delivery may lead to septicaemia and meningitis with a 50-100% mortality. 

Q3: Is there any risk of later consequences?
A3: Infection in the new-born may take the form of disseminated granulomatous disease, involving many organs including respiratory tract, eyes and nervous system.

Q4: What are the symptoms of the disease in humans?
A4: Infection in pregnancy generally presents as a mild flu-like illness.

Q5: How is the infection acquired?
A5: Infection is acquired by ingestion and most cases are probably the result of consumption of infected food. If contact with ewes at lambing time is unavoidable, washing of the hands after handling animals should prevent any possibility of infection.

Q6: How common is this infection
A6: There are usually up to 25 cases of listeriosis in pregnancy reported annually in the UK (in 1996 there were 16 cases), but it is not known how many of these, if any, are associated with contact with sheep.

Q7: What tests are available to confirm the diagnosis?
A7: The diagnosis may be made by culturing the organism from the mother's blood or faeces.

Q8: Is there any effective treatment?
A8: Listeria monocytogenes is sensitive to a number of antibiotics.

Q9: Is there any vaccine?
A9: No.

Q10: If one pregnancy is affected by Listeria , are subsequent pregnancies likely to be at any risk?
A10: No. Chronic or recurrent infection in expectant mothers is not associated with fetal infection

Q11: Is the infection common in sheep in the Great Britain?
A11: Listeria infection accounts for only 1-2% of sheep abortion incidents reported and diagnosed in Great Britain each year.
The numbers of abortions incidents recorded by DEFRA veterinary laboratories for 1991-2001 ranged from 22 - 82 incidents each year(22 in 2001). 

Q12: What are the manifestations of disease in sheep?
A12: Abortion from 12 weeks of pregnancy onwards. There may be occasional deaths in ewes. Encephalitis due to listeria infection may also be seen in sheep, but is not generally associated with abortions.


Permission has been granted for readers to copy this for their patients.
David Roberts


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