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Abortive chlamydia of small ruminants
Abortive chlamydia is one of the main causes of abortion in sheep and goats in the world, and it is very present in the Maghreb. It is caused by a bacteria, Chlamydia abortus, which lodges in the placenta and causes abortion in the last wee...
What is it?
Abortive chlamydia is one of the main causes of abortion in sheep and goats in the world, and it is very present in the Maghreb.
It is caused by a bacteria, Chlamydia abortus, which lodges in the placenta and causes abortion in the last weeks of gestation, or the birth of young people who are too weak to survive.
Its trademark is “storm” abortion: in a newly contaminated herd, many females can abort in the same season.
Key point
Serious zoonosis for pregnant women: no intervention on lambing, no handling of runt or placenta, no exceptions. Any series of abortions must be analyzed in the laboratory.
Commonly observed signs
These signs are neither exhaustive nor specific. Only a veterinarian can establish a diagnosis.
Related signs — each one links to its page:
Abortions in the last weeks of gestation, isolated or in series depending on the age of the infection in the herd.
Birth of young dead, or born alive but weak, unable to suckle, who die in the first days.
In the same litter, one young can be born alive and the other dead.
Placenta with an abnormal appearance, thickened, with altered areas: this is something that the veterinarian is looking for.
Brownish or bloody vulvar discharge before and after abortion, sometimes for several days.
The female does not generally appear ill otherwise: appetite preserved, no marked general signs.
The young survivors of an affected litter are often stunted and fall behind.
Females who have aborted are then protected for subsequent pregnancies, but can continue to excrete the bacteria during births.
When to consult without delay
This list does not replace veterinary advice. It gathers situations that justify a prompt consultation.
Causes and risk factors
The disease is caused by the bacteria Chlamydia abortus, which can only multiply inside cells.
After contamination, it remains silent in the body and reactivates during gestation, by colonizing the placenta.
Damage to the placenta deprives the young person of what he needs at the end of gestation: hence late abortion or the birth of a non-viable young person.
A female infected outside of pregnancy, or at the very end of gestation, will generally abort the following year: it is this delay which explains the waves of abortions in the following season.
Purchase of replacement females without knowledge of the status of the original herd.
Group births in a common area, where a female who aborts immediately exposes all the others.
High density during lambing, litter rarely replaced.
Absence of isolation of females who have aborted.
Mixing of herds, transhumance, gatherings.
Lambing in buildings rather than on pasture.
Young or newly formed herd, where few females have already encountered the bacteria.
Transmission
By abortion and birthing products: placenta, liquids, aborts, extremely rich in bacteria. This is the major source.
By ingestion of contaminated food, fodder or water, and by inhalation in contaminated premises.
By contact between females in the birthing area: a single female who aborts can contaminate an entire batch.
By vulvar discharge which persists several days after the abortion.
By the introduction of an infected female without apparent signs: this is the classic entry point into an uninfected herd, often an Antenaise purchased before her first birth.
By equipment, boots and soiled clothing passing from one batch to another.
Diagnosis and care
Diagnosis is the veterinarian's responsibility, based on clinical examination and laboratory tests. Care is decided case by case.
Any abortion must be reported to the veterinarian, and this is a health obligation in many countries. Several closely spaced abortions require immediate investigation.
The veterinarian removes the placenta, the runt and blood from the mother, and sends everything to the laboratory. The placenta is the most informative sample: keep it.
He is simultaneously researching other causes of abortion in small ruminants, because several of them are similar in the field and several are transmissible to humans. Only analysis allows us to decide.
A blood test on several females helps to determine the extent of the infection in the herd.
Store abortions and placentas in a closed container, with gloves, away from dogs and cats, while awaiting the visit.
Treatment
There is no treatment that rids the herd of the bacteria.
In the midst of a wave of abortions, the veterinarian can decide on an antibiotic treatment, generally from the tetracycline family, to limit the number of new abortions during the end of gestation. Its effect is partial: it reduces losses without sterilizing the animals or suppressing the excretion of bacteria.
The care of females who have aborted is the responsibility of the veterinarian: monitoring of the uterus, prevention of infections after abortion.
Hygiene and isolation measures are more important than treatment in stopping the spread.
Waiting times for milk and meat must be respected.
Treatment depends on the cause and the animal's condition: it must be determined by a veterinarian. No self-medication.
Prevention
Immediately isolate any female that aborts, and keep her away while discharge persists.
Immediately pick up the placenta and the abortion with gloves, place them in a closed container, and dispose of them according to the veterinarian's instructions. Never leave them on the ground, never give them to dogs or cats.
Clean and disinfect the area used, renew the litter in the farrowing area, avoid dry sweeping.
Organize lambings in small batches, in clean rooms, rather than in one large, cluttered room.
Only introduce replacement females whose origin is known, and respect a quarantine.
Cull females that have aborted when infection is confirmed and the herd is rebuilding, according to the strategy defined with the veterinarian.
Inform everyone on the farm of the human risk, and strictly exclude pregnant women from lambing.
Vaccination
Vaccines exist and constitute the main lever for control in affected herds. They significantly reduce the number of abortions and the quantity of bacteria released.
They are administered before mating, to non-pregnant females: vaccinating during gestation does not make sense and is not without risk depending on the type of vaccine.
The choice of vaccine, the timing and the animals concerned are the responsibility of the veterinarian, who takes into account breeding behavior and the local situation.
Vaccination of replacement females before their first mating is particularly useful, because they are the ones who pay the heaviest price.
It does not replace the isolation of females who abort or the hygiene of birthing premises.
Possible complications
Waves of abortions with loss of a significant part of the production of young over a season.
Infections of the uterus after abortion, with risk to future fertility.
Mortality of young born weak.
Long-lasting contamination of premises and the herd, with cases repeating each year on new females.
Human cases in people present at lambing, with a serious risk in pregnant women.
When to see a veterinarian
A female aborts at the end of gestation: call the veterinarian and keep the placenta and the runt, handled with gloves.
Several abortions occur within a few days or weeks: it is a health emergency, for the herd as well as for the people.
Young ones are born dead or too weak to stand up and nurse.
A female has persistent brownish vulvar discharge after having an abortion.
Renewal females abort during their first pregnancy.
A pregnant woman close to you has been in contact with lambings or abortions: she must consult her doctor without delay.
Transmission to humans
Abortive chlamydia is transmitted to humans, and the danger primarily concerns pregnant women.
Contamination occurs through contact with abortion and birthing products — placenta, liquids, aborts — through soiled hands placed on the face, or by inhalation in a contaminated birthing area.
In a pregnant woman, the infection can cause abortion, premature birth or serious generalized infection, putting her life and that of the child at risk. This risk is real and documented.
The rule is therefore simple and without exception: a pregnant woman must neither attend nor participate in lambing, must never handle an abortion, a placenta or birthing bedding, must not clean the premises concerned, and must avoid entering them during the birthing period. She should also avoid contact with farm clothing and work boots, which bring the bacteria home.
For all other people: systematic gloves for handling abortions and placentas, never contact with bare hands, careful hand washing, clothes and boots left outside the home, no consumption of raw milk.
If a pregnant woman has been exposed, or if a person on the farm has an unexplained fever, she should consult a doctor, specifying her contact with ewes or goats, particularly during the lambing period.
More broadly, several of the major causes of abortion in small ruminants are transmissible to humans: this is why a series of abortions should never be considered as a seasonal inevitability. You must have it analyzed and protect yourself while waiting for the results.
Prognosis
For the female, the vital prognosis is generally good: she recovers after the abortion and becomes immune for her following gestations.
Losses affect the young, and they can be very heavy the first year the disease enters a herd.
In the following years, it is mainly young females newly bred who abort, which maintains the disease until nothing is done.
With the vaccination of replacement females, the isolation of animals that abort and the hygiene of the birthing premises, the situation is brought under control within a few seasons.
Frequently asked questions
Several ewes have aborted this year: is this normal at the end of gestation?
No, it's never trivial. Multiple abortions in close succession in a herd almost always signal a communicable disease, and many of these diseases pass to humans. Have it analyzed by your veterinarian and protect yourself while waiting for the results.
Can my pregnant daughter or wife help with lambing?
No, under no circumstances. The risk of abortion, premature birth and serious infection is real. A pregnant woman must not approach lambings, nor handle aborts, placentas or litter, nor enter the birthing room, nor handle work clothes.
Why is it mainly young women who have abortions?
Because older females have already encountered the bacteria and are protected, while young ones bred for the first time are exposed to it defenselessly. This is why vaccinating replacement females before breeding is so useful.
Can the female who aborted stay in the herd?
She must first be isolated while she has discharge, because she contaminates others. Its conservation or culling is then decided with the veterinarian, depending on the analysis results and the strategy chosen to clean up the herd.
References
WOAH — Organisation mondiale de la santé animale (ex-OIE)
ANSES — Agence nationale de sécurité sanitaire (France)
Content reviewed by the TunisieVet editorial team · Updated 09 August 2026
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