A1061 - Chlamydophila abortus

Description:

Chlamydophila abortus (formerly contained within the Chlamydia psittaci taxon) is a cause of abortion and foetal loss in sheep, cattle and goats in many countries around the world. In cattle, chlamydial abortions tend to be sudden and sporadic, occurring near or at term in the seventh to ninth month of gestation. Prior to abortion, there is no overt evidence of clinical disease, although a serous uterine discharge may be present. Cattle in the second trimester of gestation, inoculated intravenously with a bovine abortion chlamydial strain developed fever and leukopaenia for 3-5 days afterwards. Some animals developed diarrhea and an intermittent, mucoid, vulvar discharge. Abortions occurred within 5-36 days, whereas in cows inoculated during the second trimester by other routes (i.e. intramuscularly, subcutaneously, intradermally), abortions or the delivery of weak calves occurred 33-126 days later. In field conditions, chlamydial abortions have been detected as early as the fifth month of gestation, but most occur during the third trimester. Infection sometimes results in the birth of dead calves at term, or weak calves that may die later. Cows that abort during the later stages of gestation demonstrated placental lesions and necrotic foci in foetuses. As with sheep and goats, necrotic placentitis is the major pathological feature. However, in cattle the distribution of lesions may be patchier. Chlamydiae have been isolated from a number of affected organs in aborting cattle. Abortion causes little adverse effect on dams, which appear normal, but placenta may be retained in both natural and experimental infections. In dairy cows there may be a drop in milk production and sterility may occur. Chlamydiae have been isolated from milk samples and mammary tissues from dairy cows affected by naturally occurring mastitis. The chlamydiae involved were thought to be of intestinal origin. In experimentally infected cases, cows developed a high fever of 41° C / 105.8° F. During the febrile period, cows were lethargic and off feed, and their milk production decreased sharply. Body temperature returned to normal after about six days, and milk production recovered but never returned to pre-inoculation levels
Bulls infected with C. abortus may be affected by seminal vesiculitis. In such cases, inflammation of the seminal vesicles and the epididymis may be apparent, the testes may be atrophic and semen quality affected. The bulls may transmit chlamydiae to cows as a venereal disease in semen. Chlamydiae may be naturally shed in semen, to replicate in endometrial cells of the cow, possibly leading to embryonic death. Infertility may also result.

Diagnosis:

Although culture has long been considered the 'gold standard' and most sensitive method of diagnosis for C. abortus, it has significant disadvantages. For example, a cold chain is required to protect the viability of the organism during specimen transport. Also, culture methods are often susceptible to contamination by exogenous organisms and can require anywhere from days to months to achieve conclusive results. Conventionally, various serological techniques have been used to detect C. abortus infection, however, these tests have several shortcomings. For example, antibodies to C. pecorum cross-react in the micro-immunofluorescence test with antigens of other mammalian chlamydiae including C. abortus. These cross-reactive, genus-specific antibodies interfere in the interpretation of test results and pose particular problems in sera from animals infected with strains of both species, or colonized in the intestine with clinically inapparent C. pecorum strains. Fortunately, advances in molecular diagnostics have yielded new DNA based tests that avoid the problems typically associated with conventional diagnostic methods. DNA based testing employs a technique known as the PCR (polymerase chain reaction) to effectively target the DNA of C. abortus, resulting in superior sensitivity and specificity. This test offers veterinarians and livestock owners a definitive method for diagnosis C. abortus infection.

Sample:

1. Whole blood (3ml) in a lavender top (EDTA) tube.
2. Swab of affected area in a sterile container.

Special Handling:

Store sample at 4°C until pick up or shipment.

Test Code:

A1061