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CHEKIT* Chlamydophila abortus Antibody ELISA Test Kit

HerdChek* and CHEKIT* Neospora caninum Antibody ELISA Test Kit

CHEKIT* Q Fever Antibody ELISA Test Kit

CHEKIT* Toxotest Antibody ELISA Test Kit

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August 2007 Issue

Controlling reproduction losses in herds–impact and diagnostics of four major abortive diseases:

Abortifacient infectious diseases level a massive impact on herd productivity in every region of the world. Some of these diseases can travel undetected in herds and result in unforeseen abortion outbreaks; some can cause fetal or newborn deaths and induce infertility; some can result in a persistent or recurring infection in herds with long–term poor reproductive performance. The total reproductive losses resulting from these diseases are one of the primary threats to the long–term economic vitality of herds. In addition, many of these diseases are a threat to human public health, both emphasizing the need to control transmission and complicating the procedures required to do so. This article explores four major infectious diseases affecting herd reproduction—Chlamydia, Neospora caninum, Q Fever and Toxoplasma gondii—and discusses the latest diagnostic tools to control each.

Chlamydia
Chlamydophila abortus, formerly known as Chlamydia psittaci immunotype 1, is the causative agent of ovine chlamydiosis (enzootic abortion). The disease primarily affects sheep and goats and less commonly, cattle and deer. C. abortus causes considerable reproductive losses worldwide, particularly in areas where flocks are kept closely congregated during lambing season.

The diagram demonstrates the differences between the new and old classifications of the order Chlamydiales, showing the new species classification Chlamydophila abortus.

Vast amounts of bacteria are shed at the time of abortion or birth in the placenta and uterine discharges. This contagious time period can extend from more than two weeks prior to abortion/birth to more than two weeks following. Initial C. abortus infection occurs after a susceptible animal is exposed to infected parturition material, and symptoms are often inapparent. In non–pregnant or late–gestational ewes, the infection can remain latent until the next conception.¹ Chlamydial placentitis begins around 90 days into gestation, at a moment coinciding with a period of significant fetal growth, resulting in a diffuse inflammatory response and placental tissue necrosis. Abortion occurs late–term, with no other outward symptoms.

Chlamydiosis in small ruminants is also a zoonosis, posing a particular risk for pregnant women, with documented cases of human placentitis and abortion. Any source of potential infection must be handled with biosafety precautions. Human infection response may vary from subclinical through acute influenza–like symptoms.

Direct diagnosis of an infection relies on a sympathetic history and the presence of a necrotic placenta containing a large quantity of the agent. Indirect serological testing is faster and more accessible, and antibodies can be detected in serum in the last month of gestation and following an abortion or a suspicious birth for up to 3 months.²

IDEXX Laboratories offers the CHEKIT* Chlamydia Antibody Test Kit, an indirect enzyme–linked immunoassay (ELISA) for the detection of antibodies against C. abortus in serum and plasma of ruminants. The test contains 2 plates (strips), offers results in just 2.5 hours, and is adapted to automation technologies.

The table shows the high specificity and sensitivity of the CHEKIT Chlamydia ELISA test for 81 goat samples across 6 herds from France.³

The CHEKIT Chlamydia Test Kit demonstrated 100% specificity and 89 to 95% sensitivity in a trial of 81 caprine samples across three naturally infected herds, one experimentally infected herd and two known negative herds. For bovine herds, research has found the CHEKIT Chlamydia ELISA to be more sensitive than the compliment fixation (CF) test.³

Neospora caninum
Neospora caninum is a protozoal parasite that causes neosporosis–a major source of infectious abortion in cattle. This apicomplexan species is morphologically similar to Toxoplasma gondii, with dogs serving as the definitive host. Intermediate hosts susceptible to infection include cattle, sheep, goats, dogs, horses and deer.

The primary clinical features are abortion and newborn illness or death. Seropositive cattle will continue to have elevated abortion rates in future pregnancies and an overall decreased milk production. Primary transmission is through congenital infections, the spread of N. caninum oocysts in dog feces and vertically from cow to calf. Offspring exposed in utero can be born healthy, yet be chronically–infected. If bred, these offspring may initiate seropositive pedigrees, significantly affecting reproduction and milk production rates of the herd.

Direct diagnosis of neosporosis is possible through a histological examination or by testing aborted fetal tissue for N. caninum organisms using either an immunofluorescence assay (IFA) or a polymerase chain reaction test (PCR). Indirect diagnosis can be performed on cows using an indirect IFA or an ELISA. All cows that have aborted should be screened by serological assay, and confirmed by a direct assay on fetal tissue or by performing a histopathology analysis. If any cow is positive, the entire herd should be screened for N. caninum antibodies.

CHEKIT Neospora ELISA demonstrated excellent specificity in 964 negative cattle, goat and sheep samples from different regions of Europe.4

CHEKIT Neospora ELISA detected 96.6% of bovine infections in 89 positive samples from Germany, France and Hungary.⁴

Current ELISA technology expedites and automates the process of herd screening, without compromising quality. The CHEKIT* Neospora caninum Antibody ELISA Test Kit, available from IDEXX Laboratories, offers rapid detection of antibodies against N. caninum in samples of bovine, ovine and caprine serum and plasma. A recent trial of the CHEKIT Neospora test demonstrated nearly 100% specificity and over 96% sensitivity in determining the serological status of ruminants from several regions across Europe.4

Q Fever
Q fever affects cattle, sheep, goats, domestic pets and various wild animals, and is among the most hazardous to humans of cattle–borne diseases, with human epidemics and laboratory infections being common. Coxiella burnetii–the small, intracellular bacterium that causes Q Fever–was formerly classified in the Rickettsiaceae family. However, phylogenetic investigation has shown C. burnetii to be distant from the Rickettsia genus, and it has since been reclassified into the Coxiellaceae family in the order of Legionellales. C. burnetii is distinguished from rickettsiae in that this pleomorphic bacterium produces a small, dense, highly–resistant spore–like form significant to its infectious and hardy characteristics.

C. burnetii aerosolizes on particles easily, is resistant to heat, drying and many disinfectants, and requires only a few organisms to induce disease in susceptible animals. Infection may result from inhaling airborne contaminant, contact with infected animals and their reproductive tissues, and through vertical and sexual transmission. C. burnetii is excreted in massive amounts in lochia, placentas and other birthing matter, as well as in milk, urine, feces and possibly blood. Ticks may also transmit the bacteria. As a result of its durability, ease of transmission and risk to humans, C. burnetii is listed as an OIE Containment Group 3 pathogen and is considered a potential bioterrorism threat.

In ruminants and other animals, Q Fever often has few outward symptoms until late–term abortions occur without warning, either sporadically or as part of a rare epidemic outbreak. C. burnetii infections persist for years, and may be lifelong. Additional symptoms may include the birth of dead or weak offspring, retained placenta, metritis and infertility. In humans, the infection can take two forms: 1) an acute form that can be either inapparent or result in a self–limiting fever, pneumonia or granulomatous hepatitis, treatable with antibiotics; or 2) a chronic form that manifests as endocarditis in people with valvulopathies, which can be severe or fatal without appropriate treatment. Pregnant women are at particular risk, for whom infection may cause placentitis, which can lead to premature birth, growth restriction, spontaneous abortion or fetal death.

For direct diagnosis of C. burnetii, samples can come from the placenta, vaginal discharge, aborted fetal tissue (liver, lung or stomach), milk, colostrum or feces. Indirect serological assays are often used for individual diagnosis and herd screening, including IFA, CFT and ELISA tests. Because of their ease of use, reliability and scalability, ELISA test kits have become the choice tool for veterinary diagnosis and large–scale routine herd monitoring. The IDEXX CHEKIT* Q Fever Antibody ELISA Test Kit has shown excellent specificity and high sensitivity consistently competitive with the complement fixation test.

The CHEKIT Q Fever ELISA Test correlates very well with the complement fixation test in a trial of 81 samples from six goat herds.3

Monitoring, biosafety protocols and prevention techniques are critical to protecting herds and humans from C. burnetii exposure. All late abortions in ruminants should be investigated for Q Fever, with care to protect human and other animal health. If seropositive animals are found: 1) ensure all milk is properly pasteurized; 2) disinfect animal facilities regularly–especially parturition areas–with a 10% bleach solution; 3) keep pregnant animals in separate pens; 4) always quickly remove all birthing matter, including aborted fetuses and dispose of properly to prevent contact with domestic animals or wildlife; and 5) keep manure from infected herds away from gardens and populated areas. To reduce risk of herd exposure to Q Fever, minimize introduction of new animals, regrouping of herds and exposure to ticks and wildlife.2

Toxoplasma gondii
Toxoplasmosis–caused by the intestinal coccidium Toxoplasma gondii–is a significant cause of abortion and the birth of weak offspring among sheep, goats and pigs infected during pregnancy. The female usually has no symptoms. Early–term infections can result in fetal death and resorption, causing the appearance of infertility. Infection mid–pregnancy can produce weak or stillborn offspring, often accompanied by a mummified fetus. Late–term infections produce infected but clinically normal offspring. Future pregnancies are not impacted by a past infection.

Cats are the definitive host for the sexual phase of the T. gondii life cycle, and most warm–blooded animals–including humans–can serve as intermediate hosts for the asexual phase. Cats may become infected by eating intermediate hosts such as rodents. T. gondii oocysts are shed in cat feces for several days after infection; these oocysts release infectious spores into the environment for one to five days. Sporulated oocysts are highly resistant and may remain infective in the environment for a year or more. The most likely sources of human and animal infection is through consuming raw or undercooked meat containing live T. gondii tissue cysts, or from exposure to oocysts in cat feces.

Toxoplasmosis is widespread in human populations, with about 30% of the population having had a past exposure. While most healthy people will experience no symptoms from an initial infection, very young, elderly or immunosuppressed individuals may become ill. In particular, this zoonosis is a threat to pregnant women and fetal health, and in this aspect especially, represents a significant public health concern.2

T. gondii should be suspected whenever late abortion occurs in ruminants, especially when tiny (2–3mm) white necrotic spots are visible on the cotyledons, with little or no accompanying inflammation. Direct diagnosis of T. gondii presence in tissue is difficult and expensive. A wide variety of indirect serological tests are available, including the dye test, IFA test, direct agglutination test (DAT), and ELISA test. The dye test uses live tachyzoites, so may pose a laboratory risk. The ELISA test is well suited to diagnostics in herds and offers automated interpretation. IDEXX Laboratories manufactures the CHEKIT* Toxotest Antibody ELISA Test Kit for testing the serum or plasma of ruminants, as part of its broad line of abortive disease diagnostic kits. The kit features 2 plates (strips) and gives rapid, highly sensitive results, all in a format identical to that of several other IDEXX abortive disease assay kits.

Conclusion
Tracking the causes of reproductive losses in a herd is daunting. Positive diagnosis of the cause of abortions can be inexact; in the case of fetal resorption or undefined infertility, diagnosis can be impossible. Routine monitoring of herds for exposure, controlling the introduction of potential agent carriers, appropriate biosafety procedures, and vaccination where possible are together the best security against reproductive diseases. Developing a systematic approach to disease monitoring and control can make the work of it easier to manage, and more affordable in the long–term.

1. Terrestrial animal health code 2006. 15th ed. Paris: OIE; 2006. Available at: http://www.oie.int/eng/normes/mcode/en_sommaire.htm. Accessed 2007 Jul 18.
2. Manual of diagnostic tests and vaccines for terrestrial animals 2004. 5th ed. Paris: OIE; 2004. Available at: http://www.oie.int/eng/normes/mmanual/A_summry.htm Accessed 2007 Jul 18.
3. Schalch L, Russo P, De Sa C, Reynaud A, Bommeli W. Combined testing of ruminant serum samples for Chlamydia psittaci and Coxiella burnetii specific antibodies by ELISA. Proceedings from: VIth Congress FeMeSPRum; May 14–16, 1998; Postojna, Slovenia; 514–18.
4. Specificity and sensitivity studies for CHEKIT Neospora conducted by IDEXX Switzerland, January/February 2007. Data on file with IDEXX Laboratories, Inc.

Four diseases–one protocol:
CHEKIT* ELISA abortive disease test kits offer matching formats to make testing even easier

Managing diagnostics for a production operation of any size is an immense job. IDEXX is working to standardize its diagnostics formats, to help make that job easier.

Four abortive disease antibody ELISA tests in the CHEKIT product line–Chlamydia, Neospora, Q Fever and Toxotest–now come with matching protocols. These diseases can be run virtually simultaneously, saving labor expenses and reducing errors:

• Common incubation times
• Ready–for–use conjugate
• Read at 450 nm
• 2 plate kits with strip plates for small series
• Adapted to automation
• High performance
• Fast and reliable results

In the past, when abortion occurred in a herd, screening for a possible infectious agent would take days. IDEXX has worked toward developing solutions that give you answers faster, so you can take action sooner. Check out the CHEKIT product line for more information about diagnostics and performance:

• CHEKIT Chlamydia Antibody ELISA Test Kit
• CHEKIT Neospora caninum Antibody ELISA Test Kit
• CHEKIT Q Fever Antibody ELISA Test Kit
• CHEKIT Toxotest Antibody ELISA Test Kit

Matching protocols may still require different sample dilutions

IDEXX offers four test kits that can be used to test animals for abortive diseases. The test procedures have been designed to allow for various kits to be executed at the same time. The CHEKIT* Chlamydia, Q Fever and Toxoplasma kits share the same testing protocol and sample dilution across all three assays. CHEKIT Neospora has the same protocol, but requires a different sample dilution. The similarities and differences between the kits are shown in the table below.

For the most reliable results, IDEXX recommends using high quality distilled water for preparation of the wash. It is also essential, when running these assays, to maintain the incubator temperature at 98.6°F ± 3.6°F (37°C ± 2°C).

Events around the world

• Saint Paul, Minnesota, USA—September 15–18, 2007
  Allen Leman Swine Conference
  www.cvm.umn.edu/outreach/events/adl/home.html
• Vancouver, British Columbia, Canada—September 20–22, 2007
  American Association of Bovine Practitioners, Booth 200
  www.aabp.org/meeting/default.asp
• Porto Alegre, Brasil—September 25–28, 2007
  XX Congreso Latinoamericano de Avicultura
  
• Edinburgh, Scotland—September 26–28, 2007
  Prion 2007, Booth 19
  

New name, excellence as always—
Dr. Bommeli AG is now IDEXX Switzerland AG

Effective June 6, 2007, Dr. Bommeli AG has legally changed its name to IDEXX Switzerland AG. Since 1981, Bommeli has been an internationally recognized leader in the production animal diagnostic market, offering state–of–the–art diagnostic reagents and test kits for the control of diseases.

IDEXX’s Production Animal Services (PAS) group acquired Bommeli in December 2004 from Intervet, a Netherlands–based animal health company. The PAS team completed the integration while continuing to sell core products, achieving a revenue increase of 42 percent during 2005. Products sold in Europe began distribution through IDEXX’s Netherlands headquarters in October 2005. The addition of Bommeli's CHEKIT* line of enzyme–linked immunosorbent assay (ELISA) products, highly regarded in the European market, immediately broadened and complemented IDEXX's product portfolio.

Now located in Bern, Switzerland, IDEXX Switzerland AG's ISO9001:2000–certified facility encompasses more than 1500 square meters dedicated to the production of state–of–the–art ELISAs. The location is home to more than 30 employees who work in R&D, Production, Quality Control, Packaging, Order Entry, Sales, Marketing, and Technical Support.

At center, Andre Fuchs, Director and General Manager PAS–Germany, and Andrea Ballagi, General Manager PAS–Bern, join IDEXX Switzerland AG employees at a celebration of the facility's new name.

*CHEKIT is a trademark or registered trademark of IDEXX Laboratories, Inc. in the United States and/or other countries. All other product and company names are trademarks or registered trademarks of their respective holders.