CHLAMYDIA SPECIESDomain – Bacteria, Phylum – Chlamydiae, Order -Chlamydiales, Family – Chlamydiaceae, Genus – Chlamydia,Species – C.trachomatis, C.psittaci, C.pneumoniae, C.abortus, C.
felis, C.suis,C.muradiumChlamydia organisms are obligatory intracellular parasite.
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Chlamydia lacks several metabolic and biosynthetic pathways and they depend uponhost cell machinery for their replication. Earlier days, Chlamydiaewere originally thought to be a virus but due to the presence of cell wall,DNA, RNA & ribosomes they classified as BacteriaChlamydiae are the small group of non – motile coccoid bacteria. TheirCell wall is similar to Gram – negative bacterium (but it lacksmuramic acid). Chlamydia is consider to be an obligatory intracellularparasites it require high energy compound like ATP andit depends the host cell machinery for their replication Known as “Energy parasites”. Chlamydia has uniquedevelopmental cycle.
It is a dimorphic bacterium with a two phase lifecycle can exist either in the form of Elementory body /Reticulate body.Elementary Body (EB) – size is around 200 to 300 nm in diameter. EBs is smalland infectious form which represents the extracellular form of the organism.Elementary bodies are metabolically inert and osmotically stable.They enterinto the host cell by receptor mediated endocytosisReticulate Body (RB) – Larger, intracellular form and size is around 1µm. it promote metabolic activity. Reproduction occurs by binary fissionDevelopment Cycle: -Elementary body (EB) is entering into the hostcell by using receptor mediated endocytosis. After enter into the host cell EBis transformed into active reticulate body.
Reticulate body (RB) is multipliedby binary fission. At 20 hours, reticulate body will be mature and condense toform EB. At 40 hours of infection EB are released from the host cell by lysisNatural Habitat: -Elementary bodies are relatively resistant andremain viable for several days under suitable environmental conditions. Chlamydial infections are considered to be persistentinfectionsare the rule in both birds &mammals.
C.psittaci often present in G.I tract. Organism shed in faecesfor prolonged period.Pathogenicity:-Chlamydiae do not show strict host specificity.
They infect morethan 150 avian species and large number of mammalian species. Severity ofthe infection is depends up on the strain and virulence of the agent, age, sex, physiological state andspecies of the host, route of infection,degree of exposure to Chlamydiae,environment and managementpractices Suitable samples for isolation of Chlamydia: -Abortion: – Collect Smears from the affected Cotyledons / Chorion Collection of Smears from vaginal swab (if placenta not available) within 1 to 2 days of abortion Piece of affected cotyledon, vaginal swab, foetal lung and foetal liver should be placed in the Chlamydial Transport Medium and held at 4?COtherconditions: – Polyarthritis – aspirated synovial fluid Conjunctivitis – Conjunctival swab Systemic infection – Spleen, Lung & Liver Serology – Paired serum sample (both affected & normal animals) DEMONSTRATION OF CHLAMYDIADirectMicroscopy: -q Elementarybody in smear / tissue section can be detected by the use of either chemicalstains / immunological staining techniquesModifiedZiehl – Neelsen Stain: -v Elementarybodies are clumps together and stain red against a blue background (MethyleneBlue) / green background (Malachite green)SEROLOGICAL TEST: -Enzyme Linked Immunosorbent assay (ELISA), Complement FixationTest (CFT), Indirect immunofluorescence antibody test (IFA) – used to detect antibodies directed against the common genus -specific antigen (LPS) LABORATORYDIAGNOSIS: -§ To identify Chlamydia organism three laboratory systemscan be used1. Mouse inoculation was used on older days2. Inoculation of 6 to 7 days old embryonated eggs via Yolk sacroute used to detect all Chlamydiae organism (but the main disadvantage of thismethod – laborious & more prone for bacterial contamination)3. Cell Culture – Number of continues cell lines are susceptible toChlamydial infections (McCoy, BHK – 21, L929, Vero). Chemical treatment of thecells with Cycloheximide (1 -2 µg/ml), 5-iodo-2-deoxyuridine (80 µg/ml), Cytochalasin B (I µg/ml) or Diethyl- aminoethyl – dextran (30 µg/ml). Centrifuge the sample onto the monolayer – greatly enhances thesensitivity of the isolation procedure. Use of antibiotics in the tissue culture medium to which Chlamydiaeare sensitive (oxytetracycline, erythromycin penicillin / tylosin) should beavoidedENZOOTIC ABORTION OFEWES: -Enzootic Abortion of ewes caused by C.
abortus.It is the major cause of economic loss in intensivelymanaged sheep flocks. It should be a serious problem in many sheep rearing areas ofthe world.
This condition is very rare in Australia and Iyreland.Transmission:-Infection is mainly occurs by ingestion of contaminate materialsSpread of infection is occur at the time of lambingClean flocks usuallybecome infected through the introduction of replacement breeding females whichcontaminate the flock during parturition. The following year can bring aserious outbreak with up to 30% of ewes aborting. Ewes have solid immunitypost-abortion and thereafter, only younger females will pick up the infectionand an annual incidence of 10-20% canbe expected if no control measures are put in placeDisease is mainly characterized by abortion (last 2 to 3 weeks of pregnancy),birthof premature weak lambs,diffuse and necrotic placentitisPrevention and Control: -Three vaccines available in UK thatprovide protection against EAE. Two live-attenuated vaccines can only be usedin non – pregnant females butthe inactivated vaccine can be used during pregnancy.The inactivatedvaccine has been shown to reducethe number of abortions in a flock of already infected sheep and itcan be used during an outbreak tocontrol the number of abortions.Whole – flocktreatment with long acting Oxytetracycline canbe used 3 to 6 weeks before lambing to increase the number of viable lambs bornto ewes known to be infected with EAE. Repeat injections might be necessary andewes still excrete the organism if the lambs are born alive.
In the face of anEAE outbreak, it is best to markand isolate the aborting ewes, disposes of the bedding and aborted products and disinfects the pen thoroughly.Ewes that haveaborted should not be used as foster ewes SPORADIC BOVINEENCEPHALOMYELITIS: -Sporadic Bovine Encephalomyelitis is caused by C.pecorum (biotype 2) Disease reported from the USA, Japan and Israel. It is characterizedby Inflammation of vascularendothelium throughout the body and nervous signs tend topredominate. Subclinical intestinal infections in cattle and other animalsmay be the source of infection in SBE.
The disease is most often seen in calves<6 month old and rarely in older cattle.Morbidity rates are usually low but can reach 50%. Many sickcalves die if not treated at an early stageClinicalsigns: -High fever, in coordination, depression, excessive salivation, diarrhea,weightloss, stiffness / knuckling at the fetlock, nasal discharge,finallyrecumbent & animal may develop opisthotonus (Neck bend with the eye looking upward)Chlamydia may alsocause abortion in Cattle is known as Epizootic Bovine abortion (EBA) / foothillabortionTreatment: -Antibiotics whichare effective against C.pecorum(tetracyclines, oxytetracyclines, and tylosin)Oxytetracyclines,the drug of choice is given at 10 – 20 mg/kg/day for 10 - 14 days.
High doses appear tobe more effective (if treatment is effective, the fever should dropsignificantly within 24 hr). No vaccines are available