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Serologic studies on feral, colony-held cynomolgus monkeys indicated that 61% reacted to Coxiella burnetii antigens, and 36% reacted to Rickettsia conorii antigens. The results suggest that a high percentage of cynomolgus monkeys have been exposed to these organisms.
A 59-year-old farmer developed a bilateral optic neuritis in the course of an infection with Coxiella burnetii (Q fever), resulting in a lasting unilateral blindness. A complete medical (including neurological) evaluation gave no evidence of other possible causes. A possible source of infection was cattle.
Three patients developed Q fever endocarditis on porcine bioprosthetic valves. They had a subacute or chronic course with nonspecific symptoms, enlargement of the liver and spleen, and cardiac failure due to destruction of the cusps, without disruption of the valve ring. High-phase I-specific IgG and IgA antibody titers against Coxiella burnetii were found. C. burnetii was isolated in each patient by inoculating suspensions of valve tissue into a human fetal diploid fibroblast cell line, which was grown as monolayers on slides contained inside rubber-stoppered tube cultures. Patients were treated successfully with doxycycline, cotrimoxazole, and valve replacement and were followed up for periods of 24 to 42 months; no evidence of deterioration was found. The human fetal diploid cell culture may be an expeditious, easy, and safe method to isolate C. burnetii from cardiac valves. Valve replacement seemed necessary to cure prosthetic-valve endocarditis due to C. burnetii infection. Combined therapy with doxycycline and cotrimoxazole may control the disease and prevent reinfection of the homografts replacing the valves.
We isolated lipopolysaccharides (LPSs) from phase variants of Coxiella burnetii Nine Mile and compared the isolated LPS and C. burnetii cells by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting. The LPSs were found to be the predominant component which varied structurally and antigenically between virulent phase I and avirulent phase II. A comparison of techniques historically used to extract the phase I antigenic component revealed that the aqueous phase of phenol-water, trichloroacetic acid, and dimethyl sulfoxide extractions of phase I C. burnettii cells all contained phase I LPS, although the efficiency and specificity of extraction varied. Our studies provide additional evidence that phase variation in C. burnetii is analogous to the smooth-to-rough LPS variation of gram-negative enteric bacteria, with phase I LPS being equivalent to smooth LPS and phase II being equivalent to rough LPS. In addition, we identified a variant with a third LPS chemotype with appears to have a structural complexity intermediate to phase I and II LPSs. All three C. burnetii LPS contain a 2-keto-3-deoxyoctulosonic acid-like substance, heptose, and gel Limulus amoebocyte lysates in subnanogram amounts. The C. burnetii LPSs were nontoxic to chicken embryos at doses of over 80 micrograms per embryo, in contrast to Salmonella typhimurium smooth- and rough-type LPSs, which were toxic in nanogram amounts.
Rabbits were inoculated with purified antigen preparations of Coxiella burnetii and representative species of the spotted fever and typhus groups of rickettsiae. Their antibody responses were monitored by complement fixation tests; high-titered antisera were fractionated with ammonium sulfate and then labeled with fluorescein isothiocyanate by the dialysis method. The conjugates had homologous 3+ staining titers of 1:256 to 1:2,048 and did not exhibit nonspecific staining. The Rickettsia rickettsii, R. conorii, and R. akari conjugates reacted only with rickettsiae of the spotted fever group; the R. canada, R. prowazekii, and R. typhi conjugates were specific for the typhus group rickettsiae; and the C. burnetii conjugate stained only homologous organisms. One of these conjugates (R. rickettsii) is currently being used to identify rickettsiae in clinical specimens and has already proven its value as a diagnostic tool.
A microtiter enzyme-linked immunosorbent fluorescence assay based on alkaline phosphatase conjugate and 4-methylumbelliferyl phosphate as fluorogenic substrate was developed and adapted to quantitatively analyze immunoglobulin G subclass 1 (IgG1) and IgG2 responses of vaccinated and infected cattle to proteins of Coxiella burnetii. The enzyme-linked immunosorbent fluorescence assay surpassed the conventional enzyme-linked immunosorbent assay with a 50-fold-higher sensitivity and a broader range of linear dose-response signals. Antigens of C. burnetii were purified by sodium dodecyl sulfate extraction and molecular-sieve high-pressure liquid chromatography. The purified 14-, 27-, and 30-kilodalton proteins were used as antigens without any further treatment. Vaccination with either chloroform-methanol-extracted cell residues of C. burnetii or the 27-kilodalton major surface protein evoked an early IgG2 response to the 27-kilodalton protein (2 weeks after immunization), whereas IgG2 to lipopolysaccharides of C. burnetii was detected only in the late phase (13 weeks after immunization). These results may have implications for the serodiagnosis of acute and chronic Q fever. IgG1 against these antigens was induced solely by naturally occurring C. burnetii infections, indicating that infected cattle can be distinguished from vaccinated cattle by using the enzyme-linked immunosorbent fluorescence assay and SP27 antigen.
Sheep erythrocytes sensibilized with the lipopolysaccharide (LPS) extracted from Coxiella burnetii phase 1 cells were used in indirect haemolysis test (IHT). The test was highly sensitive and specific. Its use seemed reasonable when following the chronic course of Q-fever by serologic methods.
An indirect fluorescent antibody test was performed on sera collected from dogs housed in the municipal kennel of Setúbal to assess the prevalence of antibodies to Ehrlichia canis, the causative agent of canine ehrlichiosis and to Rickettsia conorii, agent of boutonneuse fever in humans. Two other members of the family Rickettsiaceae, Coxiella burnetii and Rickettsia typhi, were included in the serosurvey. Of the 104 dogs tested, 85.6% had antibodies to R. conorii, 50% to E. canis, 26.9% to R. typhi, and 4.8% to C. burnetii. These high seroprevalence rates of dogs with antibodies all year around against Rickettsiaceae suggest that physicians, public health officers and veterinarians should more frequently consider the diagnosis of these infections in Portugal.
Dairy cows infected naturally with Coxiella burnetii as evidenced either by presence of phase II agglutinating antibodies in the blood or by shedding C. burnetii in the milk, were vaccinated subcutaneously with formalin-killed phase I C. burnetii organisms. Attempts to demonstrate C. burnetii in the milk of vaccinated dairy cows 47 days after vaccination were negative, while continuous shedding of C. burnetii in the milk of control non-vaccinated dairy cows was repeatedly demonstrated in the course of 123 days (period of investigation). No harmful systemic reaction following vaccination was observed.
Various fixatives and treatments such as acetone, methanol, Bouin fixative, modified Bouin fixative, 10% Formalin, modified methacarn, periodate-lysine-paraformaldehyde, acetone-methyl benzoate-xylene, and EDTA were evaluated for their effect on the immunoreactivity of Coxiella burnetii in paraffin-embedded tissues by using the avidin-biotin-peroxidase complex and the peroxidase-antiperoxidase procedure. C. burnetii antigen was shown to be present in liver, spleen, and uterus tissues of experimentally infected mice by all methods of fixation and treatment. A positive immunoreaction was seen in cytoplasmic vacuoles of macrophages, as extracellular rod-shaped organisms, and as residual particulate extra- and intracellular debris. Immunoreactivity and cellular preservation, however, varied substantially with the individual fixatives. Optimal immunostaining of C. burnetii was achieved by EDTA treatment and Bouin and acetone fixation. The avidin-biotin-peroxidase technique proved to be slightly more sensitive than the peroxidase-antiperoxidase procedure when primary antibody dilution was used as the criterion for sensitivity.
Thirty-three cases (24 definite, nine probable) of Q fever were diagnosed in Victoria County, Cape Breton, Nova Scotia from May to August, 1985. Twenty-six of the cases occurred in residents of Baddeck (population 900, attack rate 2.8 percent), and 21 of the cases occurred during the month of June. There was geographic clustering of the cases: 14 of the 33 (42 percent) lived or worked in four buildings located side by side in the center of town. A case control study revealed that 25 of 29 cases were exposed to a cat that gave birth to stillborn kittens on June 8, 1985 and had bled per vaginum for three weeks prior to delivery. The cat lived in one of the buildings where geographic clustering occurred and frequently visited the other buildings. None of the 40 control subjects was so exposed (p less than 0.001). This cat had an antibody titer of 1:512 to Coxiella burnetii phase 1 antigen and a titer of 1:1024 to phase 2 antigen. Exposure to cattle, sheep and goats, the traditional reservoirs of Q fever, was uncommon among patients and control subjects and none of eight cattle tested had antibodies to C burnetii phase I antigen. We conclude that the infected parturient cat was probably responsible for this outbreak of Q fever affecting 2.8 percent of the population of the town of Baddeck.
Antibodies against Coxiella burnetii and against rickettsiae of the spotted fever group were found in human sera and in sera from domestic and wild animals collected in south Bohemia. Spotted fever group rickettsiae were also discovered in the tick Ixodes ricinus. These results indicate the presence of both types of rickettsiae in this part of Czechoslovakia. As no epizootics or epidemics of Q fever have as yet been reported in the area, it can be assumed that C. burnetii occurs in the latent state. The occurrence of spotted fever group rickettsiae is probably endemic among I. ricinus ticks and among small and larger wild mammals.
Electron microscopy has provided valuable insights into the study of rickettsiae as intracellular parasites from several important perspectives. This tool has allowed researchers to delineate the fine structural features of these organisms and to show that they truly resemble free-living bacteria. Furthermore, it has been shown that there are subtle, but distinct differences in the outer envelope structure of some members of the genus Rickettsia that may explain reported differences in tinctorial properties and in their sensitivity to certain antibiotics. With Coxiella burnetii, electron microscopy has helped significantly in the characterization of the pleomorphic nature of the organism including formation of terminal bodies that resemble endospores of gram-positive bacteria. Electron microsxopy has also helped to define the relationship of the rickettsiae to their host cells. For example, ultrastructural analysis can reveal whether organisms exist free within the cytoplasm or nucleus (members of the genus Rickettsia), or whether they are bound by a phagosomal or phagolysosomal membrane (Ehrlichia and Coxiella). Finally, although all rickettsiae eventually destroy their host cell, it has been shown through transmission electron microscopy that this destruction might be mediated by different mechanisms that are specific for different rickettsial species.
Five cases of clinical Q fever were identified amongst students and staff of a Somerset secondary school between 23 October 1987 and 21 December 1987. Five goats which were kept at the school were found to have antibodies to Coxiella burnetii phase II. A cross-sectional study was conducted at the school in July 1988. A single CF test was used to identify evidence of prior infection, and a self-administered questionnaire was used to collect data on exposure variables and illness during 1987. Four hundred and ninety-nine eligible subjects took part in the study, and serological information was obtained from 461 of these. Eighty-seven subjects (18.9%) had CF titres of 20 or greater. It was estimated that only 1 in every 30 individuals with evidence of past C. burnetii infection had been recognized as a clinical case of Q fever. Antibody positive subjects were more likely to have been off school sick and to report having suffered chest pain than negative subjects. Contact with school animals, specifically cleaning the school poultry, collecting their eggs and visiting a school goat on the day of kidding, was associated with the presence of antibodies to C. burnetii. However, a large proportion of the antibody positives (24.2%) had no known contact with the school animals. Spread of organisms, either wind-borne or in straw or manure, may have been responsible for the high prevalence of unexplained infection.
Seven species of pathogenic rickettsiae were compared in five assay systems for group, species, strain, and phase differences in infectivity. The species examined include Rickettsia prowazekii (Breinl and Cairo 3 strains), R. typhi, R. canada, R. rickettsii (Sheila Smith and R strains), R. conorii, R. sibirica, and Coxiella burnetii in phases I and II. Pathogenicity was charcterized in terms of fever in guinea pigs. All comparisons of infectivity and pathogenicity were described in terms of numbers of rickettsiae in the inocula, as determined by direct rickettsial count. The data characterize the various species and strains of rickettsiae in quantitative terms, which are also estimates of the sensitivity of the assay systems used. Phase I C. burnetii was found to be the most, and R. canada the least, infective of the species examined. In general the primary chicken embryo cell culture system proved to be the most, and that of the mouse the least, sensitive assay system.
The evidence of the prolonged persistence of Coxiella burnetii in experimental animals was obtained. Cyclophosphamide was shown to be capable of activating Q rickettsiosis in guinea pigs, and the period of the aggravation of this infection was found to be accompanied by a decrease in IgG concentration and a relative increase in IgM content.
Invertebrate pathogens of the genus Rickettsiella (Order Rickettsiales) undergo a developmental cycle more characteristic of chlamydial organisms (Order Chlamydiales) than of typical rickettsiae. Moreover, among recognized species of Rickettsiella, there is considerable variation in host range and in the ultrastructure and development of the infectious stage, i.e., the elementary body. To begin an analysis of the taxonomic relationships of the invertebrate pathogens belonging to the genus Rickettsiella and of the relationship of these to chlamydiae and other rickettsiae, genomic DNA of representative species was compared with respect to restriction enzyme site polymorphism, DNA-DNA hybridization, G + C ratios, and fine melting profiles. The strains studied included isolates currently classified as Rickettsiella grylli, R. popilliae, R. chironomi, Chlamydia psittaci, C. trachomatis, Coxiella burnetii, and Rickettsia conorii. Reciprocal DNA hybridization studies carried out under high-stringency conditions (65 degrees C) showed homology between R. grylli and R. popilliae isolates but not with the others, including two isolates of R. chironomi from the midge, Chironomus dorsalis, and the scorpion, Buthus occitanus. The R. chironomi isolates shared no detectable homology with each other or with any of the other strains or species. Additionally, no homology was detected between any of the Rickettsiella isolates and the species of Coxiella, Rickettsia, or Chlamydia. Results obtained from the DNA fine melting profiles and G + C ratios corresponded with the results obtained from the DNA hybridization studies. Thus, the present study indicates that, despite similarities in developmental cycles, Rickettsiella and Chlamydia are taxonomically distinct groups appropriately placed in different orders.(ABSTRACT TRUNCATED AT 250 WORDS)
Q fever in humans and coxiellosis in livestock are on the increase in Canada. The progressive spread of Coxiella burnetii takes place in the animal reservoirs of the rickettsia, mainly domestic ruminants. Human Q fever is a reverberation of the coxiellosis situation on our farms. Increasing animal concentration resulting from the industrialization of agriculture and oversight of the infection in livestock permitted the extension of the zoonotic problem on the farms. Initiative for control of coxiellosis, however, is called for by public health interests at the present time to assure occupational health and safety for workers, and the protection of the general population residing in coxiella threatened environments.