[Isolation of chlamydophila psittaci from avian samples and establishment of a respiratory infection murine model]

OBJECTIVE

To optimize the isolation and culture technique of Chlamydophila psittaci avian strains and to establish an animal model infected with C. psittaci.

METHODS

C. psittaci ompA gene was amplified from DNA extracted from bird livers by polymerase chain reactions (PCR). For the PCR positive avian samples, the liver tissues were homogenized and used to incubated with HeLa or Vero cell monolayers for 72 h in different dilutions, and chlamydia inclusion bodies were detected by immunofluorescence or Giemsa staining. Different dose of the avian strains (2 x 10(4), 2 x 10(5), 2 x 10(6) IFUs) were used to attack C57BL/6 mice by intranasal injection,mice were sacrificed on day 5 or day 10 after infection, and the histopathology changes were analyzed by H&E and immunohistochemistry staining in different organs.

RESULTS

Six of one hundred avian samples were positive by C. psittaci ompA gene amplification,and three were positive by cell culture. The C. psittaci avian strains were cultured in Vero or HeLa cells. Vero cells showed stronger tolerance of cytolysis after chlamydia infection and chlamydia inclusion bodies were larger and more dense. Successfully establish a murine model of intranasal infection with C. psittaci, and 2 x 10(5) IFU is the suitable amount of organisms to induce respiratory chlamydia infection.

CONCLUSION

The isolation and culture condition was optimized for C. psittaci avian strains, and a murine model of respiratory tract infection by C. psittaci was successfully established, which can be applied to the clincal diagnosis of C. psittaci and epidemiological or pathogenetic study.

Atypical pneumonia due to Chlamydophila psittaci: 3 case reports and review of literature

Chlamydophila psittaci is the causative agent of psittacosis or ornithosis. The disease is transmitted to men predominantly from birds. Most commonly noted symptoms are fever, headache and cough, but a number of other symptoms or complications may arise such as renal impairment, hepatitis or neurological symptoms. In this article 3 cases of psittacosis are presented, with a review of the literature with emphasis on laboratory diagnosis.

An outbreak of psittacosis in a bird park in Japan

An outbreak of psittacosis related to a bird park occurred in Matsue City, Shimane Prefecture, Japan, during winter 2001. Seventeen cases of psittacosis (12 visitors, three staff, and two student interns) were confirmed. A cohort study was conducted among the park staff and students to determine the risk factors for the development of acute serologically confirmed psittacosis (SCP) infection. Being 'bird staff' had an increased risk of SCP infection (RR 3.96, 95% CI 1.48-10.58). Entering the staff building, where ill birds were maintained without proper isolation, was also associated with an increased risk of SCP infection (RR 3.61, 95% CI 1.03-12.6). Isolation of ill birds and quarantine measures were found to be insufficient. Dehumidifiers and a high-pressure water spray under a closed ventilation environment may have raised the concentration of Chlamydophila psittaci in the hothouses. Bird park staff and visitors should be educated about psittacosis.

[Two familial cases of psittacosis]

We report here 2 cases of psittacosis in a family. In the first case, a 51-year-old woman was admitted with fever, dry cough, and a chest radiograph showed increased opacity in the right upper lung field. On a diagnosis of atypical pneumonia, minocycline was given and her clinical symptoms and abnormal laboratory data were improved. The second case was her husband, a 58-year-old man who presented with fever 4 days after his wife's admission. His chest radiograph revealed increased opacity in the left lower lung field. The administration of azithromycin for 3 days attenuated his clinical symptoms and his abnormal laboratory data improved. The serum titer of complement fixation (CF) test and ELISA test against Chlamydophila psittaci were elevated in both cases on analysis of paired acute- and convalescent-phase serum speciments. The antigen of Chlamydophila was revealed from these parrots, which had been raised in their family. Therefore, we concluded that the psittacosis had originated from the parrots.

[Severe multiorgan psittacosis in a 10-year-old boy]

Psittacosis is rare among children and severe cases appear exceptional. We describe a child with psittacosis and multiorgan involvement.

CASE REPORT

T., a ten-year-old boy, was admitted for a prolonged fever associated with meningism. Laboratory tests showed an important inflammatory response, mild renal failure and coagulation disorders. On admission, the chest X-Ray and the cerebrospinal fluid were normal. He rapidly developed shock, acute abdomen, oxygenodependency, pneumonia and bilateral pleural effusion. No improvement was observed after 48 hours of cefotaxime therapy. History revealed the presence of two parrots at home. Treatment by intravenous clarithromycin was therefore initiated. Serology for Chlamydia psittaci was strongly positive. All symptoms disappeared a few days later.

CONCLUSION

The case reported was particular for two reasons: severe disease with multi-organ involvement and young age of the patient. We emphasize the need to search for a history of contact with birds in any case of unexplained pneumonia.

[Two cases of Chlamydia psittaci infection occurring in employees of the same pet shop]

We report here 2 cases of psittacosis in a pet shop. In the first case, a 44-year-old male was admitted with fever, and a chest radiograph showed an infiltration shadow in the right lower lung. One day later, a colleague of the first patient, a 42-year-old man, developed fever and was admitted. In this patient, chest radiography revealed an infiltration shadow in the left lower lung. Both patients had mild liver dysfunction. The serum titer of a complement fixation (CF) test against Chlamydia psittaci was elevated fourfold in the first case and sixteen-fold in the second on the analysis of paired acute- and convalescent-phase serum specimens. Clinical symptoms and abnormal laboratory data were attenuated by the administration of minocycline for 2 weeks. Since both patients worked in same pet shop and since some parakeets at the shop had died, we speculated that the psittacosis had originated from these birds.

[Ornithosis--studies in correlation with an outbreak]

An outbreak of ornithosis with 8 cases of ornithosis pneumonia and 2 lethal complications was investigated in workers in a poultry farm and processing plant and a comparative seroepidemiological study of antigen responses was performed in 3 collectives: No. I: n = 82/87 workers in the processing plant, where the outbreak occurred; No. II: n = 83 workers in a chicken slaughter-house; No. III: n = 82 as matched-pair group to collective No. I with the same age and sex, but without occupational risk. The test systems were: genus specific complement fixation reaction (CFR), Ipazyme commercial slide kit containing LGV antigen and a type-specific microimmunofluorescence (MIF) technique with antigens binding C. psittaci, pneumonia and trachomatis IgA, IgG and IgM. 57/82 (71.9%) workers in group No. I were chlamydial antibody-positive, whereas only 22/82 of the population Nr. III--control group (odds ratio 6.2/3.2-12.3 p < or = 0.05). 16/83 (19.3%) of the workers in the chicken slaughterhouse had antibodies against chlamydia group antigens. 30/82 of the collective No. I had serological evidence of a recent or current infection with higher antibody titres in CFR and IPAZYME-Test and/or antibody response against IgA and IgM (MIF). 43.3% of the latter could be serologically detected as specific infections with C. psittaci. 10 of 18 (55%) workers employed in the recent 3 months had serological signs of an acute infection. There was no association between the point of contact with the poultry (live hang areas, slaughtery, evisceration, cooling carcasses) and the prevalence of antibody response. The possible routes of infection, inhalation of dried excretions or aerosols and via hand-to-mouth contacts are discussed. In specimens of cloacal swabs and faeces of the ducks chlamydiae could be found although the animals were asymptomatic. The results of this study demonstrate that in poultry plants, where ducks and other poultry living in an aqueous habitat are slaughtered and processed, a high risk of C. psittaci infection (70.2%) and ornithosis morbidity (25%) with a lethality of 8.3% can exist. Since the eradication of C. psittaci in poultry does not seem to be possible at the moment, preventive measures e.g. gloves, masks, information and medical examinations of the workers must be implemented in those slaughterhouses and plants where C. psittaci is suspected or common.

[Nosocomial ornithosis]

Ornithosis is an occupational hazard to workers in the poultry industry, zoonosis. Own sporadic unusual case is appearing under the hospital circumstances as a nosocomial atypical pneumonia.

Detection of chlamydiosis in a shipment of pet birds, leading to recognition of an outbreak of clinically mild psittacosis in humans

Avian chlamydiosis was detected in a shipment of > 700 pet birds from a Florida bird distributor that were sold to nine Atlanta-area pet stores in August 1995. Respiratory illness among persons who had recently acquired birds from this shipment was reported to local public health officials. The attack rate of acute respiratory illness was 10.7% among persons in households exposed to birds from the implicated flock vs. 1.8% among control households (odds ratio, 6.60; 95% confidence interval, 1.39-31.2). Illness and serological evidence of infection in the absence of symptoms were more common among persons in households with recently purchased birds that were sick or that had died and among persons who had had direct contact with the birds. Clinical psittacosis or serological evidence of Chlamydia psittaci infection was found in 30.7% of households with birds from the infected flock. Mild illnesses and asymptomatic infections in exposed persons were unusual features of this outbreak.

Chlamydia psittaci infection in sheep: a paradigm for human reproductive tract infection

Chlamydiae are important reproductive tract pathogens in a wide variety of animals. In humans, chronic or repeated infection of the female genital tract with Chlamydia trachomatis has been identified as a significant factor in the development of occlusive infertility or increased risk of ectopic pregnancy. The spectrum of reproductive disease recognized in sheep to be caused by Chlamydia psittaci has been primarily restricted to pregnant animals because the organism was clearly identified as a major cause of infectious abortion. However, following pregnancy failure, a chronic chlamydial infection can become established in the reproductive tracts of experimentally infected ewes. Persistent infection of the ewe's reproductive tract may eventually result in pathology, similar to that observed in women infected with C. trachomatis, thus decreasing the breeding life of affected ewes. Furthermore, ewes that experienced C. psittaci induced abortion provide a unique opportunity to study the host: parasite dynamic as it relates to persistent infection. This natural model of persistent infection may, in some ways, be superior to more contrived models in which the chlamydial isolate is not a normal reproductive pathogen of the study animal. Thus, the study of persistent chlamydial infection in sheep may be used for the benefit of both human and veterinary medicine.

Interferon-gamma mediates long-term persistent Chlamydia psittaci infection in vitro

The long-term anti-chlamydial effects of recombinant ovine interferon gamma (rOvIFN-gamma) were studied in ovine ST-6 fibroblasts infected with the S26/3 strain of Chlamydia psittaci. Chlamydial multiplication was assessed by enzyme-linked immunosorbent assay analysis of supernate lipopolysaccharide, titration of inclusion-forming units in culture supernates, and enumeration of inclusion bodies in cultured cells at 7-day intervals. Concentrations of 250 and 1000 U/ml of rOvIFN-gamma resulted in a microbistatic inhibition of C. psittaci growth, which appeared to become microbicidal when rOvIFN-gamma was maintained in the cultures for 14 days or more. There were no signs of C. psittaci multiplication when cultures were maintained in 25 or 100 U/ml of rOvIFN-gamma. However, subsequent removal of rOvIFN-gamma from these cultures resulted in a re-emergence of viable, infectious chlamydiae, which eventually killed all the fibroblasts. This re-emergence was more rapid in cultures initially treated with 25 U/ml of rOvIFN-gamma than in those treated with 100 U/ml.

Studies on the early phase of the pathogenesis of ovine enzootic abortion in the non-pregnant ewe

The initial phase of infection of non-pregnant sheep by Chlamydia psittaci (ovis) was studied by inoculating naïve and previously exposed sheep by the oro-nasal and subcutaneous routes with the BS isolate of C. psittaci (ovis). Naive animals exhibited a marginal rise in temperature and seroconversion was detected by enzyme-linked immunosorbent assay (ELISA) as early as 9 days after inoculation. Chlamydaemia was detected using culture and an antigen detection ELISA. No faecal shedding of chlamydiae was detected in ewes kept up to 3 weeks after infection. Although chlamydial antigen was demonstrated in epithelial cells or lymphocytes in lungs, liver, spleen, kidney, abomasum, jejunum, tonsils and suprapharyngeal, mandibular, parotid and mesenteric lymph nodes of some of the naïve sheep using an ELISA and streptavidin-biotin and immunofluorescent staining techniques, the organism could not be cultured from these tissues. No chlamydial antigen was demonstrated in any of the tissues of the previously exposed sheep nor in uninoculated controls. It is concluded that previously infected sheep are capable of completely eliminating subsequent infection and that chlamydiae localize in a variety of tissues of infected naïve sheep, especially within epithelial cells and lymphocytes.

Probable transmission of Chlamydia psittaci from a macaw to a cat

A 5-year-old Siamese cat developed unilateral mucopurulent ocular discharge and conjunctivitis 1 month after the introduction of a macaw into the household. Despite treatment with antimicrobial ophthalmic ointment, the conjunctivitis became bilateral and other systemic signs developed. Intracellular inclusions consistent with a Chlamydia psittaci infection were detected in conjunctival epithelial cells stained with a fluorescein-labeled monoclonal antibody. Chlamydia psittaci was isolated from samples obtained by conjunctival scraping. Subsequently, C psittaci was recovered in samples obtained from the feces of the bird. The cat and the bird were successfully treated with doxycycline. Historic and epidemiologic findings supported the theory of orthozoonotic transmission of C psittaci from the bird to the cat.

[Bilateral pneumonia caused by Chlamydia psittaci. Description of a clinical case]

A mortal case of atypical pneumonia due to Chlamydia psittaci with acute respiratory distress, septic shock and multiple organ failure is described. Infection has been caused by an ill parrot imported clandestinely. Antibody titration with the immunofluorescence technique allowed diagnosis.

[Pigeon coryza--ornithosis--pigeon breeder's lung]

The published informations on the entities pigeon coryza and ornithosis are reviewed. On the basis of own experiences and experimental data obtained in the Landesveterinäruntersuchungsamt Koblenz, pigeon coryza apparently is a symptom rather than a clearly defined disease. Finally pigeon breeder's lung is discussed in front of the background of own observations and recommendations to be of allergic origin.

Immunity to Chlamydia psittaci with particular reference to sheep

Chlamydia psittaci, a zoonotic bacterium, is the causal agent of enzootic abortion of ewes, an important disease of sheep in many European countries. The major thrust of current chlamydial research is directed towards the human pathogen Chlamydia trachomatis. This review attempts to bring together relevant information concerning the host immune response to all members of the genus Chlamydiae and show how this has led to an increased understanding of the ovine humoral and cell mediated immune responses to C. psittaci while emphasising areas where there is still a lack of knowledge. Specifically the review looks at the common immuno-accessible antigens of the Chlamydiae and the antibody responses produced during infection, as well as covering the role of T cells and cytokines in the protective immune response.

Pathology of experimental chlamydiosis in chicks

Twelve one-day-old chicks were experimentally inoculated with Chlamydia psittaci derived from turkeys. Acute chlamydial septicemic lesions were induced by the inoculation into the air sac and trachea. No lesions were produced by the esophageal injection. Clinically, the affected chicks showed emaciation and mouth breathing, and were inactive while some birds died. Grossly, they had hepatomegaly, splenomegaly and airsacculitis. Histopathologically, fibrinopurulent airsacculitis, pneumonia and bronchitis, multiple fibrinous serositis in the hepatic and splenic capsules, peri- and epicardium, and mesenterium, focal endoarteritis in the aortae, activation of reticuloendothelial cells in the spleen, and hepatic necrosis were noted. Immunohistochemically, chlamydial antigen granules were present in the cytoplasm of epithelial cells of the respiratory system, hepatocytes, macrophages in the air sac, lung, serous membrane, liver, spleen, aortae, reticuloendothelial cells in the spleen, and mesothelial cells in various organs or tissues. Chlamydial multiplication in the cells of the organs or tissues involved was preceded to form the lesions.

[The risk of ornithosis among the staff of Copenhagen Zoo]

Because a keeper in Copenhagen ZOO had developed ornithosis, clinical and serological examination of the staff of the ZOO was instituted. The object was to demonstrate any possible threatening epidemic and also to demonstrate if the staff of the ZOO were particularly exposed to the risk of ornithosis. Neither of these could be confirmed.

Observations on the pathogenesis of Chlamydia psittaci infection of pregnant sheep

Susceptible pregnant sheep were infected with Chlamydia psittaci at different stages of early and mid-gestation. Placentas and foetuses were examined by microbiological, serological, histopathological and immunochemical methods at various intervals thereafter. While ewes were susceptible to infection from early gestation onwards and infections of placentas and foetuses occurred from about 60 days gestation (dg), pathological changes were not detected until after 90 dg. These changes consisted of initial rapid replication of C. psittaci in the trophoblast at the limbus of the placentomal hilus, leading to local necrosis and contiguous spread of infection to involve the cotyledonary and intercotyledonary placenta and apposing endometrium. Foetal pathology consisted of focal necrosis in liver and other organs suggestive of embolic dissemination of infection from the placenta. An early foetal immune response was detected including the demonstration of IgM and IgG antibody to C. psittaci and quantitative evidence of a B cell response to infection. Pathogenetic mechanisms are discussed.

Sheep-acquired severe Chlamydia psittaci infection in pregnancy

There have been five confirmed cases of severe Chlamydia psittaci infection during pregnancy, three having been treated in Edinburgh, Scotland. The most recent case is presented and previous experience is reviewed. The illness usually causes thrombocytopenia with disseminated intravascular coagulation, renal failure and hepatic dysfunction during the late second and early third trimester. The outcome for the fetus is usually fatal and the infection only resolves after delivery or abortion. The main hope is for education to prevent infection occurring in susceptible populations.

In vivo-activated mononuclear phagocytes and protective immunity to chlamydiae in mice

Peritoneal macrophages (M phi s) collected from Chlamydia psittaci 6BC-immune mice after intraperitoneal challenge with 10(6) 6BC (immune-boosted [IB] M phi s) were compared by various functional criteria with other in vivo- and in vitro-activated M phi populations. While casein-, protease peptone-, and thioglycolate (Thio)-elicited M phi s were equally susceptible to in vitro infection with 6BC, IB M phi s did not support chlamydial growth and M phi s from Mycobacterium tuberculosis BCG- or Listeria monocytogenes-sensitized mice exhibited intermediate susceptibility to infection. The resistance of IB M phi s was not due to the ingestion of fewer 6BC organisms, nor were these cells persistently infected, since chlamydiae could not be recovered from infected IB M phi s after in vitro infection, even after extended incubation times. In contrast, Thio M phi s stimulated in vitro with gamma interferon (IFN-gamma), with or without lipopolysaccharide, resulted in cells that exhibited chlamydiastatic activity which was lost shortly after IFN-gamma was removed from the culture medium. Conversely, the antichlamydial activity of IB M phi s was stable over time but not through the production of autostimulatory cytokines, as evidenced by the lack of stimulation of Thio M phi s to restrict 6BC replication in coculture experiments. IB M phi s exhibited enhanced oxidative activity, but anti-IFN-gamma antibody did not abrogate this response. IB M phi s were recovered only from immunized mice that survived an otherwise lethal 6BC intraperitoneal challenge. These cells appear to be important for development of protective immunity to chlamydiae, and evidence suggests that stimulation by cytokines other than IFN-gamma (with or without lipopolysaccharide) is required for the observed heightened in vivo activation.

Reactive arthritis and psittacosis

A 54-year old man had severe inflammatory polyarthritis 10 days after the onset of an acute febrile illness that was serologically documented to be psittacosis. The pattern and chronicity of the articular symptoms, the response to nonsteroidal anti-inflammatory agents, and the presence of HLA-B7-CREG strongly suggest that this was a reactive arthritis. The association of psittacosis and reactive arthritis has previously been reported in the British literature, but this may be the first reported North American case.

An epidemic of mild pneumonia due to an unusual strain of Chlamydia psittaci

An epidemic of mild pneumonia was discovered during a chest radiographic survey of adolescents and young adults in two communities 110 kilometers apart in northern Finland. Antibodies to chlamydial antigens were found in 32 of 34 persons with pneumonitis. Microimmunofluorescence antibody tests suggest that the etiologic agent is closely related or identical to TW-183, an unusual strain of Chlamydia psittaci isolated from the eye of a child in Taiwan. The point prevalence of pneumonitis with antibody to TW-183 in school children at the time of the survey was high-15 and 19 patients per 1,000 students in the two communities. There was no evidence of avian transmission in the epidemic.

Abortion due to infection with Chlamydia psittaci in a sheep farmer's wife

A farmer's wife who had helped with lambing aborted spontaneously in March after a short febrile illness in the 28th week of her pregnancy. She developed disseminated intravascular coagulation post partum with acute renal failure and pulmonary oedema. Recovery was complete after two weeks of hospital care. A strain of Chlamydia psittaci, probably of ovine origin, was isolated from the placenta and fetus. The patient's serum showed rising titres of antibody against chlamydia group antigen; the placental and fetal isolates; and a known ovine abortion, but not a known avian, strain of C psittaci. IgG against both ovine abortion and enteric strains of C psittaci was detected, but IgM against only an abortion strain was detected. Histological examination showed pronounced intervillus placentitis with chlamydial inclusions in the trophoblast but no evidence of fetal infection or amnionitis. Laboratory evidence of chlamydial infection was found in an aborting ewe on the farm in January and in remaining sheep and lambs in July. Doctors should recognise the possible risk to pregnant women in rural areas where chlamydial infections in farm animals are widespread.

Psittacosis centenary -- 'pneumotyphus' reviewed

Since 1979, when psittacosis, human infection with Chlamydia psittaci, became a notifiable disease in South Africa, only 4 cases have been reported to the State health authorities. While this is not a common illness and some cases may not be reported, there is a strong possibility that this infection is being overlooked because of lack of awareness of its wide range of manifestations. A characteristic case is described and the complications and management of psittacosis are reviewed with particular reference to South Africa.

Inapparent chlamydial infection in the urogenital tract of guinea-pigs

Microbiologically inapparent urogenital infection appeared to be induced in male guinea-pigs inoculated intra-urethrally with low doses of the guinea-pig inclusion conjunctivitis strain (GP-IC) of Chlamydia psittaci. This state was indicated by the ability of inoculated animals to donate eye infection to normal animals caged with them. Donors failed to develop overt urogenital infection throughout the period of transmission judged by both absence of infected cells in urethral scrapings and failure to isolate GP-IC in cell culture; however, inoculation of donors with 5-iododeoxyuridine led to transient appearance of infectivity in scrapings. In distinction from overtly infected animals, donors failed to develop serum antibody and remained susceptible to urethral challenge with larger doses of GP-IC. Animals that had recovered from overt urethral infection were resistant to challenge and appeared unable to transmit eye infection.

Experimental chlamydial salpingitis in immunosuppressed guinea pigs infected in the genital tract with the agent of guinea pig inclusion conjunctivitis

At necropsy indication of spread of infection to fallopian tubes was found in 25 of 41 (60%) female guinea pigs infected in the genital tract with the chlamydial agent of guinea pig inclusion conjunctivitis and immunosuppressed with cyclophosphamide. Eighteen were examined histologically, and the diagnosis of acute salpingitis was confirmed in 10, based on inflammatory reaction, detection of guinea pig inclusion conjunctivitis in tissue, and formation of cysts (pyosalpinx and hydrosalpinx). Infection of fallopian tube tissue was confirmed by indirect immunofluorescence and electron microscopy. Infection of endometrial tissue and peritoneum was also recognized. Data suggested that the immunosuppression mediated by cyclophosphamide resulted in a prolonged genital tract infection and concomitant ascending infection leading to salpingitis.

Ornithopulmonary disease

Severe pulmonary infections in man may be caused by exposure to infected birds or their droppings. Ornithosis, histoplasmosis and cryptococcosis develop as a result of inhalation of an infective agent. Pigeon-breeder's lung is an allergic alveolitis caused by a hypersensitivity reaction to avian droppings or feathers. This condition is recurrent and is best treated by avoidance of further exposure. Corticosteroids are useful in acute cases.

Psittacosis: the reservoir persists

During a one-year period, 101 parakeets and parrots were submitted for laboratory examination. The birds were sick, dead, or from premises where morbidity had been observed. Tissue specimens from these birds were tested for the presence of Chlamydiapsittaci by two methods. A tissue culture system using McCoy cells treated with 5-iodo-2-deoxyuridine was found to be more sensitive than intraperitoneal inoculation of mice for isolation of the chlamydiae. Chlamydiae were recovered from 21 (34%) of 61 parakeets and 16 (40%) of 40 parrots tested. This high rate of infection persists despite the availability of effective chemotherapeutic regimens for control of chlamydial infection in psittacines. The origins of some of the infected birds were traced to aviaries where subsequent treatment with chlortetracycline was successful in eradication of the chlamydial infection. Other infected birds had been imported recently and could be traced back to quarantine centers where (by law) the birds received chemoprophylaxis for chlamydial infection. Our results suggest that this program is an administrative failure.

[Respiratory diseases due to noxious agents in agriculture workers]

Better working and living conditions resulted by scientific technical revolution in agriculture. Nevertheless specialization of agricultural labor created a higher risk against inhalative hazards among few professions. Among biological hazards that are for instant zoonoses and ornithosis, Q-fever, tularemia and tuberculosis. A series of allergenic dusts is of vegetable origin. Among chemical hazards pesticides, fertilizers and disinfectants and other hazards are discussed. Among physical hazards in building and in repair shops for agricultural machines single risk is possible by silicosis and asbestosis but dominating are unspecific dusts.