Autoantibody profiles in the sera of patients with Q fever: characterization of antigens by immunofluorescence, immunoblot and sequence analysis

Recent reports have shown that some of the immunological aspects of Q fever, a rickettsiosis caused by Coxiella burnetii, could be related to self-antigen responses. The aim of this study was to determine the specificity of the autoantibody response of patients with acute and chronic Coxiella infections. Smooth muscle and cardiac muscle-specific autoantibodies were observed in significant percentages in acutely or chronically affected Q fever patients when compared to healthy volunteers. Moreover, the incidence of cardiac muscle-specific autoantibody was significantly higher among chronically ill patients compared to acutely ill patients. Moreover, a band of 50 kD of a HeLa extract was detected in most of the sera of individuals with chronic infections and previous sequence analysis suggests that this antigen presents a high degree of homology with the human actin elongation factor 1 alpha. Further research would be necessary to confirm if antibodies to human cytoskeletal proteins could be of clinical importance in chronically infected Q fever patients.

Guidelines for the diagnosis of tick-borne bacterial diseases in Europe

Ticks are obligate haematophagous acarines that parasitise every class of vertebrate (including man) and have a worldwide distribution. An increasing awareness of tick-borne diseases among clinicians and scientific researchers has led to the recent description of a number of emerging tick-borne bacterial diseases. Since the identification of Borrelia burgdorferi as the agent of Lyme disease in 1982, 11 tick-borne human bacterial pathogens have been described in Europe. Aetiological diagnosis of tick-transmitted diseases is often difficult and relies on specialised laboratories using very specific tools. Interpretation of laboratory data is very important in order to establish the diagnosis. These guidelines aim to help clinicians and microbiologists in diagnosing infection transmitted by tick bites and to provide the scientific and medical community with a better understanding of these infectious diseases.

Role of immunoglobulin G subclasses in Q fever

The progression of Q fever to either acute or chronic disease has been attributed both to biological characteristics of the bacteria and to the host immune response. In order to determine whether a specific immunoglobulin G (IgG) subclass distribution could play a diagnostic or prognostic role in Q fever, IgG subclass levels were measured in patients with acute or chronic disease. It was observed that (i) IgG1 and IgG3 levels were elevated in patients with chronic Q fever compared to patients with acute disease or normal controls; (ii) variations over time reflected inverse complementary relationships of subclass levels, such as between IgG1 and IgG3 compared with IgG2 and IgG4, or an inverse relationship between IgG1 and IgG2; (iii) variations in IgG2 and IgG3 total subclass levels during follow-up of patients with chronic Q fever showed a decrease in IgG2 with a concomitant increase in IgG3 two years from disease onset. These findings indicate that measurements of IgG subclasses may be a simple, additional tool useful in the diagnosis of Q fever. This data raises the question of an unusual immunoregulatory mechanism in Q fever that is implicated in the presentation of the clinical disease.

Acute respiratory disease in Spain: seven years of experience

The clinical and epidemiologic features of viral and nonviral pathogens involved in acute respiratory diseases are described in the context of cases of infection (especially atypical pneumonia and bronchiolitis) studied at the Centro Nacional de Microbiología, Virología e Immunología Sanitarias in Madrid during a 7-year period (1979-1986). These etiologies were demonstrated in 1,637 (36.2%) of 4,521 cases. Among viruses, respiratory syncytial virus most frequently infected children; influenza virus showed the same pattern of circulation as in other European countries. Of nonviral agents, Mycoplasma pneumoniae and C. burnetii were most often involved in lower respiratory tract infections, with a variable predominance in patients of different ages. A high proportion of cases of M. pneumoniae infection occurred in infants and children aged less than 1 year, and most of these cases occurred during spring and summer. The majority of Q fever cases, including those observed in two outbreaks, occurred in the northern region.

Study of C. burnetii human and animal seroprevalence in a rural population in Madrid community

A pilot study on human seroprevalence of antibodies to C. burnetii in the Madrid region, initiated in a small rural population, shows a 15.4% positivity by the indirect immunofluorescence test. An urban sample shows an 8.8% positivity. Animal seroprevalence in livestock located in the village under study is 76.6% in caprine and 17.7% in bovine. A high risk epidemiological situation is detected.

Glomerular nephropathy associated with chronic Q fever

Of three patients with Coxiella burnetii endocarditis, two developed focal segmental proliferative glomerulonephritis (GN), and the third developed diffuse intracapillary proliferative glomerulonephritis. In one case, a good therapeutic response was followed by partial remission of the renal alterations, but 10 months later there were clinical and histological signs of active glomerular nephropathy, suggesting that the antigenic stimulus persisted. In another case, poor evolution of the infection was accompanied by clinically and histologically aggressive glomerular nephropathy, and advanced renal failure. The third patient, who had diffuse proliferative glomerulonephritis, underwent renal biopsy earlier than the other two cases, and the behavior of the nephropathy has not been aggressive to date. Immunohistopathologic study revealed a diffuse granular deposit of IgM and C3 in all three cases; the first two also presented a discrete linear IgG deposit in the capillary loops. Attempts to identify C burnetii antigen at the glomerular level by immunohistologic techniques failed in two patients. The literature on the association of chronic Q fever with glomerulonephritis is briefly reviewed.

Q fever in Spain: acute and chronic cases, 1981-1985

Two hundred forty-nine cases of Q fever were documented at the laboratories of the Centro Nacional de Microbiología, Virología e Inmunología Sanitarias (CNMVIS) during the 5-year period 1981-1985. Two hundred thirty-four cases corresponded to acute infections, mostly sporadic but including two epidemics. The clinical presentation was respiratory in 74% of the cases and febrile in 18%. Fifteen cases, all but one of which were endocarditis, were categorized as chronic. The cases studied were referred from almost every region of Spain. The clinical and epidemiologic analyses and the number of cases reported permit only an approximation of the true incidence and characteristics of Q fever in Spain.