Studies on Chlamydia pneumoniae, strain TWAR infection. 2. Seroepidemiology of TWAR on healthy controls and patients with acute respiratory infections

To determine of Chlamydia pneumoniae, TWAR infection is common in Japan. The author performed a spot antibody prevalence study of adults and children living in Okayama prefecture. This study was carried out by microplate immunofluorescence antibody technique (MFA) using in situ inclusions of Chlamydia pneumoniae (TW-183), Chlamydia trachomatis (L2) and Chlamydia psittaci (Cal 10) as antigens respectively. And each chlamydial antiserum IgG, IgA, IgM titers were determined by the dilution and point for specific staining of the inclusions. The author studied people with and without evidence of acute respiratory infections, as determined by physical examination and medical history. 2050 sera of 1477 cases were collected from both groups between 1987 and 1989. The criteria for judgement the positivity of antibodies to chlamydia species are as follows: By comparing the IgG antibody titers determined with different chlamydia antigen, a case was regarded as having an antibody specific to a particular chlamydia species when the titer was highest for that strain and the titer was greater than x 64. In cases which blood was collected more than once, the point in time at which IgG showed the highest titer was used. TWAR specific antibody was detected to be 52/143 cases (36.4%) of healthy children (age 0-15) and 319/531 cases (60.1%) of healthy adults (age 16-85). It was also detected to be 134/478 cases (27.9%) of child patients with acute respiratory infections (age 0-15), and 231/325 cases (71.1%) of adult patients (age 16-95).(ABSTRACT TRUNCATED AT 250 WORDS)     

Immunoglobulin Classes of Antibody for Human T-Lymphotropic Virus Type-I (HTLV-I) in Healthy Donors and HTLV-I-Associated Disorders

Healthy blood donors, patients with adult T-cell leukemia (ATL) and HTLV-I-associated myelopathy (HAM) and recipients of unscreened blood (SR) who had seroconverted and were followed-up for more than 2 years were examined for HTLV-I antibodies of immunoglobulin G (IgG) and M(IgM) classes. The overall infection rate in donors was 4.9%, as determined by screening with a particle agglutination method (PA). The rate increased with increasing age. Positive sera with a low titer in the PA test (1/16, 1/32 and 1/64) contained IgM antibodies in 32.5% (titer 1/16) to 36.1% (titer 1/64) of the cases, but IgG antibodies were detected in only 5.6% of the sera with a titer of 1/16 and in 36.1% of the sera with a titer of 1/64. Conversely, in high titer sera (1/128 or higher) IgG antibodies were almost always detectable (99.0%) and IgM antibodies less frequently (25.5%). Sera from acute, chronic and pre-ATL, HAM and SR patients contained IgG antibodies in high titer in all cases. The incidence of IgM antibodies was 7.7, 30.0, 53.3, 72.3, and 77.8%, respectively. IgM antibodies were demonstrated repeatedly in some cases who were followed up for a year. Only IgM antibodies from HAM patients occurred in high titers and had strong reactivity to the p24 antigens of HTLV-I in Western blot testing. It is concluded that it is important to detect IgM antibodies not only in primary infections but also in persistent infections of HTLV-I.     

A primary study on the relationship between the acute infection of chronic obstructive pulmonary disease (COPD) and mycoplasma pneumoniae]

The specific antibodies of Mycoplasma Pneumoniae (MP) in the sera of 227 normal adult controls and 187 adult patients with acute infections of COPD were measured by immunofluorescence assay (IFA). The findings showed: 1. in the sera of control group, the titer of specific IgM antibody of MP were lower than 1:8 in 224 cases (98%) and the specific IgG antibody were below 1:16 in 218 cases (96%). 2. Positive results for MP antibodies (the IgM 1:8 or/and the IgG 1:16) were found in 70 cases (37.4%) of adult patients with acute infections of COPD. We suggest that Mycoplasma Pneumoniae is a common pathogen for the adult acute infections of COPD.     

Dengue infections in the Philippines: clinical and virological findings in 517 hospitalized patients

From May 1983 to January 1984, 517 patients with laboratory confirmed dengue were studied at a hospital in Manila. Secondary dengue infections were diagnosed in 78% of these cases. Peak admission (28%) occurred towards the end of the rainy season in November. Most patients (78%) were less than 15 years old but only 3 were infants. Although some type of hemorrhagic finding occurred in 460 cases (89%), only 110 were classified as dengue hemorrhagic fever and the remainder as dengue fever with hemorrhagic manifestations. The clinical course was usually mild. Gastrointestinal bleeding was present in 65 cases, but only 2 patients developed shock. No fatalities occurred. Dengue 2 was the predominant serotype with 53 isolates, followed by dengue 1 with 48 isolates, dengue 3 with 39 isolates, and dengue 4 with only 8 isolates. Dengue 2 was the only serotype with more isolates from sera with a homologous HI antibody titer greater than 1:20 (57%) than from sera with a homologous HI titer less than or equal to 1:20 (43%). In contrast, most of the dengue 1 isolates (63%) were from sera with a homologous HI antibody titer less than 1:10, and this serotype was strongly associated with primary infections. This study shows that dengue infections remain an important cause of pediatric hospitalization in the Philippines; however, the occurrence of life-threatening dengue hemorrhagic fever as has been described in several other large urban areas of Southeast Asia appears to be rare.     

Diagnosis of human ehrlichiosis with the indirect fluorescent antibody test: kinetics and specificity

Human ehrlichiosis, an acute febrile illness caused by Ehrlichia canis or a closely related rickettsial organism, was first identified in 1986. From 1986 through 1988, sera from 85 patients demonstrated a fourfold rise or fall in antibody titer to E. canis. Seven (22%) of 32 patients initially tested during the first week after onset of illness. 17 (68%) of 25 tested during the second week, and all 18 tested during the third week had titers that exceeded the minimum positive titer of greater than or equal to 80. Of the 85 confirmed ehrlichiosis patients, 31 (36.5%) also had indirect fluorescent antibody titers considered diagnostic of infection with Rickettsia rickettsii, Rickettsia typhi, or Coxiella burnetti, but in most these diagnoses were not supported by epidemiologic, clinical, or serologic evidence. These results emphasize that patients suspected of having a tick-borne infection should be tested for antibodies to E. canis as well as for those to other rickettsiae.     

Group- and type-specific serologic response in infants and children with primary rotavirus infections and gastroenteritis caused by a strain of known serotype

Antibody response to group A rotavirus (RV), investigated in paired sera from 72 infants and young children with acute gastroenteritis caused by an RV infection, was diagnosed on the basis of a fourfold or greater rise in group A common RV IgG antibody titer. Virus-specific IgM was detected in sera from 64 patients showing seroconversion; these were considered primary infection. RV was detected in stools of 56 (77.8%) patients with serologic evidence of infection and 54 were considered primary infection isolates: 39, serotype 1; 11, serotype 4; and 2, serotype 2. Two could not be typed. Neutralizing antibody studies showed that in primary infections serotype 1 induced an antibody response to serotype 4 at least fourfold lower than the homotypic response; serotype 2 elicited antibody titers to serotypes 1 and 4 at least fourfold lower than homotypic titer; and serotype 4 infections produced a response to serotype 1 as high as the homotypic response. Of 12 patients with primary infection, virus was not typed in 2 or detected in 10; however, the infecting serotype was identified on the basis of distinct patterns of homotypic and heterotypic antibody response.     

Detection of specific IgM antibodies for the diagnosis of Mycoplasma pneumoniae infections: a clinical evaluation

The diagnostic value of detection of specific IgM antibodies was analysed in Mycoplasma pneumoniae infections. In a retrospective clinical and serological study, M. pneumoniae IgM antibodies were determined by a mu-capture ELISA using enzyme-labelled antigen. The study group consisted of 91 patients with significantly raised titers in paired sera or a single high titer of complement fixation antibodies. About 40% of the patients had been treated with antibiotics ineffective against M. pneumoniae infections prior to admission to hospital. Treatment with erythromycin or tetracycline was shown to give a shorter period of fever compared to if no or ineffective therapy was given. Specific IgM antibodies were detected in about 80% of sera sampled 9 days or more after onset of symptoms. In sera sampled at 7-8 days after onset IgM antibodies were found in about 40% of the sera but only occasionally in sera sampled earlier. In the age group 0-20 years 88% of the patients developed an IgM response. In the higher ages (greater than 60 years) a significantly lower rate of IgM responders was observed.     

Prevalence of complement fixing antibody to Mycoplasma pneumoniae in Thai children.

The prevalence of antibodies to Mycoplasma pneumoniae was determined in normal Thai children by means of complement fixation. There were 445 children (243 boys and 202 girls) of different ages, ranging from newborn to 15 years. The lowest frequency of complement-fixing antibody was found in children age 1-3 months, and highest in children age 6-10 years which corresponds to the age distribution of symptomatic M. pneumoniae infection. The lowest and highest titers measured were less than 1:8 and 1:512 respectively. The prevalence of complement fixing antibody of titers more than or equal to 1:8, 1:32, 1:64 and 1:128 were 61.3, 31.7, 25.4 and 10.3 per cent of total children, respectively. Among children less than one month old, the frequency of complement fixing antibody of titers greater than or equal to 1:32 was 12.2 per cent and decreased to 1.3 per cent among children from the age 1-3 months. This decrease probably represented the disappearance of maternal antibody over this period. An increase in both the frequency and the geometric mean titer was seen thereafter. The peak frequency of high titers (greater than or equal to 1:32), 81.1 per cent, occurred in children 6-10 year of age. Paired sera were obtained from 72 children with high titers of greater than or equal to 1:64, 9.7 per cent had four fold changes of titer which indicated recent infection.(ABSTRACT TRUNCATED AT 250 WORDS)     

Detection of cryptococcal antigen in bronchoalveolar lavage fluid: a prospective study of diagnostic utility.

Cryptococcal pneumonia is associated with significant morbidity and mortality in immunocompromised patients. We examined the utility of screening bronchoalveolar lavage (BAL) fluid for cryptococcal antigen. In a pilot study, we found that cryptococcal antigen was always positive in unprocessed BAL specimens of seven patients with cryptococcal pneumonia and negative in 44 patients with other granulomatous diseases who acted as the control subjects. A prospective study was done of 220 immunocompromised patients (188 with human immunodeficiency virus infection, 32 with other causes of immunosuppression) undergoing BAL for fever and pulmonary symptoms. The eventual diagnosis of cryptococcal pneumonia was made in eight patients. All eight patients had a cryptococcal antigen titer greater than or equal to 1:8. There were four patients without cryptococcal pneumonia who had cryptococcal antigen titers of 1:8, there were none with higher titers. For a titer of cryptococcal antigen titer of greater than or equal to 1:8, there was 100% sensitivity, 98% specificity, a positive predictive value of 67%, and a negative predictive value of 100%. The measurement of cryptococcal antigen in the BAL can be a rapid, simple way to make a diagnosis of cryptococcal pneumonia in immunosuppressed patients with pneumonia.     

Trends in survival of Danish AIDS patients from 1981 to 1989

Length of survival was analysed in relation to year of diagnosis, AIDS-indicative disease, age, risk behaviour, zidovudine therapy, and CD4 cell count and serum immunoglobulin (Ig) levels at the time of diagnosis in a group of 231 consecutive adult Danish AIDS patients reported before 1 January 1988. The cumulative survival rate was 53% (95% confidence interval 47-59%) at 1 year, 29% (22-36%) at 2 years and 18% (10-26%) at 3 years. Length of survival increased significantly (P less than 0.001) over time for patients who were initially diagnosed with Pneumocystis carinii pneumonia (PCP), 17% (3-31%) at 2 years prior to 1986, 32% (16-49%) in 1986 and 52% (34-69%) in 1987, whereas survival remained stable for patients with other AIDS-indicative diseases. Survival was similar for patients who were diagnosed with Kaposi's sarcoma alone and PCP alone. Independent predictors of a shortened survival were a CD4 cell count less than 200 x 10(6)/l, a serum IgA level greater than 4 g/l, and an initial diagnosis with opportunistic infections other than PCP. In addition, the multivariate analysis suggested an improved survival in recent years for patients diagnosed with PCP, independent of other factors examined. We conclude that length of survival in AIDS patients is highly variable. Determinants of progression include CD4 cell count, serum IgA level, and presenting disease. Survival has increased markedly for patients with PCP and median survival now exceeds 24 months.     

Dual antibody rises to cytomegalovirus and human herpesvirus type 6: frequency of occurrence in CMV infections and evidence for genuine reactivity to both viruses

The frequency of high (greater than 256) IgG anti-human herpesvirus type 6 (HHV-6) titers in sera known to be positive for IgM anti-cytomegalovirus (CMV) or IgM anti-Epstein Barr virus (EBV) was significantly greater than in sera from healthy controls or from a group of ill patients who were CMV and EBV IgM-negative (15/25 and 17/25 vs. 1/25 and 2/25, respectively, P less than .001). There was serologic evidence of simultaneous HHV-6 infection or reactivation (a rise in IgG anti-HHV-6 titer or the presence of IgM anti-HHV-6) in sera from 14 of 17 primary CMV infections. In 5 of the 10 patients with concurrent rises in IgG titers to both viruses, the rise in IgG anti-HHV-6 preceded that of IgG anti-CMV. Complete removal of IgG anti-CMV reactivity from 5 sera from patients who had a primary CMV infection with a rise in IgG anti-HHV-6 titer had no effect on the IgG anti-HHV-6 titer of those sera, demonstrating that the rise in HHV-6 IgG titer was not a consequence of anti-CMV antibodies cross-reacting in the HHV-6 IgG assay.     

Seroepidemiology of amebiasis in the Orang Asli (Western Malaysian aborigine) and other Malaysians.

The indirect hemagglutination test was used to study antibody titers to Entamoeba histolytica in different Malaysian populations. Eighty-seven percent of Orang Asli (western Malaysian aborigines) adults and 79% of Orang Asli children with acute amebic dysentery were seropositive. However, significantly fewer children (39%) with amebic dysentery had high titer responses (titer greater than or equal to 1:1,280) than did adults with amebic dysentery (76%). No correlation between proctoscopic severity and amebic titer was found. Forty-four percent of asymptomatic family members were seroresponders. Satak, an Orang Asli village located near towns, had significantly more seroresponders (32%) than did the isolated, deep jungle village, Belatim (4%).     

Significance of false-positive serologic tests for histoplasmosis and blastomycosis in an endemic area

False-positive serologic tests for histoplasmosis (H) and blastomycosis (B) are common in populations from endemic areas. In order to determine the significance of false-positive test results, we reviewed the final diagnoses of all patients whose sera were submitted to our laboratory for radioimmunoassay (RIA) and immunodiffusion (ID) during a 3-yr period. Of the 263 patients whose sera were examined, 29 (11%) had H or B; 41 (17.5%) of the remaining 234 patients had false-positive test results. Of these 41 patients, 31 were positive for H alone, and 10 had antibodies to both H and B. All three patients with false-positive ID tests for histoplasmosis also had positive titers (greater than or equal to 1:16) on RIA. No patient had a false-positive ID result for blastomycosis. The percentage of patients in each of five major diagnostic categories with and without false-positive serologic tests was similar (p greater than 0.05). The majority of patients had pulmonary infections, almost half of which were granulomatous infections other than H or B; this reflects the clinical indications for requesting fungal serologic tests. A positive fungal serology is not useful in suggesting the presence of a pulmonary disease other than H or B in patients from an endemic area suspected of having a pulmonary mycosis.     

Indirect immunofluorescence test for human Babesia microti infection: antigenic specificity

An indirect immunofluorescence (IIF) test was performed with human sera to detect cross-reactivity of Babesia microti antibodies with other species of Babesia parasites, with other blood and tissue parasites, and with various tick-borne organisms. Antisera to B. microti cross reacted with other Babesia species, but at lower dilutions than with the homologous antigens, and occurred most often during the acute phase of the disease. Cross-reactions with antibodies to malaria, Colorado tick fever, and a variety of other parasitic diseases were uncommon. However, acute and convalescent phase sera from 4 patients with suspected or confirmed Rocky Mountain spotted fever showed a rise in titer to B. microti antigen. In addition, 6 of 185 serum samples from children on an Indian reservation in North Carolina had IIF titers of greater than or equal to 1:256, suggesting a possible focus of B. microti infections in humans.     

Epidemic of fever of unknown origin in rural Thailand, caused by influenza A (H1N1) and dengue fever

In the late summer (rainy season) of 1987, a sharp outbreak of fever of unknown origin (FUO) in rural southern Thailand was investigated by a field epidemiology team. In a random survey of households, 40 percent of the children and 20 percent of adults were reported to have had febrile illnesses within the last month. There was at least one death, possibly from Reye's syndrome. Testing 34 pairs of acute and convalescent sera showed significant HI antibody titer rises to influenza A (Taiwan/(H1N1) (9 cases) and dengue virus (12 cases). Testing 79 single sera with the antibody capture ELISA test for dengue, revealed that 23 percent had high titers in the IgM serum fraction suggesting recent infection. There were also six antibody titer rises to coxsackie B viruses, three from well controls. Dengue has previously been observed as a cause of FUO in rural areas in the tropics, but finding a combined epidemic of dengue and influenza was unexpected. With cooperative villagers, adequate personnel and laboratory support, especially the antigen capture ELISA test for dengue infections, it is feasible to successfully investigate disease outbreaks with serologic methods in remote villages.     

Evaluation of serology and nasopharyngeal cultures for diagnosis of pertussis in a vaccine efficacy trial

Nasopharyngeal cultures and titer rises in paired sera were evaluated in a placebo-controlled pertussis vaccine efficacy trial. IgG ELISA for filamentous hemagglutinin (FHA) identified 30 (88%) of 34 placebo recipients and 33 (89%) of 37 vaccine recipients with culture-verified Bordetella pertussis infections, whereas IgG ELISA for pertussis toxin (PT) showed higher diagnostic sensitivity in the placebo group than in the vaccine groups. The CHO cell assay did not improve sensitivity. Children with Bordetella parapertussis infections had rises of titers of antibody to FHA of the same magnitude as children with B. pertussis infections. Sensitive serologic criteria, based on the intraassay variations, identified 105 additional culture-negative cases with significant titer rises in paired sera. IgG ELISA for FHA and PT and IgA ELISA for FHA were reliable assays, and bacterial isolation rates were lower in vaccine recipients than in placebo recipients with serologically defined pertussis.     

Isolation of Chlamydia pneumoniae and antibodies to the agent in patients with acute bronchitis]

Isolation of Chlamydia pneumoniae and serologic tests were performed on 85 children and adults patients with acute bronchitis admitted to the Kitasato Institute Hospital from January 1989 to May 1991. C. pneumoniae was isolated from sputa or tonsillar swabs in 11 of 57 (19%) patients examined. Of these, 10 patients were tested serologically and 9 (90%) had 16 or higher titer of IgG antibody. A total of 68 patients were tested serologically, and 17 (25%) revealed positive; 14 had a fourfold rise or more in the titer of IgG antibody, or IgM titer of 16 or more, and 3 had IgG antibody with a titer of 512 or greater. In 34 patients, sera were tested for evidence of acute infections not only with C. pneumoniae, but also with Mycoplasma pneumoniae, influenza A virus, influenza B virus, adenovirus, respiratory syncytial virus, coxackie A9 virus, parainfluenza virus type I, II, and III. Two of the 34 patients were associated with influenza A virus, 4 with influenza B virus, whereas 6 were associated with C. pneumoniae. The data available suggest that C. pneumoniae cause bronchitis much more than has been suspected, and also confirm earlier suggestions that the agent played an important role in respiratory tract infections. Chlamydia trachomatis was recovered from sputa and tonsillar swabs in 6 adults patients with acute bronchitis. Studies are needed for a better understanding of the epidemiology and clinical relevance of this microorganism to lower respiratory tract diseases in adults.     

Antibody-dependent enhancement of dengue virus growth in human monocytes as a risk factor for dengue hemorrhagic fever

Serum specimens collected during a prospective study of dengue infections among schoolchildren in Bangkok were tested for their ability to enhance dengue 2 (DEN-2) virus growth in human monocytes in vitro. Two groups of dengue-immune sera were compared: 32 dengue antibody positive serum specimens from children who subsequently developed asymptomatic secondary dengue infections; and 9 dengue antibody positive serum specimens from children who subsequently developed severe symptomatic secondary dengue infections, 8 of which were clinically diagnosed as dengue hemorrhagic fever. Antibody-dependent enhancement of virus growth was quantitated by measurement of virus yields in supernatant fluids of normal human monocyte cultures that were infected with DEN-2 virus in the presence of undiluted test serum. Only 4 of 32 (12%) preinfection sera from asymptomatic children, but 6 of 9 (67%) preinfection sera from symptomatic children, had significant enhancing activity (P less than 0.001). High serum DEN-2 antibody dependent enhancing activity is a significant (relative risk = 6.2) risk factor for severe illness among children in a dengue hemorrhagic fever endemic region. Dengue antibodies can be neutralizing and therefore protective, or they can be enhancing and increase the risk of dengue hemorrhagic fever.     

Immunofluorescent antibody test in American visceral leishmaniasis: sensitivity and specificity of different morphological forms of two Leishmania species

This study was designed to determine which morphologic form and species of Leishmania is most suitable for detection of antibody in sera from American visceral leishmaniasis (AVL) patients by the indirect fluorescent antibody test (IFAT). Promastigotes and amastigotes of Leishmania mexicana or Leishmania donovani chagasi were used as sources of antigen. A total of 70 sera, including 30 from AVL patients, 30 from healthy subjects and 10 from Chagas' disease patients, were used in the study. Titers of antibody up to a dilution of 1:64 were found with all four antigens. At a titer of 1:128, the sensitivity of the IFAT using L. d. chagasi promastigotes as a source of antigen was 100% and the specificity at a titer of 1:32 was 98%. Although the sensitivity of the amastigote forms was close to 100% at a similar titer, the specificity at a titer of 32 using the L. d. chagasi amastigotes was 91% and using L. mexicana amastigotes was only 80%. The L. d. chagasi promastigote antigen was also the one that showed less cross reaction with sera from Chagas' disease patients. Since cross reactivity between Trypanosoma cruzi and Leishmania species is well known in serological tests, and minimizing of such cross reactivity is of critical importance for diagnosis, we suggest that L. d. chagasi promastigotes should be the antigen of choice for diagnosis of visceral leishmaniasis by IFAT in areas also endemic for trypanosomiasis.     

Immunodiffusion and agglutination tests for Candida in patients with neoplastic disease: inconsistent correlation of results with invasive infections.

A serological study of candidiasis was conducted with use of (1) sera sent to the laboratory by clinicians who suspected infections due to various organisms including Candida species, and (2) sera available in our serum bank from patients with candidiasis proven at autopsy and from those with documented candidemia. With this population of patients, we were able to evaluate both potential false-negative and false-positive results. Microimmunodiffusion and slide agglutination tests were used. In many cases, serial specimens were available for measurement of rises or falls in titers of agglutinating antibody. Sera from less than one-half of the patients with disseminated or invasive gastrointestinal candidiasis exhibited positive immunodiffusion reactions, titers of agglutinating antibody of greater than 1:16, or fourfold rises in titer of agglutinins. Sera from several patients with pharyngitis due to Candida and from several who were only colonized with Candida or for whom clinical or cultural evidence of candidiasis was lacking showed positive immunodiffusion reactions or agglutinin titers of greater than 1:16, and some showed fourfold rises in titer. Conversions from negative to positive immunodiffusion reactions were not consistently correlated with invasive candida infection. Using the methods described, we have not found immunodiffusion tests and titers of agglutinating antibody to be reliable indicators of invasive candida infection, since false-positive as well as false-negative reactions occur. Greater specificity for invasiveness as well as greater sensitivity in immunosuppressed patients are necessary before these tests can become important adjuncts to the evaluation of patients with suspected invasive candidiasis.