An outbreak of psittacosis in a boys' boarding school

Human psittacosis: a review with emphasis on surveillance in Belgium

Chlamydia psittaci causes psittacosis in humans, mainly in persons in contact with birds in either the setting of occupational or companion bird exposure. Infection is associated with a range of clinical manifestations from asymptomatic infection to severe atypical pneumonia and systemic disease. This paper reviews new knowledge on psittacosis, its legal and regulatory aspects and presents epidemiological data on psittacosis in Belgium. In Belgium, the number of reported positive laboratory results increased slowly since 2010, and in 2017, the number almost doubled compared to the two previous years. The number of psittacosis cases in Belgium, as in other countries, is probably highly underestimated, because of underdiagnoses and underreporting. Over the 3-year period, the mandatory notification system registered 24% only of all reported positive laboratory result. Therefore, increased awareness among general and occupational physicians, clinicians and the public is needed. Policies aimed at reducing psittacosis disease burden are justified, nevertheless national health authorities should provide more legal and financial support to implement more adequate C. psittaci diagnostic tools.

Laboratory methods for case finding in human psittacosis outbreaks: a systematic review

Background

Psittacosis outbreak investigations require rapid identification of cases in order to trace possible sources and perform public health risk assessments. In recent outbreaks in the Netherlands, such investigations were hampered by the non-specificity of laboratory testing methods to identify human Chlamydia psittaci infections.

Method

A systematic search of PubMed and Scopus databases of literature published between 01 January, 1986 and 03 July, 2017 was done to find best practices of laboratory-testing methods used in psittacosis outbreaks of two or more human cases. Reference lists of included articles were hand searched to identify additional articles.

Results

Thirty-seven eligible articles were identified, describing 44 human psittacosis outbreaks in 12 countries. Laboratory tests performed were PCR (with various targets), serologic tests (complement binding reactions, ELISA’s, immunofluorescence tests and immuno-peroxidase tests) and culture, in various combinations. The literature provided no ‘gold standard’ laboratory testing strategy to identify recent human C. psittaci infections. In most psittacosis outbreaks, for a considerable number of cases (or tested individuals in an exposed cohort), C. psittaci infection could not be confirmed, nor excluded as causative pathogen. None of the testing strategies was found to be suitable for (nearly) full case finding.

Conclusion

PCR enables rapid identification of human psittacosis patients and helps source finding by genotyping but has the disadvantage that sensitivity is high only in the acute phase. In outbreak situations, there is often a time delay and therefore, there is a need for new serologic testing methods next to PCR, with good specificity and sensitivity. Moreover, serum is easier to collect than the preferred diagnostic materials for PCR. A serologic test that can reliably confirm infection status without the necessity of convalescent serum sampling would enhance case finding, source tracing, identification of risk factors and assessment of burden of disease in various settings.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3317-0) contains supplementary material, which is available to authorized users.

Association of Alzheimer's disease and Chlamydophila pneumoniae

This paper critically reviews the association of infection by Chlamydophila pneumoniae (C. pneumoniae) and Alzheimer's disease (AD). The aging population has increased interest in finding the cause of AD, but studies have yielded contradictory results that are likely due to varying diagnostic tools and different uses of diagnostic tests. Knowledge of AD's characteristics, risk factors, and hypothesized etiologies has expanded since Alois Alzheimer's initial description of AD. Epidemiologic and projection studies provide incidence estimates of AD through a two-stage method: (1) primary diagnosis of dementia by cognitive testing such as Mini-Mental State Examination (MMSE), and (2) clinical diagnosis of AD through criteria such as National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders Association (NINCDS-ADRDA). Cross-sectional studies yield prevalence estimates of infection by C. pneumoniae by detecting immunoglobulins through laboratory tests such as microimmunofluorescence (MIF). Studies examining the association of C. pneumoniae and AD are limited, but brain autopsy provides information about presence, proximity to areas associated with AD, and bacterial load. Standardization of diagnostic techniques would allow for better comparability of studies, but uncertainty about the best method of diagnosis of infection by C. pneumoniae and AD may call for revised or novel diagnostic tools.

An epidemic of a pertussis-like illness caused by Chlamydia pneumoniae

BACKGROUND

Between June and July, 1994, we encountered an epidemic of a pertussis-like illness in adolescents in a junior high school located in a rural area of Japan. The purposes of this study were to record the clinical manifestations and to identify an etiology.

PATIENTS AND METHODS

We interviewed patients and parents and we performed physical examinations on patients with cough during the epidemic. The chest radiographs were also reviewed by us. To identify an etiology we performed culture and serologic studies for a variety of bacteria, Mycoplasma, chlamydiae and viruses. Polymerase chain reaction (PCR) for Chlamydia pneumoniae was carried out on throat swab specimens.

RESULTS

Of a total of 230 students 136 (59%) had severe cough illnesses. One developed pneumonia, 9 had bronchitis and the remaining 126 (93%) presented upper respiratory tract infections (URI). The mean duration of cough in cases with URI was 17.4 days and that in cases with bronchitis and pneumonia was 30.4 days. Serology and/or cultures for Bordetella pertussis, Bordetella parapertussis, Mycoplasma pneumoniae, Chlamydia trachomatis, Chlamydia psittaci or viruses were negative. Detection of C. pneumoniae infection was carried out in 46 patients with pneumonia, bronchitis or URI by serology and PCR. The patient with pneumonia, 7 of 7 patients with bronchitis and 32 (84%) of 38 patients with URI were documented to be infected by C. pneumoniae either by serology, PCR or both tests.

CONCLUSION

An epidemic of a pertussis-like illness in a junior high school population was caused by C. pneumoniae.

A review of outbreaks of infectious disease in schools in England and Wales 1979-88

In this review of 66 outbreaks of infectious disease in schools in England and Wales between 1979-88, 27 were reported from independent and 39 from maintained schools. Altogether, over 8000 children and nearly 500 adults were affected. Most of the outbreaks investigated were due to gastrointestinal infections which affected about 5000 children: respiratory infections affected a further 2000 children. Fifty-two children and seven adults were admitted to hospital and one child with measles died. Vaccination policies and use of immunoglobulin for control and prevention of outbreaks in schools have been discussed.

Chlamydia pneumoniae, strain TWAR, as the cause of an outbreak in a boys' school previously called psittacosis

Sera from an outbreak of acute respiratory illness in a boys boarding school originally thought to have been due to psittacosis (1) have been re-examined and evidence is presented that suggests that the outbreak was caused by Chlamydia pneumoniae, strain TWAR (2).

Current knowledge on Chlamydia pneumoniae, strain TWAR, an important cause of pneumonia and other acute respiratory diseases

This article reviews current knowledge of Chlamydia pneumoniae strain TWAR, a newly recognized Chlamydia organism that causes acute respiratory infection, especially atypical pneumonia. Information is included on the microbiology, classification and laboratory diagnosis of the organism. Details of a series of studies of both endemic and epidemic respiratory infections are reviewed to present information on both the clinical and epidemiological characteristics of infection with strain TWAR. Laboratory studies of antibiotic sensitivity and recommendations for treatment are presented.

Psittacosis--a review of 135 cases

We reviewed retrospectively 135 cases of serologically-confirmed psittacosis that were admitted to Fairfield Hospital between January 1, 1972 and March 31, 1986. The average age of the patients was 46 years. The majority (85%) of patients described a history of recent exposure to birds. The clinical features, investigations, treatment and subsequent response were analysed in 129 patients. Psittacosis was a well-defined illness that was characterized by an abrupt onset of fever, rigors, sweats, and prominent headache, and a mild dry cough which appeared late frequently. However, respiratory symptoms were absent in 18% of patients. Diarrhoea and sore throat were occasional complaints. Over 90% of cases had an abnormal chest x-ray film, or abnormal chest signs, or a combination of both. Most patients had a normal leukocyte count. Tetracycline drugs were used for treatment in 87% of the patients. Defervescence occurred in 92% of patients after 48 h of tetracycline treatment. There were no recrudescences of psittacosis and no fatalities. The clinical diagnosis of psittacosis can be made early usually, particularly in the presence of pneumonitis on a chest x-ray film and a positive history of bird contact. Treatment with doxycycline (100 mg twice a day for 14 days) is recommended.

Psittacosis in a highly endemic area in Italy

In one locality in Italy where the incidence of psittacosis has increased rapidly since 1980, a hospital-based study and a seroepidemiological survey were carried out in order to define the clinical and epidemiological features of psittacosis in that area. Registers of the Virology Unit of the University of Ancona, Italy, were reviewed and all hospitalized patients with a serological diagnosis of psittacosis were identified. A total of 76 cases were found and studied. A presumptive bird source was identified in 80% of 62 patients, on whom a detailed investigation had been possible. Poultry represented the most frequent probable source of infection. Clinically, the predominant pattern of illness was a moderately severe lower respiratory tract infection, with chest X-rays showing pulmonary shadowings in 68 patients (89%). In the seroepidemiological study, 51 out of 143 subjects were exposed to birds (35.7%), but only 7 out of 96 urban adult blood donors (7.3%) were positive for chlamydial antibodies using the microimmunofluorescence test.

Clinical conditions associated with positive complement fixation serology for Chlamydiae

The hospital records of 242 patients with diagnostic chlamydial complement fixation (CF) titres (seroconversion and/or titre greater than or equal to 64) found among 60,000 patients screened for suspected viral illnesses were reviewed to study the clinical conditions associated with positive CF serology for Chlamydiae. After excluding typical genital C. trachomatis infections, the majority of the remainder were considered to represent C. psittaci infections. Respiratory symptoms were the most common clinical manifestations of chlamydial infections detectable by CF, but the majority (58%) of the patients did not have pneumonia. Abdominal, neurological as well as urinary tract symptoms were common. Cutaneous, joint, cardiac, genital and ocular manifestations were also noted. Fever (greater than or equal to 38.5 degrees C) was present in 62% of the patients. The ESR was raised (greater than or equal to 20 mm/h) in the majority of the patients (83%), but the leucocyte count was usually (86%) within normal limits. Because the clinical spectrum of C. psittaci infections is apparently broad, serological tests for detecting antibodies to C. psittaci (e.g. CF) should be used widely in various clinical conditions and not for patients with pneumonia alone.

Prevalence in human beings of antibodies to Chlamydia IOL-207, an atypical strain of chlamydia

Samples of serum from 18353 persons from the U.K. and abroad, were tested for type-specific antibodies to Chlamydia spp. Antibodies to an atypical strain, Chlamydia IOL-207, were detected in each population tested. Overall, the prevalence of these antibodies (19.9%) was similar to that of antibodies to C. trachomatis (21.6%). In the U.K., antibodies to C. IOL-207 were rare in children under the age of 5 years but became more common with increasing age. In adults the prevalence of these antibodies increased annually between 1979 and 1984. Antibodies to C. IOL-207 were not associated with sexually transmitted disease and only rarely with ocular disease. Their association with a common complaint such as mild respiratory illness is postulated. The presence of these antibodies within a population may lead to the over-diagnosis of C. trachomatis infections or psittacosis if only genus-specific serological tests are used.

Psittacosis in general practice: implications for control

In one general practice over a six-week period three patients with atypical pneumonia were shown serologically to have psittacosis. All three patients had been exposed to the same flock of ducks but veterinary investigation three months after the first case had been reported did not show the ducks to be infected. However, in a retrospective review of laboratory-diagnosed psittacosis, a likely source of infection was found in 11 out of 24 cases and in most of these full medicoveterinary investigation would have been warranted. Early diagnosis, reporting quickly to the medical officer for environmental health and early liaison with the divisional veterinary officer are essential prerequisites if psittacosis is to be controlled. If psittacosis were made a statutory notifiable disease this would encourage a more energetic approach to its control. The proposed cutbacks in the veterinary investigation service will make full investigations more difficult.