The term psittacosis is applied to the human C. psittaci dis ease acquired from contact with birds and also the infection of psittacine birds (eg, parrots, parakeets, and cockatoos). The term ornithosis is applied to infection with similar agents in all types of domestic birds (eg, pigeons, chickens, ducks, geese, and turkeys) and free-living birds (eg, gulls, egrets, and petrels). In humans, C. psittaci produces a spectrum of clinical manifestations ranging from severe pneumonia and sepsis with a high mortality rate to a mild inapparent infection.

Properties of the Agent

 C. psittaci can be propagated in embryonated eggs, in mice and other animals, and in some cell cultures. The heat-stable group-reactive CF antigen resists proteolytic enzymes and appears to be a lipopolysaccharide. Treatment of C. psittaci infection with deoxycholate and trypsin yields extracts that contain group-reactive CF antigens, but the cell walls retain the species-specific antigen. Antibodies to the species-specific antigen are able to neutralize toxicity and infectivity. Specific serovars characteristic for certain mammalian and avian species may be demonstrated by immunofluorescence typing. Neutralization of infectivity of the agent by specific antibody or cross-protection of immunized animals can also be used for serotyping, and the results parallel those of immunofluorescence typing.

Pathogenesis and Pathology

The agent enters through the respiratory tract, is found in the blood during the first 2 weeks of the disease, and may be found in the sputum at the time the lung is involved.

Psittacosis causes a patchy inflammation of the lungs in which consolidated areas are sharply demarcated. The exudates are predominantly mononuclear. Only minor changes occur in the large bronchioles and bronchi. The lesions are similar to those found in pneumonitis caused by some viruses and mycoplasmas. The liver, spleen, heart, and kidney are often enlarged and congested.

Clinical Findings

A sudden onset of illness taking the form of influenza or non-bacterial pneumonia in a person exposed to birds is suggestive of psittacosis. The incubation period averages 10 days. The onset is usually sudden, but can be insidious, with malaise, fever, anorexia, sore throat, photophobia, and severe headache. The disease may progress no further, and the patient may improve in a few days. In severe cases, the signs and symptoms of bronchial pneumonia appear at the end of the first week of the disease. The clinical picture often resembles that of influenza, nonbacterial pneumonia, or typhoid fever. The mortality rate may be as high as 20% in untreated cases, especially in elderly adults.

Laboratory Diagnosis

 A. Culture

Culture of C. psittaci can be dangerous, and detection of the organism using immunoassays or PCR is preferred.

If necessary, C. psittaci can be cultured from blood or sputum or from lung tissue by culture in tissue culture cells, embryonated eggs, or mice in an appropriate biosafety level-3 laboratory. Isolation of C. psittaci is confirmed by the serial transmission, its microscopic demonstration, and serologic identification.

B. Antigen Detection of Chlamydia psittaci

Antigen detection by DFA staining or by immunoassay or molecular diagnosis by PCR is done in reference or research laboratories.

C. Serology

A diagnosis of psittacosis is usually confirmed by demonstrating complement-fixing or microimmunofluorescent antibodies in serum specimens. A confirmed case is one with a positive culture result or associated with a compatible clinical illness plus a fourfold or greater change in antibody titer to at least 1:32 or a single MIF IgM titer of at least 1:16. A probable case is one associated with a compatible illness linked epidemiologically with a confirmed case or a titer of at least 1:32 in a single specimen. The CF test is cross-reactive with C. trachomatis and C. pneumoniae. The MIF test is more sensitive and specific than the CF test, but cross-reactions do occur. MIF allows detection of IgM and IgG. Although antibodies usually develop within 10 days, the use of antibiotics may delay their development for 20–40 days or suppress it altogether.

In live birds, infection is suggested by a positive CF test result and an enlarged spleen or liver. This can be confirmed by demonstration of particles in smears or sections of organs and by passage of the agent in mice and eggs.

D. Molecular Methods

 Multiple PCR assays have been developed to detect C. psittaci in respiratory tract specimens, vascular tissues, serum, and mononuclear cells from peripheral blood. These tests are done in reference or research laboratories.

Immunity

 Immunity in animals and humans is incomplete. A carrier state in humans can persist for 10 years after recovery. During this period, the agent may continue to be excreted in the sputum.

Live or inactivated vaccines induce only partial resistance in animals. They have not been used in humans.

Treatment

Because of the difficulty in obtaining laboratory confirmation of C. psittaci infection, most infections are treated based only on the clinical diagnosis. Information on therapeutic efficacy comes from several clinical trials. Doxycycline and tetracycline are the preferred agents for treatment; macrolides and fluoroquinolones may be alternatives.

Epidemiology and Control

Outbreaks of human disease can occur whenever there is close and continued contact between humans and infected birds that excrete or shed large amounts of infectious agent. Birds often acquire infection as fledglings in the nest, may develop diarrheal illness or no illness, and often carry the infectious agent for their normal lifespan. When subjected to stress (eg, malnutrition or shipping), birds may become sick and die. The agent is present in tissues (eg, the spleen) and is often excreted in feces by healthy birds. The inhalation of infected dried bird feces is a common method of human infection. Another source of infection is the handling of infected tissues (eg, in poultry rendering plants) and inhalation of an infected aerosol.

Birds kept as pets have been an important source of human infection. Foremost among these were the many imported psittacine birds. Latent infections often flared up in these birds during transport and crowding, and sick birds excreted exceedingly large quantities of infectious agent. Control of bird shipment, quarantine, testing of imported birds for psittacosis infection, and prophylactic tetracyclines in bird feed have helped to control this source. Pigeons kept for racing or as pets or raised for squab meat have been important sources of infection. Pigeons populating buildings and thoroughfares in many cities, if infected, shed relatively small quantities of agent.

اخر الاخبار

اخبار العتبة العباسية المقدسة

وزارة التعليم العالي تكرم جامعة العميد لحصولها على جائزة المكتبة الأكاديمية المتميزة

جمعية العميد تناقش استعداداتها لانطلاق فعاليات المؤتمر العلمي الرابع لإحياء تراث أمير المؤمنين (عليه السلام)

أكاديمية التطوير الإداري تواصل برنامج الخطة الخمسينية لعدد من ملاكات العتبة العباسية المقدسة

المجمع العلمي يواصل تقديم دورته التطويرية لعدد من الملاكات التربوية في الديوانية

المزيد

الآخبار الصحية

الرياضة وحدها لا تكفي.. كيف يؤثر الجلوس الطويل على الصحة؟

دراسة: بدائل السكر ليست آمنة على الكبد

تفاحة قبل النوم.. عادة بسيطة مفيدة أم خطر على الصحة؟

احذر مشاركتها مع الآخرين.. 3 أدوات شائعة قد تنقل أمراض خطيرة

المزيد

الآخبار التكنلوجية

الهنغاري لاسلو كراسناهوركاي يفوز بجائزة نوبل للآداب 2025

رسميا.. إعلان الفائز بجائزة نوبل للسلام لعام 2025

باحثون: تشات جي بي تي ونماذج الذكاء الاصطناعي يمكن "تسميمها"

عالمان في الأعصاب يرفعان دعوى قضائية ضد شركة آبل

المزيد

مواضيع ذات صلة

Chlamydia Pneumonia and Respiratory Infections

Chlamydia trachomatis Genital Infections and Inclusion Conjunctivitis

Trachoma

Coxiella burnetii

Ehrlichia and Anaplasma

Rickettsia and Orientia

Cultivation of Mycoplasma and Ureaplasma

Laboratory Diagnosis of Mycoplasma and Ureaplasma

Epidemiology and Pathogenesis of Mycoplasma and Ureaplasma

Tropheryma whipplei

Mycoplasma Pneumonia and Atypical Pneumonias

Leptospira and Leptospirosis