H5N2 strains of low-pathogenicity avian influenza virus (LPAIV) have been circulating for at least 17 years in some Mexican chicken farms. We measured the rate and duration of viral excretion from Pekin ducks that were experimentally inoculated with an H5N2 LPAIV that causes death in embryonated chicken eggs (A/chicken/Mexico/2007). Leghorn chickens were used as susceptible host controls. The degree of viral excretion was evaluated with real-time reverse transcriptase-polymerase chain reaction (RRT-PCR) using samples from oropharyngeal and cloacal swabs. We observed prolonged excretion from both species of birds lasting for at least 21 days. Prolonged excretion of LPAIV A/chicken/Mexico/2007 is atypical.
Animals ; Chickens ; Cloaca/virology ; *Ducks ; Influenza A Virus, H5N2 Subtype/*physiology ; Influenza in Birds/*physiopathology/virology ; Oropharynx/virology ; Poultry Diseases/physiopathology/virology ; Real-Time Polymerase Chain Reaction/veterinary ; Reverse Transcriptase Polymerase Chain Reaction/veterinary ; Time Factors ; *Virus Shedding

OBJECTIVETo identify histopathologic changes of major organs and to correlate clinical symptoms in patients infected by avian influenza H5N1.

METHODSAutopsy study was performed in two patients died of avian influenza HSN1 infection, following conventional protocols and strict safety procedures. Tissue samples from all major organs of two cases and lung samples of one case were collected and fixed in 4% formaldehyde. Histopathologic changes were evaluated by light microscope.

RESULTSDiffuse alveolar damage (DAD) of the lung was seen in both cases. Lesions at various stages of development were seen involving different areas of the lung. At the early stages, the lungs exhibited exudative changes, including capillary congestion, necrosis of alveolar epithelial cells, and intra-alveolar edema. Hyaline membranes were prominent and diffusely distributed along alveoli. In the middle-late stages of the disease, the lungs exhibited proliferative and fibrotic changes, including proliferation of pneumocytes and bronchial epithelium, fibrosis of the interstitium and alveolar spaces. Lung biopsy tissue of one case showed DAD and interstitial fibrosis in a background of bronchiectasis. Lymph nodes and spleens showed quantity reduction of lymphocytes and active hemophagocytosis. Other changes in major organs included interstitial carditis in one case and acute renal tubular necrosis in one case. In one case, the brain showed edema with cytoplasmic eosinophilia, loss of structure, axon welling and focal necrosis around ventricle. Multiple foci of trophoblastic necrosis with dystrophic calcification were observed in placenta of one pregnant patient. Acute necrotizing deciduitis was found focally. Sections of fetal lung showed edema and scattered interstitial neutrophils were consistent with acute interstitial pneumonitis.

CONCLUSIONSThe respiratory tract is the major target of avian influenza A H5N1 virus infection. The changes of DAD in the lungs resulted in hypoxia, leading to multiple organ failure and death.

Adult ; Alveolar Epithelial Cells ; pathology ; Animals ; Birds ; Fatal Outcome ; Female ; Humans ; Influenza A Virus, H5N1 Subtype ; pathogenicity ; Influenza in Birds ; pathology ; physiopathology ; virology ; Influenza, Human ; pathology ; Male ; Pregnancy ; Pulmonary Fibrosis ; etiology ; pathology

OBJECTIVETo summarize and analyze the clinical characteristics and diagnostic and therapeutic measures for the first human case of H5N1 avian influenza pneumonia in mainland of China.

METHODSThe clinical data of the first case of H5N1 avian influenza virus infection in China were analyzed and summarized.

RESULTSThe case is a 9-year old boy, who developed acute symptoms of a light common respiratory infection, including fever and dry cough without obvious catarrh. On the 7th day after onset, his temperature reached 40 degrees C, tachypnea occurred, distinct rales could be heard and large areas of consolidation were seen in the lungs on chest X-ray. The patient's peripheral blood leukocyte count was 2.81 x 10(9)/L and neutrophils dominated. After comprehensive therapeutic approaches, including antiviral therapy (amantadine) and use of low-dosage glucocorticoid, the patient's temperature returned to normal on the 3rd hospitalization day, chest X-ray showed absorbed inflammatory change on the 5th day after admission, and leukocyte count became normal on the 6th day. No complication occurred during the whole course. The case was diagnosed by the 4 fold raised antibody to the H5N1 influenza virus in recovery stage serum because the H5N1 nucleic acid test in early stage was negative. The case was cured and discharged after 3 weeks comprehensive treatment.

CONCLUSIONSIt is very important for clinicians to pay enough attention to epidemiological history, especially history of exposure to avian influenza virus contaminated material, which will be very helpful for early detection, early diagnosis of the disease, and also very important for effective treatment and better prognosis.

Amantadine ; therapeutic use ; Animals ; Antibodies, Viral ; blood ; immunology ; Antiviral Agents ; therapeutic use ; Birds ; Child ; China ; Glucocorticoids ; therapeutic use ; Humans ; Influenza A Virus, H5N1 Subtype ; immunology ; isolation & purification ; Influenza in Birds ; transmission ; Influenza, Human ; complications ; diagnosis ; Male ; Pneumonia ; diagnosis ; drug therapy ; physiopathology ; virology ; Treatment Outcome