The Study

In 2003, infection with low pathogenic avian influenza A (H7N2) virus was identified in an immunocompromised man with fever and community-acquired pneumonia in New York, USA. The patient recovered. Although the source of the virus was not identified, this case indicates the usefulness of virus culture for detecting novel influenza A viruses.

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A tuberculin skin test was reactive (20-mm induration).HIV ELISA/Western blot test results were positive (HIV test result from 3 years earlier was reportedly negative), and CD4 count was 300 cells/μL.Treatment was switched to rifampin, isoniazid, pyrazinamide, ethambutol, and pyridoxine.Bronchoalveolar lavage (BAL) performed on November 7 yielded infl uenza A virus by tissue cell culture at the Westchester County Department of Laboratories and Research and was negative for Pneumocystis spp., Legionella spp., and other bacterial or viral pathogens.A second BAL and biopsy performed later during hospitalization to evaluate adenopathy indicated infl ammation without defi nitive pathology.The lower respiratory tract disease improved after 13 days, and the patient was empirically prescribed tuberculosis treatment (directly observed therapy) and discharged while mycobacterial culture results were pending.After 8 weeks, mycobacterial culture of the BAL specimen was negative for Mycobacterium tuberculosis but yielded M. avium complex.
The patient lived in an apartment with his wife and 4 children, none of whom were sick during his illness.He denied recent travel and had not traveled outside the United States for 4 years.He worked in a cafeteria as a dishwasher and handled food and garbage until 1 month before hospitalization.He denied any known risk factors for HIV infection.
The infl uenza A virus isolate was diffi cult to grow in culture, reacted minimally with antiserum to hemagglutinin H1, and was sent to the Centers for Disease Control and Prevention (CDC) for further characterization.On March 19, 2004, CDC reported that the infl uenza isolate, designated A/New York/107/2003, was an LPAI A (H7N2), not subtype H1N1, virus.
An epidemiologic investigation was initiated by the Westchester County Department of Health.During 3 interviews (with a Creole interpreter), the patient denied any exposure to live or dead poultry, wild birds, or bird feces.No live poultry markets or poultry were found on the surrounding property or in the neighborhood.
Serum samples obtained during the patient's hospitalization on November 5, 2003, and on April 4, 2004, were tested at CDC by microneutralization assay with the LPAI A (H7N2) virus from the patient.The acute-phase serum sample was negative (titer 10), but the convalescentphase serum sample was positive (infl uenza [H7N2] virus neutralizing antibody titer 80), indicating seroconversion and evidence of infection with LPAI A (H7N2) virus.A confi rmatory Western blot assay detected H7 hemagglutinin-specifi c antibody in the convalescent-phase serum sample.Testing of paired serum samples by ELISA demonstrated a 16-fold rise in H7 hemagglutinin-specifi c IgG. Serum samples collected from the patient's wife and 3 of the children on April 4, 2004, were seronegative for infl uenza A (H7N2) neutralizing antibodies.

Conclusions
In this immunocompromised man with pneumonia, the contribution of infl uenza A (H7N2) virus infection to his lower respiratory tract disease is unclear.The diagnosis of infl uenza A (H7N2) virus infection was not made until long after the patient had been discharged, and no infl uenza antiviral treatment was administered.The patient's history and clinical fi ndings were consistent with HIV and community-acquired pneumonia with possible clinical response to the antimicrobial drug therapy or improvement of self-limiting viral pneumonia.In patients with HIV infection, M. avium complex is often detected as an indolent pathogen, especially associated with disseminated disease in patients with advanced AIDS; clinical resolution usually requires prolonged multidrug treatment (7).Isolation of infl uenza A (H7N2) virus from a BAL specimen and resolution of lower respiratory tract disease during hospitalization suggest that this infection might have contributed to the pulmonary disease.The clinical spectrum of human infection with LPAI viruses, including subtype H7, is generally mild, ranging from conjunctivitis to infl uenza-like illness (1-6), although hospitalization of patients with infl uenza A (H7N2) virus infection has been reported (6).
Conjunctival infection with infl uenza A subtype H7 viruses in persons with conjunctivitis has been confi rmed by reverse transcription PCR or virus isolation (1)(2)(3)5).The patient initially reported ophthalmologic symptoms.Because conjunctival specimens were not available for virus testing, the role of infl uenza A (H7N2) virus in the conjunctivitis is unknown.However, intraocular inoculation of mice with the infl uenza A (H7N2) virus from the patient (A/New York/107/2003) did not result in infection, and the virus replicated at relatively low levels in murine corneal epithelial cells ex vivo (8,9).Intranasal inoculation with the LPAI A (H7N2) virus caused respiratory symptoms, elevated mean lung titers, and cytokine increases in mice; among ferrets, the virus replicated effi ciently in the upper respiratory tract and was transmissible through direct contact (8,10).
The source of the patient's infection with infl uenza A (H7N2) virus was not determined, although exposure to poultry was suspected.A limitation is that the investigations were conducted 5 months after the patient was hospitalized, after the infl uenza A isolate was identifi ed as an LPAI A (H7N2) virus.LPAI A (H7N2) viruses have been documented among birds in live poultry markets in the northeastern United States, including New York (11)(12)(13).Such viruses have receptor-binding properties consistent with receptors found in the human upper respiratory tract (10).
This case of LPAI A (H7N2) virus infection was detected through infl uenza virus surveillance of specimens submitted from outpatients and hospitalized patients to the Westchester County Department of Laboratories and Research and illustrates the value of virus culture for detection of human infections with novel infl uenza A viruses, which are nationally notifi able.For the patient reported here, neither seasonal infl uenza nor zoonotic infl uenza was suspected.Whether HIV infection might have made the patient more susceptible to lower respiratory tract infection with LPAI A (H7N2) virus is unknown, but a case of pulmonary infection with LPAI A (H9N2) virus in an immunosuppressed adult has been reported (14).A serologically confi rmed case of LPAI A (H7N2) virus infection in the United States was associated with upper respiratory tract illness (4).Although information about the frequency of human infection with LPAI A H7 viruses is limited, 1 study reported antibody detection in 3.8% of exposed poultry workers after an outbreak of LPAI A (H7N3) virus infection among poultry in Italy (15).More information is needed to clarify the risk for LPAI A H7 virus infections among immunocompetent and immunocompromised persons.

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