Evidence of transmission and risk factors for influenza A virus in household dogs and their owners.

BACKGROUND: The possible transmission of influenza A virus between dogs and humans is important, as in Mexico City there are approximately 1·2 million dogs. We present the first evidence of influenza A virus infection in household dogs in Mexico. OBJECTIVES: The objective of this study was to identify the presence of antibodies against influenza A virus in dogs and their owners, as well as the presence of RNA of influenza A virus in nasal exudates of dogs and, thereby, assess the possible transmission of the virus between humans and dogs. METHODS: Serum samples from household dogs and their owners were analyzed to detect the presence of antibodies against three subtypes of human influenza virus (H1N1pdm09, H1N1, and H3N2), as well as subtype H3N8 of equine influenza. We analyzed dog nasal exudates to detect influenza viral RNA. The relationship between the seropositivity of dogs and various factors (age, sex, constantly at home, and seropositivity of owners) was statistically analyzed. RESULTS: Seroprevalence for human influenza in dogs was 0·9% (1 of 113), and it was 4% (5 of 113) for equine influenza. In humans, seroprevalence was 22% for subtype H1N1pdm09, 20% for subtype H1N1, and 11% for subtype H3N2. No significant association (P>0·05) was found between seropositivity and any of the assessed factors. Furthermore, no viral RNA was detected in the nasal exudate samples. CONCLUSIONS: Results revealed seroprevalence of the influenza virus in household dogs in Mexico City. It can be assumed that dogs are currently becoming infected with different subtypes of influenza viruses.

Retrospective serological survey of influenza viruses in backyard pigs from Mexico City.

BACKGROUND: In the present study, we analyzed the presence of antibodies to four different influenza viruses (pH1N1, hH1N1, swH1N1, and swH3N2) in the sera of 2094 backyard pigs from Mexico City. The sera were obtained between 2000 and 2009. OBJECTIVES: The aim of this study was to perform a retrospective analysis of the 2000-2009 period to determine the seroprevalence of antibodies against pH1N1, hH1N1, swH1N1, and swH3N2 viruses in sera obtained from backyard pigs in Mexico City. METHODS: Antibody detection was conducted with hemagglutination inhibition assay (HI) using four influenza viruses. We used linear regression to analyze the tendency of antibody serum titers throughout the aforementioned span. RESULTS: We observed that the antibody titers for the pH1N1, swH1N1, and swH3N2 viruses tended to diminish over the study period, whereas the antibodies to hH1N1 remained at low prevalence for the duration of the years analyzed in this study. A non-significant correlation (P > 0.05) between antibody titers for pH1N1 and swH1N1 viruses was observed (0.04). It contrasts with the significance of the correlation (0.43) observed between the swH1N1 and swH3N2 viruses (P < 0.01). CONCLUSIONS: Our findings showed no cross-antigenicity in the antibody response against the same subtype. Antibodies against pH1N1 virus were observed throughout the 10-year study span, implying that annual strains shared some common features with the pH1N1 virus since 2000, which would then be capable of supporting the ongoing presence of these antibodies.

Inflammatory profiles in severe pneumonia associated with the pandemic influenza A/H1N1 virus isolated in Mexico City.

The immune mechanisms underlying the pathogenesis of severe pneumonia associated with the A/H1N1 virus are not well known. The objective of this study was to determine whether severe A/H1N1-associated pneumonia can be explained by the emergence of particular T-cell subsets and the cytokines/chemokines they produced, as well as distinct responses to infection. T-cell subset distribution and cytokine/chemokine levels in peripheral blood and bronchoalveolar lavage (BAL) were determined in patients with severe A/H1N1 infection, asymptomatic household contacts, and healthy controls. Cytokine and chemokine production was also evaluated after in vitro infection with seasonal H1N1 and pandemic A/H1N1 strains. We found an increase in the frequency of peripheral Th2 and Tc2 cells in A/H1N1 patients. A trend toward increased Tc1 cells was observed in household contacts. Elevated serum levels of IL-6, CXCL8, and CCL2 were found in patients and a similar cytokine/chemokine profile was observed in BAL, in which CCL5 was also increased. Infection assays revealed that both strains induce the production of several cytokines/chemokines at 24 and 72 h, however, IL-6, CCL3, and CXCL8 were strongly up-regulated in 72-h cultures in presence of the A/H1N1 virus. Several inflammatory mediators are up-regulated in peripheral and lung samples from A/H1N1-infected patients who developed severe pneumonia. In addition, the A/H1N1 strain induces higher levels of pro-inflammatory cytokines and chemokines than the seasonal H1N1 strain. These findings suggest that it is possible to identify biomarkers of severe pneumonia and also suggest the therapeutic use of immunomodulatory drugs in patients with severe pneumonia associated with A/H1N1 infection.

Molecular characterization of Histoplasma capsulatum isolated from an outbreak in treasure hunters Histoplasma capsulatum in treasure hunters.

BACKGROUND: In Mexico, primary pulmonary histoplasmosis is the most relevant clinical form of the disease. The geographical distribution of specific strains of Histoplasma capsulatum circulating in Mexico has not been fully established. Outbreaks must be reported in order to have current, updated information on this disease, identifying new endemic areas, manner of exposure to the fungi, and molecular characterization of the causative agents. We report a recent outbreak of histoplasmosis in treasure hunters and the molecular characterization of two isolates obtained from these patients. METHODS: Six patients admitted to the National Institute of Respiratory Diseases (INER) in Mexico City presented severe respiratory symptoms suggestive of histoplasmosis. They acquired the infection in the Veracruz (VZ) endemic zone. Diagnosis was made by X-ray and Computed tomography (CT), liver function, immunological techniques, and culture. Identification of H. capsulatum isolates was confirmed by using Polymerase chain reaction (PCR) was conducted with a probe from the M antigen, and the isolates were characterized by means of Random amplification of polymorphic DNA (RAPD)-PCR employed the 1253 oligonucleotide and a mixture of oligonucleotides 1281 and 1283. These were compared to eight reference strain isolates from neighboring areas. RESULTS: X-ray and CT revealed disseminated micronodular images throughout lung parenchyma, as well as bilateral retrocaval, prevascular, subcarinal, and hilar adenopathies, hepatosplenomegaly, and altered liver function tests. Five of the six patients developed disseminated histoplasmosis. Two H. capsulatum strains were isolated. The same band profile was detected in both strains, indicating that both isolates corresponded to the sole H. capsulatum strain. Molecular characterization of the isolates was similar in 100% with the EH-53 Hidalgo human (HG) strain (reference strain integrated into the LAm A clade described for Latin America). CONCLUSIONS: The two isolates appeared to possess the same polymorphic pattern; they are indistinguishable from each other and from EH-53. It is important to remain updated on recent outbreaks of histoplasmosis, the manner of exposure to the fungi, as well as the molecular characterization of the isolates. The severity of cases indicates that this strain is highly virulent and that it is probably prevalent in Hidalgo and Veracruz states.

Detection of human papillomavirus and relevant tumor suppressors and oncoproteins in laryngeal tumors.

PURPOSE: The mechanism of larynx oncogenesis is complex and controlled by various factors, most of them involved in cell proliferation and apoptosis. In this study, we evaluated the levels of two suppressor proteins (pRb and p53) and two oncogenic proteins (c-Myc and Bcl-2), as well as the apoptotic levels and the presence of human papillomavirus (HPV) in both tumor types. EXPERIMENTAL DESIGN: Low- or high-risk HPV viral DNA was determined by PCR and in situ PCR; the level of cellular proteins was examined by immunohistochemistry; the presence of apoptotic cells was evaluated by in situ cell death detection. RESULTS: Most laryngeal papillomatosis samples contained low-risk HPV determined by both techniques. However, 25% of laryngeal carcinoma samples were positive for HPV employing PCR or in situ PCR. In papillomatosis, pRb and p53 levels were higher than in normal larynxes, whereas laryngeal cancer presented the lowest levels. c-Myc oncogene expression was very low in normal and cancer tissues but highly increased in papillomatosis. Bcl-2 expression was low and showed no significant difference between laryngeal papillomatosis and normal larynxes. By contrast, Bcl-2 was clearly up-regulated in cancer. Normal larynx samples and those from laryngeal papillomatosis exhibited similar relatively high numbers of apoptotic cells, whereas in malignant tumors, these cells were scarce. CONCLUSION: Our results suggest that HPV is an important risk factor in papillomatosis and in some malignant larynx tumors with a strong participation of cellular genes, specifically involved in proliferation and apoptosis. In benign papillomatosis lesions but not in larynx cancer, high p53 activity might preserve the apoptosis process. In larynx cancer, low p53 levels and high bcl-2 expression may be playing an important role to block apoptosis.