Complications of influenza infection in children

Analysis of Clinical Manifestations and Laboratory Findings in Children with Influenza B-Associated Myositis: A Single Center Study

Background

Influenza-associated myositis (IAM) is a rare and poorly recognized complication of influenza infection in children, and is characterized by acute onset of severe pain in the lower extremities and a refusal to ambulate walk. We sought to understand the association between IAM and influenza B infection and to investigate its clinical and laboratory characteristics in affected children.

Methods

Influenza B-associated myositis (IBAM) cases diagnosed in the pediatrics department of Wonkwang University Hospital from January 2010 and March 2016 were analyzed retrospectively.

Results

Medical records of affected children were examined, and clinical characteristics and laboratory findings were recorded. Of the 536 children diagnosed with influenza B infection, 47 children complained of bilateral calf pain with or without gait disturbance. All children exhibited elevated serum aspartate aminotransferase (AST) level. The median serum creatine kinase (CK) and lactate dehydrogenase (LDH) levels, reportedly elevated in myositis, were 2,597 IU/L and 678 IU/L, respectively. While the immunofluorescence test results were negative for some patients, the polymerase chain reaction test results indicated influenza B infection in all 47 children. At the time of hospital discharge, the patients' symptoms had resolved, and their CK levels had improved.

Conclusion

IBAM was generally benign and short, and although the blood AST, CK, and LDH levels were markedly high, the erythrocyte sedimentation rate and C-reactive protein levels were normal. Further, the duration of IBAM symptoms correlated with the duration of fever. The IBAM-associated clinical and laboratory findings are highly characteristic and may allow its rapid diagnosis during the influenza season.

Anti-influenza virus activity of tricin, 4',5,7-trihydroxy-3',5'-dimethoxyflavone

BACKGROUND

We examined the anti-influenza virus activity of tricin, 4',5,7-trihydroxy-3',5'-dimethoxyflavone, against five viruses: A/Solomon islands/3/2006 (H1N1), A/Hiroshima/52/2005 (H3N2), A/California/07/2009 (H1N1pdm), A/Narita/1/2009 (H1N1pdm) and B/Malaysia/2506/2004 strains in vitro and against A/PR/8/34 virus in vivo.

METHODS

The effect of tricin was studied by an infectious virus yield reduction assay. The anti-influenza virus mechanism of the tricin was examined by western blot analysis, real-time reverse transcriptase PCR analysis, haemagglutination inhibition (HI) assay and neuraminidase (NA) inhibition assay. The anti-influenza virus efficacy of tricin was further examined in a murine influenza virus infection model.

RESULTS

Tricin of 3.3 to 30 μM significantly reduced seasonal A (H1N1), (H3N2) viruses, novel A (H1N1pdm) virus, as well as B virus in a dose-dependent manner. The 50% effective concentrations of tricin were 3.4 μM for seasonal A (H3N2) virus, 4.9 μM for B virus and 8.2 μM for A/Narita (H1N1pdm) virus. Tricin decreased the expression of haemagglutinin (HA) protein and matrix (M) protein, and messenger RNA expression of HA and M of influenza virus in the infected cells. Tricin exhibited little or no effects on influenza virus HI and NA activities. In the mouse infection model, tricin was significantly effective in reducing body weight loss, and also effective in prolonging survival times of infected mice.

CONCLUSIONS

Tricin was indicated to possess anti-influenza virus activity and to ameliorate body weight loss and survival rate of influenza-A-virus-infected mice. Tricin is a novel compound with potential anti-influenza virus activity in vitro and in vivo.

Shedding of live vaccine virus, comparative safety, and influenza-specific antibody responses after administration of live attenuated and inactivated trivalent influenza vaccines to HIV-infected children

HIV-infected children (N=243), >or=5 to <18 years old, receiving stable antiretroviral therapy, were stratified by immunologic status and randomly assigned to receive intranasal live attenuated influenza vaccine (LAIV) or intramuscular trivalent inactivated influenza vaccine (TIV). The safety profile after LAIV or TIV closely resembled the previously reported tolerability to these vaccines in children without HIV infection. Post-vaccination hemagglutination inhibition (HAI) antibody responses and shedding of LAIV virus were also similar, regardless of immunological stratum, to antibody responses and shedding previously reported for children without HIV infection. LAIV should be further evaluated for a role in immunizing HIV-infected children.

Clarithromycin inhibits progeny virus production from human influenza virus-infected host cells

In vitro effects of macrolide clarithromycin (CAM) on influenza A virus-infected cells were examined using plaque reduction assay by treating cells either before or after viral adsorption. The significant inhibitory effect on influenza virus infection was detected only when the cells were treated with CAM after viral adsorption. The predominant inhibitory effect was observed during 4-7th hour after viral adsorption using viral production assay. CAM did not exhibit inhibitory effects on influenza virus hemagglutination, membrane fusion and viral sialidase activities. These findings indicate that CAM acts on a middle to late stage of the viral replication cycle resulting in inhibition of progeny virus production from the infected cells.

Frequency and Effects of Bacterial Infection in Children with Influenza Under Oseltamivir Treatment

BACKGROUND

New antiviral drugs can rapidly improve the symptoms of influenza, but some patients still have prolonged fever and complications. The cause of the prolonged symptoms despite antiviral therapy remains unclear. Recent studies have shown a synergistic effect between influenza viruses and bacteria. This study investigated the frequency of bacterial infection in such patients and its effects on the clinical course to determine the need for antibiotics.

METHODS

In two seasons (December 2001 through March 2002, and December 2002 through March 2003), throat cultures were obtained from 387 patients with influenza being treated with oseltamivir, and clinical courses were observed. Control throat cultures were obtained from 109 healthy children.

RESULTS

The detection rate of pathogens was higher in patients with influenza (54.3%) than in control (23.9%, p<0.001). The most common pathogen was Streptococcus pneumoniae (49.7%) in patients with influenza and was Haemophilus influenzae (69.2%) in controls. Of the patients with normal flora, 4.1% had fever for 4 or more days and showed pathogens in throat cultures on day 4. Of the patients with pathogen-positive cultures who did not receive antibiotics, 40.3% had fever for 4 or more days.

CONCLUSION

Throat cultures obtained on the first or fourth day of treatment with oseltamivir were positive for pathogenic bacteria in all patients with fevers for 4 or more days. Our observations suggest that patients with influenza and prolonged fever despite receiving oseltamivir should be given antibiotics.

Effect of maclorides on duration and resolution of symptoms and complication of pneumonia in children with influenza

We randomly administered cephalosporins or macrolides to 365 pediatric patients with influenza-like symptoms and compared the clinical course and complication rate of pneumonia. One hundred and fifty-four patients received cephalosporins (Group 1) and 211 received macrolides (Group 2). There were no significant differences in age, male/female ratio and body weight between the two groups. Macrolides alleviated fever significantly faster than cephalospoins (3.8plus minus 1.4 days vs 4.3plus minus 1.4 days), though maximum body temperature showed no significant difference between the two groups. Thirty-nine patients underwent laboratory examinations and twenty-nine had high influenza A (H3N2) virus haemagglutinate inhibition (HI) titer, six had high influenza B (B1) virus HI titer and four did not show any elevation of influenza virus HI titer. Thirteen patients in Group 1 and two patients in Group 2 suffered from pneumonia and the complication rate was significantly lower in Group 1 than in Group 2 (8.4% vs 0.9%). All of them recovered within two weeks and did not have any other complications.

CONCLUSION

Macrolides are more effective in reducing the time required to alleviate fever and complication rate of pneumonia than cepharosporines in children with influenza and influenza-like illness. These results indicate that macrolides may have therapeutic value for influenza virus infection.