Randomized Trial Evaluating the Impact of Ribavirin Mono-Therapy and Double Dosing on Viral Kinetics, Ribavirin Pharmacokinetics and Anemia in Hepatitis C Virus Genotype 1 Infection

In this pilot study (RibaC), 58 hepatitis C virus (HCV) genotype 1 infected treatment-naive patients were randomized to (i) 2 weeks ribavirin double dosing concomitant with pegylated interferon-alpha (pegIFN-alpha), (ii) 4 weeks ribavirin mono-therapy prior to adding pegIFN-alpha, or (iii) standard-of-care (SOC) ribavirin dosing concurrent with pegIFN-alpha. Four weeks of ribavirin mono-therapy resulted in a mean 0.46 log(10) IU/mL HCV RNA reduction differentially regulated across IL28B genotypes (0.89 vs. 0.21 log(10) IU/mL for CC and CT/TT respectively; P = 0.006), increased likelihood of undetectable HCV RNA week 4 after initiating pegIFN-alpha and thus shortened treatment duration (P <0.05), and decreased median IP-10 concentration from 550 to 345 pg/mL (P <0.001). Both experimental strategies impacted on ribavirin concentrations, and high levels were achieved after one week of double dosing. However, by day 14, double dosing entailed a greater hemoglobin decline as compared to SOC (2.2 vs. 1.4 g/dL; P = 0.03). Conclusion: Ribavirin down-regulates IP-10, and may have an antiviral effect differently regulated across IL28B genotypes.Peer reviewe

Cutaneous resistance against Francisella tularensis

Francisella tularensis, the causative agent of tularemia, is a potent pathogen in humans and other mammals. The ulceroglandular form of the disease is the most common expression in humans with a clinical picture characterized by a skin ulcer, enlarged regional lymph nodes and fever. Despite being a preferred route of infection, the skin also affords an effective defense barrier against F. tularensis. Doses required to induce infection by intradermal inoculation are several logs higher than those needed for infection by other routes. In the present thesis, the requirements for the local and systemic host defense to intradermal infection with F. tularensis was studied in experimental mouse models. Naïve mice and mice immunized by previous infection were challenged, mostly with the live vaccine strain F. tularensis LVS but also with a clinical isolate of F. tularensis. In naïve mice, intradermal inoculation of F. tularensis LVS resulted in a rapid increase of bacterial numbers during the first few days in the skin, lymph nodes, spleen and liver, followed by a decrease and eradication of the bacteria within two weeks of inoculation. Immune mice controlled the infection at the site of infection and very few bacteria spread to internal organs. When immunohistochemical staining of skin specimens was performed during the first 3 days, naïve mice showed a weak or barely discernible local expression of TNF-α, IL-12 and IFN-γ. In immune mice, the expression of all three cytokines was strongly enhanced, TNF-α and IL-12 within 24 h and IFN-γ within 72 h of inoculation. To investigate the role of T cells in the defense against intradermal infection with F. tularensis LVS, naïve and immune T-cell knockout mice (e.g., αβ TCR-/-, γδ TCR-/-, αβγδ TCR-/-) were used. Naïve mice lacking the αβ TCR had persistently high bacterial numbers in all organs and died at 4 weeks. Mice lacking the γδ TCR, on the other hand, controlled the infection as effectively as did wild-type mice. To enable αβ TCR-/- and αβγδ TCR-/- mice to survive, antibiotic treatment was given from day 10 to 20 of infection. When intradermally challenged 2 weeks later, these animals were found to control a secondary infection, resulting in decreasing viable counts in skin and lymph nodes and prevention of spread to liver and spleen. The results indicated the presence of a T-cell independent mechanism of resistance and analyses of serum showed high levels of F. tularensis-specific IgM, findings suggesting a role for antibodies in the protection against cutaneous tularemia. To study the effect of F. tularensis-specific antibodies on host resistance, we adoptively transferred immune serum to B-cell-deficient mice. After receiving immune serum, both naïve and immunized mice became capable of surviving an otherwise lethal dose of F. tularensis LVS. Moreover, transfer of immune serum to wild type mice, afforded significant protection to a lethal dose of a wild-type strain of F. tularensis subsp. holarctica, as disclosed by reduced bacterial counts in spleen and liver. Finally, we studied the effect of immune serum on the local expression of proinflammatory cytokines and neutrophils in response to an intradermal injection of F. tularensis LVS. As compared to normal serum, transfer of immune serum resulted in increased expression of TNF-α, IL-12 and neutrophils. These findings afford a possible explanation for the effect of specific antibodies in the local host protection in the skin against tularemia

Distinct Roles of Reactive Nitrogen and Oxygen Species To Control Infection with the Facultative Intracellular Bacterium Francisella tularensis

Reactive nitrogen species (RNS) and reactive oxygen species (ROS) are important mediators of the bactericidal host response. We investigated the contribution of these two mediators to the control of infection with the facultative intracellular bacterium Francisella tularensis. When intradermally infected with the live vaccine strain F. tularensis LVS, mice deficient in production of RNS (iNOS(−/−) mice) or in production of ROS by the phagocyte oxidase (p47(phox−/−) mice) showed compromised resistance to infection. The 50% lethal dose (LD(50)) for iNOS(−/−) mice was <20 CFU, and the LD(50) for p47(phox−/−) mice was 4,400 CFU, compared to an LD(50) of >500,000 CFU for wild-type mice. The iNOS(−/−) mice survived for 26.4 ± 1.8 days, and the p47(phox−/−) mice survived for 10.1 ± 1.3 days. During the course of infection, the serum levels of gamma interferon (IFN-γ) and interleukin-6 were higher in iNOS(−/−) and p47(phox−/−) mice than in wild-type mice. Histological examination of livers of iNOS(−/−) mice revealed severe liver pathology. Splenocytes obtained 5 weeks after primary infection from antibiotic-treated iNOS(−/−) mice showed an in vitro recall response that was similar in magnitude and greater secretion of IFN-γ compared to cells obtained from wild-type mice. In summary, mice lacking expression of RNS or ROS showed extreme susceptibility to infection with F. tularensis LVS. The roles of RNS and ROS seemed to be distinct since mice deficient in production of ROS showed dissemination of infection and died during the early phase of infection, whereas RNS deficiency led to severe liver pathology and a contracted course of infection

Syndromic Surveillance for Outbreak Detection and Investigation

For the purpose of developing a national system of outbreak surveillance, we compared local outbreak signals in three sources of syndromic data: telephone triage of acute gastroenteritis, web queries about symptoms of gastrointestinal illness, and OTC pharmacy sales of anti-diarrhea medication. The sensitivity and specificity were highest for telephone triage data. It provided the most promising source of syndromic data for surveillance of point-source outbreaks. Currently, a project has been initialized to develop and implement a national system in Sweden for daily syndromic surveillance based on 1177 Health Care Direct, supporting regional and local outbreak detection and investigation

Post-infection symptoms following two large waterborne outbreaks of Cryptosporidium hominis in Northern Sweden, 2010-2011

Background: In 2010-2011, two large waterborne outbreaks caused by Cryptosporidium hominis affected two cities in Sweden, Ostersund and Skelleftea. We investigated potential post-infection health consequences in people who had reported symptoms compatible with cryptosporidiosis during the outbreaks using questionnaires. Methods: We compared cases linked to these outbreaks with non-cases in terms of symptoms present up to eleven months after the initial infection. We examined if cases were more likely to report a list of symptoms at follow-up than non-cases, calculating odds ratios (OR) and 95 % confidence intervals (CI) obtained through logistic regression. Results: A total of 872 (310 cases) and 743 (149 cases) individuals responded to the follow-up questionnaires in Ostersund and Skelleftea respectively. Outbreak cases were more likely to report diarrhea (Ostersund OR: 3.3, CI: 2.0-5.3. Skelleftea OR: 3.6, CI: 2.0-6.6), watery diarrhea (Ostersund OR: 3.4, CI: 1.9-6.3. Skelleftea OR: 2.8, CI: 1.5-5.1) abdominal pain (Ostersund OR: 2.1, CI: 1.4-3.3, Skelleftea OR: 2.7, CI: 1.5-4.6) and joint pain (Ostersund OR: 2.0, CI: 1.2-3.3, Skelleftea OR: 2.0, CI: 1.1-3.6) at follow-up compared to non-cases. Conclusions: Our findings suggest that gastrointestinal-and joint symptoms can persist several months after the initial infection with Cryptosporidium and should be regarded as a potential cause of unexplained symptoms in people who have suffered from the infection