Leo G. Visser

The effect of anti-tumour necrosis factor α treatment on the antibody response to influenza vaccination

Objectives: The effect of anti-tumour necrosis factor (TNF) therapy on the antibody responses to vaccines is the subject of ongoing debate. Therefore, we investigated the effect of the three currently available anti-TNF agents on influenza vaccination outcomes in a patient population with long-standing disease. Methods: In a prospective cohort study, we assessed the antibody response upon influenza vaccination in 112 patients with long-standing autoimmune disease treated with immunosuppressive medication either with anti-TNF (etanercept, adalimumab or infliximab; n = 64) or without anti-TNF (n = 48) and a control group of 18 healthy individuals. Antibody responses were determined by haemagglutination inhibition assay, before and 4 weeks after vaccination. Results: The proportion of individuals with a protective titre (⩾40) after vaccination was large (80–94%) and did not significantly differ between the three groups. Post-vaccination geometric mean antibody titres against influenza (A/H3N2 and B) were significantly lower in the 64 patients treated with anti-TNF compared with the 48 patients not receiving anti-TNF, and the healthy controls. Conclusions: The antibody response to influenza vaccination in patients treated with anti-TNF is only modestly impaired. The proportion of patients that achieves a protective titre is not significantly diminished by the use of TNF blocking therapies.

Extended-Spectrum β-Lactamase–producing Enterobacteriaceae among Travelers from the Netherlands

A prospective cohort study was performed among travelers from the Netherlands to investigate the acquisition of carbapenemase-producing Enterobacteriaceae (CP-E) and extended-spectrum β-lactamase–producing Enterobacteriaceae (ESBL-E) and associated risk factors. Questionnaires were administered and rectal swab samples were collected and tested before and after traveler return. Of 370 travelers, 32 (8.6%) were colonized with ESBL-E before trave,; 113 (30.5%) acquired an ESBL-E during travel, and 26 were still colonized 6 months after return. No CP-E were found. Independent risk factors for ESBL-E acquisition were travel to South and East Asia. Multilocus sequence typing showed extensive genetic diversity among Escherichia coli. Predominant ESBLs were CTX-M enzymes. The acquisition rate, 30.5%, of ESBL-E in travelers from the Netherlands to all destinations studied was high. Active surveillance for ESBL-E and CP-E and contact isolation precautions may be recommended at admission to medical facilities for patients who traveled to Asia during the previous 6 months.

Treatment outcome of intravenous artesunate in patients with severe malaria in the Netherlands and Belgium

BackgroundIntravenous (IV) artesunate is the treatment of choice for severe malaria. In Europe, however, no GMP-manufactured product is available and treatment data in European travellers are scarce. Fortunately, artesunate became available in the Netherlands and Belgium through a named patient programme. This is the largest case series of artesunate treated patients with severe malaria in Europe.MethodsHospitalized patients treated with IV artesunate between November 2007 and December 2010 in the Netherlands and Belgium were retrospectively evaluated. Patient characteristics, treatment and clinical outcome were recorded on a standardized form and mortality, parasite clearance times and the occurrence of adverse events were evaluated.ResultsOf the 68 treated patients, including 55 with severe malaria, two patients died (2/55 = 3.6%). The mean time to 50% parasite clearance (PCT50), 90% and 99% were 4.4 hours (3.9 - 5.2), 14.8 hours (13.0 - 17.2), and 29.5 hours (25.9 - 34.4) respectively. Artesunate was well tolerated. However, an unusual form of haemolytic anaemia was observed in seven patients. The relationship with artesunate remains uncertain.ConclusionsData from the named patient programme demonstrate that IV artesunate is effective and well-tolerated in European travellers lacking immunity. However, increased attention needs to be paid to the possible development of haemolytic anaemia 2-3 weeks after start of treatment.Treatment of IV artesunate should be limited to the period that IV treatment is required and should be followed by a full oral course of an appropriate anti-malarial drug.

Cytotoxic Markers Associate With Protection Against Malaria in Human Volunteers Immunized With Plasmodium falciparum Sporozoites

Background. Immunization of healthy volunteers by bites from Plasmodium falciparum–infected mosquitoes during chloroquine chemoprophylaxis (hereafter, chemoprophylaxis and sporozoites [CPS] immunization) induces sterile protection against malaria. CPS-induced protection is mediated by immunity against pre-erythrocytic stages, presumably at least partially by cytotoxic cellular responses. We therefore aimed to investigate the association of CPS-induced cytotoxic T-cell markers with protection. Methods. In a double-blind randomized controlled trial, we performed dose titration of CPS immunization followed by homologous challenge infection in 29 subjects. Immune responses were assessed by in vitro restimulation of peripheral blood mononuclear cells and flow cytometry. Results. Dose-dependent complete protection was obtained in 4 of 5 volunteers after immunization with bites from 45 P. falciparum–infected mosquitoes, in 8 of 9 volunteers with bites from 30, and in 5 of 10 volunteers with bites from 15 (odds ratio [OR], 5.0; 95% confidence interval [CI], 1.5–17). Completely protected subjects had significantly higher proportions of CD4 T cells expressing the degranulation marker CD107a (OR, 8.4; 95% CI, 1.5–123; P = .011) and CD8 cells producing granzyme B (OR, 11; 95% CI, 1.9–212; P = .004) after P. falciparum restimulation. Conclusions. These data underline the efficiency of CPS immunization to induce sterile protection and support a possible role for cytotoxic CD4 and CD8 T-cell responses in pre-erythrocytic immunity. Clinical Trials Registration. NCT01218893.

Local or systemic treatment for New World cutaneous leishmaniasis? Re-evaluating the evidence for the risk of mucosal leishmaniasis.

This review addresses the question of whether the risk of developing mucosal leishmaniasis (ML) warrants systemic treatment in all patients with New World cutaneous leishmaniasis (CL) or whether local treatment might be an acceptable alternative. The risk of patients with New World CL developing ML after the initial infection has been the main argument for systemic treatment. However, this statement needs re-evaluation and consideration of all the available data. The putative benefit of preventing ML should outweigh the toxicity of systemic antileishmanial therapy. To assess the need for and risk of systemic treatment the following factors were reviewed: the incidence and prevalence of ML in endemic populations and in travellers; the severity of mucosal lesions; the efficacy of current options to treat ML; the toxicity and, to a lesser extent, the costs of systemic treatment; the risk of developing ML after local treatment; and the strengths and limitations of current estimates of the risk of developing ML in different situations. Local treatment might be considered as a valuable treatment option for travellers suffering from New World CL, provided that there are no risk factors for developing ML such as multiple lesions, big lesions (>4 cm(2)), localisation of the lesion on the head or neck, immunosuppression or acquisition of infection in the high Andean countries, notably Bolivia.

Intradermal influenza vaccination in immunocompromized patients is immunogenic and feasible

BACKGROUND Many strategies, including intradermal vaccination, have been tested to augment antibody responses upon vaccination. This strategy has not been evaluated in different groups of immunocompromized patients. We conducted a prospective, randomized study to compare the humoral response upon standard intramuscular influenza vaccination with the response upon reduced-dose intradermal vaccination in patients treated with anti-tumor necrosis factor (TNF)-alpha, human immunodeficiency virus (HIV)-infected patients, hematologic stem cell transplantation (HSCT) patients, and healthy controls. METHODS In total 156 immunocompromized patients and 41 healthy controls were randomized to receive either 0.5mL of the 2005/2006 trivalent influenza vaccine intramuscular or 0.1mL intradermal. Humoral responses, determined by hemagglutination inhibition assay, were measured before and 28 days postvaccination. Geometric mean titers (GMTs) and protection rates (PRs) are reported as primary outcomes, adverse events as a secondary outcome. RESULTS Reduced-dose intradermal vaccination leads to similar GMTs and PRs, within all tested groups, compared to the standard intramuscular vaccination. Healthy controls yielded significantly better GMTs and PRs than immunocompromized patients. Local skin reactions after intradermal vaccination occurred less frequent and were milder in immunocompromized patients than in healthy subjects and were predictive for a positive vaccination outcome for individual subjects. CONCLUSIONS Intradermal influenza vaccination is a feasible alternative for standard intramuscular vaccination in several groups of immunocompromized patients, including those treated with anti-TNF, HIV-infected patients and HSCT patients. The occurrence of a local skin reaction after intradermal vaccination is predictive of a response to at least one of the vaccine antigens.

Response to 2009 Pandemic Influenza A (H1N1) Vaccine in HIV-Infected Patients and the Influence of Prior Seasonal Influenza Vaccination

Background The immunogenicity of 2009 pandemic influenza A(H1N1) (pH1N1) vaccines and the effect of previous influenza vaccination is a matter of current interest and debate. We measured the immune response to pH1N1 vaccine in HIV-infected patients and in healthy controls. In addition we tested whether recent vaccination with seasonal trivalent inactivated vaccine (TIV) induced cross-reactive antibodies to pH1N1. (clinicaltrials.gov Identifier:NCT01066169) Methods and Findings In this single-center prospective cohort study MF59-adjuvanted pH1N1 vaccine (Focetria®, Novartis) was administered twice to 58 adult HIV-infected patients and 44 healthy controls in November 2009 (day 0 and day 21). Antibody responses were measured at baseline, day 21 and day 56 with hemagglutination-inhibition (HI) assay. The seroprotection rate (defined as HI titers ≥1∶40) for HIV-infected patients was 88% after the first and 91% after the second vaccination. These rates were comparable to those in healthy controls. Post-vaccination GMT, a sensitive marker of the immune competence of a group, was lower in HIV-infected patients. We found a high seroprotection rate at baseline (31%). Seroprotective titers at baseline were much more common in those who had received 2009–2010 seasonal TIV three weeks prior to the first dose of pH1N1 vaccine. Using stored serum samples of 51 HIV-infected participants we measured the pH1N1 specific response to 2009–2010 seasonal TIV. The seroprotection rate to pH1N1 increased from 22% to 49% after vaccination with 2009–2010 seasonal TIV. Seasonal TIV induced higher levels of antibodies to pH1N1 in older than in younger subjects. Conclusion In HIV-infected patients on combination antiretroviral therapy, with a median CD4+ T-lymphocyte count above 500 cells/mm3, one dose of MF59-adjuvanted pH1N1 vaccine induced a high seroprotection rate comparable to that in healthy controls. A second dose had a modest additional effect. Furthermore, seasonal TIV induced cross-reactive antibodies to pH1N1 and this effect was more pronounced in older subjects.

Synergistic immunosuppressive effect of anti-TNF combined with methotrexate on antibody responses to the 23 valent pneumococcal polysaccharide vaccine

INTRODUCTION The efficacy of the immune response upon vaccination in patients treated with anti-tumor necrosis factor-alpha (anti-TNF) with or without methotrexate is the subject of debate. We studied the effect of immunosuppressive treatment, including anti-TNF and methotrexate, on the response to pneumococcal polysaccharide (PPS) vaccine. METHODS Fifty-two patients treated with immunosuppressives including anti-TNF (anti-TNF group), 41 patients given a similar immunosuppressive regimen without anti-TNF (no anti-TNF group), and 18 healthy controls were vaccinated with a 23 valent PPS vaccine. The percentage of patients treated with methotrexate in the anti-TNF and no anti-TNF group was 65% and 76%, respectively. Antibodies against four of the vaccine antigens (PPS 6B, 9V, 19F and 23F) were measured before and 4 weeks after vaccination. The primary outcome was the response rate, defined as the percentage with a postvaccination titer 0.35 microg/ml in combination with at least a twofold increase in antibody titer. The protection rate was defined as a postvaccination titer > or = 0.35 microg/ml. RESULTS The use of methotrexate was the strongest predictor of impaired vaccination outcome. Anti-TNF caused an additional immunosuppressive effect in the presence of methotrexate, leading to the lowest response percentages in patients using the combination of these two drugs. The underlying disease, other immunosuppressives such as prednisone or type of anti-TNF agent used did not influence vaccination outcome. CONCLUSIONS Patients who were treated with the combination of methotrexate and anti-TNF demonstrated a significantly impaired immune response following pneumococcal polysaccharide vaccination as compared to patients treated with either methotrexate or anti-TNF only or immunosuppressives excluding these two compounds.

Intradermally Administered Yellow Fever Vaccine at Reduced Dose Induces a Protective Immune Response: A Randomized Controlled Non-Inferiority Trial

Background Implementation of yellow fever vaccination is currently hampered by limited supply of vaccine. An alternative route of administration with reduced amounts of vaccine but without loss of vaccine efficacy would boost vaccination programmes. Methods and Findings A randomized, controlled, non-inferiority trial was conducted in a Dutch university center between August 2005 and February 2007. A total of 155 primary vaccinated and 20 previously vaccinated volunteers participated. Participants were randomly assigned in a 1∶1 ratio to receive intradermal (i.d.) vaccination with live attenuated yellow fever 17D vaccine at a reduced dose (1/5th; 0·1 mL) or the conventional subcutaneous (s.c.) vaccination (0·5 mL). Antibody neutralization titers were determined at 2, 4 and 8 weeks and 1 year after vaccination by counting the reduction in virus-induced plaques in the presence of serial serum dilutions. Adverse events were documented in a 3-week dairy. Viraemia was measured 5 days after vaccination. From 2 weeks up to one year after vaccination, the maximum serum-dilution at which 80% of the virus plaques were neutralized, which indicates protection against yellow fever, did not differ between those given a reduced i.d. dose or standard s.c. dose of vaccine. In all cases the WHO standard of seroprotection (i.e. 80% virus neutralization) was reached (in 77/77 and 78/78, respectively). Similar results were found in the previously vaccinated individuals. Viraemia was detected in half of the primary vaccinated participants, which was not predictive of serological response. In revaccinees no viraemia was detected. Conclusions Intradermal administration of one fifth of the amount of yellow fever vaccine administered subcutaneously results in protective seroimmunity in all volunteers. Albeit this vaccination route should enable vaccination of five-times as many individuals at risk for disease, these results should now be confirmed in field studies in areas with potential yellow fever virus transmission to change vaccination policy. Trial Registration Nederlands Trial Register ISRCTN46326316

The low and declining risk of malaria in travellers to Latin America: is there still an indication for chemoprophylaxis?

A comparison was made between local malaria transmission and malaria imported by travellers to identify the utility of national and regional annual parasite index (API) in predicting malaria risk and its value in generating recommendations on malaria prophylaxis for travellers.Regional malaria transmission data was correlated with malaria acquired in Latin America and imported into the USA and nine European countries. Between 2000 and 2004, most countries reported declining malaria transmission. Highest APIs in 2003/4 were in Surinam (287.4) Guyana (209.2) and French Guiana (147.4). The major source of travel associated malaria was Honduras, French Guiana, Guatemala, Mexico and Ecuador. During 2004 there were 6.3 million visits from the ten study countries and in 2005, 209 cases of malaria of which 22 (11%) were Plasmodium falciparum. The risk of adverse events are high and the benefit of avoided benign vivax malaria is very low under current policy, which may be causing more harm than benefit.