Prevalence of antibodies against influenza A and B viruses in children in Germany, 2008 to 2010.

The prevalence of influenza A and B virus-specific IgG was determined in sera taken between 2008 and 2010 from 1,665 children aged 0-17 years and 400 blood donors in Germany. ELISA on the basis of whole virus antigens was applied. Nearly all children aged nine years and older had antibodies against influenza A. In contrast, 40% of children aged 0-4 years did not have any influenza A virus-specific IgG antibodies. Eightysix percent of 0-6 year-olds, 47% of 7-12 year-olds and 20% of 13-17 year-olds were serologically naïve to influenza B viruses. By the age of 18 years, influenza B seroprevalence reached approximately 90%. There were obvious regional differences in the seroprevalence of influenza B in Germany. In conclusion, seroprevalences of influenza A and influenza B increase gradually during childhood. The majority of children older than eight years have basal immunity to influenza A, while comparable immunity against influenza B is only acquired at the age of 18 years. Children aged 0-6 years, showing an overall seroprevalence of 67% for influenza A and of 14% for influenza B, are especially at risk for primary infections during influenza B seasons.

Seroprevalence of campylobacteriosis and relevant post-infectious sequelae.

Post-infectious sequelea such as Guillain Barré syndrome (GBS), reactive arthritis (RA), and inflammatory bowel disease (IBD) may arise as a consequence of acute Campylobacter-enteritis (AE). However, reliable seroprevalence data of Campylobacter-associated sequelae has not been established. The objectives of this study were, first, to identify the most specific and sensitive test antigen in an optimized ELISA assay for diagnosing a previous Campylobacter-infection and, second, to compare the prevalence of anti-Campylobacter antibodies in cohorts of healthy blood donors (BD), AE, GBS, RA, and IBD patients with antibodies against known GBS, RA and IBD triggering pathogens. Optimized ELISAs of single and combined Campylobacter-proteins OMP18 and P39 as antigens were prepared and sera from AE, GBS, RA and IBD patients and BD were tested for Campylobcter-specific IgA and IgG antibodies. The results were compared with MIKROGEN™-recomLine Campylobacter IgA/IgG and whole cell lysate-immunoblot. Antibodies specific for Helicobacter pylori, Mycoplasma pneumoniae, Yersinia enterocolitica, and Borrelia afzelii were tested with commercial immunoblots. ROC plot analysis revealed AUC maxima in the combination of OMP18 and P39 for IgA and in the P39-antigen for IgG. As a result, 34-49 % GBS cases, 44-62 % RA cases and 23-40 % IBD cases were associated with Campylobacter-infection. These data show that Campylobcater-seropositivity in these patient groups is significantly higher than other triggering pathogens suggesting that it plays an important role in development of GBS and RA, and supports the hypothesis that recurrent acute campylobacteriosis triggers IBD.

Influenza vaccination is associated with reduced severity of community-acquired pneumonia.

Pneumonia is an important cause of influenza-associated morbidity and mortality. Influenza vaccination has been shown to reduce morbidity and mortality during influenza seasons. Protection from severe pneumonia may contribute to the beneficial effect of influenza vaccination. Therefore, we investigated the impact of prior influenza vaccination on disease severity and mortality in patients with community-acquired pneumonia (CAP). Analysis from an observational, multicentre cohort study initiated by the German competence network for CAP was performed. Patients were analysed separately as an influenza season and off-season cohort. Associations between vaccination status and outcome parameters were evaluated by multivariate analyses. In the season cohort (2,368 patients) CAP in vaccinated patients was significantly less severe according to most analysed parameters (CURB index ≥ 1: OR 0.76, 95% CI 0.60-0.98; procalcitonin ≥ 2.0 ng·mL(-1): OR 0.53, 95% CI 0.35-0.81; procalcitonin ≥ 0.5 ng·mL(-1): OR 0.71, 95% CI 0.51-0.99) and these patients showed a significantly better overall survival within the 6-month follow-up period (HR 0.63, 95% CI 0.45-0.89). Within the off-season cohort (2,632 patients) there was no significant influence of vaccination status on CAP severity or disease outcome. In conclusion, prior influenza vaccination was associated with less severe clinical course and improved overall long-term survival in patients with CAP during influenza seasons.

Seroprevalence of influenza A and B in German infants and adolescents.

The objective of this study was to provide seroepidemiological information on influenza A and B antibodies in children and adolescents. Viral immunoglobulin G antibodies were determined retrospectively using enzyme-linked immunosorbent assays in a group of 1,111 children and adolescents. Sera (809) from healthy adult blood donors served as controls. In children, the prevalence of antibodies against influenza A was 82.0% and against influenza B 9.6%, whereas in adults the prevalence of antibodies against influenza A was calculated as 99.4% and against influenza B 56.7%. After decline of maternal antibodies during the first year of life, there was an increase of prevalence of influenza A antibodies up to 100% by the age of 12 years. In contrast, only 1-2% of children up to 9 years had influenza B antibodies increasing to 25% by the age of 18 years and to 70% among adults aged 30 years. Children aged 0-6 years had significantly lower concentrations and >12-15-year-old adolescents had significantly higher concentrations of antibodies against influenza A than adults. For all age groups of children and adolescents, significantly lower antibody concentrations against influenza B were measured in comparison to the blood donor control group. In conclusion, the annual influenza vaccination in children and adolescents may improve considerably the protection against influenza virus infection occurring during epidemics.

Low interleukin-12 activity in severe Plasmodium falciparum malaria.

We compared interleukin-12 (IL-12) and other cytokine activities during and after an acute clinical episode in a matched-pair case-control study of young African children who presented with either mild or severe Plasmodium falciparum malaria. The acute-phase, pretreatment plasma IL-12 and alpha interferon (IFN-alpha) levels, as well as the acute-phase mitogen-stimulated whole-blood production capacity of IL-12, were significantly lower in children with severe rather than mild malaria. IL-12 levels, in addition, showed strong inverse correlations both with parasitemia and with the numbers of circulating malaria pigment-containing neutrophils. Acute-phase plasma tumor necrosis factor (TNF) and IL-10 levels were significantly higher in those with severe malaria, and the concentrations of both of these cytokines were positively correlated both with parasitemia and with the numbers of pigment-containing phagocytes in the blood. Children with severe anemia had the highest levels of TNF in plasma. In all the children, the levels in plasma and production capacities of all cytokines normalized when they were healthy and parasite free. The results indicate that severe but not mild P. falciparum malaria in young, nonimmune African children is characterized by down-regulated IL-12 activity, contrasting markedly with the up-regulation of both TNF and IL-10 in the same children. A combination of disturbed phagocyte functions resulting from hemozoin consumption, along with reduced IFN-gamma responses, may contribute to these differential effects.

Antibody responses to Plasmodium falciparum: evolution according to the severity of a prior clinical episode and association with subsequent reinfection.

We measured sporozoite- and total parasite antigen-specific IgG and IgM antibodies before and after treatment in matched groups of Gabonese children who presented with either mild or severe Plasmodium falciparum malaria. We investigated the influence of various parameters on these antibody responses, including clinical presentation, age, and post-treatment reinfection profiles. IgG but not IgM responses were strongly influenced by both clinical and parasitological status. IgG responses to the repeat region of the circumsporozoite protein, which were low at admission, particularly so in those with severe anemia, increased after treatment but showed no association with either age or reinfection profiles. Total parasite antigen-specific IgG responses were strongly influenced by parasitological status, and also differed significantly when segregated according to clinical status at admission, age, and reinfection histories. Most notably, anti-parasite IgG responses measured when children were parasite-free were higher and a good indicator of recent reinfections in those who presented with mild rather than with severe malaria. The profile of responses in the latter group suggests some immune system dysfunction, which may reflect the induction of tolerance to parasite antigens.

Topical treatment with hexadecylphosphocholine (Miltex) efficiently reduces parasite burden in experimental cutaneous leishmaniasis.

Ether-lipids and alkylphosphocholines have been found to have anti-leishmanial activity. Oral treatment with hexadecylphosphocholine (HePC) efficiently reduces parasite burden in murine visceral leishmaniasis. Drugs for the treatment of cutaneous leishmaniasis are most commonly administered parenterally, whereas efficient drugs for topical treatment are not in current use. Here we investigate the efficacy of topical treatment with HePC in mice infected with Leishmania mexicana or L. major, causative agents of cutaneous leishmaniasis in the New and Old World, respectively. BALB/c, CBA/J and C57BL/6 inbred mice do not control infection with L. mexicana because they do not mount an efficient Th1-type anti-parasitic lymphocyte response. In contrast, C57BL/6 mice are resistant to an infection with L. major, developing only transient lesions that heal spontaneously owing to an efficient Th1 response. BALB/c, CBA/J and C57BL/6 mice were infected subcutaneously with L. mexicana amastigotes, causing nodular lesions after 5 months. Topical treatment with HePC (Miltex) was highly effective in reducing parasite burden and healed established lesions. The treatment did not induce a Th1 response in L. mexicana-infected susceptible mice and most of the mice relapsed. In resistant C57BL/6 mice infected subcutaneously with 2 x 10(6) L. major promastigotes at the tail base, nodular lesions developed after 2 weeks. Topical treatment with Miltex reduced the parasite load and the mice healed their lesions much faster than the untreated infected controls. The clinical application of Miltex for treatment of cutaneous leishmaniasis may be highly efficient because humans, similarly to resistant mice, in general do not relapse after healing. Clinical trials should be straightforward considering that Miltex is an approved drug for the treatment of breast cancer metastases.

Low-dose treatment with sulfadoxine-pyrimethamine combinations selects for drug-resistant Plasmodium falciparum strains.

A total of 252 children were enrolled in a drug trial to assess the effect of minimal doses of sulfadoxine (Sdx) and pyrimethamine (Pyr). Parasite samples isolated from these patients were analyzed before and after treatment to investigate the level of drug-resistant strains. The parasite genes encoding dihydrofolate reductase (DHFR) and dihydropteroate synthase (DHPS) were assayed for point mutations that are associated with resistance against drugs. Before treatment, Pyr(r) genotypes of the DHFR gene were found in 42% of all samples, 8% of the patients harbored a mixed parasite population and 50% had a sensitive DHFR genotype. In terms of the DHPS gene, we found mutations in 45% of the parasites. Twenty-four percent had a Ser(436) mutation, and 26% had a Gly(437) mutation. Recrudescent parasites were highly enriched for both Pyr(r) and Sdx(r) strains after treatment (P < 0.001 and P = 0.029, respectively).

High oxygen radical production is associated with fast parasite clearance in children with Plasmodium falciparum malaria.

It has been hypothesized that reactive oxygen intermediates (ROI) released by leukocytes play a major role in the immune response to many infectious agents. In the present study, the parasitologic and clinical courses of 75 Gabonese children with Plasmodium falciparum malaria were compared with the ability of their granulocytes to produce oxygen radicals. The luminol-dependent chemiluminescence in granulocyte suspensions for the children was measured without stimulation and after stimulation with phorbol-12-myristate-13-acetate, N-formyl-methionyl-leucyl-phenylalanine, or tumor necrosis factor. A significant association was found between fast parasite clearance time and high oxygen radical generation in both the unstimulated and stimulated granulocyte preparations. No correlation was found between fever clearance time and ROI generation. These findings suggest that ROI play a pivotal role in the immune response as a first line of defense against P. falciparum malaria.

Interferon-gamma responses are associated with resistance to reinfection with Plasmodium falciparum in young African children.

The contribution of T cell-mediated responses was studied with regard to resistance to reinfection in groups of Gabonese children participating in a prospective study of severe and mild malaria due to infection with Plasmodium falciparum. In those admitted with mild malaria, but not in those with severe malaria, production of IFN-gamma by peripheral blood mononuclear cells (PBMC) in response to either liver-stage or merozoite antigen peptides was associated with significantly delayed first reinfections and with significantly lower rates of reinfection. Proliferative or tumor necrosis factor responses to the same peptides showed no such associations. Production of interferon-gamma by PBMC in response to sporozoite and merozoite antigen peptides was observed in a higher proportion of those presenting with mild malaria. Differences in the Th1/Th2 cytokine balance may be linked to the ability to control parasite multiplication in these young children, helping to explain the marked differences observed in both susceptibility to infection as well as in clinical presentation.

The role of red blood cell polymorphisms in resistance and susceptibility to malaria.

In regions highly endemic for Plasmodium falciparum malaria, red cell polymorphisms that confer resistance to severe disease are widespread. Sickle cell trait, alpha-thalassemia, glucose-6-phosphate dehydrogenase deficiency, and blood groups were determined in 100 children from Gabon with severe malaria who were matched with 100 children with mild malaria and followed up for evaluation of reinfections. The sickle cell trait was significantly associated with mild malaria and blood group A with severe malaria. During follow-up, the original severe cases had significantly higher rates of reinfection than the original mild cases, with higher parasitemia and lower hematocrit values. Incidence rates did not differ in the context of erythrocyte polymorphisms, but patients with sickle cell trait presented with markedly lower levels of parasitemia than those without. Thus, the severity of malaria is partly determined by the presence of blood group A and the sickle cell trait. The different presentation of reinfections in severe versus mild cases probably reflects different susceptibility to malaria.

No influence of socioeconomic factors on severe malarial anaemia, hyperparasitaemia or reinfection.

Malaria is responsible for nearly 500 million clinical cases per year, only a small proportion of whom will become severely ill. Socioeconomic risk factors may play a role in the development of severe malaria in African children and in their susceptibility to reinfection. In Gabon, 100 children suffering from severe malaria, defined as hyperparasitaemia and/or severe anaemia, were matched for sex, age and provenance to 100 children with mild malaria. Socioeconomic factors were assessed using a standard questionnaire and compared between the 2 groups. The children were followed-up and the time to first reinfection was recorded. No significant influence of socioeconomic factors could be detected on the severity of disease or the time to first reinfection. Socioeconomic factors are not major determinants of severe malarial anaemia and hyperparasitaemia in children in Gabon.

Merozoite surface antigen 1 and 2 genotypes and rosetting of Plasmodium falciparum in severe and mild malaria in Lambaréné, Gabon.

We present a case-control study to investigate the distribution of Plasmodium falciparum genotypes in patients with severe and mild malaria. We compared clinical and parasitological data with the parasites' genotype and rosetting. The study group consisted of 100 children suffering severe malaria, defined as severe anaemia and hyperparasitaemia. These children were matched by age, sex and provenance with 100 children with mild malaria. For characterization of the parasites we used the polymerase chain reaction to determine merozoite surface antigen (MSA) 1 and 2 genotypes and the phenomenon of rosette formation. We found a significant association between rosette formation and disease severity, and a significant association of severe anaemia with the presence of the MSA-1 allele K1. Infections with 2 genotypes in the severely affected group were significantly associated with severe anaemia and the presence of MSA-1 allele K1. Comparison with the findings of other groups led to the conclusion that the occurrence of P. falciparum genotypes seems to differ geographically.

Parasite antigen-specific interleukin-10 and antibody reponses predict accelerated parasite clearance in Plasmodium falciparum malaria.

Using strict inclusion criteria, we conducted a hospital-based, case-control study in which 100 Gabonese children with severe Plasmodium falciparum malaria were matched for age, gender and provenance with 100 children presenting with mild malaria. Parasite antigen-specific cellular and humoral immunological responses were measured and compared with post-treatment parasite clearance times in each group. Significantly faster parasite clearance times were associated with in vitro production of IL-10 by acute-phase peripheral blood mononuclear cells (PBMC) in response to both liver and asexual stage parasite antigens, but not with proliferative, IFN-gamma, or TNF responses to the same antigens. In addition, in those children with mild malaria, higher levels of acute-phase antibody responses to liver stage antigen-1 (LSA-1) were associated with faster parasite clearance times, and were correlated with the presence of IL-10 responses to the same antigen. No such associations were found for IL-10 or antibody responses to a range of asexual blood stage antigens. Those with severe malaria had significantly lower levels of anti-LSA-1 antibodies compared to their counterparts with mild malaria. In conclusion, the results of this study suggest that parasite antigen-specific IL-10-mediated antibody responses may play a role in the control of asexual stage parasite multiplication in P. falciparum malaria.