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Herd Immunity (herd + immunity)
Selected AbstractsPrevalence of high antibody titers of pertussis in Turkey: reflection of circulating microorganism and a threat to infantsJOURNAL OF CLINICAL LABORATORY ANALYSIS, Issue 3 2007Berrin Esen Abstract Acute pertussis infection among adults can cause its transmission to the larger population, especially to infants and young children, who can develop severe disease. In order to determine an age-dependent pertussis immune response, anti-pertussis toxin (PT) antibody was detected by the indirect enzyme-linked immunosorbent assay (ELISA) method in serum samples from 2,085 healthy subjects ranging in age from 6 months to ,60 years. Also included in the evaluation were responses to a questionnaire including sociodemographic characteristics, vaccination, and infection history. Titers of 50,99 ELISA units (EU)/mL and of ,100,EU/mL were accepted as indicative for recent exposure or infection. In addition, 30,EU/mL was estimated to be a sufficient titer in women of childbearing age to protect their newborns until administration of their first dose of pertussis vaccine. After the age of 4,5 years, presence of high-titered antibodies that increase with age might be a reflection of circulating infection and indicate the magnitude of the threat to infants. According to the questionnaires, in the groups younger than 15 years old, three to four doses of diphtheria toxoid-whole cell pertussis-tetanus toxoid (DwPT) were administered in 47.2 to 77.4%, 91.2 to 100.0%, and 83.5 to 100.0% of participants in Diyarbakir, Samsun, and Antalya, respectively. In addition, up to half of the expectant mothers we studied lacked a sufficient level of estimated antibody titers. To protect infants from life-threatening pertussis infection, improving vaccination coverage to ensure herd immunity and uniformly establishing coverage throughout the country are essential. Furthermore, revaccination with acellular vaccine for schoolchildren as well as for the households of pregnant women is recommended. J. Clin. Lab. Anal. 21:154,161, 2007. © 2007 Wiley-Liss, Inc. [source] Seasonal shifts of group A rotavirus strains as a possible mechanism of persistence in the human populationJOURNAL OF MEDICAL VIROLOGY, Issue 3 2009Gabriel I. Parra Abstract This article demonstrates how the seasonal predominance of a new rotavirus strain in Asuncion, Paraguay is correlated with a wide spectrum of age groups of children infected in that given season. Therefore, this study provides new evidence to support the idea that seasonal shift of rotavirus strains is a possible mechanism used by the virus to evade herd immunity (acquired by the population due to previous infections) and, thus, ultimately persist in that population. J. Med. Virol. 81:568,571, 2009. © 2009 Wiley-Liss, Inc. [source] Hepatitis A and B vaccination and public healthJOURNAL OF VIRAL HEPATITIS, Issue 2007F. Blaine Hollinger Summary., The introduction and implementation of hepatitis B vaccination programmes in areas of high endemicity has been very stressful. However, this initial accomplishment has led to the reassessment of priorities in some countries which could undermine these early successes. Work still remains to be done to support and implement interventions that will bring us closer to the WHO goal and to the control of hepatitis B in the community at large. Hepatitis A vaccine strategy for immunizing toddlers is shifting to those countries with intermediate endemicity where increasing morbidity in adults is being observed. Accumulating evidence indicates that such programmes can result in impressive reductions in the incidence of hepatitis A by herd immunity. Monitoring of these populations to determine durability of protection will be important to avoid shifting the infection to the older age population, when symptoms are more likely to occur. National policies need to consider hepatitis A vaccination in the context of other public health priorities. [source] Measles-Associated Encephalopathy in Children with Renal TransplantsAMERICAN JOURNAL OF TRANSPLANTATION, Issue 6 2006A. Turner Two children, boys of 8 and 13 years, presented with measles-associated encephalopathy several years after kidney transplantation for congenital nephrotic syndrome. In the absence of prior clinical measles, the neurological symptoms initially eluded diagnosis, but retrospective analysis of stored samples facilitated the diagnosis of measles-associated encephalopathy without recourse to biopsy of deep cerebral lesions. Each had received a single dose of measles mumps and rubella vaccine before 12 months of age. Prior vaccination, reduction of immunosuppression and treatment with intravenous immunoglobulin and ribavirin may have contributed to their survival. Persistent measles virus RNA shedding, present in one child, was not controlled by treatment with i.v. ribavirin. Two years later, both patients continue to have functioning allografts with only minimal immunosuppression. These cases illustrate the difficulty in diagnosing measles-associated encephalopathy in the immunocompromised host, even in the era of molecular diagnostics, and highlight the renewed threat of neurological disease in communities with incomplete herd immunity. [source] Sequence analysis of measles virus strains collected during the pre- and early-vaccination era in Denmark reveals a considerable diversity of ancient strainsAPMIS, Issue 2 2002L. Siig Christensen A total of 199 serum samples from patients with measles collected in Denmark, Greenland and the Faroe Islands from 1964 to 1983 were analysed by PCR. Measles virus (MV) RNA could be detected in 38 (19%) of the samples and a total of 18 strains were subjected to partial sequence analysis of the hemagglutinin gene. The strains exhibited a considerable genomic diversity, which is at odds with the assumption that one genome type prevailed among globally circulating MV strains prior to the advent of live-attenuated vaccines. Our data indicate that the similarity of the various vaccine strains is attributed to their having originated from the same primary isolate. Consequently, it is implied that a small number of clinical manifestations of MV worldwide from which strains similar to the vaccine strain were identified were vaccine related rather than being caused by members of a persistently circulating ancient genome type. The Danish pre- and early-vaccination era MV strains seem to change the evolutionary spectrum of genome types A, C2 and E into one coherent group, suggesting that the genome types of MV strains circulating in the world at present do not represent far ranging evolutionary lineages but merely members of an evolutionary continuum of pre-vaccination era MV strains which by chance or due to an improved capability survived the worldwide partial herd immunity accomplished through vaccination. [source] | ||||||||||