Seroepidemiology of mumps in Europe (1996-2008): why do outbreaks occur in highly vaccinated populations?

Mumps outbreaks have recently been recorded in a number of highly vaccinated populations. We related seroprevalence, epidemiological and vaccination data from 18 European countries participating in The European Sero-Epidemiology Network (ESEN) to their risk of mumps outbreaks in order to inform vaccination strategies. Samples from national population serum banks were collected, tested for mumps IgG antibodies and standardized for international comparisons. A comparative analysis between countries was undertaken using age-specific mumps seroprevalence data and information on reported mumps incidence, vaccine strains, vaccination programmes and vaccine coverage 5-12 years after sera collection. Mean geometric mumps antibody titres were lower in mumps outbreak countries [odds ratio (OR) 0·09, 95% confidence interval (CI) 0·01-0·71)]. MMR1 vaccine coverage ⩾95% remained protective in a multivariable model (P < 0·001), as did an interval of 4-8 years between doses (OR 0·08, 95% CI 0·01-0·85). Preventing outbreaks and controlling mumps probably requires several elements, including high-coverage vaccination programmes with MMR vaccine with 4-8 years between doses.

Standardization of measles, mumps and rubella assays to enable comparisons of seroprevalence data across 21 European countries and Australia.

The aim of the European Sero-Epidemiology Network is to establish comparability of the serological surveillance of vaccine-preventable diseases in Europe. The designated reference laboratory (RL) for measles, mumps, rubella (MMR) prepared and tested a panel of 151 sera by the reference enzyme immunoassay (rEIA). Laboratories in 21 countries tested the panel for antibodies against MMR using their usual assay (a total of 16 different EIAs) and the results were plotted against the reference results in order to obtain equations for the standardization of national serum surveys. The RL also tested the panel by the plaque neutralization test (PNT). Large differences in qualitative results were found compared to the RL. Well-fitting standardization equations with R2> or =0.8 were obtained for almost all laboratories through regression of the quantitative results against those of the RL. When compared to PNT, the rEIA had a sensitivity of 95.3%, 92.8% and 100% and a specificity of 100%, 87.1% and 92.8% for measles, mumps and rubella, respectively. The need for standardization was highlighted by substantial inter-country differences. Standardization was successful and the selected standardization equations allowed the conversion of local serological results into common units and enabled direct comparison of seroprevalence data of the participating countries.

Characterization of tick-borne encephalitis virus from Latvia.

Viruses of the tick-borne encephalitis (TBE) antigenic complex, within the family Flaviviridae, cause a variety of diseases including uncomplicated febrile illness, encephalitis, meningo-encephalitis, hemorrhagic fever and chronic disease in humans, domesticated animals or wildlife species. TBE is a serious problem in Latvia with up to a 1,000 patients confirmed serologically annually 1994-1995. No previous data had been reported on the causative agent of TBE in Latvia. In the present study, a virus was isolated from serum of a patient with clinical symptoms of an acute TBE infection. Nucleotide sequence information obtained by direct reverse transcription-polymerase chain reaction (RT-PCR) and the serological characteristics of the isolated virus strain, designated TBE-Latvia-1-96, indicated a closer relationship to the Vasilchenko strain, isolated in Novosibirsk (Siberia, Russia), as compared to the western European or far eastern subtypes of TBE viruses. In a mouse neurovirulence assay, a significant difference in survival rates (days) was shown between Latvia-1-96 and the western European TBE virus subtype.

[Interrelationship between the chain length of poly-L-lysine and the degree of protection of polyribonucleotide interferon inducers from human blood nucleases]. / Vzaimosviaz' mezhdu dlinoi tsepi ékraniruiushchego poli-L-lizina i stepen'iu zashchity poliribonukleotidnykh induktorob interferona ot nukleas krovi cheloveka.

The action of the human total blood serum on polynucleotide interferon inducers, larifan and ridostin (natural double-stranded RNAs) and poly(I).poly(C) (a double-stranded complex of synthetic polyribonucleotides) used both in the free state and in the state shielded with poly-L-lysine was studied. The rate of the accumulation of the acid soluble products was compared with the residual interferon-inducing activity in mice. All the unshielded inducers were shown to completely loose their activity after a 4-hour contact with the serum. The protective activity of poly-L-lysine increased in parallel with the increase of its molecular weight and was maximal for the preparation with the molecular weight of 12300 +/- 1000 Da. Differences in the structure of the inducers and the mechanism of their biosynthesis and degradation must be taken into account.

[The treatment of chronic myeloleukemia with recombinant alfa-2 interferon]. / Lechenie khronicheskogo mieloleikoza rekombinantnym al'fa 2-interferonom.

A trial has been conducted of recombinant alpha 2-interferon (reaferon) used in 32 patients with Ph'[correction of Rh']-positive chronic myeloid leukemia (CML). A chronic stage was in 3, transient in 3 and blast in 1 patients. 25 CML patients were newly diagnosed. The treatment lasted from 2 months to 3 years. Clinicohematological remission was confirmed conventionally and by the degree of Ph'-positive clone reduction. An attempt is made to clarify the mechanism underlying the resistance to reaferon basing on the immunological data (detection of antireaferon neutralizing antibodies). The authors propose a combined treatment (myelosan plus reaferon) of CML which has obvious advantages over myelosan monotherapy.

Effect of natural and synthetic immunomodulators on the synthesis of interferon by peritoneal cells of mice.

The effect of different natural and synthetic immunomodulators on the spontaneous interferon (IFN) synthesis by freshly isolated resident peritoneal cells of BALB/c, NZB and C3H mice was investigated. Actinomycetal glycolipids isolated from Curtobacterium betae, Faenia rectivirgula, Rothia dentocariosa and Saccharopolyspora hirsuta at the concentration 1-20 micrograms/ml were found to potentiate the IFN synthesis by the peritoneal cells of BALB/c mice. Similar results were obtained when dsRNA, LPS of Shigella sonnei and lipid A isolated from the LPS were used. The effect of potentiation of the physiological IFN production by the immunomodulators was observed also in the cells of C3H and NZB mice. In contrast, the inhibition of the IFN synthesis was observed when the peritoneal cells of BALB/c and NZB mice were treated with imuthiol at concentration 0.1-10 micrograms/ml. Thymomodulin (TFX-Polfa) at concentration of 1-100 micrograms/ml had no effect on the spontaneous IFN production.

Nucleic acid as interferon inducer. Its antiviral and antitumor activity.

The results of the present study have demonstrated that dsRNA obtained in the system E. coli--bacteriophage is an interferon inducer and possesses antiviral and antitumoral activities.