Human parvovirus B19 (B19V) infection in immunocompetent patients usually has a mild clinical course, but during pregnancy it can cause serious and even fatal complications in the fetus. The most common clinical presentation of B19V infection is erythema infectiosum and in this case laboratory confirmation is required for differentiation from other exanthematous diseases. Measles and rubella negative sera collected in Belarus between 2005 and 2008 from 906 patients with a rash and fever were screened for B19V infection by ELISA. More than 35% of the samples (322/906) were positive for B19V. The proportion ranged from 10.1% in 2008 to 53.2% in 2006 when an outbreak took place in Minsk city. All B19V outbreaks and cluster cases occurred during the winter-spring period, but sporadic cases were recorded basically throughout the year. The majority of the cases (56.5%) occurred among the 2 till 10 year old children, and 27.3% of the cases were observed in adults between 19 and 53 years. All 104 B19V strains sequenced in the NS1/VP1u region belonged to genotype 1 with a maximal genetic distance of 1.75%. The two phylogenetic clusters reflected the geographic origins of the viruses within the country. Forty-two unique nucleotide mutations as compared to sequences downloaded from GenBank were found in the VP1u and NS1 regions; most of these changes were nonsynonymous. This report highlights the importance of B19V infection in patients with a rash and fever in Belarus. J. Med. Virol. 84:973-978, 2012. © 2012 Wiley Periodicals, Inc.

Enzyme immunoassay (Dade Behring Enzygnost diagnostic kit, Germany) was used to estimate the levels of measles virus IgG antibodies in 72 samples of blood serum and eluates of the whole blood dried on the Whatman 3M filter paper. The sensitivity of the dried blood test was 98.4%. The regression analysis showed a high correlation of the results (r2 = 0.89; regression coefficient 0.89). Measles virus IgG antibodies were ascertained to be retained in the dried blood at room temperature long (for at least 2 years). After 2-year storage at +4 degrees C, there was a reduction in the concentration of antibodies; however, they were still detectable in 62 (96.9%) out of 64 positive samples. The dried blood test is recommended for wide use to study immunity to measles virus.

The ten-years experience of acute flaccid paralysis (AFP) surveillance in Belarus has been summarized. Among 456 AFP cases reported from 1996 to 2005, 11 were classified as vaccine-associated paralytic poliomyelitis (VAPP), 445--as non-polio AFP. The risk of VAPP for the period 1996-2001 was 1 case per 745,000 used doses of oral poliovaccine (OPV). For the recipients of OPV the risk was 1 case per 911,700 doses and for the first-dose recipients--1 case per 96,000 doses. The high incidence of VAPP was a reason for implementation of sequential polio vaccination schedule in 2000. Guillain-Barre syndrome dominated among non-polio AFP (39.3% of cases); more rare were traumatic neuritis (27.9% of cases), transient monoparalysis (12.1%), myelitis (7.6%). Non-polio AFP differed from VAPP by following epidemiological and virological characteristics: predominance of previously repeatedly vaccinated against poliomyelitis; development of paralysis in long-term period after vaccination; isolation of non-polio viruses belonged to three serotypes of Coxsackie B viruses (B1, B4, B6) and six serotypes of Echo viruses (6, 7, 11, 14, 24, 25) in 8.1% of cases; absence of typical for polio residual paralyses in patients who excreted vaccine polioviruses.

According to the WHO global polio eradication initiative acute flaccid paralysis (AFP) surveillance has been conducted in Belarus since 1996. For the period 1996-2002, 295AFP cases were reported. The main indices ofAFP surveillance in Belarus met the WHO criteria. A11 AFP cases, with the exception of one, were virologically examined. Polioviruses (PV) were isolated from 28 (9.5%) of them. Results of intratypic differentiation (a neutralization test with type-specific monoclonal antibodies and a restriction fragment length polymorphism assay) proved vaccine origin of all isolated PV. According to the final classification, 11 AFP cases were classified as vaccine-associated paralytic poliomyelitis (VAPP). Nine VAPP cases were recipient [six of them developed after the first, two--after the third and one--after the fourth oral poliovirus vaccine (OPV) dose] and two cases in non-vaccinated children were classified as contact VAPP cases. PV of all three serotypes were isolated with an equal frequency from the recipient cases and only PV2--from contact ones. Immunological investigations of children with VAPP showed that the majority of them had disorders in B-cell immunity. A risk of one VAPP case per 96,000 first OPV doses and per 745,000 distributed ones was estimated. The other 284 AFP cases were classified as AFP of non-polio etiology (non-polio AFP). Among them Guillain-Barré syndrome (118 cases, 41.5% of all non-polio AFP cases), traumatic neuritis (63 cases, 22.2%), transient monoparesis of limb (35 cases, 12.3%), myelitis (26 cases, 9.2%) were registered most frequently. Vaccine PV were isolated from 19 (6.7%) children with non-polio AFP, 28 (9.9%) children excreted non-polio enteric viruses. In contrast to VAPP, other AFP with PV isolation had no clinical picture typical of poliomyelitis, and had no any residual paralysis 60 days after the onset of paralysis. PV isolation from them seemed to be not related to the etiology of the disease, but was a mere coincidence of paralysis with the recent vaccination. Results of AFP surveillance supported the previous data on the absence of classical poliomyelitis cases caused by wild PV in Belarus for more than 35 years.

A total of 135 polioviruses (PV), including 25 wild and 110 vaccine-related, isolated in Belarus in 1957-1999 were studied by the analysis of the polymorphism of the restriction fragments lengths of two distal regions of the genome: the region (480 oligonucleotide pairs) coding the N-terminal fragment of capsid protein VP1 (RLFP-1) and the region (291 oligonucleotide pairs) coding the N-terminal fragment of nonstructural protein of 3D-polymerase (RLFP-3D1). The genetic analysis of the viruses made it possible to determine 3 epidemiologically different periods of PV circulation:(1) the prevaccination period (1957-1959) when wild PV of all 3 serotypes circulated on the territory of Belarus;(2) the early period of the use of Oral Poliomielytis Vaccine (1960-1966), characterized by simultaneous circulation of wild and vaccine PV, as well as vaccine/wild recombinant PV;(3) the period of the elimination of wild PV of indigenous origin and the circulation of vaccine-related viruses (1967-1999). The characteristic feature of wild PV was their pronounced genetic variability. 8 genetic variants of PV1, including 4 genetic groups, 2 genetic variants of PV2 and 1 genetic variant of PV3 were detected; 2 vaccine/wild recombinant PV were detected in 1960 and 1966. More than 40% of the vaccine-related PV under study had altered genetic characteristics (mutations and/or recombinations. Reverse variability, linked with the loss of a number of signs of attenuation, was shown to be characteristic of vaccine PV1. Recombinants occurred most frequently among PV3 (44.9%) and PV2 (40.0%), their recombinations being formed mainly with PV1. Recombinants PV2/PV1 and PV3/PV1 were found to have high frequency of reversion in the "PV1" fragment of the genome; this frequency exceeded that in PV1 with the homotypical genome (66.7 and 44.4% in contrast to 12.5%).

The frequency of vaccine poliovirus isolation from children aged under 3 years was studied in Belarus, a country with a high level of immunization against poliomyelitis. Antigenic and genetic characteristics of the isolated strains were studied. Vaccine poliovirus detection rate was high (11.8%). Polioviruses were isolated from children immunized recently (27.2%), immunized more than 2 months before (7.5%), and from non-immunized children (9.8%). An appreciable number (36.1%) of the isolated strains were antigenically and/or genetically modified derivatives of Sabin virus. Epidemiological data and genetic characteristics of the isolated polioviruses indicate that some of them can be sufficiently transmissive for maintaining their "silent" circulation even in a population with a high level of immunization.

Specific humoral immunity, total immune status and typing of HLA antigens, class 1, in loci A and B were studied in children with vaccine-associated paralytic poliomyelitis (VAPP). The immune status investigation revealed that changes in the content of serum immunoglobulins were most frequent. Out of 8 examined children, 5 children had IgA deficiency and 1 child had total variable immunodeficiency. In one case disturbances in cell-mediated immunity prevailed. Tissue typing revealed the presence of HLA A2 and B44 in 5 out of 6 examined children, which considerably exceeded their average occurrence among the Belorussian population. In spite of frequent detection of immunological disturbances in VAPP patients, out of 38 serologically examined children 36 (95%) were found to have virus-neutralizing serum antibodies to poliovirus, which was indicative of the capacity of their immune system for response to the administration of vaccine virus. To minimize the risk of VAPP in children and to achieve the goal of poliomyelitis eradication the combined immunization scheme consisting of 1-3 vaccinations with inactivated poliovaccine with subsequent administration of oral vaccine prepared from attenuated Sabin viruses is regarded as most promising.

One hundred and eight vaccine-derived strains of types 1, 2, and 3 poliovirus (25 PV1, 34 PV2, and 48 PV3) isolated in Belarus in 1960-1999 were analyzed by double restriction fragment length polymorphism assay (RFLP-1,-3D1). Forty-four (40.7%) of strains were genetically modified. Eight (7.4%) PV were modified by mutation, 16 (14.8%) by recombination, and 20 (18.5%) by both mutation and recombination. The genomes of 16 PV were analyzed by multiple RFLP technique covering VP1-, VP1/VP2A-, P2-, 3AC-, and 3D1-coding regions. The majority of recombinants were "simple"(with one crossing over site). One strain was "double" recombinant (two crossings over sites) and one more "multiple" recombinant (three crossing over sites). Partial nucleotide sequencing of some recombinant strains showed that the degree of these strains' divergence was less than 1% in comparison with the original vaccine viruses.

In the Republic of Belarus, immunization of children against measles and mumps had been carried out using monovalent preparations according to the national schedule of measles vaccination at 12 months of age and mumps vaccination at 24 months of age. A rise of rubella incidence in the last few years (i.e., for the official registration period 1980 to 1998, there was an increase from 72.2 to 607.5 cases per 100,000 population) made it necessary to implement immunization against this infection, as well. Therefore, in 1996, combined vaccination against measles, mumps, and rubella of 12-month-old children was carried out for the first time in a clinical trial that used the vaccine Trimovax [Aventis Pasteur (formerly, Pasteur Mérieux Connaught), Lyon, France]. The reactogenicity of the vaccine was investigated in 372 children. Post-vaccination reactions were noted in 5.6% of children; in 1.3% of children the reactions were classified as severe [i.e. associated with body (axillary) temperature > or = 38.6 degrees C]. For the evaluation of immunogenicity, sera from 324 children were obtained 2 to 2.5 months after inoculation, and serum antibody levels were measured by enzyme immunoassays. Among the vaccines, protective antibody titers (expressed in inverse of dilution units) were observed to measles (> or = 1:50) in 97.8%, to mumps (> or = 1:50) in 93.8%, and to rubella (> or = 1:100) in 96.0% of children. Antibodies to all three components of the vaccine were mainly present in intermediate (1:200-1:800) or high (> or = 1:1600) titers: to measles in 96.3%; to mumps in 75.8%; and to rubella in 73.5% of vaccines. The results of these trials are evidence of the good safety and immunogenicity of this MMR vaccine, which provides an alternative to the currently used measles and mumps monovaccines, with the additional benefit of providing immunity against rubella, as well.