Maternal first-trimester enterovirus infection and future risk of type 1 diabetes in the exposed fetus.

Previous studies have suggested that enterovirus infections during pregnancy may increase the risk of type 1 diabetes in the offspring. Our aim was to evaluate the role of first trimester enterovirus infections in a larger cohort of pregnant women. Two series of pregnant women were analyzed as follows: 948 women (series 1) and 680 women (series 2) whose child developed clinical diabetes before the ages of 15 or 7 years, respectively. An equal number of control women with a nondiabetic child was selected. Acute enterovirus infections were diagnosed by measuring IgM class antibodies against coxsackievirus B5 (series 1) and a mixture of coxsackievirus B3, coxsackievirus A16, and echovirus 11 antigens (series 2). In series 2, all sera were also analyzed for IgG class antibodies against an enterovirus peptide antigen. In addition, 152 randomly selected case-control pairs and all IgM-positive mothers' sera were tested for enterovirus RNA (series 2). In series 1, 3.1% of case women had IgM antibodies against coxsackievirus B5 antigen compared with 4.1% of control women (NS). In series 2, 7.1% of case and 5.3% of control women had IgM against the mixture of enterovirus antigens (NS). IgG class enterovirus antibodies did not differ between the groups. Enterovirus RNA was found only in one case woman (0.3%) of the subgroup of samples and in 5.7% of 70 IgM-positive women. The results suggest that enterovirus infection during the first trimester of pregnancy is not associated with increased risk for type 1 diabetes in the child.

Two viral strains and a possible novel recombinant are responsible for the explosive injecting drug use-associated HIV type 1 epidemic in Estonia.

HIV-1 infection has been rare in Estonia. In 2000, an explosive epidemic among injecting drug users was detected in the Eastern border region, resulting in 3603 newly reported cases by the end of 2003. The molecular epidemiology of the outbreak was studied to establish whether the Estonian epidemic is linked to the epidemics in Eastern Europe. Over 200 newly infected individuals were prospectively sampled from June 2000 to March 2002 in a geographically representative way, with known dates of diagnosis and information of probable route of transmission. Viral regions coding for two viral gene regions were directly sequenced from plasma viral RNA and phylogenetically analyzed. In addition, a larger region coding for the entire env gene was sequenced from one sample and studied for indications of possible recombinant structure. The Estonian HIV outbreak was found to be caused by simultaneous introduction of two strains: a minor subtype A strain very similar to the Eastern European subtype A strain (approximately 8% of cases), and a second major strain (77%) found to be most closely related to the CRF06-cpx strain, previously described only from African countries. The variability in the two clusters was very low, suggesting point source introductions. Ten percent of cases seemed to be newly generated recombinants of the A and CRF06-cpx strains. Analysis of viral diversification over time revealed a rate of change within the V3 region of 0.83%/year for the CRF06-cpx strain, consistent with findings from other subtypes. Due to the relatively frequently found novel recombinant forms, the Estonian HIV-1 epidemic may allow studies of coinfection and intersubtype recombination in detail.

Persistence of measles, mumps, and rubella antibodies in an MMR-vaccinated cohort: a 20-year follow-up.

BACKGROUND: The persistence of antibodies against measles, mumps, and rubella induced by the measles-mumps-rubella (MMR) vaccine and the kinetics of antibody decline after the second MMR vaccine dose were studied in the same cohort for 20 years. METHODS: Measles, mumps, and rubella antibodies were measured by enzyme immunoassay in 20-year follow-up serum samples (n= 183) of twice-vaccinated individuals, and measles antibodies were also measured in oral fluids (n = 177). Antibody decay was determined in a group (n = 58) with subsequent samples collected 1, 8, and 15 years after the second MMR dose. RESULTS: In total, 95%, 74%, and 100% of 183 vaccinees were still seropositive for measles, mumps, and rubella, respectively, and 85% of 177 vaccinees had measurable measles antibodies in their oral fluids. The antibody levels declined significantly after the second dose, but subsequently the rate of decline was slower. CONCLUSIONS: A high rate of seropositivity was found 20 years after the first MMR dose, particularly for rubella and measles. Our results show that MMR vaccine-induced antibodies wane significantly after the second dose. According to epidemiological data, the protection induced by MMR vaccination in Finland seems to persist at least until early adulthood. However, the situation requires constant vigilance.

Etiology of mumps-like illnesses in children and adolescents vaccinated for measles, mumps, and rubella.

The possible viral etiology of mumps-like illnesses in patients vaccinated for measles, mumps, and rubella (MMR) was studied by use of serum samples prospectively collected, during 1983-1998, from 601 acutely ill Finnish children and adolescents with mumps-like symptoms. Mumps virus was excluded by testing serum samples for mumps antibodies, and the serum samples were further tested for antibodies to adenovirus, enterovirus, Epstein-Barr virus, parainfluenza virus types 1-3, and parvovirus B19. The serum samples of 114 children <4 years old were also tested for antibodies to human herpesvirus 6 (HHV-6). A viral etiology was verified in 84 cases (14%), most commonly Epstein-Barr virus (7%), followed by parainfluenza virus types 1, 2, or 3 (4%) and adenovirus (3%). HHV-6 infection was found in 5 children <4 years old (4%). This study confirms that mumps-like symptoms in MMR-vaccinated children and adolescents are often not caused by mumps virus infection. Careful laboratory-based diagnostic testing of MMR-vaccinated children and adolescents who develop clinical symptoms compatible with those of mumps is important in the treatment of individual patients, in the comprehension of the true epidemiology of these illnesses, and in the evaluation of the impact of MMR vaccination programs.

Tick-borne encephalitis virus infections in Lithuanian domestic animals and ticks.

In order to obtain information about the distribution of tick-borne encephalitis virus (TBEV) in Lithuania, sera of domestic animals were screened for TBEV antibodies by haemagglutination inhibition test. Samples were collected in 2001 from 423 cows, 561 goats and 118 sheep during a prophylactic examination or vaccination by a local veterinary specialist. In addition, a total of 3234 Ixodes ricinus ticks in 436 pools were collected and tested by RT-PCR for the presence of TBEV RNA (detailed analysis with genetic characterization is published separately [Han et al, J Med Virol 2005 (in press)]). Domestic animal sera from 8/18 districts were positive with an overall seropositivity of 1.7% with considerable regional differences. Sheep from the Radviliskis region had the highest seropositivity rate (16%). In comparison, the proportion of tick pools positive for TBEV-RNA was 1.38%, ranging from 1.03% in Panavezys, 3.33% in Siauliai to 16% in Radviliskis.

Molecular epidemiology of tick-borne encephalitis virus in Ixodes ricinus ticks in Lithuania.

In Lithuania, 171-645 serologically confirmed cases of tick-borne encephalitis occurred annually [Mickiene et al. (2001): Eur J Clin Microbiol Infect Dis 20:886-888] in 1993-1999, and the tick-borne encephalitis virus (TBEV) seroprevalence in the general population was found previously to be 3.0% [Juceviciene et al. (2002): J Clin Virol 25:23-27]. To assess the risk for TBEV virus infection in Lithuania and to characterize the agent a panel of 3,234 ticks combined into 436 pools [Juceviciene et al., 2005] were tested for presence of TBEV RNA by a nested RT-PCR targeting at the NS5 gene. Six pools were confirmed positive and the prevalence of the infected ticks was 0.2% (if one tick per pool [Juceviciene et al., 2005] was considered positive) and the proportion of positive tick pools was 1.4%. The prevalence of the infected ticks in the Panevezys, Siauliai, and Radviliskis regions (in central Lithuania) was 0.1%, 0.4%, and 1.7% corresponding with a higher TBE disease burden in these regions. The 252-nucleotide NS5-region amplicons, and a longer sequence (737 nucleotides) obtained from one sample from the PrM-E gene region, were sequenced. Phylogenetic analysis of the latter showed that all western type TBEV PrM-E sequences, including the Lithuanian strains, were monophyletic, showed no clustering and had very little variation. The NS5 sequences, although identical within one locality, did not show any mutations common to strains from the two Lithuanian regions, nor could any geographical clustering be found among western type TBEV strains from other areas.