Yair Aboudy

High Genetic Diversity of Measles Virus, World Health Organization European Region, 2005–2006

Importation of viruses from other continents caused prolonged circulation and large outbreaks in the WHO European Region.

Global distribution of rubella virus genotypes.

Phylogenetic analysis of a collection of 103 E1 gene sequences from rubella viruses isolated from 17 countries from 1961 to 2000 confirmed the existence of at least two genotypes. Rubella genotype I (RGI) isolates, predominant in Europe, Japan, and the Western Hemisphere, segregated into discrete subgenotypes; intercontinental subgenotypes present in the 1960s and 1970s were replaced by geographically restricted subgenotypes after ~1980. Recently, active subgenotypes include one in the United States and Latin America, one in China, and a third that apparently originated in Asia and spread to Europe and North America, starting in 1997, indicating the recent emergence of an intercontinental subgenotype. A virus that potentially arose as a recombinant between two RGI subgenotypes was discovered. Rubella genotype II (RGII) showed greater genetic diversity than did RGI and may actually consist of multiple genotypes. RGII viruses were limited to Asia and Europe; RGI viruses were also present in most of the countries where RGII viruses were isolated.

Phylogenetic Analysis of Human Parvovirus B19 Sequences from Eleven Different Countries Confirms the Predominance of Genotype 1 and Suggests the Spread of Genotype 3b

ABSTRACT Phylogenetic analysis of 166 human parvovirus B19 sequences from 11 different countries attributed 91.57% to genotype 1, 5.42% to genotype 3b, and 3.01% to genotype 3a. Very similar viruses of genotype 1 circulated widely in Europe and Israel. Genotype 3b seems to show an increasing spread outside of Africa.

Characterization of Large Mumps Outbreak among Vaccinated Palestinian Refugees

During a large mumps virus (MuV) outbreak which occurred in the Palestinian refugee camps of the West Bank, 68.1% (2,636/3,871) of the cases were vaccinated with one dose of trivalent measles, mumps, and rubella (MMR) vaccine. Attack rates by camp ranged from less than 1 case per 1,000 people in the population to 43/1,000 (overall, 11/1,000). The outbreak lasted from December 2003 to June 2005, with two peaks, one from April to May 2004 and the other from March to April 2005. To control the outbreak, a mass MMR vaccination campaign was conducted in May 2005. Evaluation of the immune status of cases (n = 59) and healthy controls (n = 51) revealed high levels of mumps immunoglobulin G (IgG) and a low MuV-specific IgM in clinical cases indicative of a booster immune response. This suggested a secondary rather than a primary infection due to the insufficient protection conferred by the single vaccine dose included in the vaccination program. This prediction was further confirmed by the low seroprevalence (68.6%) found in the healthy control group, which was below the threshold level required for MuV herd immunity. Mumps diagnosis was established mainly by reverse transcription-PCR in clinical samples obtained within 48 h from the onset of disease. Of the parotid fluids and nasopharyngeal aspirates analyzed, 92% were positive for MuV RNA, while only 33% of the urine samples were positive. Phylogenetic analysis of the MuV SH gene identified the outbreak strain as the H genotype, which has been in circulation worldwide at least since 1989.

A new serotype of the outer capsid protein VP4 shared by an unusual human rotavirus strain Ro1845 and canine rotaviruses

The VP4 protein of human rotavirus (HRV) strain Ro1845 and canine rotavirus strains K9 and CU-1 exhibited greater than 98% amino acid identity within their group, but showed less identity with VP4 proteins of other HRV and animal rotavirus strains, the simian rotavirus strain RRV VP4 being most similar to them (90% amino acid identity). To exclude the possibility that these three strains were members of the RRV VP4 serotype P3, neutralization studies were performed using antisera to reassortant viruses containing the VP4 gene from each of Ro1845, CU-1 and RRV. The result established close antigenic similarity among the VP4 proteins of Ro1845, K9 and CU-1 and revealed only a marginal degree of similarity between the VP4 proteins of these three strains and that of strain RRV. These sequence and serological data suggest that the VP4 proteins of Ro1845, K9 and CU-1 represent a new P serotype which we propose to assign P13.

Rubella seroprevalence in the first birth cohort reaching fertility age after 20 years of two dose universal vaccination policy in Israel

BACKGROUND A national program of a 2-dose universal childhood MMR vaccination policy has been in effect in Israel since 1988. As the 1988 birth cohort reached fertility age, questions regarding immunity against rubella were raised. OBJECTIVE To assess the seroprevalence of rubella IgG antibodies among young Israeli adults born after 1987 in comparison to previous birth cohorts, in order to determine evidence based policy for prevention of rubella and congenital rubella syndrome. METHODS We conducted a seroprevalence study of rubella IgG antibodies among 416 Israeli adults (42.5% females) born in 1988-1989, based on a representative sample of sera collected at age 18-19 upon recruitment to mandatory military service in 2007. RESULTS In total, 87.7% were seropositive (>15 IU/ml) as compared with 84.8% in the 1999 recruitment (P=0.26) and 93.4% in 1987 (P=0.004). Yet there was a difference by gender. The proportion of seropositives among female young adults (92.7%) was significantly lower as compared to those measured in the 1999 (99.2%, P=0.001) and 1987 (99.0%, P=0.006) recruitments. The proportion of seropositives among males (84.1%) was significantly higher as compared to those measured in 1999 (73.0%, P<0.001) but similar to those of 1987 (88.8%, P=0.13). Females born in the FSU were found to be high risk groups as 11.5% were seronegative. CONCLUSIONS Our findings indicate that despite a successful program of congenital rubella syndrome prevention in Israel, there is a decline in seroprevalence among female young adults, especially immigrants from the FSU. A proactive catch-up program for females, especially for those of higher risk for susceptibility should be considered in Israel and in other countries.

Sub-optimal prevalence of mumps antibodies in a population based study of young adults in Israel after 20 years of two dose universal vaccination policy

BACKGROUND A recent mumps outbreak in Israel despite an ongoing national program of a 2-dose universal childhood vaccination policy since 1988, raised questions regarding population immunity among young adults. OBJECTIVE To assess the seroprevalence of mumps antibodies among young Israeli adults born after 1987 in order to determine evidence based vaccination policy. METHODS We conducted a seroprevalence study of mumps IgG antibodies among 441 Israeli adults born in 1988-9, based on a representative sample of sera collected upon recruitment to mandatory military service in 2007. RESULTS The overall seroprevalence of IgG antibody to mumps virus among 1988-9 born was 83.7%, 82.1% among males and 85.7% among females. Seroprevalence among 2007 recruits was similar to 1999 recruits (83.3%, P=0.89) and significantly lower than 1987 recruits (94.1%, P<0.0001). The absolute decrease between 2007 and 1987 for males was 13.1% (P<0.0001) and for females 7.0% (P=0.02). Seroprevalence was not significantly higher among native Israelis (84.9%) than among young adults born in the Commonwealth of Independent States (81.1%, P=0.46) and significantly higher compared to young adults born in Western Europe or North America (68.2%, P=0.045). CONCLUSIONS Our findings indicate sub-optimal population seroprevalence despite a 2-dose universal childhood vaccination policy. This study allows better understanding of current mumps outbreaks in Israel and elsewhere following periods of low circulation of wild virus. These findings support mumps vaccination, even for populations and individuals that received two doses during childhood, as means for outbreak containment among young adults, especially in crowded settings, and serve as a reminder to the need for dynamic vaccination policy, supported by health promotion activities.

Prevalence of mumps antibodies in the Israeli population in relation to mumps vaccination policy and incidence of disease.

We examined the prevalence of mumps antibodies in the Israeli population in relation to mumps vaccination policy and past and subsequent incidence of disease. The levels of specific IgG antibodies against mumps were tested in 3330 residual sera collected during 1997-1998 from an age-stratified population sample. Against the background of a consistent MMR vaccination coverage of >90%, the age- and sex-adjusted seropositivity to mumps was 77.0%. No significant differences between genders were found. Seropositivity in the 10-13 years age group, born just before the introduction of the MMR vaccine, was the lowest (59%). These birth cohorts were the target of an outbreak of mumps in 2005 that occurred among high-school students and military recruits. A trend of waning immunity was observed between the first and second vaccine doses. The seroepidemiological data demonstrate that immunity levels below the herd immunity threshold, along with social mixing and crowded conditions facilitated the occurrence of mumps outbreaks. Periodical serosurveys are an essential component in the evaluation of the vaccination policy against mumps.

Sero-prevalence of mumps antibodies in subpopulations subsequently affected by a large scale mumps epidemic in Israel

BACKGROUND AND AIMS Despite the high national vaccination coverage, a large outbreak of mumps occurred in Israel, in 2009-2010, with onset and heavy transmission in ultraorthodox Jewish communities and further country-wide spread. We examined the sero-prevalence of mumps antibodies in the subpopulations subsequently affected by this large mumps outbreak, compared with the general population. METHODS The study was conducted in ultraorthodox Jewish communities, in Jerusalem district (N=251), in Bnei Brak city in Tel Aviv district (N=453), and in the general population (N=1846), using residual sera of 1-20 year old subjects. Mumps IgG antibodies were measured using Enzygnost anti-parotitis virus IgG ELISA kit. RESULTS Mumps sero-positivity was significantly lower in Jerusalem: 51.8% (95% CI 51.9-61.0), and Bnei Brak: 56.5% (95% CI 45.6-57.9), than in the general population: 68.1% (95% CI 66.0-70.2). Sero-positivity increased with age, however in Jerusalem it was substantially low (46%) in the age group 10-20 years. This age group comprised a significant portion of mumps patients in the 2009-2010 outbreak. CONCLUSIONS Low immunity levels, combined with overcrowding and social mixing, were the main predisposing factors of the enhanced epidemic transmission of mumps in the ultraorthodox Jewish communities and further country-wide spread.

Seroprevalence of measles, mumps and rubella among young adults, after 20 years of universal 2-dose MMR vaccination in Israel

Evidence-based vaccination policy is important for the global and local efforts of achieving control over measles. In 2007, the first Israeli birth cohort to be twice vaccinated during childhood with Measles-Mumps-Rubella vaccine reached adulthood. In parallel, Israel experienced its largest measles outbreak since 1994. We aimed to assess the seroprevalence of measles IgG antibodies and concordance with rubella and mumps seroprevalence among young Israeli adults born 1988–9 in comparison to previous birth cohorts, in order to inform evidence based prevention policy. We conducted a seroprevalence study of IgG antibodies among 439 Israeli adults born in 1988–9, based on a representative sample of sera collected at age 18–19 upon recruitment to mandatory military service in 2007. In total, 85.7% were seropositive for measles as compared with 95.6% in the 1996 recruitment (P < 0.001). The absolute decline was significant both for males (8.8%, P = 0.001) and females (12.1%, P < 0.001). There were no significant differences in seropositivity by gender, years of education, country of birth or smoking status. Rubella seropositivity among measles seropositives was 90.4%, significantly (P < 0.001) higher than 72.1% among measles seronegatives. Mumps seropositivity among measles seropositives was 87.0%, significantly (P < 0.001) higher than 62.3% among measles seronegatives. Results were similar for Israeli-born only. Our findings indicate that measles seroprevalence decreased after the last change in vaccination policy and reach sub-optimal level. Until global eradication is reached, a proactive vaccination program to supplement routine childhood vaccination program should be considered in Israel and in other countries.