[German Health survey 1997/98: immune status against poliomyelitis]

Sero-survey of polio antibodies during wild poliovirus outbreak in southern Xinjiang Uygur Autonomous Region, China

Background

After being polio free for more than 10 years, an outbreak following importation of wild poliovirus (WPV) was confirmed in Xinjiang Uygur Autonomous Region, China, in 2011.

Methods

A cross-sectional study was conducted prior to supplementary immunization activities (SIAs), immediately after the confirmation of the WPV outbreak. In selected prefectures, participants aged ≤60 years old who visited hospitals at county-level or above to have their blood drawn for reasons not related to the study, were invited to participate in our study. Antibody titers ≥8 were considered positive.

Results

Among the 2,611 participants enrolled, 2,253 (86.3%), 2,283 (87.4%), and 1,989 (76.2%) were seropositive to P1, P2 and P3 respectively, and 1744 (66.8%) participants were seropositive to all the three serotypes. Lower antibody seropositivities and geometric mean titers were observed in children <1 year of age and in adults aged 15–39 years.

Conclusion

Serosurveys to estimate population immunity in districts at high risk of polio importation might be useful to gauge underlying population immunity gaps to polio and possibly to guide preparedness and response planning. Consideration should be given to older children and adults during polio risk assessment planning and outbreak response.

Seroprevalence of antipolio antibodies among children <15 years of age in border provinces in China

Despite remarkable progression toward polio eradication worldwide, wild poliovirus (WPV) importation has been a great challenge for China, as it shares borders with countries where WPV is endemic. The objective of this study was to estimate poliovirus antibody seroprevalence among children <15 years of age in 3 border provinces (Yunnan Province, Tibet Autonomous Region, and Xinjiang Uygur Autonomous Region) in China. A cross-sectional, hospital-based study was undertaken in 3 border provinces in 2010. Individuals <15 years old who visited hospitals at the prefecture level or above to have their blood drawn for any reason were invited to participate in our study. Neutralizing antibody titers to polio serotypes 1 (P1), P2, and P3 were assayed according to the World Health Organization manual for the virological investigation of polio. Antibody titers of ≥8 were considered positive. Among the 1,360 subjects enrolled, 1,220 (89.7%), 1,259 (92.6%), and 1,112 (81.8%) were seropositive to P1, P2, and P3, respectively, and 1,051 (77.3%) subjects were seropositive to all three serotypes. The highest seropositive rates were observed in Xinjiang Uygur Autonomous Region. By age, 3- to 5-year-old subjects had the highest rate of seropositivity, and seropositivity decreased significantly with increasing age. The risk of WPV importation will continue until WPV transmission has been interrupted worldwide. Consistent with the Global Polio Eradication Initiative's polio endgame strategy, China must maintain its polio-free status by ensuring adequate population immunity against polio. Because immunity wanes with increasing age, a booster dose with bivalent type 1 and 2 oral poliovirus vaccine could be considered for teenagers in China.

Poor immunity status against poliomyelitis in medical students: a semi-anonymous study

In spite of almost complete eradication, poliomyelitis continues to be a global threat even in non-endemic countries due to the ever-increasing international travel activities. Health care workers are at a special risk in acquiring pathogens from travelers returning from endemic countries. Polio vaccines are fairly well accepted throughout the German population. Yet, laboratory controls for successful immunization are carried out only sporadically in the general population, and not even the medical staff are routinely tested for polio immunity. The present study was initiated in order to assess the immunity status of young people at the very beginning of their career in clinical medicine. Within their first clinical semester, all students are supposed to undergo an obligatory health check in our Occupational Medicine Unit. A blood sample is taken and sent under a personal code to our diagnostic laboratories for virus serology, and for cryoconservation of residual serum, if available. Within the periods 2004–2006 and 2008–2010, we analyzed sera from 424 and 427 individuals, respectively, for anti-polio types 1, 2, 3 antibodies by a microneutralization assay. In the latest study period, there was a slight increase in the rate of fully protected persons: 63.9 % triple-seropositivity versus 57.1 % in the period 2004–2006. By the end of the second clinical semester, students with low or negative antibody levels (1:<10) were informed, and a (booster) vaccination was recommended.

Immunity status of adults and children against poliomyelitis virus type 1 strains CHAT and Sabin (LSc-2ab) in Germany

BACKGROUND

In October 2007, the working group CEN/TC 216 of the European Committee for standardisation suggested that the Sabin oral poliovirus vaccine type 1 strain (LSc-2ab) presently used for virucidal tests should be replaced by another attenuated vaccine poliovirus type 1 strain, CHAT. Both strains were historically used as oral vaccines, but the Sabin type 1 strain was acknowledged to be more attenuated. In Germany, vaccination against poliomyelitis was introduced in 1962 using the oral polio vaccine (OPV) containing Sabin strain LSc-2ab. The vaccination schedule was changed from OPV to an inactivated polio vaccine (IPV) containing wild polio virus type 1 strain Mahoney in 1998. In the present study, we assessed potential differences in neutralising antibody titres to Sabin and CHAT in persons with a history of either OPV, IPV, or OPV with IPV booster.

METHODS

Neutralisation poliovirus antibodies against CHAT and Sabin 1 were measured in sera of 41 adults vaccinated with OPV. Additionally, sera from 28 children less than 10 years of age and immunised with IPV only were analysed. The neutralisation assay against poliovirus was performed according to WHO guidelines.

RESULTS

The neutralisation activity against CHAT in adults with OPV vaccination history was significantly lower than against Sabin poliovirus type 1 strains (Wilcoxon signed-rank test P < 0.025). In eight sera, the antibody titres measured against CHAT were less than 8, although the titre against Sabin 1 varied between 8 and 64. Following IPV booster, anti-CHAT antibodies increased rapidly in sera of CHAT-negative adults with OPV history. Sera from children with IPV history neutralised CHAT and Sabin 1 strains equally.

CONCLUSION

The lack of neutralising antibodies against the CHAT strain in persons vaccinated with OPV might be associated with an increased risk of reinfection with the CHAT polio virus type 1, and this implies a putative risk of transmission of the virus to polio-free communities. We strongly suggest that laboratory workers who were immunised with OPV receive a booster vaccination with IPV before handling CHAT in the laboratory.

Monitoring of poliovirus neutralizing antibodies in São Paulo State, Brazil

As the world envisions poliomyelitis eradication, objective parameters are needed to ascertain whether immunocompetence against the virus provided by vaccine campaigns has been attained. The presence of neutralizing antibodies is considered a surrogate marker of protective immune response to the agent. Neutralization of three poliovirus serotypes were evaluated in a total of 411 sera samples collected from 1999 to 2005 in São Paulo State, Brazil. Antibody titres >/=1:8 were presented at 88.1% (362/411), 88.8% (365/411) and 61.6% (253/411) of samples for 1, 2 and 3 serotypes, respectively. Evaluation of poliovirus immune status may be a useful tool to support decisions concerning polio vaccine policy.

Kinder- und Jugendgesundheitssurvey (KiGGS): Immunitätslage gegen Poliomyelitis

One of the goals of the WHO is the worldwide eradication of poliomyelitis in the coming years. Europe was declared poliofree in 2002, but increasing migration may lead to a come-back of circulating polioviruses. A high level of population immunity protects against imported wild viruses from endemic areas. The first seroprevalence data since the switch from live to inactivated vaccine in Germany (OPV to IPV) are provided. A serum panel was tested (n=2,046) in order to study the serological status against poliomyelitis. The microneutralization test on RD cells was used. Overall, neutralizing antibodies against poliovirus types 1, 2 and 3 were detected in 97.4%, 97.6%, and 93.6% of samples, respectively. Of the test persons, 91.7% had antibodies against all three virus types. Only 26 children simultaneously lacked neutralizing antibodies for all three serotypes (1.3%). No significant correlation between gender, region (East/West)), migration status (with/without migration background) and antibody prevalence to polioviruses was found. The seroprevalence of antibodies against all three types of polioviruses indicates a very high level of population immunity in German children. It must be maintained through consequently performed vaccination programmes.

Seroprevalence of vaccine preventable and blood transmissible viral infections (measles, mumps, rubella, polio, HBV, HCV and HIV) in medical students

In the course of clinical training medical students are in particular exposed to infectious diseases. Therefore, the present study was performed to investigate the immunity status of 223 medical students in their first clinical semester to job-related diseases. Specific serological antibody testing of hepatitis B-virus (HBV), hepatitis C-virus (HCV), human immunodeficiency virus (HIV), varicella zoster- (VZV), measles-, mumps-, rubella and polioviruses' type 1, 2 and 3 were performed. The results yielded, that 69.5% of the students had an anti-HBs-level > or =10 IU/l and 54.7% > or =100 IU/l. Neither HCV infection nor HIV infection were found, but one student showed an active HBV infection. Virus specific immunity rates were found in 91.5% for measles, 80.3% for mumps, 90.1% for rubella and 96.9% for varicella. Furthermore the medical students demonstrated neutralizing antibodies to polioviruses: 95.1% (type 1), 96.9% (type 2) and 70% (type 3). 68.2% had antibodies (titer 1:> or =10) against all three virus types. The partly significant gaps of immunity in the students need to be closed prior to the first contact with patients.