Outbreak of poliomyelitis in Finland in 1984. Description of nine cases with persisting paralysis

Lessons learnt to keep Europe polio-free: a review of outbreaks in the European Union, European Economic Area, and candidate countries, 1973 to 2013

Between 1973 and 2013, 12 outbreaks of paralytic poliomyelitis with a cumulative total of 660 cases were reported in the European Union, European Economic Area and candidate countries. Outbreaks lasted seven to 90 weeks (median: 24 weeks) and were identified through the diagnosis of cases of acute flaccid paralysis, for which infection with wild poliovirus was subsequently identified. In two countries, environmental surveillance was in place before the outbreaks, but did not detect any wild strain before the occurrence of clinical cases. This surveillance nonetheless provided useful information to monitor the outbreaks and their geographical spread. Outbreaks were predominantly caused by poliovirus type 1 and typically involved unvaccinated or inadequately vaccinated groups within highly immunised communities. Oral polio vaccine was primarily used to respond to the outbreaks with catch-up campaigns implemented either nationwide or in restricted geographical areas or age groups. The introduction of supplementary immunisation contained the outbreaks. In 2002, the European region of the World Health Organization was declared polio-free and it has maintained this status since. However, as long as there are non-vaccinated or under-vaccinated groups in European countries and poliomyelitis is not eradicated, countries remain continuously at risk of reintroduction and establishment of the virus. Continued efforts to reach these groups are needed in order to ensure a uniform and high vaccination coverage.

Role of environmental poliovirus surveillance in global polio eradication and beyond

Environmental poliovirus surveillance (ENV) means monitoring of poliovirus (PV) transmission in human populations by examining environmental specimens supposedly contaminated by human faeces. The rationale is based on the fact that PV-infected individuals, whether presenting with disease symptoms or not, shed large amounts of PV in the faeces for several weeks. As the morbidity:infection ratio of PV infection is very low, this fact contributes to the sensitivity of ENV which under optimal conditions can be better than that of the standard acute flaccid paralysis (AFP) surveillance. The World Health Organization has included ENV in the new Strategic Plan of the Global Polio Eradication Initiative for years 2010–2012 to be increasingly used in PV surveillance, supplementing AFP surveillance. In this paper we review the feasibility of using ENV to monitor wild PV and vaccine-derived PV circulation in human populations, based on global experiences in defined epidemiological situations.

Outbreak of poliomyelitis in Finland in 1984-85 - Re-analysis of viral sequences using the current standard approach

In 1984, a wild type 3 poliovirus (PV3/FIN84) spread all over Finland causing nine cases of paralytic poliomyelitis and one case of aseptic meningitis. The outbreak was ended in 1985 with an intensive vaccination campaign. By limited sequence comparison with previously isolated PV3 strains, closest relatives of PV3/FIN84 were found among strains circulating in the Mediterranean region. Now we wanted to reanalyse the relationships using approaches currently exploited in poliovirus surveillance. Cell lysates of 22 strains isolated during the outbreak and stored frozen were subjected to RT-PCR amplification in three genomic regions without prior subculture. Sequences of the entire VP1 coding region, 150 nucleotides in the VP1-2A junction, most of the 5' non-coding region, partial sequences of the 3D RNA polymerase coding region and partial 3' non-coding region were compared within the outbreak and with sequences available in data banks. In addition, complete nucleotide sequences were obtained for 2 strains isolated from two different cases of disease during the outbreak. The results confirmed the previously described wide intraepidemic variation of the strains, including amino acid substitutions in antigenic sites, as well as the likely Mediterranean region origin of the strains. Simplot and bootscanning analyses of the complete genomes indicated complicated evolutionary history of the non-capsid coding regions of the genome suggesting several recombinations with different HEV-C viruses in the past.

Duration of immunity in cats after vaccination or naturally acquired infection

The necessity for cats to be vaccinated annually against common pathogens has been questioned because sarcomas have infrequently been reported at the injection site. However, with few exceptions, the duration of immunity induced by vaccination or infection is uncertain, and there may therefore be a risk associated with a decision not to revaccinate. This article reviews the information available about the duration of immunity induced by vaccination or infection in cats, and reveals many shortcomings that make blanket recommendations impossible. Each vaccine must be considered individually.

Duration of immunity in dogs after vaccination or naturally acquired infection

This paper reviews current scientific information about the duration of immunity induced in dogs by infection or vaccination. It describes the shortcomings of the methods used to measure the immune responses of dogs, and explains the need for basic studies on the nature of protective humoral and cellular responses, and standardised assays for the long-term duration of immunity to pathogens other than rabies. The information is inadequate to warrant uniform recommendations on the ideal intervals for vaccination; each vaccine must be evaluated on the basis of its own merits and the characteristics of the disease it is intended to guard against.

Control of poliomyelitis in Kuwait

The use of oral poliovirus vaccine (OPV) in the early 1960s marked the beginning of the State's effort in controlling poliomyelitis in Kuwait. During the next two decades, despite the vaccine's availability and use, the disease continued to cause disability and death. However, with the massive and sustained use of the trivalent OPV since 1963G and the introduction of neonatal supplementary immunization with monovalent type 1 (MOPV) in 1976G along with strengthening of the surveillance activities against poliomyelitis, the incidence of the paralytic disease began declining and by the mid-eighties it disappeared altogether. With no cases of paralytic poliomylelitis reported in Kuwait since 1986G, the disease is largely controlled. The epidemiology of poliomyelitis in Kuwait has been examined here in retrospect. The paper profiles about 3 1/2 decades (1958G to 1992G) of efforts that led to this impressive virtual elimination of poliomyelitis. In order to maintain this status and eventually achieve the goal of eradication without the rare occurrence of vaccine-associated paralysis, it is, in our opinion, necessary to adopt an approach of combined vaccination with the inactivated polio vaccine (IPV), preferably in the neonatal age, followed by OPV. Simultaneously, monitoring the presence and circulation of wild poliovirus in the environment and continuous surveillance should be carried out for timely intervention.

Swedish inactivated polio vaccine: laboratory standardization and clinical experience over a 30-year period

Swedish inactivated polio vaccines have contained per single human dose a mean amount of viral antigen equivalent to 1 x 10(7.5) CCID50 of type 1, 1 x 10(7.4) of type 2 and 1 x 10(7.8) of type 3 produced on primary monkey kidney cells. Potency tests were made in comparison with an equivalent amount of live virus suspension of all three types. Validation of tests has been based on the response to type 1 only. Based on clinical experience with vaccine lots from 1957 and the establishment of the second live reference virus suspension in 1966, the minimum limit of immune response in guinea-pigs--expressed in extinction values--was decided as 1.5 for type 1 and type 3, and 1.0 for type 2. The potency test method used since 1959 in Sweden was two subcutaneous injections 2 weeks apart using 10 guinea-pigs per dilution and blood collected 1 week thereafter. Potency tests made according to European Pharmacopoeia revealed a somewhat lower value for type 2. D-antigen content in Swedish vaccines was low, however, the Swedish vaccine has protected against many episodes or outbreaks of wild virus in Sweden and immunized individuals elsewhere in the world. For the Swedish population a clear-cut clinical motivation for requiring a higher potency for type 2 as required in the European Pharmacopoeia or increased levels of D-antigen in the final product has not been presented. It was concluded that the European Pharmacopoeia method did not distinguish between doses of 0.5-1.0 ml. The minimum limit extinction value for type 2, i.e. 2.0 seemed to high.(ABSTRACT TRUNCATED AT 250 WORDS)

Isolation of polioviruses from sewage and their characteristics: experience over two decades in Sweden

Indigenous polio ceased in Sweden in 1962 after 5 years' use of killed polio vaccine. In 1967, it was considered of interest to investigate whether poliovirus was present in the sewage. A method for selective isolation of poliovirus from sewage was developed. The method appeared to increase the yield. The studies were carried out at intervals up to 1990. In 1989-90, the virus isolates were characterized by the use of monoclonal antibodies differentiating between vaccine-like (Sabin-like) and non-vaccine-like strains. Polioviruses of both kinds were isolated throughout the period. Two periods were of special interest. The first was in 1977, when a single, paralytic, type-2 case occurred in Sweden in an unvaccinated sect. The second was in 1984-85 when a type-3 epidemic broke out in Finland, followed by vaccinations of the whole Finnish population with live oral polio vaccine. On both occasions the implicated viruses could be traced to a high degree in sewage in Sweden. The absence of poliovirus isolations from faecal specimens of patients and the isolation of live poliovirus vaccine virus, i.e. a vaccine not used in Sweden, indicate that the virus strains are imported.

Polio immunization policy in the United States: a new challenge for a new generation

The primary reason that live poliovirus vaccine is recommended in the United States today is because it may immunize contacts who have not otherwise chosen to be vaccinated. This policy places contacts at risk of paralysis from an untested, unlicensed "spread virus" vaccine and places infants at risk for an unproven, theoretical benefit to others, not themselves. The licensed killed poliovirus vaccine provides equivalent protection to those vaccinated, with no risk to recipients or contacts. The preceding analysis by Hinman, et al, is an interesting exercise in modeling, but many of their assumptions are open to question. Their sweeping conclusions are not justified by the type of analysis performed, which should yield an overall assessment of a decision environment not a single optimal choice. No measure of perceived social consequence or patient attitude is included, although this is of central importance today. Their report lends an aura of credibility to one conclusion, but this credibility is illusory at best. The major social issue today is not which vaccine to use, but how should polio immunization policy be evaluated.

Viruses in sewage waters during and after a poliomyelitis outbreak and subsequent nationwide oral poliovirus vaccination campaign in Finland

During an outbreak of paralytic poliomyelitis in Finland in 1984 and 1985 the widespread circulation of the causative wild-type serotype 3 poliovirus in the population was documented by demonstrating the virus in sewage water specimens in 13 different locations in the greater Helsinki district and in 13 other cities or towns all over the country. After the nationwide campaign with oral poliovirus vaccine in 1985, poliovirus serotypes 2 and 3 were readily isolated from sewage waters for up to 2 months, whereas type 1 poliovirus seemed to disappear from the sewage more rapidly. All of these isolates were temperature sensitive and therefore most likely vaccine related. The efficacy of the vaccination campaign in regard to elimination of the epidemic type 3 strain was evaluated by a follow-up study on viruses in sewage waters continued for 12 months through the subsequent expected season of poliomyelitis. Several types of enteroviruses, including five vaccine-related poliovirus strains, were identified in the 72 virus-positive specimens out of 93 studied. No wild-type polioviruses were found, indicating the success of the campaign.

Proportions of immunoglobulin isotypes in paralytic poliomyelitis and after vaccination

Immunoglobulin isotype composition of poliovirus antibodies was studied by isotype-specific solid-phase radio-immunoassay (RIA) in four patients with paralytic poliomyelitis, five adults receiving live poliovirus vaccine as a booster immunization, and seven children receiving first doses of inactivated poliovirus vaccine. In paralytic poliomyelitis serum and cerebrospinal fluid (CSF) poliovirus antibodies were mainly of IgG1, IgG3, and IgA isotypes. IgM antibodies were found in sera but not in CSF. Either IgG2 and IgG4 antibodies were undetectable or the titers were low. In adults who had received live trivalent poliovirus vaccine, antibodies against poliovirus type 3 were detected in IgG1 (53% of total antibodies), IgG3 (25%), IgM (9%), IgA (8%), IgG2 (3%), and IgG4 (2%) isotypes. In prevaccination and late postvaccination sera the share of IgG3 antibodies was exceptionally high (35%). In children who received inactivated poliovirus vaccine, antibodies developed in IgG1 (53-61% of total antibodies for poliovirus types 1, 2, and 3), IgG3 (12-21%), and IgM (23-33%) isotypes. Antibody levels in IgG2, IgG4, and IgA isotypes were low and observed only in a few cases. Like other viral antibodies IgG1 and IgG3 isotypes were the major IgG subclasses in poliovirus antibodies.

Acute transverse myelopathy successfully treated with plasmapheresis and prednisone in a patient with primary Sjögren's syndrome

We report a case of acute transverse myelopathy in a patient with primary Sjögren's syndrome of 3 years duration. Our patient's acute transverse myelopathy developed within 1 week and resulted in complete paraparesis below the mamillary level. Extensive laboratory investigation ruled out viral, bacterial, and fungal etiology, Guillain-Barré syndrome, poliomyelitis, and multiple sclerosis. At diagnosis, treatment was initiated immediately with prednisone (80 mg/day) and plasmapheresis, which was performed as a first-aid measure. Improvement was noted as early as 10 days after the start of therapy. Within 5 1/2 months of the first symptoms of paralysis, the patient walked without difficulty and returned to her normal activities. A causal relationship between plasmapheresis/prednisone therapy and recovery has not been proven but merits further consideration.

A study of the sero-immunity that has protected the Swedish population against poliomyelitis for 25 years

Although the population was highly susceptible to poliomyelitis on account of its low natural immunity, the general vaccination with inactivated polio vaccine eliminated poliomyelitis in Sweden within 6 years (1957-62). This status remains after 25 years, although challenges from the introduction of virus occur constantly. Over 99% of the population born in the forties and later is estimated to have been vaccinated, as well as at least 90% of those born earlier. The mean antibody levels of vaccinees against polio range from 100 (type 3) and 500 (type 1) up to 800 (type 2). Seronegative persons are seen only in a small percentage. Evaluation of the duration of immunity indicates that, after the post-vaccination fall in titre which occurs within 2-5 years after immunization, the immune levels remain fairly stable or decline very slowly. Sera from 12-year-old Swedish vaccinees neutralized the type 3 Saukett strain used for vaccine production 5 times better than a type 3 strain isolated during the Finnish outbreak 1984.

Detection of poliovirus antigen by enzyme immunoassay

A solid-phase enzyme immunoassay (EIA) was developed for the detection of poliovirus antigen. Rabbit and guinea pig antisera for the assay were raised against purified poliovirus type 3/Fin (strain 3/Fin/K) isolated from a fecal specimen from a meningitis patient during an outbreak of poliomyelitis in Finland in 1984. The EIA was highly specific for poliovirus type 3, and it was about 30 times more sensitive for strain 3/Fin/K than for strain 3/Saukett used in the inactivated poliovirus vaccine. The sensitivity of the EIA was 2 to 5 ng of purified strain 3/Fin/K per ml, whereas disrupted viruses and soluble viral proteins were almost undetectable by the assay. Only 5 of 51 (10%) stool specimens containing poliovirus type 3/Fin detected by virus isolation were positive by the EIA. Quantitation by the EIA, using purified poliovirus 3/Fin/K as a standard, revealed that concentrations of poliovirus type 3 in undiluted fecal specimens of patients with natural poliovirus infection were only 50 ng/ml or less. In conclusion, owing to the small amount of poliovirus in feces, the EIA is not suitable for the diagnosis of poliovirus infections directly from clinical specimens, but it can be used to detect, type, and quantitate poliovirus antigen in infected cells.

Outbreak of poliomyelitis in Finland: no distinct HLA association

In 1984 to 1985 an outbreak of poliomyelitis was found after a 20-year free period in Finland. The 10 patients with central nervous system disease were studied for HLA antigens. Additionally, two families with two and four affected siblings from the previous outbreak were analysed. The affection of the central nervous system seems not to depend on HLA-associated genetic factors.

Outbreak of paralytic poliomyelitis in Finland: widespread circulation of antigenically altered poliovirus type 3 in a vaccinated population

An outbreak of 9 cases of paralytic poliomyelitis and 1 non-paralytic case occurred in Finland between August, 1984, and January, 1985, after two decades of freedom from the disease attributable to a successful immunisation programme. During the outbreak poliovirus type 3 was isolated from the patients, from about 15% of healthy persons tested, and from sewage water. At least 100 000 persons were estimated to have been infected. With 1.5 million extra doses of inactivated poliovirus vaccine to children under 18 years of age and an oral poliovirus vaccine campaign covering about 95% of the entire population in February-March, 1985, the outbreak was halted in February, 1985. Impaired herd immunity to the epidemic strain of poliovirus type 3, which differed from the type 3 vaccine strains in both immunological and molecular properties, was important in the emergence of this outbreak. The inactivated poliovaccine that had been used in the vaccination programme was relatively weakly immunogenic, especially as regards the type 3 component. Whether continuous antigenic variation of poliovirus type 3 has wider epidemiological implications is not known.