Enterovirus 71 isolated from cases of epidemic poliomyelitis-like disease in Bulgaria

Virological and serological studies of an epidemic disease in Bulgaria, 1975, were carried out. Epidemiologically, clinically and pathomorphologically, the disease simulated almost all known forms of poliomyelitis, acute stem encephalitis, encephalomyocarditis and aseptic meningitis. The studies completely rules out the participation of polioviruses and provided comprehensive evidence for the etiological role of a peculiar enterovirus subsequently identified as enterovirus (EV) type 71 known in the literature since 1974. Altogether, in 1975 and 1976 from 65 cases of poliomyelitis-like disease (PLD) 92 strains of EV71 were isolated, including 37 strains from the brain and medulla, 1 from the cerebrospinal fluid, 10 from mesenterial lymph nodes and tonsils and 44 from faeces. In addition, in 282 convalescent cases of the disease, diagnostic seroconversion or high titers of antibody to this virus were demonstrated. The most successful virus isolation was achieved by inoculation of green monkey kidney cell cultures and newborn white mice. Bulgarian strains of enterovirus 71 regularly caused paralysis in monkeys and morphological poliomyelitis-like lesions in their CNS, and paralysis and myositis with Zenker necrosis in newborn white mice, cotton rats, Syrian hamsters, and 3-week-old cotton rats. The diseased rodents had much more virus in their mucles than in brains.

The long-term outcomes of human West Nile virus infection

Since its introduction to North America in 1999, human infection with West Nile virus (WNV) has resulted in considerable acute morbidity and mortality. Although the ongoing epidemic has resulted in a great increase in our understanding of the acute clinical features of human illness and helped to define associated clinical syndromes, far less is known about potential long-term clinical and functional sequelae. Several recent assessments, however, suggest that patients--even those with apparently mild cases of acute disease--frequently have subjective, somatic complaints following WNV infection. Persistent movement disorders, cognitive complaints, and functional disability may occur after West Nile neuroinvasive disease. West Nile poliomyelitis may result in limb weakness and ongoing morbidity that is likely to be long term. Although further assessment is needed, the long-term neurological and functional sequelae of WNV infection are likely to represent a considerable source of morbidity in patients long after their recovery from acute illness.

Host nutritional status: the neglected virulence factor

The emergence of new infectious diseases and old diseases with new pathogenic properties is a burgeoning worldwide problem. Severe acute respiratory syndrome (SARS) and acquired immune deficiency syndrome (AIDS) are just two of the most widely reported recent emerging infectious diseases. What are the factors that contribute to the rapid evolution of viral species? Various hypotheses have been proposed, all involving opportunities for virus spread (for example, agricultural practices, climate changes, rainforest clearing or air travel). However, the nutritional status of the host, until recently, has not been considered a contributing factor to the emergence of infectious disease. In this review, we show that host nutritional status can influence not only the host response to the pathogen, but can also influence the genetic make-up of the viral genome. This latter finding markedly changes our concept of host–pathogen interactions and creates a new paradigm for the study of such phenomena.

Two models for multiple sclerosis: experimental allergic encephalomyelitis and Theiler's murine encephalomyelitis virus

In this review, we compare and contrast two popular models for multiple sclerosis (MS), Theiler's murine encephalomyelitis virus (TMEV) disease and experimental allergic encephalomyelitis (EAE). These models are used to investigate the viral and autoimmune etiology of MS, respectively. Infection with live TMEV is an essential component of TMEV demyelinating disease. TMEV-specific cellular and humoral immunity and apoptosis of infected cells eliminate virus from the gray matter of the central nervous system (CNS) during the acute phase of TMEV disease. In contrast, during the chronic phase, TMEV persistently infects glial cells and/or macrophages in the white matter. During the chronic phase, recruitment of macrophages, TMEV-specific T cells and antibody, with the induction of apoptosis are harmful to the host, leading to inflammation and demyelination. In EAE, induction of encephalitogenic CD4+ T cells is an important component for disease. After stimulation and activation, these T cells upregulate adhesion molecules and are able to enter the CNS. Th1 cytokines augment the recruitment of mononuclear cells in the CNS. Macrophages and/or glial cells secrete cytotoxic factors leading to demyelination in conjunction with B cells secreting anti-myelin antibody. Although immunopathological pathways during the course of the demyelination in TMEV infection and EAE are not always the same, oligodendroglial apoptosis is observed in both models, suggesting that their demyelinating processes share a common terminal pathway and finally lead to quite a similar clinical and pathological picture.

Epidemiology of hodgkin's disease in the young

Many features of Hodgkin's disease (HD) among adolescents and young adults suggest that it has an infectious etiology. However, the proposal that HD is a contagious disease which can be transmitted by patients or their close contacts has not been substantiated. An alternative infectious disease model is suggested by analogy with paralytic poliomyelitis (PP). For both diseases, the peak age of incidence is delayed as living conditions improve. For both, increased risk is associated with higher social class and small family size. Like PP, HD may be a rare manifestation of a common infection with the probability of disease development increasing as age at infection is delayed. This analogy is supported by the report that the risk of HD is higher for persons who had a low frequency of childhood infectious diseases. If this model is valid, HD patients represent no hazard to their contacts. However, the incidence of HD among young adults may increase in the coming decade because of the current high standard of living and small family size.

Evolution of the T-cell repertoire during the course of experimental immune-mediated demyelinating diseases

Fig. 6 depicts a model for epitope spreading in T cell-mediated demyelination. The acute phase of disease is due to T cells specific for the initiating epitope, which can be either a determinant on the CNS target organ of the autoimmune response or a determinant on a persisting, CNS-tropic virus. The primary T cell response is responsible for the initial tissue damage by the production of proinflammatory Th1 cytokines which can affect myelination directly (Selmaj et al. 1991) and indirectly by their ability to recruit and activate macrophages to phagocytize myelin (Cammer et al. 1978). As a result of myelin damage and opening of the blood-brain-barrier during acute disease, T cells specific for endogenous epitopes on the same and/or different myelin proteins are primed and expand either in the periphery or locally in the CNS. These secondary T cells initiate an additional round of myelin destruction, leading to a clinical relapse by production of additional pro-inflammatory cytokines, similar to the bystander demyelination operative during acute disease. It will be of great interest to determine the relative contributions of local and systemic immune responses to these endogenous neuroepitopes. It is possible that local CNS presentation of endogenous neuroepitopes following acute CNS damage could be mediated by infiltrating inflammatory macrophages, activated microglial cells, endothelial cells and/or astrocytes. These tissue resident antigen presenting cells have been shown to upregulate expression of MHC class II (Sakai et al. 1986, Traugott & Lebon 1988), certain adhesion molecules (Cannella et al. 1990), and B7 costimulatory molecules (K. M. Nikcevich, J. A. Bluestone, and S. D. Miller, in preparation) in response to pro-inflammatory cytokines. The data on epitope spreading provided by the murine demyelinating disease models clearly illustrate the dynamic nature of the T cell repertoire during chronic inflammation in a specific target organ. The contribution of epitope spreading to chronic CNS demyelination could be considered to be a special case since tolerance to myelin epitopes would be expected to be inefficient due to their sequestration behind the blood-brain-barrier. However, the recent description of epitope spreading in response to pancreatic antigens in spontaneous diabetes in the NOD mouse may indicate that this phenomenon is operative in a variety of organ-specific experimental and spontaneous autoimmune diseases.(ABSTRACT TRUNCATED AT 400 WORDS)

Risks of paralytic disease due to wild or vaccine-derived poliovirus after eradication

After the global eradication of wild polioviruses, the risk of paralytic poliomyelitis from polioviruses will still exist and require active management. Possible reintroductions of poliovirus that can spread rapidly in unprotected populations present challenges to policymakers. For example, at least one outbreak will likely occur due to circulation of a neurovirulent vaccine-derived poliovirus after discontinuation of oral poliovirus vaccine and also could possibly result from the escape of poliovirus from a laboratory or vaccine production facility or from an intentional act. In addition, continued vaccination with oral poliovirus vaccines would result in the continued occurrence of vaccine-associated paralytic poliomyelitis. The likelihood and impacts of reintroductions in the form of poliomyelitis outbreaks depend on the policy decisions and on the size and characteristics of the vulnerable population, which change over time. A plan for managing these risks must begin with an attempt to characterize and quantify them as a function of time. This article attempts to comprehensively characterize the risks, synthesize the existing data available for modeling them, and present quantitative risk estimates that can provide a starting point for informing policy decisions.

Vaccine policy changes and epidemiology of poliomyelitis in the United States

CONTEXT

The last case of poliomyelitis in the United States due to indigenously acquired wild poliovirus occurred in 1979; however, as a consequence of oral poliovirus vaccine (OPV) use that began in 1961, an average of 9 cases of vaccine-associated paralytic poliomyelitis (VAPP) were confirmed each year from 1961 through 1989. To reduce the VAPP burden, national vaccination policy changed in 1997 from reliance on OPV to options for a sequential schedule of inactivated poliovirus vaccine (IPV) followed by OPV. In 2000, an exclusive IPV schedule was adopted.

OBJECTIVE

To review the epidemiology of paralytic poliomyelitis and document the association between the vaccine schedule changes and VAPP in the United States.

DESIGN AND SETTING

Review of national surveillance data from 1990 through 2003 for cases of confirmed paralytic poliomyelitis.

MAIN OUTCOME MEASURES

Number of confirmed paralytic poliomyelitis cases, including VAPP, and ratio of VAPP cases to number of doses of OPV distributed that occurred before, during, and after implementation of policy changes.

RESULTS

From 1990 through 1999, 61 cases of paralytic poliomyelitis were reported; 59 (97%) of these were VAPP (1 case per 2.9 million OPV doses distributed), 1 case was imported, and 1 case was indeterminate. Thirteen cases occurred during the 1997-1999 transitional policy period and were associated with the all-OPV schedule; none occurred with the IPV-OPV schedule. No cases occurred after the United States implemented the all-IPV policy in 2000. The last imported poliomyelitis case occurred in 1993 and the last case of VAPP occurred in 1999.

CONCLUSION

The change in polio vaccination policy from OPV to exclusive use of IPV was successfully implemented; this change led to the elimination of VAPP in the United States.

Chronic progressive poliomyelitis secondary to vaccination of an immunodeficient child

We investigated an immunodeficient child in whom chronic progressive poliomyelitis developed after she had received live oral poliovirus vaccine. Poliovirus, Type II, was isolated from throat and stool during life and from several sites within the brain at autopsy. The brain isolate was classified as vaccine-like on the basis of temperature sensitivity and antigenic markers. However, in the monkey neurovirulence test, the brain isolate produced moderately severe lesions throughout the spinal cord and brainstem and appeared nonvaccine-like. Thus, the brain isolate demonstrated a dissociation between the antigenic and neurovirulence markers. Our observations suggest that, under unusual circumstances, such as immunodeficiency, attenuated poliovirus can produce a chronic progressive neurologic disease. This case also emphasizes the need to diagnose immunodeficiency as early as possible, so that live-virus vaccines will not be administered.

Multiple genetic changes can occur in the oral poliovaccines upon replication in humans

Poliovirus isolates of serotypes 2 and 3 from patients whose paralytic poliomyelitis cases were classified as oral vaccine-associated were analysed by oligonucleotide mapping of the virus genomes and by polyacrylamide gel electrophoresis of the virus proteins. Oligonucleotide maps of all isolates were similar to the maps of the corresponding oral vaccine strain. No two isolates gave identical maps. Most maps differed from that of the vaccine strain by at least one oligonucleotide spot. Maps of some isolates revealed numerous differences, indicating that multiple (greater than 100) genetic changes had occurred in the vaccine virus genomes during replication in one or two individuals. In contrast, maps of some neural tissue isolates showed minimal differences from the reference vaccine maps, raising the possibility that neurovirulence may be restored by a small number of genetic changes. For many isolates, changes were also detected in the mobilities of processing rates of the virus proteins.

Amyotrophic lateral sclerosis and parkinsonian syndromes in high incidence among the Auyu and Jakai people of West New Guinea

Amyotrophic lateral sclerosis (ALS) and parkinsonism-dementia (PD) occur in the highest recorded incidence among primitive Auyu and Jakai people on the southern coastal plain of West New Guinea, in association with a heretofore unrecognized subacute, often recurrent, paralytic "poliomyeloradiculitis" (PMR). Ninety-seven cases of ALS, 19 cases of PD and 18 cases of PMR were recorded, with mean ages of onset of 33, 43, and 26, respectively, in a small affected population of only about 7000. The ecology, culture, and diet of the remote, primitive ALS- and PD-affected people are indistinguishable from that of their unaffected neighbors, except for a remarkable deficiency of calcium and magnesium in their soil and drinking water. The distribution of affected and nonaffected villages indicates that communicable infectious or genetic etiology is unlikely. As a result of the isolation and primitive technology, domestic animals (except dogs and pigs) were not found among the Auyu and Jakai, and no manufactured products (including metals, ceramics, textiles, petrochemicals, medicines, food additives, condiments, paints, dyes, or solvents) were available to them.

Failure to clear persistent vaccine-derived neurovirulent poliovirus infection in an immunodeficient man

BACKGROUND

Individuals who chronically excrete neurovirulent poliovirus of vaccine-origin are of considerable concern to the Global Polio Eradication programme. Chronic infection with such polioviruses is a recognised complication of hypogammaglobulinaemia.

METHODS

We did a series of in-vitro and in-vivo therapeutic studies, with a view to clearing persistent neurovirulent poliovirus infection in an individual with common variable immunodeficiency, using oral immunoglobulin, breast milk (as a source of secretory IgA), ribavirin, and the anti-picornaviral agent pleconaril. We undertook viral quantitation, antibody neutralisation and drug susceptibility assays, and viral gene sequencing.

FINDINGS

Long-term asymptomatic excretion of vaccine-derived neurovirulent poliovirus 2 was identified in this hypogammaglobulinaemic man, and was estimated to have persisted for up to 22 years. Despite demonstrable in-vitro neutralising activity of immunoglobulin and breast milk, and in-vitro antiviral activity of ribavirin, no treatment was successful at clearing the virus, although in one trial breast milk significantly reduced excretion levels temporarily. During the course of study, the virus developed reduced susceptibility to pleconaril, precluding the in-vivo use of this drug. Sequence analysis revealed the emergence of a methionine to leucine mutation adjacent to the likely binding site of pleconaril in these isolates.

INTERPRETATION

Chronic vaccine-associated poliovirus infection in hypogammaglobulinaemia is a difficult condition to treat. It represents a risk to the strategy to discontinue polio vaccination once global eradication has been achieved.

Polioviruses with natural recombinant genomes isolated from vaccine-associated paralytic poliomyelitis

To determine how oral poliovirus vaccine (Sabin) strains evolve during replication in humans and to confirm the etiology of vaccine-associated paralytic poliomyelitis (VAPP), we examined 70 vaccine-derived strains isolated from VAPP cases. Two distant sequences of the poliovirus genome were targeted for a double restriction fragment length polymorphism assay (RFLP) of reverse-transcribed genomic segments amplified by PCR, an extension of the method that we described previously (Balanant et al., 1991). One (RFLP-1) was a 480-long nucleotide sequence coding for the N-terminal part of the VP1 capsid polypeptide, situated in the 5' third of the viral genome (nucleotides 2401-2880). The other (RFLP-3D1) was a 291-long nucleotide sequence coding for a part of the viral polymerase, situated near the 3' end of the genome (nucleotides 6086-6376). Strain-specific restriction profiles could be generated for different field isolates by using three restriction enzymes in each case: HaeIII, DdeI, and HpaII for RFLP-1 and HaeIII, DdeI and RsaI for RFLP-3D1. With few exceptions, the vaccine-specific RFLP profiles were found to be conserved in both regions during replication of these viruses in humans. Thus, RFLP could be used as a marker so as to identify the origin of viral isolates at both ends of their genome. Whether viral isolates were vaccine-derived was determined by using strain-specific monoclonal antibodies and RFLP-1. Among the 70 isolates, 21 of the 43 type 2 strains and 15 of the 22 type 3 strains had a recombinant genome. None of the 5 type 1 Sabin-derived isolates was found to be recombinant. Both intertypic vaccine/vaccine and vaccine/non-vaccine recombinants were detected. Partial nucleotide sequencing confirmed the RFLP results in all cases that were investigated. In one case, it was possible to predict the recombination junction site from the restriction profiles. This site was more precisely localized by sequencing. The C6203 > U nucleotide substitution, which is suspected to contribute to the reversion toward neurovirulence of the attenuated Sabin 1 strain, was detected in almost all the recombinant genomes containing Sabin 1-specific sequences at the 3' extremity. This mutation was detected by identification of the modified RsaI profile in the RFLP-3D1. The results presented in this paper suggest that recombination, alone or together with mutation, might be one of the mechanisms of the reversion toward neurovirulence of attenuated vaccine strains and of the natural evolution of poliovirus.

Epidemiology of Hodgkin's disease

Hodgkin's disease displays an intriguing variation in incidence with age. For adult disease, there is striking bimodality in incidence with peaks in young adulthood and in older adulthood. On epidemiologic grounds, there appear to be three different diseases: childhood (0-14 years), young adult (15-34 years), and older adult Hodgkin's disease (55+ years). There are marked geographic variations in Hodgkin's disease incidence, but the variations are different for the three age groups. There are also interesting associations between Hodgkin's disease and markers of social class. For the young adult disease, the higher the socioeconomic status of a person, the greater the Hodgkin's disease risk. Additionally, Hodgkin's disease patients appear to have had fewer of the childhood infectious diseases or to have had these diseases at older ages than controls. These factors suggest an analogy between young adult Hodgkin's disease and Epstein-Barr virus, poliomyelitis, and tuberculosis infections. Thus, the descriptive epidemiology of Hodgkin's disease suggests an infectious disease process underlying its etiology in young adulthood and perhaps in childhood. There is a curious relationship between Hodgkin's disease and Epstein-Barr virus infection. Persons with Epstein-Barr virus infection have an increased risk of developing Hodgkin's disease, and the Epstein-Barr virus infection precedes the development of Hodgkin's disease. The virus has never been isolated from or identified in Hodgkin's disease tissue. The mechanisms underlying this association are unknown and may provide important clues to the etiology of Hodgkin's disease and other lymphomas. It is likely that there is no direct person-to-person spread of Hodgkin's disease. This is suggested by several negative studies of linkages between cases, time-space clustering, and aggregation of exposures at schools. Studies have shown that neither physicians nor nurses, groups with greater likelihood of encountering Hodgkin's disease patients than the general public, have an increased risk. There appears to be familial aggregation of Hodgkin's disease. Siblings of young adult cases are at increased risk, whereas siblings of older adult cases have no increase in risk. Among sibling pairs with Hodgkin's disease, there is a marked excess of like-sex pairs. Like-sex siblings have almost twice the risk of discordant-sex siblings, suggesting an interaction between environmental and genetic factors. Thus, it would be of interest to known the risk to spouses of cases who share environments but who do not share genes.(ABSTRACT TRUNCATED AT 400 WORDS)

Implications of a circulating vaccine-derived poliovirus in Nigeria

BACKGROUND

The largest recorded outbreak of a circulating vaccine-derived poliovirus (cVDPV), detected in Nigeria, provides a unique opportunity to analyze the pathogenicity of the virus, the clinical severity of the disease, and the effectiveness of control measures for cVDPVs as compared with wild-type poliovirus (WPV).

METHODS

We identified cases of acute flaccid paralysis associated with fecal excretion of type 2 cVDPV, type 1 WPV, or type 3 WPV reported in Nigeria through routine surveillance from January 1, 2005, through June 30, 2009. The clinical characteristics of these cases, the clinical attack rates for each virus, and the effectiveness of oral polio vaccines in preventing paralysis from each virus were compared.

RESULTS

No significant differences were found in the clinical severity of paralysis among the 278 cases of type 2 cVDPV, the 2323 cases of type 1 WPV, and the 1059 cases of type 3 WPV. The estimated average annual clinical attack rates of type 1 WPV, type 2 cVDPV, and type 3 WPV per 100,000 susceptible children under 5 years of age were 6.8 (95% confidence interval [CI], 5.9 to 7.7), 2.7 (95% CI, 1.9 to 3.6), and 4.0 (95% CI, 3.4 to 4.7), respectively. The estimated effectiveness of trivalent oral polio vaccine against paralysis from type 2 cVDPV was 38% (95% CI, 15 to 54%) per dose, which was substantially higher than that against paralysis from type 1 WPV (13%; 95% CI, 8 to 18%), or type 3 WPV (20%; 95% CI, 12 to 26%). The more frequent use of serotype 1 and serotype 3 monovalent oral polio vaccines has resulted in improvements in vaccine-induced population immunity against these serotypes and in declines in immunity to type 2 cVDPV.

CONCLUSIONS

The attack rate and severity of disease associated with the recent cVDPV identified in Nigeria are similar to those associated with WPV. International planning for the management of the risk of WPV, both before and after eradication, must include scenarios in which equally virulent and pathogenic cVDPVs could emerge.

Evolving epidemiology of poliovirus serotype 2 following withdrawal of the serotype 2 oral poliovirus vaccine

Although there have been no cases of serotype 2 wild poliovirus for more than 20 years, transmission of serotype 2 vaccine-derived poliovirus (VDPV2) and associated paralytic cases in several continents represent a threat to eradication. The withdrawal of the serotype 2 component of oral poliovirus vaccine (OPV2) was implemented in April 2016 to stop VDPV2 emergence and secure eradication of all serotype 2 poliovirus. Globally, children born after this date have limited immunity to prevent transmission. Using a statistical model, we estimated the emergence date and source of VDPV2s detected between May 2016 and November 2019. Outbreak response campaigns with monovalent OPV2 are the only available method to induce immunity to prevent transmission. Yet our analysis shows that using monovalent OPV2 is generating more paralytic VDPV2 outbreaks with the potential for establishing endemic transmission. A novel OPV2, for which two candidates are currently in clinical trials, is urgently required, together with a contingency strategy if this vaccine does not materialize or perform as anticipated.

High diversity of poliovirus strains isolated from the central nervous system from patients with vaccine-associated paralytic poliomyelitis

To establish the etiology of vaccine-associated paralytic poliomyelitis (VAPP), isolates from the central nervous system (CNS) from eight patients with VAPP were compared with stool isolates from the same patients. The vaccine (Sabin) origin was checked for all of the available isolates. Unique and similar strains were recovered from paired stool and CNS samples for five of the eight VAPP cases and the three wild-type cases included in the study. In the remaining three VAPP cases, the stool samples and, in one case, the CNS samples contained mixtures of strains. In two of these cases an equivalent of the CNS isolate was found among the strains separated by plaque purification from stool mixtures, and in one case different strains were isolated from CNS and stool. This shows that the stool isolate in VAPP might not be always representative of the etiologic agent of the neurological disease. A wide variety of poliovirus vaccine genomic structures appeared to be implicated in the etiology of VAPP. Of nine CNS vaccine-derived strains, four were nonrecombinant and five were recombinant (vaccine/vaccine or even vaccine/nonvaccine). The neuropathogenic potential of the isolates was evaluated in transgenic mice sensitive to poliovirus. All of the CNS-isolated strains lost the attenuated phenotype of the Sabin strains. However, for half of them, the neurovirulence was lower than expected, suggesting that the degree of neurovirulence for transgenic mice is not necessarily correlated with the neuropathogenicity in humans.

Mechanism of injury-provoked poliomyelitis

Skeletal muscle injury is known to predispose its sufferers to neurological complications of concurrent poliovirus infections. This phenomenon, labeled "provocation poliomyelitis," continues to cause numerous cases of childhood paralysis due to the administration of unnecessary injections to children in areas where poliovirus is endemic. Recently, it has been reported that intramuscular injections may also increase the likelihood of vaccine-associated paralytic poliomyelitis in recipients of live attenuated poliovirus vaccines. We have studied this important risk factor for paralytic polio in an animal system for poliomyelitis and have determined the pathogenic mechanism linking intramuscular injections and provocation poliomyelitis. Skeletal muscle injury induces retrograde axonal transport of poliovirus and thereby facilitates viral invasion of the central nervous system and the progression of spinal cord damage. The pathogenic mechanism of provocation poliomyelitis may differ from that of polio acquired in the absence of predisposing factors.

A Sabin 3-derived poliovirus recombinant contained a sequence homologous with indigenous human enterovirus species C in the viral polymerase coding region

Outbreaks of poliomyelitis caused by circulating vaccine-derived polioviruses (cVDPVs) have been reported in areas where indigenous wild polioviruses (PVs) were eliminated by vaccination. Most of these cVDPVs contained unidentified sequences in the nonstructural protein coding region which were considered to be derived from human enterovirus species C (HEV-C) by recombination. In this study, we report isolation of a Sabin 3-derived PV recombinant (Cambodia-02) from an acute flaccid paralysis (AFP) case in Cambodia in 2002. We attempted to identify the putative recombination counterpart of Cambodia-02 by sequence analysis of nonpolio enterovirus isolates from AFP cases in Cambodia from 1999 to 2003. Based on the previously estimated evolution rates of PVs, the recombination event resulting in Cambodia-02 was estimated to have occurred within 6 months after the administration of oral PV vaccine (99.3% nucleotide identity in VP1 region). The 2BC and the 3D(pol) coding regions of Cambodia-02 were grouped into the genetic cluster of indigenous coxsackie A virus type 17 (CAV17) (the highest [87.1%] nucleotide identity) and the cluster of indigenous CAV13-CAV18 (the highest [94.9%] nucleotide identity) by the phylogenic analysis of the HEV-C isolates in 2002, respectively. CAV13-CAV18 and CAV17 were the dominant HEV-C serotypes in 2002 but not in 2001 and in 2003. We found a putative recombination between CAV13-CAV18 and CAV17 in the 3CD(pro) coding region of a CAV17 isolate. These results suggested that a part of the 3D(pol) coding region of PV3(Cambodia-02) was derived from a HEV-C strain genetically related to indigenous CAV13-CAV18 strains in 2002 in Cambodia.

Intramuscular injections within 30 days of immunization with oral poliovirus vaccine--a risk factor for vaccine-associated paralytic poliomyelitis

BACKGROUND

In Romania the rate of vaccine-associated paralytic poliomyelitis is for unexplained reasons 5 to 17 times higher than in other countries. Long ago it was noted that intramuscular injections administered during the incubation period of wild-type poliovirus infection increased the risk of paralytic disease (a phenomenon known as "provocation" poliomyelitis). We conducted a case-control study to explore the association between intramuscular injections and vaccine-associated poliomyelitis in Romania.

METHODS

The patients were 31 young children in whom vaccine-associated paralytic poliomyelitis developed from 1988 through 1992. Eighteen were vaccine recipients, and 13 had acquired the disease by contact with vaccine recipients. Each of these children was matched with up to five controls according to health center, age, and in the case of vaccine recipients, history of receipt of the live attenuated oral poliovirus vaccine. Data were abstracted from medical records that documented the injections administered in the 30 days before the onset of paralysis.

RESULTS

Of the 31 children with vaccine-associated disease, 27 (87 percent) had received one or more intramuscular injections within 30 days before the onset of paralysis, as compared with 77 of the 151 controls (51 percent) (matched odds ratio, 31.2; 95 percent confidence interval, 4.0 to 244.2). Nearly all the intramuscular injections were of antibiotics, and the association was strongest for the patients who received 10 or more injections (matched odds ratio for > or = 10 injections as compared with no injections, 182.1; 95 percent confidence interval, 15.2 to 2186.4). The risk of paralytic disease was strongly associated with injections given after the oral polio virus vaccine, but not with injections given before or at the same time as the vaccine (matched odds ratio, 56.7; 95 percent confidence interval, 8.9 to infinity). The attributable risk in the population for intramuscular injections given in the 30 days before the onset of paralysis was 86 percent (95 percent confidence interval, 66 to 95 percent); that is, we estimate that 86 percent of the cases of vaccine-associated paralytic poliomyelitis in this population might have been prevented by the elimination of intramuscular injections within 30 days after exposure to oral poliovirus vaccine.

CONCLUSIONS

Provocation paralysis, previously described only for wild-type poliovirus infection, may rarely occur in a child who receives multiple intramuscular injections shortly after exposure to oral poliovirus vaccine, either as a vaccine recipient or through contact with a recent recipient. This phenomenon may explain the high rate of vaccine-associated paralytic poliomyelitis in Romania, where the use of intramuscular injections of antibiotics in infants with febrile illness is common.

Vaccine-associated poliomyelitis in a child with sex-linked agammaglobulinemia

Paralytic poliomyelitis was observed in a child with a sex-linked defect in immunoglobulin synthesis. Evidence is presented that this was secondary to administration of oral, live poliovaccine. The demonstration of a familial sex-linked gammaglobulin deficiency and the failure to document a defect in cell-mediated immunity in this child extends the risk of vaccine associated poliomyelitis to virtually all forms of immunodeficiency. The critical host factors in the pathogenesis of poliovirus vaccine infection and in particular its unfavorable outcome appear to include either a deficiency in the humoral (B cell) system or in the cell-mediated (T cell) system.