Intestinal immunity following a combined enhanced inactivated polio vaccine/oral polio vaccine programme in Israel.

Intestinal immunity was studied in a polio-free community immunised with a combined enhanced inactivated/oral polio vaccine (EIPV/OPV) vaccination programme. Poliovirus excretion was evaluated in three groups of infants primed with a partial (2 EIPV+2 OPV) or complete (3 EIPV+3 OPV) dose schedule. Poliovirus replicated in the gut of 59.8-55.8% of infants in the three groups 7 days after administration of an additional OPV dose. Significant decreases in the percent of type-specific-virus excreters appeared after 14 and 21 days for serotypes 1 and 2, and after 21 and 28 days for serotype 3. The percent of excreters was inversely correlated with pre-challenge neutralising antibody (NA) titers (p<0.05). Intrafamilial virus transmission to mothers and siblings was minimal. The principal factor for interruption of disease and virus transmission in the community was a strong and persistent humoral immunity with immunological memory. A satisfactory level of family hygiene contributed towards breaking the chain of transmission of poliovirus to contacts.

Immune response to a diphtheria and tetanus toxoid administration in a three-dose diphtheria tetanus whole-cell pertussis/enhanced inactivated poliovirus vaccination schedule: a 7-year follow up.

The immune response to diphtheria and tetanus toxoid components of a combined diphtheria tetanus whole-cell pertussis/enhanced inactivated poliovirus (DTwP/eIPV) vaccine, administered in a three-dose schedule to infants at 2, 3 1/2 and 10 months of age and followed by a booster at the age of 8 years, was compared with the immune profile of a group of children at the same ages given the customary DTwP vaccine schedule at 2, 4, 6, and 12 months of age and a booster at the age of 8. Diphtheria- and tetanus-antitoxin titers were measured in parallel enzyme-linked immunosorbent assay (ELISA) and radioimmunoassay (RIA). After the reinforcing dose given at 10 months of age, diphtheria antitoxin concentrations of > or = 0.01 IU/ml were found in 100% of infants in the study group, 91.7% of whom reached a titer of > or = 0.1 IU/ml and a geometric mean titer (GMT) of 0.40 and 0.93 IU/ml in ELISA and RIA, respectively. At 3 and 6 years of age, diphtheria antitoxin values of > or = 0.01 IU/ml were detected in 100 and 94% of children with GMT of 0.043 and 0.024 IU/ml, respectively. Seropositivity and GMT values indicative of protection were measured by both ELISA and RIA after the booster at the age of 8 years. Similar results were found in the control group, although the GMT tended to be higher. A good correlation between results obtained by ELISA vs. RIA was evident throughout. Priming at 2 and 3 1/2 months with diphtheria and tetanus antitoxin, as a component of a DTwP program, and reinforcing 6 months later induced an immune response indicative of protection against the diseases, which persisted up to the age of the booster recommended at school entry.

Influenza surveillance during winter 1997-1998 in Israel.

BACKGROUND: Each winter influenza activity is a major cause of morbidity and mortality both in Israel and worldwide. OBJECTIVES: To identify the influenza viruses active in Israel during the winter season and to assess the extent of influenza morbidity. METHODS: Information was collected on a population of 18,684 individuals enrolled in two community clinics in central Israel. It included the total number of visits for acute respiratory infection--including influenza and influenza-like illness (ARI/flu-like)--during a 20 week surveillance period (23 November 1997 to 27 March 1998) and the percent of influenza virus isolates in nasopharyngeal specimens from a sample of patients with ARI/flu-like collected on a weekly basis during the same period. RESULTS: A total of 5,947 visits for ARI/flu-like were recorded among 18,684 enrolled patients in two community clinics (18.1%). The progressive increase in the number of visits for ARI/flu-like reached a peak on week 2/98 with 597 visits and a rate of 31.95 visits per 1,000 population. After this, a decrease to the initial values was evident by week 12/98. Most affected patients were in the age groups 5-14 and 65 years and over, with a rate of 733.5 and 605.3 visits per 1,000 population, respectively. Influenza virus was isolated from 92 of the 426 nasopharyngeal specimens (21.6%). The most commonly detected strain was A/Sydney/5/97 (H3N2) like (77.2%). The peak rate of isolates was recorded at the beginning of January (01/98). CONCLUSIONS: A/Sydney/5/97 (H3N2) like-strain was the dominant influenza virus. Its presence did not prevent the simultaneous activity of influenza A/H1N1 virus. The dynamic of the clinical disease as expressed by the weekly visit rate for ARI/flu-like was similar to the temporal pattern of the virological findings. The extent of morbidity suggests moderate epidemic activity.

Immune response to an intercalated enhanced inactivated polio vaccine/oral polio vaccine programme in Israel: impact on the control of poliomyelitis.

A combined enhanced inactivated polio vaccine (EIPV) and oral polio vaccine (OPV) programme was introduced in Israel in 1990, with the purpose of providing a solution to the persistent polio morbidity in spite of a 30 year long OPV programme. The schedule comprised two doses of EIPV administered at the age of 2 and 4 months, intercalated with two doses of OPV at 4 and 6 months, followed by a reinforcing dose with the two vaccines simultaneously administered at 12 months. The 5-year evaluation of the programme included: the assessment of clinical suspicions of polio, early immune response in successive cohorts administered the new schedule, dynamics of the immune profile in a cohort followed up to the age of 5, and monitoring of wild poliovirus excretion in sewage specimens collected in 25 permanent sites throughout Israel as well as from the Palestinian Authority. No paralytic polio cases associated with a wild or vaccinal poliovirus strain were detected since the introduction of the programme. At the age of 4 months, one week after administration of the second EIPV and first OPV dose, 100% seropositivity and high geometric mean titres (GMTs) of neutralizing antibody (NA) to the three vaccinal and to the wild poliovirus type 1, responsible for the 1988 polio outbreak, were observed. No change in percent of seropositivity occurred between the age of 6 and 12 months. Thirty days after the IPV and OPV reinforcing doses, GMTs to each of the four poliovirus strains were > or = 3037. Up to the age of 5, the seropositivity was unchanged. After a 2.5-10-fold decline in the first year following the completion of the programme, GMTs to the three vaccinal and the wild poliovirus strain levelled off at rather high values, considered protective. Between 1990 and 1995, 16 wild poliovirus type 1 strains were isolated in three separate episodes in Gaza Strip sewage and once only in one Israeli site very close to Gaza City. The rapidly established, high and persistent NA titre to the vaccinal and wild poliovirus strains and the presence of immunological memory are indicative of high individual protection throughout the first 5 years of life. The only one-time introduction, without circulation, of a wild poliovirus strain in a single Israeli settlement suggests community protection. The intercalated programme offers a contribution to polio eradication by providing a solution to the primary and secondary failure associated with OPV, as well as to the control of vaccine-associated paralytic poliomyelitis.

Progress in polio eradication.

PIP: The World Health Organization resolved 41 years ago to eradicate poliomyelitis by the year 2000. Cost-effectiveness studies estimate that more than $300 million will be saved annually in the US alone by its eradication worldwide. Additional savings will be enjoyed in the indirect costs of pain, suffering, and lost productivity. Even so, the Poliomyelitis Eradication Initiative has been hindered by a lack of urgency, by insufficient donor participation, and a lack of political support in many countries. Moreover, the achievement of the ultimate goal of eradication is hampered by the poor immunogenicity of oral polio vaccine in many tropical areas, high population density, poor sanitation and hygiene, the ability of wild polioviruses to circulate in partly immune populations, and poorly developed epidemiological and laboratory-based surveillance systems to monitor the occurrence of disease. Controversy also remain over the respective merits of and problems with oral and inactivated poliovirus vaccines. Sections discuss prospects for global eradication, choice of vaccine, and development of a common prescription.^ieng

Basic conditions for the eradication of poliomyelitis--indications for a common prescription.

The efforts of the last decade to achieve the world eradication of poliomyelitis have resulted in several problems of methodology and field implementation of the polio control program: (1) The concept of eradication. Its present definition refers to the complete absence of activity of the wild poliovirus. It is the result of the decision to recommend the use of OPV for the world control of polio and leaves unanswered the problem of the paralytic disease associated with OPV. (2) Besides a successful vaccination policy the control of polio implies a satisfactory environment. Risk factors in the environment mean persistence of endemicity and reoccurrence of disease, even after several years of absence of polio activity. (3) Concerning the limitations of the two available vaccines, problems of immunogenicity, safety, and thermostability are associated with OPV. Use of EIPV requires a high coverage of all the ages at risk of infection, and gut immunity is lower than that induced by OPV. On the other hand, several observations point to the limitation of OPV to prevent the spread of the wild virus into the vaccinated community, as claimed for EIPV. Limitations of OPV are mainly vaccine associated paralytic disease in the developed countries, and wild virus associated disease in "vaccinated" individuals in the developing countries. Disease associated with EIPV programs is observed practically only in nonvaccinated individuals. EIPV, particularly if associated with OPV, offers a clear advantage over OPV alone, in terms of immunogenicity, safety, and protective efficacy. (4) Total elimination of paralytic poliomyelitis can hardly be conceived of without the use of the EIPV.

Israel in the elimination phase of poliomyelitis--achievements and remaining problems.

Following the introduction of a combined EIPV and OPV schedule in 1990, no more cases of paralytic poliomyelitis were diagnosed and no wild poliovirus strain was isolated in the sewage. 100% seropositivity and high geometric mean titers (GMTs) to the three types of poliovirus vaccine strains and to the type 1 poliovirus 1988 epidemic strain were observed at the completion of the immunization schedule and one year later. The study of the immune profile of various age groups vaccinated with either EIPV or OPV had shown that the immunity to the epidemic poliovirus strain was less satisfactory, in terms of percent of seropositivity and GMTs, than to the poliovirus vaccine strains. In individuals previously immunized with either EIPV or OPV a high and quick immune response to both the 1988 epidemic and vaccine strains was observed after a booster dose of OPV. Follow-up to four years after the booster pointed to some decrease in the extent and intensity of the seropositivity to the 1988 epidemic strain as compared to the immune profile to the poliovirus vaccine strains. Maintaining Israel in the phase of polio elimination requires: > 95% national coverage, homogenously distributed; maintaining high immune profile to the three poliovirus types, including a satisfactory immune level to the 1988 epidemic strain in all the age groups at risk of polio; early detection of the introduction of wild poliovirus into the environment and of the occurrence of foci of indigenous activity; reducing the risk of exposure to massive infectious doses.(ABSTRACT TRUNCATED AT 250 WORDS)

Six years of public health surveillance of measles in France.

Data provided by the Sentinel General Practitioners (SGP) to the French Communicable Diseases Computer Network (FCDN) have been used to present the epidemiological characteristics of measles observed during a 6-year period in France. The estimated annual incidence rates per 100,000 population were 376 in 1985, 603 in 1986 and 983 in 1987, then declined during the following 3 years to 297, 258, and 263 per 100,000 population in 1988, 1989 and 1990 respectively. There is a marked seasonal change with a high early summer peak. The mean age among the cases for the 6 years of study varied from 5.4 to 6.0 years. There is an increase in the percentage of cases with a past history of measles vaccination, from 6.7% in 1985 to 12.8% in 1990. This increase may be interpreted as a consequence of a substantial increase of the vaccine coverage during the same period.

Preventive strategies against poliomyelitis.

Successful poliomyelitis prevention depends upon the epidemiological characteristics of the infection and the immune status of the population in the area. Presently available polio vaccines may prove very useful for progress with polio control, provided the prevention programme has been adequately chosen and the limitations of the vaccine used have been taken into consideration. In the present and near future, polio prevention should aim at the containment and local elimination of the paralytic disease, which can be obtained with either OPV or E-IPV. The vaccine-associated disease remains an unsolved issue in an OPV programme. The association of OPV and E-IPV offers a clear advantage over the immunization with a single vaccine, particularly with OPV alone. Global eradication of polio, possible in principle, will be difficult to achieve by the year 2000, because of the present global dimensions of polio infection and the unequal environmental development of the world.

[Alternating rifampicin and ceftriaxone for Neisseria meningitidis eradication in contacts].

Following the occurrence of a case of meningococcal disease in a kibbutz, extensive preventive measures were instituted, consisting of alternate courses of rifampicin (10 mg/kg for 2 consecutive days) and ceftriaxone (single IM injection of 125 mg). Throughout the observation period Neisseria meningitidis was absent from oropharyngeal secretions of all those treated, but was found in those of an untreated control group. The alternate use of rifampicin and ceftriaxone should be considered for the long-term prevention of the occurrence of oropharyngeal carriers of Neisseria meningitidis.

Immunologic memory induced at birth by immunization with inactivated polio vaccine in a reduced schedule.

One hundred forty-one healthy newborns were immunized 24 hours after birth with one dose of inactivated polio vaccine (IPV) of enhanced potency. Following the administration of a second vaccine dose six months later, a considerable proportion of babies responded with neutralizing antibody (NA) to the three poliovirus types. The very rapid occurrence and high antibody titer were indicative of an anamnestic response. Twenty-one infants who still had NA less than 1:4 to one-more poliovirus types after the second vaccine dose responded with very high NA values 7-10 days after a supplementary dose of IPV. It appears that IPV of enhanced potency administered at birth is apt to induce immunologic memory, which should provide the basis for protection against paralytic poliomyelitis in case of exposure to wild poliovirus later in life.

Use of a combined DTP-polio vaccine in a reduced schedule.

A five-year serologic follow-up and a four-year monitoring of the polio and pertussis morbidity in an area immunized with a 2 + 1 dose schedule of a combined DTP-Po vaccine have shown that: the individual protection against polio measured by the presence of neutralizing antibody persists at a very adequate level five years after the first booster; after three years of a steady high proportion of children with pertussis antibody, a considerable drop is observed and in about 28% of individuals agglutinin levels of less than 1:20 were found five years after booster; the community protection against paralytic poliomyelitis and pertussis is satisfactory up to four years after the introduction of the program. Continuation of immunization with a 2 + 1 dose schedule at a maximal coverage and close seroepidemiologic surveillance are necessary in order to draw definite conclusions, because of the potentially strong impact of very dynamic ecological factors present in our geopolitical area upon the agent-host interrelationship.

Rubella immunity measured by hemagglutination inhibition and enzyme-linked immunosorbent assay.

Evaluation of the immunity to rubella by the hemagglutination inhibition (HI) test and an enzyme-linked immunosorbent assay (ELISA), in a series of 1,697 sera collected from women of childbearing age, showed a 65% agreement; 33% were ELISA-positive and HI-negative at a 1:16 dilution and only 2% were ELISA-negative and HI-positive. Among 241 women given the rubella vaccine following an HI titer of less than 1:16, no change was observed in 208 in the postimmunization HI test, but only 11 were negative when ELISA was used. The retesting by ELISA of 110 preimmunization sera showed that 67 (61%) were positive, and therefore the vaccine had been unnecessarily administered. In a series of 72 HI tests that did not permit interpretation because of a nonspecific reaction, ELISA provided quite clear results. ELISA appears to be a sensitive technique for the evaluation of the true immune status to rubella in sera with low HI levels (less than 1:16), as well as in circumstances where the HI test reacts nonspecifically.

Epidemiology of rubella and congenital rubella infection in Israel, a country with a selective immunization program.

A rubella immunization program directed at girls aged 12 years started in Israel in 1973, and its extension in 1980 to women of childbearing age had produced by 1983 several changes in the epidemiologic pattern of rubella infection in women of childbearing age and in the risk of congenital rubella: a 55%-77% decline in the incidence of the disease in the 15-44-year age group; a progressive reduction in the rate of seronegativity among women from greater than 20% to less than 10%; a risk of infection during pregnancy and a percentage of abortions associated with rubella infection in the 1983 outbreak that were one-twelfth and one-tenth, respectively, the values associated with the 1978 and 1979 epidemics; and an evident decrease in the frequency of cases of congenital rubella, as detected by either passive or active surveillance. It is predicted that of the women who will be pregnant in 1985, 98.2% and 94.3% of those in the 18-23 year and 24-44 year age groups, respectively, will be immune by the end of 1984.

A modified schedule for routine pertussis immunization.

As part of a study with a quadruple inactivated vaccine (diphtheria-pertussis-tetanus-polio), the serologic response to the pertussis antigen was investigated in infants at the age of routine immunization, inoculated with one of the following two regimens: either 0.5 ml vaccine at 2 and 3 1/2 months and a booster six months later, or an identical dose of vaccine given at 2, 4 and 6 months and a booster at the age of 12 months. A pertussis agglutination titer of greater than or equal to 1:10 was considered an immune response to the administration of the antigen. Two basic doses of pertussis antigen induced an immune response in about 92% of children, which was very close to that following three basic doses. A 100% seroconversion was observed in both groups one month after the booster dose, and geometric mean values were high in both regimens. At one and two years after the booster, the pertussis agglutinins were present in 100% of children of both groups, with higher geometric mean values in the group given the three basic doses regimen.

Comparison of inactivated poliovirus vaccine and oral poliovirus vaccine programs in Israel.

In spite of high vaccination coverage, paralytic poliomyelitis still occurs in Israel, either in sporadic form in the urban area or in small outbreaks in the rural, non-Jewish segment. At high risk are mainly very young infants, not yet protected by poliovirus vaccine and children who have failed to seroconvert after a full course of oral poliovirus vaccine ( OPV ). In these circumstances, a new program for vaccination of young infants early in life with a quadruple vaccine containing inactivated poliovirus vaccine (IPV) and diphtheria, tetanus, and pertussis vaccines (DTP) has been tested. Administration of two doses of IPV up to the age of three and one-half months followed by a booster at the age of 10 months has produced a very satisfactory antibody response (100% seroconversion and high geometric mean titers of antibody to the three antigens), which has occurred early in life and persisted up to two years after booster. This response was similar to that observed after four doses of trivalent OPV ( TOPV ) reinforced with one dose of monovalent type 1 OPV . Two doses of the quadruple vaccine have also induced an antibody response to pertussis antigen in greater than 90% of the infants. After booster, a greater than 99% conversion rate has been recorded, which has remained unchanged at one year of follow-up. The above data have led to the modification of the poliovirus vaccination schedule in the areas at risk.

Prevention of measles in Israel: implications of a long-term partial immunization program.

Following the introduction of routine measles immunization in Israel in 1967, rapid and persistent modifications in the pattern of the disease were observed, including much more limited and more widely spaced epidemics, a change in the age distribution of measles cases, and a progressively increasing herd immunity that was estimated, following the 1982 epidemic, at 91.6 percent for the first 26 generations. This pattern supports the expectation that measles can be eliminated in Israel provided a herd immunity greater than or equal to 94 percent can be achieved before the next epidemic, which is predicted for 1988-89. A logistic approach to the elimination of measles in Israel requires (a) maintenance of an immunization rate of at least 90 percent in each newborn generation; (b) identification and immunization of still susceptible children in the 1-5 year and 6-9 year age groups, to attain vaccination coverage for at least 97 percent of this population (which should result in immunity among at least 94 percent); (c) provision of similar coverage for older, susceptible individuals in selected groups of children, adolescents, and young adults at high risk; (d) disease surveillance based on an early identification of the main sources of infection and monitoring of the active foci of disease in the neighbouring territories, which are an important potential source of the introduction of infection.

The Arjenyattah epidemic. A mass phenomenon: spread and triggering factors.

A massive epidemic of psychogenic aetiology occurred in three districts of the West Bank over two weeks in March-April, 1983. It affected 949 individuals, 727 (77%) of them adolescent females. The symptoms were not accompanied by positive physical signs or by laboratory findings. The epidemiological pattern was pathognomonic of that of a psychogenic disorder. The initial trigger was probably the odour of H2S escaping from a faulty latrine in the schoolyard of the first affected school. Subsequent spread of the disease was due to psychological and extra-medical factors, including publicity by the mass media. Spread was stopped immediately after closure of schools.

Present and future use of viral vaccines in Israel.

Implementation of a routine immunization program is the result of the changing pattern of infectious diseases in the area, or of the availability of new vaccines against diseases of importance. Thus, on the one hand, smallpox and BCG vaccination at birth have been discontinued and inactivated polio vaccine (IPV) has been added to the routine program; on the other hand, mumps vaccine, already available, is a very serious candidate for inclusion in the immunization schedule, while prevention of hepatitis A awaits an effective vaccine that is acceptable for mass use.