Immunity to poliomyelitis, diphtheria and tetanus in pediatric patients before and after renal or liver transplantation.

Few studies have considered the safety, efficacy and appropriateness of vaccinations in pediatric patients before and after solid organ transplantation. The aim of this study was to evaluate the immune status after primary vaccination to diphtheria, tetanus and poliomyelitis in pediatric patients before and after hepatic transplantation and to poliomyelitis in pediatric patients before and after renal transplantation. All the patients had received a complete primary immunization schedule for diphtheria and tetanus and poliomyelitis. Immunity to the three polioviruses was evaluated in 56 patients with renal transplant, 27 on chronic dialysis and 33 controls and in 39 patients with hepatic transplant, 25 with chronic hepatic failure and their 36 controls. Immunity to diphtheria and tetanus was evaluated in 52 liver transplant patients, 29 children with chronic hepatic failure and 54 healthy children. Renal transplant patients were less protected and had lower antibody geometric mean titers than healthy controls for polioviruses 1 and 2. Whereas, protection in the children liver transplant patients was similar to that in their controls. Patients with chronic hepatic failure had higher antibody geometric mean titers to diphtheria and polioviruses 1 and 3 than their control group. Immunosuppression after transplantation has a negative influence on the immune status after primary vaccination in children with renal transplant. Whereas children with chronic hepatic failure have higher antibodies than a normal population. When possible, it could be advisable to individualize immunization schedules in patients at high risk.

Diagnosis of congenital cytomegalovirus infection by detection of viral DNA in dried blood spots.

BACKGROUND: The reference method of cytomegalovirus (CMV) isolation from urine or saliva is not a feasible routine technique for all newborns, and laboratory diagnosis of this infection would be useful both for epidemiological purposes and to enable prompt institution of adequate measures to identify and correct late sequelae. Extraction and amplification of viral DNA from dried blood spots (DBS) collected from babies in the first days of life during routine screening for genetic and metabolic disorders has been proposed for the early diagnosis of viral congenital infections. OBJECTIVES: To test the method for CMV DNA extraction from DBS and to evaluate the results obtained in newborns with and without a diagnosis of congenital infection based on viral isolation from urine and or saliva at birth. STUDY DESIGN: DBS from Guthrie cards collected in babies who underwent virological tests for CMV infection were tested for CMV DNA by observers blinded to the virological results. DNA was extracted from DBS both in water and in cell culture medium according to Shibata et al. with minor modifications. The products of nested polymerase chain reactions (PCR) amplifying two regions in the IE1 and gp58 genes were detected by agarose gel electrophoresis. Strict control measures were adopted to avoid carryovers and contaminations. RESULTS: DBS from the eight symptomatic and 11 asymptomatic congenitally infected babies were positive when extraction was performed in medium, whereas extraction in water failed to identify two of the asymptomatic cases. The results obtained with the two extraction methods agreed in the remaining cases; the 71 CMV negative control babies were negative and two out of 21 cases of supposed postnatal infection were diagnosed as congenital on the basis of a positive DBS. All positive cases were identified by gp58 PCR but only slightly over half of them by IE1 PCR. Extraction in medium was more efficient than in water. CONCLUSIONS: The method of CMV DNA extraction in medium followed by amplification of the gp58 region showed 100% sensitivity and specificity compared with isolation in cell culture. Therefore, we propose this procedure to diagnose congenital CMV infection at birth and also later.

Immunity to polioviruses and tetanus after bone marrow transplantation in children.

Immunity to tetanus toxoid and polioviruses was studied in 34 (27 allografted, 7 autografted) children who underwent bone marrow transplantation (BMT). At a median time of 3 years after BMT, only one recipient was seronegative for tetanus toxoid. On the contrary 73% of children were seronegative for at least one of the three poliovirus types and 30% for all virus types. Undetectable antibody titers were more frequently found against type 3 than the other two types. We recommend that reimmunizations of children after BMT be based on serologic tests for antibody titers.

Immunization in children with HIV seropositivity at birth: antibody response to polio vaccine and tetanus toxoid.

OBJECTIVE: To evaluate the humoral response to routine childhood immunization of HIV-infected children. DESIGN: Response rate, antibody titres and persistence after polio and tetanus vaccination were compared in 72 children with HIV seropositivity at birth and divided according to HIV infection status as determined by clinical and laboratory tests. METHODS: Polio antibodies were titred in a microneutralization test (positive titres, > or = 1:4), and antibody to tetanus toxoid with a passive haemagglutination method (protective titres, > or = 1:1024). RESULTS: The response rates to polio and tetanus vaccination (> 80 and > 75%) were similar in the HIV-infected and non-infected children, as were antibody levels. In the subgroup with sera obtained some months after the last dose of vaccine, polio antibody levels decreased in all four HIV-infected and in three of the seven non-infected children; protective tetanus antitoxin levels were detected in three of the six infected and in all three non-infected children. CONCLUSIONS: This study demonstrates the ability of children with HIV infection to respond adequately to the two vaccines considered, although tetanus antitoxin levels were inferior, compared with those in the seroreverted children. The unsatisfactory antibody levels observed in the admittedly few HIV-positive children studied some months after the last vaccination could be the result of a lower initial protective level and not necessarily an expression of severely impaired immunocompetence. The administration of booster doses in addition to the traditional immunization schedule could be useful in children with HIV infection.

Antibody response to inactivated polio vaccine (E-IPV) in children born to HIV positive mothers.

In order to evaluate the response to immunization of HIV-infected children we studied the humoral response to an enhanced potency inactivated poliovaccine (E-IPV) of 43 children born of HIV seropositive mothers. All these subjects have been followed for 32 (15-48) months in order to ascertain their infection status. After a course of 2 doses of E-IPV, 88% of children had neutralizing antibody (n.a.) titers greater than 1:4 to the 3 poliovirus serotypes and 100% to at least 2 polio strains. No statistically significant differences both as rates of n.a. positive subjects and as antibody levels were found between HIV infected children and those who lost HIV antibodies. The poorest response was observed in subjects with full-blown immunodeficiency (CD4 less than 1000/mm3, reduced response to PWM). Sixteen children also received a booster dose of vaccine one year after the completion of the primary cycle. Infected and non-infected subjects responded to the same extent with high levels of n.a. to this immunization. Interestingly, the recall dose was also able to induce high n.a. titers in those HIV infected children who showed significant decreases of n.a. titers in the months following the end of the primary cycle.