[Influence of helminthic infections and nutritional status on immune response in Venezuelan children]

We investigated the influence of nutritional status, as determined from anthropometric measurement, and of helminthic infections on the immune response of children of low socioeconomic status in two rural communities in Venezuela: El Cardón in the state of Nueva Esparta and San Daniel in the state of Miranda. A total of 125 boys and girls between 2 and 15 years old participated in the study. Their socioeconomic stratum was determined by a modified Graffar method. A physical examination was performed, as was also an anthropometric evaluation that took into account three indicators--weight-for-height, weight-for-age, and height-for-age--according to parameters established by the World Health Organization. Other examinations included feces, secretory IgA in saliva, total serum IgE, and anti-Ascaris-specific immunoglobulins. The children in both of the communities were in strata IV and V of the of Graffar scale, with a significantly greater number of stratum V inhabitants in San Daniel (P < 0.001). The results suggest that exposure level and individual susceptibility to the parasites are determining factors in parasitic infection and immune system behavior. The intensity of the parasitic burden plays an important role in stimulating polyclonal IgE, which diminishes the effectiveness of the specific response to those infections. On the other hand, nutritional deficiencies could change the immune mechanisms of the mucous membranes, negatively influence the synthesis of secretory IgA, and stimulate the production of polyclonal IgE. Poor sanitary and socioeconomic conditions promote more exposure to gastrointestinal parasites and a deficient nutritional status, which modulates the immune response and affects serum IgE and secretory IgA production mechanisms.

Impaired immune response to natural infection as a correlate of vaccine failure in a field trial of killed oral cholera vaccines

In a field trial carried out in 1985 in Matlab, Bangladesh, the authors evaluated whether subjects who developed Vibrio cholerae 01 infections during the first year after earlier receipt of B subunit-killed whole cell (BS-WC) or killed whole cell-only (WC) oral cholera vaccines exhibited deficient serum vibriocidal immune responses to these infections. After severe V. cholerae 01 infections (n = 70) in subjects > 5 years of age, the age group in which both vaccines were efficacious, a 6.5 geometric mean-fold rise of serum vibriocidal antibodies was observed among vaccinees, compared with an 18.6 geometric mean-fold rise in placebo-recipients (p < 0.01). Depressions of serum vibriocidal responses among vaccinees were even more marked after asymptomatic infections (n = 30): a 1.1 geometric mean-fold rise in vaccinees versus a 5.9 geometric mean-fold rise in placebo-recipients (p < 0.01). The authors conclude that subjects who failed to be protected by BS-WC and WC, despite being in the age group for which these vaccines were protective, exhibited poor immune responses even to the vigorous stimulus of natural infection. These findings raise the possibility that immune hyporesponsiveness may limit the potential efficacy attainable by cholera vaccines in populations with endemic cholera.

Immune activation is a dominant factor in the pathogenesis of African AIDS

The AIDS epidemic in Africa is very different from the epidemic in the West. As suggested here by Zvi Bentwich, Alexander Kalinkovich and Ziva Weisman, this appears to be primarily a consequence of the over-activation of the immune system in the African population, owing to the extremely high prevalence of infections, particularly helminthic, in Africa. Such activation shifts the cytokine balance towards a T helper 0/2 (Th0/2)-type response, which makes the host more susceptible to infection with human immunodeficiency virus (HIV) and less able to cope with it.

Efficacy of hepatitis B vaccine in the Gambian expanded programme on immunisation

Because of the high prevalence of hepatitis B virus (HBV) infection in The Gambia, HBV vaccination has been incorporated into the national expanded programme on immunisation. We have assessed the efficacy of the vaccine against HBV infection and chronic carriage by examining 720 3-4-year-old children who had received the vaccine in infancy and 816 who had not received it. The vaccine was 84% (95% CI 78-89%) effective against infection and 94% (84-98%) effective against chronic carriage. Vaccinated infants of mothers positive for hepatitis B surface and e antigens were at greater risk of breakthrough infection and chronic carriage than infants of uninfected mothers. The high vaccine efficacy against the HBV carrier state, the main risk factor for the development of chronic liver disease and liver cancer, offers hope that the prevalence of these diseases may be reduced in the future.

BCG vaccination of full-term infants with chronic intrauterine malnutrition: influence of immunization age on development of post-vaccination, delayed tuberculin hypersensitivity

To determine the effect of intrauterine growth retardation (IUGR) on the response to BCG vaccination, we evaluated the specific delayed tuberculin hypersensitivity of 57 full-term infants with symmetric IUGR (SGA or small for gestational age) and 52 full-term infants with normal intrauterine growth (AGA or appropriate for gestational age). The infants were evaluated using post-vaccination skin tests to tuberculin purified protein derivative (PPD) and tuberculin lymphocyte transformation tests. Using a positive response to the skin test as an indicator of delayed hypersensitivity, we found that the rate of response to BCG in the SGA and AGA groups was similar. A total of 65% of infants with IUGR responded to BCG vaccination. The response rate among SGA infants who were vaccinated at 5 days of age, about 26 days of age (weight > or = 2500 g), 3 months of age, and 6 months of age was 68%, 47%, 69%, and 88%, respectively. The overall response rate for infants with no IUGR was 71%; the rate response to BCG vaccination among this group was 52% (those vaccinated at 5 days of age), 90% (3 months of age), and 80% (6 months of age). Our data suggest that the immunogenicity of BCG vaccine is similar in term infants who have normal or abnormal intrauterine growth and the presence of IUGR should not be a reason for delaying BCG vaccination.

Poliomyelitis case confirmation: characteristics for use by national eradication programmes

Highly sensitive case definitions were first introduced by national poliomyelitis eradication programmes to avoid missing true cases of the disease, though false-positive diagnostic errors could still occur owing to low specificity. Extensive data from all 1620 cases of acute, flaccid paralysis reported in Brazil during 1987-88 provided an opportunity to study the characteristics of confirmed poliomyelitis cases and epidemiologically to evaluate potential case definitions that maximized both sensitivity and specificity. Cases that had been confirmed by wild poliomyelitis virus isolation were compared with those that had been rejected (non-polio cases). To guarantee the consistency of clinical, epidemiological and laboratory investigations, only cases less than 10 years of age that had been investigated within 15 days of the onset and with complete laboratory specimens were included. No single practical case definition combining both high sensitivity and high specificity emerged from the study. However, the results showed that poliomyelitis endemic countries with limited resources should give priority to the investigation of cases in less than 5-year-olds, cases with prodromal fever, cases without involvement in all four limbs, cases without progression greater than 3 days after the onset, and cases occurring in areas where poliomyelitis had recently been confirmed. In countries without laboratory resources, cases of acute, flaccid paralysis with initial involvement in one or both lower limbs and residual neurological sequelae at 60 days should be confirmed. Countries that are close to eradication may selectively reject any cases lacking laboratory confirmation, despite adequate specimen collection, if they do not have initial involvement in one or both lower limbs and residual neurological sequelae at 60 days.

Prevalence of Giardia lamblia antibodies in serum and milk in lactating women from different social classes in Egypt

Prevalence and levels of systemic and milk antibodies to G. lamblia in the different social classes of the population were studied using the IFAT and nor-partigen immunoglobulin plates. Blood and milk samples were collected simultaneously from lactating women in urban (Cairo) and rural (Benha) areas. Serum IgG was present in 90% of rural low standard mothers, 58% of urban moderate standard mothers, and 25% or urban high standard mothers (P less than 0.01, P less than 0.001 and P less than 0.01). Antilog of mean of antibody titers was significantly higher in the low standard rural mothers than in the urban moderate and high standard ones. Specific secretory IgA antibody in milk was found in 71% of rural low standard mothers, 31% of urban moderate standard mothers, and 16.6% of urban high standard mothers (P less than 0.001, P less than 0.01 and P greater than 0.05). The antilog of mean S-IgA titers was also higher in the low standard rural mothers. The titer levels of S-IgA in the three classes did not show any correlation with the quantitative levels of total IgA in milk, while specific IgG showed a positive correlation with the total serum IgG in the low standard rural mothers only (P less than 0.05). This study documented the widely different antibody response to G. lamblia in individuals living in different social classes.

The WHO Task Force on Vaccines for Fertility Regulation. Its formation, objectives and research activities

Over the past 18 years, the WHO Task Force on Vaccines for Fertility Regulation has been supporting basic and clinical research on the development of birth control vaccines directed against the gametes or the preimplantation embryo. These studies have involved the use of advanced procedures in peptide chemistry, hybridoma technology and molecular genetics as well as the evaluation of a number of novel approaches in general vaccinology. As a result of this international, collaborative effort, a prototype anti-HCG vaccine is now undergoing clinical testing, raising the prospect that a totally new family planning method may be available before the end of the current decade.

Zona pellucida: current status as a candidate antigen for contraceptive vaccine development

The porcine zona pellucida represents a unique immunocontraceptive target antigen. Initial active immunization studies using crude or partially purified zona components as immunogens resulted in adverse, nonreversible effects on ovarian folliculogenesis, but more recent findings in nonhuman primates indicate that such effects are not as severe and are reversible. Consequently, current efforts are directed toward identifying a zona immunogen that elicits contraceptive antibodies that produce no adverse effects on the ovary. Other studies are in progress to determine optimal injection/immunization format, proper immunogen dosage, and appropriate adjuvant for use in the zona-antizona immunocontraceptive system. Recent data have been very encouraging and emphasize the contraceptive efficacy of this approach to reproduction control.

Unique pattern of HTLV-III (AIDS-related) antigen recognition by sera from African children in Uganda (1972)

Of 75 sera collected in the West Nile district of Uganda over a 1-year period between 1972 and 1973, 50 (66%) had antibody reactivity to human T-cell lymphotropic virus subgroup III (HTLV-III) at low titer levels. Sera were initially screened by HTLV-III enzyme linked immunosorbent assay and sera with values less than normal mean + 2 SD were removed from testing. The remaining sera were tested for positivity by an amplified Western blotting procedure which incorporated a three-layer immunoperoxidase procedure. Immunoglobulin reactive with HTLV-III Mr 24,000, 41,000, and 76,000 proteins were present in nearly all positive sera. The antibody status of this group was unlike any normal or acquired immunodeficiency syndrome-risk group previously tested. The high prevalence and relatively low titers suggest the detection as early as 1972 of a relative or predecessor of HTLV-III or of HTLV-III itself but existing in a population acclimated to its presence. It further suggests a likely African origin of HTLV-III.

Incidence of cutaneous diphtheria in Bangladesh

Corynebacterium diphtheriae (C. diphtheriae) was isolated from 23 (7%) skin ulcers out of 327 cases studied. Eight (33%) of the 23 positive cases belonged to the age group of 6 to 10 years. Of the 19 strains of C. diphtheriae typed, 18 (95%) were gravis and of which 14 (77%) were toxigenic. More than 90% of the C. diphtheriae positive ulcer cases had serum anti-toxin level at or above the protective level as against 49% of control. No diphtheria bacilli were isolated from throat of any of the skin positive cases. All the ulcers from which C. diphtheriae were isolated also harboured other definite wound pathogens. It is believed that the presence of toxigenic C. diphtheriae in skin wound might play an important role in the spread of faucial diphtheriae. It is evident from serum anti-toxin level that infected persons develop natural immunity.

Japan's experience in pertussis epidemiology and vaccination in the past thirty years

The experience in Japan that pertussis was controlled by the nation-wide regular vaccination and that the reincrease of case notification occurred recently after the decrease of vaccine acceptance rate upholds the view that pertussis vaccine produced under the national control system is fully protective. Though the recent decrease of the vaccine acceptance rate was due to the public reaction to rather imbalaanced arguments concerning the vaccine risk, it is also true that a more potent and less toxic component vaccine is urgently needed at this moment.