Showing papers by "World Health Organization published in 1975"

A survey of species A and B of the Anopheles gambiae Giles complex in the Kisumu area of Kenya prior to insecticidal spraying with OMS-43 (fenitrothion).

Abstract: Throughout 1972 surveys were made in Kenya on the Anopheles gambiae Giles complex in an area near Kisumu, part of which was to have all houses sprayed with OMS-43 (fenitrothion) the following year. Pre-spray data was collected on monthly hut densities, man-biting rates, parity and the human blood indices and sporozoite rates of A. gambiae caught in both an area designated for spraying (evaluation zone) and a comparison zone which was to remain unsprayed. The sporozoite rates, host preferences, and population size of the A. gambiae comples in relation to the human population were similar in the two zones. Few adults were collected from artificial pit-shelters in either zone. Cytotaxonomic identifications showed that although species A of the A. gambiae comples predominated throughout the year, the population of species B decreased relatively less in the drier months than that of species A. No marked differences were found between the host preferences or sporozoite rates of the two species.

Studies on the Thymic Dependence of the Immunoglobulin Classes of the Mouse

Abstract: SummaryThe influence of the thymus on serum immunogobulin (Ig) concentration was studied by a comparison of serum Ig levels in congenitally athymic (nu/nu) mice versus control littermate heterozygotes and adult thymsctomized, irradiated, bone marrow reconstituted mice (ATx + B) versus adult thymectomized, irradiated mice reconstituted with bone marrow and thymus (ATx + BT). In the former group IgGl. IgA, and IgG2a were 8%, 17%, and 31% of controls. IgM levels were increased (340%) compared to controls. When ATx + B mice were compared with nonirradiated controls significant depressions were noted in serum IgGl and IgM. The only significant decrease in serum Ig levels between ATx + B and ATx + BT was in IgGl. These results are discussed in terms of the effects of thymic influence, residual T lymphocyte population differences between the two groups, and the effect of irradiation.We gratefully acknowledge the skillful technical assistance of E. Modder and G. Brighouse. We thank Dr. G. Torrigiani for his encou...

Japanese encephalitis surveillance in China (Province of Taiwan) during 1968-1971. I. Geographical and seasonal features of case outbreaks.

Abstract: During 1968-1971 Japanese encephalitis (JE) surveillance was conducted with WHO-assisted programs in Taiwan area. Emphasis was placed on: (1) active case-finding by hospital visits; (2) blood collection from every patient at the suitable time; and (3) the enforcement of standard diagnostic criteria on the results of hemagglutination-inhibition tests. Each year, approximately 90% of reported patients were etiologically examined. JE virus etiology was established in 277 (1968), 279 (1969), 269 (1970) and 158 (1971) cases. Despite the apparent concentration of cases in several cities, practically all the cultivated plains and basins were established as potentially endemic for JE. JE outbreak is found to have been clearly associated with season, not only in subtropical but also in tropical Taiwan. Each year it occurred consistently in mid-July in the southernmost county, 2-3 weeks after the peak of rice transplantation and its duration was a few weeks. On the western side of the island, although less consistently, JE outbreak seems to occur one to three weeks later than in the south. Outbreak in eastern Taiwan was a mid-September phenomenon for 3 years. Observed seasonal lag, which was significant between two neighboring localities on same latitude, suggests that paddy water management is more directly related to date of outbreak than local climate. Seasonal characteristics further suggests that the area may be separated into eight ecologic subdivisions. JE-virus transmission to a man during April at temperatures below the average of 20 C was discussed.

Incidence of cancer in patients with leprosy.

Abstract: Individuals with congenital immunodeficiences and patients who are immuno-suppressed for maintenance of organ allografts experience a marked increase in the occurrence of malignancy. Patients with lepromatous leprosy also have depressed cellular immunity, but our study of 195 autopsied subjects with leprosy did not reveal an increase in the occurrence of cancer. Thirty-three of the 195 subjects with leprosy or 16.9% died of cancer, which is comparable to an age-matched group of individuals.

Antibody-induced movement of protozoan surface membrane antigens.

Abstract: Direct and indirect immunofluorescence techniques were used to study the effects of host antibodies on surface membrane antigens of viable Leishmania parasites in vitro. Antisera to L. enriettii and L. tropica caused surface membrane antigens of these parasites to aggregate, move toward the poles of the parasite, and to eventually disappear. This sequence did not occur at low temperature or in the presence of some metabolic inhibitors. Antigen subsequently reappeared on the parasite membrane. These phenomena appear to be similar to those described in mammalian cells. Antibodies may therefore effect an alteration in the surface membrane structure of living protozoan parasites.

Toxicological decisions and recommendations resulting from the safety assessment of pesticide residues in food.

Abstract: The FAO/WHO Expert Committee on Pesticide Residues since 1963 has been entrusted by the World Health Organization and the Food and Agriculture Organization with the responsibility of assessing possible hazards to man from the occurrence of residues of pesticides in foods. The toxicological and administrative decisions of this expert group are reviewed in this paper with particular regard to the scientific background which served as a basis to the allocation of acceptable daily intakes (ADIs). Exhaustive references to documents issued after each meeting have been assembled in a way intended to facilitate the search for important sources of information to the worker in toxicology who might not be completely familiar with the dynamics of this activity at the international level.

State of the art of the toxicological evaluation carried out by the Joint FAO/WHO Expert Committee on Pesticide Residues. I. Organohalogenated pesticides used in public health and agriculture

Abstract: At a meeting of a WHO Expert Committee on Pesticide Residues held jointly with the FAO Panel of Experts on the Use of Pesticides in Agriculture in 1961 (FAO/WHO 1962), a recommendation was made that studies be undertaken to evaluate possible hazards to man arising from the occurrence of residues of pesticides1 in foods. Following this meeting, which was endorsed by an intergovernmental meeting in Rome in 1962, Joint Meetings of the WHO Expert Committee on Pesticide Residues and the FAO Committee on Pesticides in Agriculture were held in 1963 (FAO/WHO 1964) and 1965 (FAO/WHO 1965 a). These meetings were concerned with establishing acceptable daily intakes (ADI’s). The reports from these meetings and the supporting documents were then considered by the FAO Working Party on Pesticide Residues with a view to recommending tolerances and appropriate methods of analysis.

Simulation Models for Genetic Control Alternatives

Abstract: The problems in relation to the use of pesticides (e.g. environmental pollution, selection of resistant strains) have stimulated research in genetical methods of control and/or eradication of pest and vector populations. These methods aim at reducing the fertility by releasing either sterile males or strains with translocations. The paper surveys the mathematical models describing the various genetical control methods and predicting the outcomes of specified release strategies. It is shown that success and failure depend crucially on the density-dependent mechanism that regulates the natural population densities. Computer simulations allow us to optimize the timing of the releases in relation to the seasonal pattern of the carrying capacity of the environment. Particular reference is made to the genetic control of mosquito vector populations. In practice, the release of partially fertile males and even females together with the sterile males cannot be avoided. Under certain assumptions it can be shown that the release ratios have to be between certain boundaries in order to achieve population reduction. Transmission models help to assess the effects of a certain reduction in vector density on the transmission of the disease.

Host Factors in the Response to Immunization

Abstract: Aside from the scientific concepts that arouse interest for their own sake in the factors that determine the character and magnitude of the response to immunization, the subject has many self-evident practical applications. Until recently, problems raised by the limitations in the response to immunization have generally been side-stepped by simple empirical solutions such as injecting more antigen per dose, or giving more injections. However, this approach is frustrating, not only because it is empirical (and not always rational), but also because it requires money, personnel and logistic facilities that can be provided, as a rule, only in the affluent countries. For the developing countries there is a real need for more simplified immunization schedules; and it is largely with this objective in mind that our more recent studies on the factors affecting the immune response have been carried out.

The relation between immunofluorescence patterns of glomerular deposits and subclasses of IgG in patients with nephropathies associated with malaria.

Abstract: There is enough evidence that immune complex-type lesions exist in malaria; nephropathies associated with Plasmodium falciparum infections are somewhat acute and in most casesrespond t o antimalarial therapy. Conversely, nephropathies associated with P. malariae have a rather chronic progressive character and d o not respond t o antimalarial treatment. In collaboration with several colleagues, we have been interested in chronic lesions and have had an opportunity t o study renal biopsies of Nigerian patients by light, fluorescence, and electron microscopy and b y other techniques (e.g., elution studies). Immunofluorescence studies detected deposits of immunoglobulins G and M in 96%, the third component of complement in 63%, and P. malariae antigens in 25% of cases in glomerular capillary walls. The specificity of P. malariae antibodies eluted from kidney specimens was confirmed by several techniques. $ 2 The pattern of deposits was always granular but varied from coarse t o fine with a mixture of both (mixed type). Coarse granular deposits were mostly positive for both immunoglobulins G and M and also for complement; conversely, the majority of cases with a fine granular pattern of fluorescence had IgC only and were complement n e g a t i ~ e . ~ The examination of 1gG subclasses (immunofluorescence technique with FITC-conjugated specific antisera kindly provided by I. F. Skvaiil, Bern, Switzerland) revealed that the coarse granular pattern of immunoglobulin deposits in glomerular capillary walls always had the positive G3 subclass alone or in combination with other subclasses but never G 2 . The mixed-type pattern also always had C,, but in some cases, G 2 participated. Cases with a fine granular pattern revealed a certain predominance of the G2 subclass of IgG, and in five patients, G2 was the only immunoglobulin detected in the deposits (all of the latter were complement negative). The correlation of immunofluorescence findings with response of patients t o the treatment and t o the outcome showed that the fine granular pattern of deposits was associated with poorly selective proteinuria, n o response t o the therapy, and an unfavorable 0utcome.l Therefore, examination of renal biopsies by the immunofluorescence technique might have not only diagnostic but also prognostic value.

Extended Plain Sedimentation

Abstract: Extended plain sedimentation could be a possible alternative for pretreatment of surface waters in water purification. It does not add pollution to the environment and its sludge is less objectionable for disposal. Theoretical investigation shows that gravitational effect dominates settling down to the particle size of 1 μ\N. Experimental results indicate that extended plain sedimentation is technically feasible to remove a substantial amount of turbidity with residual turbidity down to less than 10 FTU. An 88% turbidity removal could be achieved in a settling tank of 7.5-day detention. Suspended solids concentration appears to be more appropriate as an indicator of the performance of settling of natural waters. From the viewpoint of functioning of settling tanks, extended plain sedimentation should mean extension towards a lower design overflow rate rather than towards longer detention periods.

Contribution of Haffkine to the Concept and Practice of Controlled Field Trials of Vaccines

Abstract: The rationale for large-scale use of any vaccine in the prevention of an infectious disease lies in the demonstration of its effectiveness in man. Uncontrolled observations of the effect of vaccines in the field may be misleading; therefore, properly designed controlled field trials are required for their evaluation. In the past, most authors did not consider this type of study essential for evaluation of the efficiency of vaccines, and, therefore, failed to set up field studies according to the principles of controlled field trials, which became widely recognized only recently [1].

International Cooperation on Non-Ionizing Radiation Protection

Abstract: The increased use in recent years of non-ionizing radiation (NIR) devices has led to the development by the World Health Organization’s Regional Office for Europe (WHO/EURO) of a programme on NIR protection. As part of this programme, WHO/EURO convened two working groups to review the general situation in Europe and to evaluate the results of an international symposium in Warsaw, 1973, on effects from microwaves. A third working group, on health effects from lasers, will take place later in 1974. Other activities of an international nature related to NIR have been undertaken by the Commission of the European Communities and the International Radiation Protection Association. In view of the growing need for inter-country co-operation and agreement on NIR units, definitions and standards, a proposal has been made for the establishment, along the lines of the existing international commissions on ionizing radiation, of a Commission on NIR (CONIR), which could devote itself to these tasks.

Whatever happened to “culture change"?

Abstract: Robert L. Bee. Patterns and Processes: An Introduction to Anthropological Strategies for the Study of Sociocultural Change. New York: The Free Press, 1974. xi + 260 pp. Bibliography and index. $3.95 (paper).

Effect of repetitive health examinations on blood sugar levels: the Zagreb preliminary study.

Abstract: In this study recruitment rates of subjects with borderline glucose tolerance were investigated (using the specific procedure described below) and were shown to be 1.8% of the population approached and 2.5% of the population screened. 75 g glucose load yielded higher numbers of subjects with borderline glucose tolerance levels at screening than a 50 g glucose load. However, the numbers of the people finally recruited into the cohort by confirmatory screening were the same when only the 50 g load was used at confirmatory screenings. Subjects recruited in this way remained in the study for 24 months. Repeated health checks had an effect of lowering concentrations of blood glucose after an oral load in treated and control groups, and in those with borderline and those with normal blood glucose values at the initial screening. It is concluded that the process of screening and observation itself has an effect upon glucose tolerance, independent of formal ‘treatment’.