Showing papers in "Bulletin of The World Health Organization in 1982"

The magnitude of the global problem of acute diarrhoeal disease: a review of active surveillance data.

Abstract: Data from 24 published studies were anlayzed in order to estimate the annual morbidity and mortality from acute diarrheal diseases in the developing world. 22 of the studies involved frequent surveillance through home visits to families in communities; the other 2 were multicountry studies in which diarrhea mortality was calculated on the basis of death certificate information. Morbidity rates were found to be highest in the 6-11 month age group while the mortality rates were greatest in infants under 1 year of age and children 1 year old. For children under 5 years of age the median incidence of diarhhea was 2.2 episodes/child/year for all studies and 3.0 episodes/child/year for the studies that had the smallest populations and most frequent surveillance. Using 1980 population estimates the estimated total yearly morbidity and mortality from diarrheal diseases for children under 5 years of age in Africa Asia (excluding China) and Latin America were 744-1000 million episodes and 4.6 million deaths. (authors) (summary in FRE)

Cluster sampling to assess immunization coverage: a review of experience with a simplified sampling method.

Abstract: The Expanded Program on Immunization (EPI) is using a simplified cluster sampling method based on the random selection of 210 children in 30 clusters of 7 children each to estimate immunization coverage levels. This article analyzes the results of this method in actual and computer simulated surveys. Results from 60 actual surveys conducted in 25 countries were available for analysis for a total of 446 sample estimations of immunization coverage. 83% of the sample results had 95% confidence limits within + or - 10% and none of the surveys had 95% confidence limits exceeding + or - 13%. In addition 12 hypothetical population strata with immunization coverage rates ranging from 10%-99% were established for the purposes of computer simulation and 10 hypothetical communities were established by allocating to them various proportions of each of the strata. These simulated surveys also supported the validity of the EPI method: over 95% of the results were less than + or - 10% from the actual population mean. The precision of this method as estimated from the results of both actual and simulated surveys is considered satisfactory for the requirements of the EPI. Among the actual surveys the proportion of results whose confidence limits exceeded + or - 10% was greatest (50%) when immunization coverage in the sample was 45%-54%.

Collaborative study on antigens for immunodiagnosis of schistosomiasis

Abstract: Eight research laboratories in Europe and the United States of America were selected on the basis of having published data on Schistosoma mansoni and S. japonicum antigens to participate in a study of various antigen/test combinations for immunodiagnosis of schistosomiasis. The serum bank consisted of 395 well documented sera from four endemic areas in Brazil (2 areas), Kenya, and the Philippines. Altogether, 21 S. mansoni and four S. japonicum antigen and immunoassay combinations were evaluated.S. mansoni egg antigens yielded a higher combined sensitivity than adult worm antigens, irrespective of their purity, in active S. mansoni infections before and after specific treatment. Quantitative seroreactivity of characterized S. mansoni egg antigens showed good correlation with faecal egg counts in the 5-14 year age group. No correlation between morbidity related to S. mansoni and seroreactivity was observed in any test system.Three S. japonicum egg antigens showed high sensitivity and specificity in relation to the presence or absence of eggs in the stool. The quantitative seroreactivity of the characterized S. japonicum egg antigens correlated directly with the intensity of S. japonicum infection in all age groups.The enzyme-linked immunosorbent assay (ELISA), using several different procedures, performed well with the antigens used in the study. The indium slide immunoassay (ISI), a simple qualitative visual test system using an S. mansoni egg antigen, demonstrated a high degree of sensitivity and specificity.The results did not indicate the superiority of any particular immunodiagnostic method for detecting antischistosome antibodies. This collaborative study is considered a first step towards developing and standardizing antigens for immunodiagnosis of schistosomiasis.

A simple field test for the detection of faecal pollution in drinking water.

Abstract: A comprehensive field investigation in several parts of India has revealed that the presence of coliforms in drinking water is associated with hydrogen sulfide-producing organisms. This paper describes a simple, rapid, and inexpensive field test for the screening of drinking water for faecal pollution, based on the detection of hydrogen sulfide. The new test showed good agreement with the standard most probable number (MPN) test. It proved highly successful in the field when it was used to detect faecal pollution and to monitor water quality during an outbreak of water-borne hepatitis A infection in the city of Gwalior. The test is reliable and simple to perform, and will be especially useful for screening rural water supplies and for large-scale screening of urban water supplies where resources, time, manpower, and laboratory facilities are limited.

Survey of pesticide poisoning in Sri Lanka.

Abstract: This study included a sample survey of the clinical records of patients admitted to the different hospitals in Sri Lanka, and showed that approximately 13 000 patients are admitted to hospital annually for pesticide poisoning and that each year 1000 of them die. Suicidal attempts account for 73% of the total, and occupational and accidental poisoning accounts for 24.9%. It is recommended that urgent action be taken to minimize the extent of the problem.

Plasma concentrations in pyrimethamine and sulfadoxine and evaluation of pharmacokinetic data by computerized curve fitting.

Abstract: For the determination of the plasma concentration profiles of pyrimethamine and sulfadoxine after the administration of 1 tablet of Fansidar, highly specific analytical methods are needed as the pyrimethamine concentration is low (0.2 - 0.02 mg/litre) and the concentration ratio of the two components in the plasma is high (> 1: 500). The microbiological method described in this paper fulfils these requirements for high specificity and sensitivity (the sensitivity limit for sulfadoxine is 1 mg/litre and for pyrimethamine is 0.013 mg/litre).Pharmacokinetic data were evaluated for 14 volunteers after administration of 1 tablet of Fansidar, and a computer simulation of multiple dosing (1 tablet per week) was performed.

Epidemiology of eltor cholera in rural Bangladesh: importance of surface water in transmission.

Abstract: In order to define the role of water used for drinking, cooking, bathing, and washing in the transmission of Vibrio cholerae biotype eltor infections in an area with endemic cholera, surveillance was initiated in neighbourhoods with a culture-confirmed cholera index case and others with index cases with non-cholera diarrhoea as controls. In neighbourhoods with cholera infection, 44% of surface water sources were positive for V. cholerae, whereas only 2% of surface sources were positive in control neighbourhoods. Canals, rivers, and tanks were most frequently positive. There was an increased risk of infection for families using water from culture-positive sources for drinking, cooking, bathing, or washing and for those using water sources used by index families for drinking, cooking or bathing. Analysis of the results for individuals showed that in this case there was an increased risk of infection associated with using water from culture-positive sources for cooking, bathing, or washing, but not with using water from culture-positive sources for drinking. Individuals who used the same water source as an index family for bathing were more likely to be infected than those using different sources. For families drinking from a culture-negative source, there was an association between infection and bathing in a positive source. For families using a different bathing source from the index family there was an association between infection and drinking from the same source as the index family, and for families using a different drinking source from the index family there was an association between infection and bathing in the same source as the index family. These data suggest that use of surface water is important in the transmission of V. cholerae and that, in addition to providing safe drinking water, education regarding the risk of transmission of infection by water from potentially contaminated sources used for other purposes, especially bathing, may also be necessary to control transmission in areas where eltor cholera is endemic.

An evaluation of five regimens for the outpatient therapy of falciparum malaria in Thailand 1980-81.

Abstract: Five regimens for the radical treatment of falciparum malaria were compared in five geographically separate areas of Thailand. The cure rate for sulfadoxine-pyrimethamine was found to be low in the area of the Kampuchean border and in the northeastern and western parts of the country. This distribution may be related to the spread of resistant parasites through the migration of labourers. A 7-day course of quinine was found to be uniformly effective, with an overall cure rate of 90% in these primary infections with comparatively low parasitaemia.

Avian influenza A viruses of southern China and Hong Kong: ecological aspects and implications for man

Abstract: Continuous surveillance of the influenza viruses isolated from domestic poultry from southern China and Hong Kong over more than 4 years resulted in the isolation of influenza viruses possessing 46 different combinations of haemagglutinin (H) and neuraminidase (N) subtypes. Of these, 43 were obtained from ducks from China. In all cases, infection appeared to be asymptomatic. The antigenic combination found most commonly in the viruses isolated was H4N6, which accounted for approximately one-quarter of the duck isolates, its occurrence being more frequent than expected from a statistical analysis of the observed frequencies of the haemagglutinin and neuraminidase genes among all the isolates. Some combinations of H and N occurred less frequently than expected or not at all. Influenza viruses tended to be isolated more frequently from ducks during the summer months in comparison with paramyxoviruses, which were more commonly encountered in the winter. Possible reasons for the great antigenic diversity of influenza A viruses in the poultry, especially the ducks, in the region are discussed together with the potential significance of these viruses to the emergence of human influenza pandemics.

Epidemiology of human Schistosoma haematobium infection around Volta Lake, Ghana, 1973-75.

Abstract: There was a dramatic rise in the prevalence of urinary schistosomiasis around Volta Lake within a year of its full impoundment in 1968. Research was undertaken to investigate the epidemiology of the disease in preparation for a control programme. The interplay of three factors-age, sex, and ethnic affiliation-largely defined the demographic patterns of the prevalence and the intensity of infection. Both of these increased in young children up to a peak at age 10-14 years, and then declined, the intensity of infection more rapidly than the prevalence. The prevalence and intensity of infection were both greater in males than females (above ages 15-24 years and 5-9 years, respectively), and differences between the two main ethnic groups were related to differences in their lake-related activities. Differences between the patterns of prevalence and intensity of infection are attributed to the greater sensitivity of the latter measurement in indicating changes in the level of transmission. Practical difficulties were encountered in obtaining a precise measurement of incidence, the most important being the considerable degree of population movement. A field cohort study showed a seasonality of transmission, greatest between January and April, during the period of high level of the lake and in the early part of the draw-down.Research on the intermediate snail host (Bulinus truncatus rohlfsi) and lakeside ecology established the focality of transmission at human water-contact sites serving the shore-line communities and, in conjunction with parasitological surveys, its seasonality: variations in ecology that accompanied the annual rise and fall of the lake led to high levels of transmission when the water level was high and lower levels during the draw-down.The geographical distribution of the infection was also affected by differences in ecology, specifically by variations in the distribution and abundance of the aquatic weed Ceratophyllum demersum. A non-seasonal decline in transmission observed in one locality during the period from 1973 to 1975 resulted from a local decrease in the amount of Ceratophyllum.

Use of tetanus toxoid for the prevention of neonatal tetanus. 1. Reduction of neonatal mortality by immunization of non-pregnant and pregnant women in rural Bangladesh.

Abstract: PIP: 1 approach to the prevention of tetanus neonatorum (a leading cause of infant death throughout the world) is improving the quality of prenatal, obstetric, and postnatal maternal and child health services. Another complementary approach is the active immunization of women before or during pregnancy with tetanus toxoid. Work in progress at the Matlab field station of the International Center for Diarrheal Disease Research in Bangladesh (ICDDR,B) provided a unique opportunity to study the effectiveness of certain aspects of these 2 strategies. In 1974, during a field trial of cholera toxoid vaccine, 2 injections of an aluminum phosphate tetanus-diphtheria toxoid were provided as a control to a randomly assigned group of nonpregnant women. Beginning in June 1978, a program of immunizing women during pregnancy with aluminum phosphate-absorbed tetanus toxoid was initiated in conjunction with the implementation of a village based maternal and child health and family planning program in half of the same Matlab surveillance area. Throughout the period of these 2 programs, the ICDDR,B maintained an independent, longitudinal, vital registration system, identifying all births and deaths in the study area. In this analysis, all live births registered in the Maternal and Child Health-Family Planning and comparison areas during the September 1, 1978 until December 31, 1979 period were identified. These records were linked with any deaths recorded within 28 days of birth. The acceptance of tetanus vaccination during the 1974 cholera vaccine trial, by the mothers of these live births, was ascertained from the 1974 vaccine registers. The acceptance of vaccination during the 1978-1979 program was obtained from the field registers. For infants whose mothers had received 2 tetanus injections 48-64 months prior to delivery, the neonatal mortality rate was 63.8/l000 live births compared with 78.3/1000 for infants whose mothers did not receive tetanus immunization. Immunization of women with 2 tetanus injections during pregnancy reduced neonatal mortality rates to 42.8/1000, a reduction of 35.5/1000. Mortality on days 4-14 was reduced by about 70%. 1 injection during pregnancy did not appear to provide protection against tetanus neonatorum.

Purification of mature schizonts of Plasmodium falciparum on colloidal silica gradients.

Abstract: The density of human erythrocytes infected in vitro with Plasmodium falciparum has been measured by isopycnic centrifugation in colloidal silica gradients The densities of uninfected cells, rings, trophozoites, young schizonts, and mature schizonts were approximately 1110, 1110, 1106, 1097, and 1090 g/ml, respectively This information has been used to design a simple procedure for the separation of schizonts from other parasite stages and uninfected erythrocytes By using synchronized cultures it is possible to obtain essentially pure schizonts after two centrifugations using a bench centrifuge Such preparations are an excellent source of parasite antigen for immunological studies

Recent developments in the field of Chagas' disease

Abstract: Chagas' disease is an endemic human trypanosomiasis produced by Trypanosoma cruzi, which is usually transmitted by blood-sucking triatomid bugs. This article reports recent developments in research on Chagas' disease and outlines some of the basic investigations that have immediate practical application or that contribute to our knowledge of the parasite and its relationship with the vertebrate host.Much progress has been made recently in the development of techniques for characterization of T. cruzi strains, e.g., isoenzyme electrophoresis and analysis of kinetoplast DNA, and in research on the biochemistry of the parasite. Studies on membrane components have detected a number of distinct surface glycoproteins which may be important in the interaction between parasite and host cells. New methods of investigating ultrastructural membrane components are also being developed.There is a great need for an animal model in which T. cruzi induces a chronic infection resembling the human disease. Recent work has shown that the rabbit could be a suitable model; monkeys, dogs, and mice are also susceptible to T. cruzi but may not be useful as a model of the disease in man.A number of serological tests are available for the diagnosis of Chagas' disease, e.g., complement-fixation test, immunofluorescence, ELISA haemagglutination, direct agglutination. However, both tests and reagents need to be standardized and active reference centres are necessary to help improve the reliability of the reactions in the different endemic areas.

Comparison of gingival index and sulcus bleeding index as indicators of periodontal status

Abstract: Although the gingival index and sulcus bleeding index have been widely used as indicators of periodontal status, there is some disagreement among investigators as to their meaning and significance. A clinical study was undertaken to monitor the occurrence of gingival bleeding, oedema, and change in colour in subjects with and without periodontal disease, and it was found that the combinations of these clinical symptoms often did not correspond exactly with an index score. It is therefore suggested that any study of periodontal disease should be based on fundamental criteria, such as bleeding or oedema, rather than on composite indices.

Review of data on susceptibility of mosquitoes in the USSR to imported strains of malaria parasites.

Abstract: Studies on the susceptibility of mosquitos in the USSR to imported species and strains of human malaria parasites have revealed that Anopheles atroparvus, A messeae, and A sacharovi are highly susceptible to strains of Plasmodium vivax from Africa, Asia, and South America There was no significant variation in the level of adaptation to the various vector species In experiments on infection of A atroparvus and A messeae with imported strains of P falciparum from Africa and southern Asia, all the results were negative It was possible to infect A subalpinus with an African strain of P falciparum, sporozoites being found in the salivary glands of all the mosquitos studied Contradictory results have been obtained on the development of tropical strains of P falciparum in A sacharovi In most experiments the parasite did not develop but in 5 experiments, oocysts and sporozoites were seen in 9 mosquitos Attempts to infect A atroparvus with West African strains of P ovale and P malariae were unsuccessful

An intervention study of oral cancer and precancer in rural Indian populations: a preliminary report.

Abstract: A large-scale epidemiological study of oral cancer and precancer was initiated in 1966 in several regions of India. Phase 1 of the study consisted of a cross-section survey to determine the prevalence of cancer and precancerous lesions, while phase 2 was a 10-year follow-up survey to determine the incidence and natural history of oral precancer. Following these preliminary investigations, an intervention study was started to try to persuade subjects to give up tobacco, and to measure the subsequent changes in the incidence and regression rate of oral precancer. In each of the three study areas, 12 000 adult tobacco users were selected, examined, and interviewed in a house-to-house survey. Information on the ill effects of tobacco use was given through individual discussions with a social scientist, film shows, and posters. The population was reviewed after one year and the proportions of subjects who had discontinued tobacco use were found to be 2% in Ernakulam, 1% in Bhavnagar, and 5% in Srikakulam. Additionally, between 1% and 16% had reduced their tobacco use. In Bhavnagar and Ernakulam the regression rate of leukoplakia was significantly higher among those who had stopped or reduced their tobacco consumption. In Srikakulam there was a highly significant correlation between reduction in tobacco consumption and regression of palatal lesions.

Immunity in tuberculosis.

Abstract: In this review various aspects of tuberculo-immunity and of the pathogenesis and diagnosis of tuberculosis (TB) are examined in the light of current immunological knowledge. Successful resistance in TB is not easily predicted by the presence or absence of an immune response but it is a balance between the various types of immune responses of the host and the strength of the infecting bacterial strain for that individual host. Primary infection is usually acquired through the inhalation of infected droplets; the probability of the development of disease among TB-positive individuals varies from 30/100000 in Denmark to 600/100000 in some Eskimo populations. Even if TB were eradicated however sporadic cases would continue to occur since for TB acquired from the environment control would necessitate lowering the rate of infection in bird and animal groups. 4 groups of TB patients include: 1) those in which cell-mediated activity is fully active 2) those in which cell-mediated immunity is not detected 3) an intermediate group leaning more towards group 1 and 4) an intermediate group leaning towards group 2. The cells involved in the outcome of a TB infection macrophages and lymphocytes are discussed individually. The thick cell wall of the Mycobacterium tuberculosis resists destruction by enzymes antibodies and other factors and requires a mechanism that will activate macrophages and histocytes to breach this cell wall and lead to cell death. A vaccine against TB should be long lasting such as BCG although BCG has not been found to be effective in all populations. The degree of immune response to TB will depend on: 1) the degree of sensitivity the mycobacterial species is capable of inducing and 2) how much of this sensitivity is cross-reactive with M. tuberculosis. High effectiveness of BCG immunization has been related to a low endemicity of non-TB mycobacteria; it should be administered early in life in countries with a high prevalence of TB. The pathogenesis and pathology of TB is discussed as are immunological tests such as the tuberculin tests which indicates TB sensitivity in vitro tests for cellular hypersensitivity and dual skin tests. Future research should focus on the BCG vaccine better in vitro tests and standardization of reagents.

Immunogenicity and reactogenicity of a Q fever chemovaccine in persons professionally exposed to Q fever in Czechoslovakia.

Abstract: An immunization trial carried out on 1310 persons professionally exposed to Q fever confirmed the suitability of a chemovaccine for field use. Its immunogenicity and reactogenicity differed in three groups of subjects who differed in their previous experience of Q fever and who were given different lots of the vaccine. There was some correlation between reactogenicity of the vaccine and pre-immunization positivity in the microagglutination and skin tests as indicators of a previous exposure. The skin test was more reliable for predicting post-immunization reactions.

Cost-effectiveness appraisal of immunization programmes.

Abstract: This paper describes a cost-effectiveness analysis of the immunization programs in Indonesia the Philippines and Thailand using the program costing guidelines developed for the WHO Expanded Program on Immunization (EPI). The principal organizational features of each program are outlined and total costs and costs/fully immunized infant are assessed at a small sample of health centers in each country. Costs were found to average US $2.86 in Indonesia US $4.97 in the Philippines and US $10.73 in Thailand. At each health center the main element of total immunization costs was fixed so that average costs/fully immunized child fell as coverage levels and activity rates rose. The implications of this preliminary analysis are considered for each country and common managerial issues in EPI in particular and primary health care in general are detailed. Program organization health care input costs and population accessibility are considered as explanations of the observed differences in immunization costs. The feasibility of undertaking routine cost-effectiveness monitoring of immunization and other primary health care programs is considered. (authors) (summary in FRE)

The spread of Rift Valley fever and approaches to its control.

Abstract: Rift Valley fever (RVF) is primarily a disease of sheep, cattle, other domestic animals, and man; it was believed to be relatively benign for man until 1977 when it spread to Egypt. There it caused enormous losses of sheep and cattle, and thousands of human cases occurred, with nearly 600 reported deaths. Although mosquitos are known to transmit RVF virus in epizootics and epidemics, the reservoir and means of inter-epizootic maintenance are not known. RVF epizootics can be recognized by a combination of observations: abortions and neonatal death in sheep and cattle at times when mosquitos are abundant, accompanied by cases of fever in man, which are complicated in a minority of patients by haemorrhagic fever, encephalitis, and retinitis with blindness. Vaccination of livestock with available killed or live attenuated vaccines should prevent transmission to both human subjects and animals. Although routine quarantine of animals is not deemed a practical measure, movement of animals should be restricted when an epizootic is in progress. Since it is possible that RVF may spread from Africa in the future, serological surveillance in man and animals is recommended in potentially receptive countries of the Mediterranean Basin and South-West Asia to establish baseline data and to familiarize staff with the methods of RVF diagnosis.

Diagnosis of Plasmodium falciparum infection in man: detection of parasite antigens by ELISA.

Abstract: An ELISA method has been developed for the diagnosis of Plasmodium falciparum infection in man. Parasites from in vitro cultures of P. falciparum were used as source of antigen for the solid phase and the source of specific antibody was immune Gambian sera; binding of antibody in antigen-coated wells was registered by means of alkaline phosphatase-conjugated anti-human IgG. Parasites were detected on the basis of inhibition of antibody-binding. The test was applied to the detection of parasites in human red blood cells (RBC) from in vitro cultures of P. falciparum and in RBC from infected Gambians; RBC from 100 Geneva blood donors served as normal, uninfected controls. In titration experiments, the degree of antibody-binding inhibition correlated with the number of parasites in the test RBC. Parasites were detected at a level of 8 parasites/106 RBC. Samples of RBC were tested from 126 Gambians with microscopically proven infection; significant antibody-binding inhibition was found in 86% of these cases, where parasitaemia ranged from 10 to 125 000/μl of blood. The presence of high-titre antibody in the test preparations was found to reduce the sensitivity of parasite detection in infected RBC from in vitro cultures mixed with equal volumes of different antibody-containing sera. The sensitivity was restored in most cases by recovering the RBC by centrifugation before testing. In a preliminary experiment, there was no significant difference in antibody-binding inhibition using fresh infected RBC and RBC dried on filter-paper and recovered by elution, although there was greater variation in the latter samples.

Use of tetanus toxoid for the prevention of neonatal tetanus. 2. Immunization acceptance among pregnant women in rural Bangladesh.

Abstract: In a rural area of Bangladesh 2 injections of aluminum phosphate absorbed tetanus toxoid were offered to pregnant women within the context of a maternal-child health and family planning program. Over the first 16 months of the program only 34.2% of pregnant women identified by fieldworkers accepted full immunization and 4.8% accepted partial immunization. A comparison of acceptors and nonacceptors of immunization showed only small differences between the 2 groups in terms of their sociodemographic characteristics such as age religion education number of children and occupation. The main reasons reported for nonacceptance were objection by husbands and mothers-in-law fear of harming the fetus exacerbated by village rumors and failure to inform women sufficiently early during pregnancy. The most frequently reported reason for failure to accept the 2nd injection among the partially immunized was the temporary migration of women from the usual residence for confinement in their parents house. Confusion caused by local names for neonatal tetanus may have adversely affected perception by the community of the effectiveness of the vaccine. The study demonstrated that previous use of injectable and other contraceptives did not decrease subsequent acceptance of tetanus immunization. The families of tetanus immunization acceptors appeared also to adopt home-based oral rehydration therapy for diarrhea more readily than families of nonacceptors. (authors) (summary in FRE)

An outbreak of hand, foot, and mouth disease in Singapore

Abstract: Epidemiological studies were carried out during an extensive outbreak of hand, foot and mouth disease caused by coxsackievirus A 16 in Singapore in 1981. Most of the cases were concentrated in densely populated public housing estates, and the morbidity rate was highest in children under 5 years of age. The mean secondary attack rate for children under 12 years of age was 76.7% compared with an overall rate of 31.3%. The incubation period ranged from 1 to 7 days. Factors favouring the transmission of infection within a household included sharing of household and personal articles with the index case. The disease was mild and self-limiting.

Epidemiological models of poliomyelitis and measles and their application in the planning of immunization programmes.

Abstract: This report describes the construction and application of epidemiological models of measles and poliomyelitis In these models, epidemiological classes and their age structure have been based on the natural history of these diseases in the population aged 0 - 19 years The flow of the population through the classes has been expressed as an equation system suitable for computer interpretation The models have been used to simulate both the natural course of the diseases and the effect of various immunization schemes The models were also used to explore prospects for control and eradication of these diseases with specific immunization programmes, and their relative effectiveness and cost-effectiveness are discussed

Single-dose treatment of falciparum malaria with mefloquine: field studies with different doses in semi-immune adults and children in Burma.

Abstract: Different doses of mefloquine (20 and 30 mg/kg of body weight in children, and 750 and 1000 mg in adults) were tested in controlled clinical trials in 89 children and 60 adults who were semi-immune carriers of Plasmodium falciparum. There was no significant difference in the efficacy of the two doses, either in the children or in the adults. An RI-type resistance was found in 1 adult, when recrudescence occurred on day 7, and in 4 children, who showed recrudescence on day 14. In all 5 patients, spontaneous disappearance of parasites was observed at further parasitological checks, thus indicating that mefloquine has a prolonged action. One patient who vomited after taking the drug was successfully retreated with mefloquine on day 14. Nausea, giddiness, and vomiting are the three symptoms most frequently attributed to mefloquine. The incidence of nausea and giddiness was similar in both dosage groups, but the adults in the higher dosage group had a significantly higher frequency of vomiting than those in the low-dose group. In view of the rapid and reliable action of a single dose, mefloquine seems to be the drug of choice for treatment of cases of falciparum malaria that are resistant to 4-aminoquinolines and to sulfonamide-pyrimethamine combinations. A dose of 20 mg per kg of body weight for children and 750 mg for adults is sufficient for treatment of semi-immune persons.

Rotavirus and acute diarrhoeal disease in children in a southern Indian coastal town.

Abstract: Rotavirus was found by electron microscopy in the stools of 707% of a representative sample (368) of the 3355 children with acute diarrhoea admitted to hospital over a period of 16 months in Calicut on the west coast of India The prevalence of the virus was high (nearly 100% of cases examined) in the period from November to January and lowest in May just before the onset of the monsoon Prevalence was high (751%) in infants aged from 6 to 23 months, but was considerably lower in those under 6 months of age (348%) The management of cases and the planning of control measures for this disease are discussed in the light of knowledge of the high prevalence of rotavirus

Role of a modified ovitrap in the control of Aedes aegypti in Houston, Texas, USA.

Abstract: A modified ovitrap from which larvae could not escape was employed for one year for the control of Aedes aegypti at Blossom Heights, Houston, Texas. At the end of this period, the Breteau index in the ovitrap area had declined by 36%, in contrast to a sharp increase of nearly 500% in the non-ovitrap area. The premises index in the ovitrap area remained unchanged, while the index in the non-ovitrap area increased by 440%. The problems associated with this control campaign and the use of these "autocidal" ovitraps are discussed.Annual fluctuations in the egg populations of A. aegypti and A. triseriatus were studied by weekly collections of eggs from the ovitrap paddles. The weekly fluctuations of egg numbers, the percentage of ovitraps with eggs of Aedes mosquitos, as well as the ovitrap premises index (i.e., percentage of premises with at least one ovitrap positive) all exhibited a similar fluctuation pattern, with a distinct peak extending from June to October.

Meningococcal disease and its control with meningococcal polysaccharide vaccines

Abstract: This article summarizes background information and specific evidence regarding the use of meningococcal polysaccharide vaccines. On the basis of currently available data, it seems premature to recommend that immunization against meningococcal disease be included within routine immunization programmes in developing countries. Factors contributing to this judgement include the irregularity of epidemics, the changing serogroups of meningococci, the different age distribution of cases in different areas, low efficacy of a single dose of meningococcal vaccine in children below 2 years of age, short duration of post-immunization immunity in infants and young children, and finally, the still high cost of current meningococcal vaccines.The meningococcal vaccines can be effective, however, in controlling epidemics due to meningococci of serogroups A or C provided they are quickly administered to the age groups within the population who are most at risk.