Showing papers in "Bulletin of The World Health Organization in 1980"

Cerebrovascular disease in the community: results of a WHO collaborative study.

Abstract: In a cooperative study coordinated by WHO, stroke was registered between 1971 and 1974 in 17 centres both in developing and developed countries. A common operating protocol was used to obtain comparable data. Age-adjusted incidence of stroke shows moderate geographical variations, cerebrovascular accidents being common in all the contrasting populations studied in various parts of the world. Data were also obtained on the types of management of stroke patients, their survival rates, and functional prognosis. Control of hypertension, although known to be effective in the prevention of stroke, seemed to be insufficient in most countries. It is concluded that stroke registers may be used as a source of information for the planning and implementation of stroke control programmes in the community.

The control of leishmaniases

Abstract: Human leishmaniases are caused by at least 13 different species and subspecies of parasite of the genus Leishmania. These parasites are transmitted to man from other infected persons or mammals by sandflies when taking a blood meal. Leishmaniases have been reported from about 80 countries and probably some 400 000 new cases occur each year. Clinically the leishmaniases can be divided into three major groups: visceral leishmaniases, which are usually fatal if untreated; cutaneous leishmaniases, which often produce permanent facial disfigurement; and mucocutaneous leishmaniasis of the New World, which produces severe mutilation by destruction of the naso-oro-pharyngeal cavity and sometimes death. Since the various forms of leishmaniasis differ substantially from each other in their epidemiology, the strategy for control must be adapted to the local situation in each endemic area, after thorough ecological and epidemiological studies of the vectors, the hosts, and the landscape. If insufficient baseline information is available, failure of haphazardly applied control measures can be expected. Peridomestic insecticide spraying together with treatment of patients is effective in certain foci of anthroponotic cutaneous leishmaniasis, urban visceral leishmaniasis, and uta. Extensive programmes to eradicate desert rodents, combined with land reclamation, resulted in a considerable decrease in the incidence of zoonotic cutaneous leishmaniasis in vast areas of the USSR. Since control of zoonotic cutaneous/mucocutaneous leishmaniasis of the New World is hardly feasible at present, the only rational approach to prevent some of mucosal lesions is early diagnosis and radical treatment of patients with the rather unsatisfactory drugs at present available.

Dengue haemorrhagic fever--a public health problem and a field for research.

Abstract: Dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS) is an enigmatic and growing public health problem which is confined at present to countries of South-East Asia. Since 1956, over 350 000 patients have been hospitalized and nearly 12 000 deaths have been reported. Dengue viruses, a group of four flaviviruses, are transmitted to man by Aedes aegypti. Currently, dengue viruses are actively transmitted in 61 countries which circle the globe in the tropical zone and have a combined population of 1500 million. Because the precise antecedents to DHF/DSS are unknown, the public health hazard posed by this syndrome is potentially worldwide. Epidemiological studies in South-East Asia clearly link DHF/DSS to individuals who have had a previous dengue infection or who have acquired maternal dengue antibody. Such antibody may serve as an opsonin, enhancing dengue virus infection of mononuclear phagocytes-the type of cell in man to which dengue infection may be confined. Antibody-mediated infection of these cells is the central concept in the hypothesis of immune infection enhancement. This hypothesis provides a conceptual framework for design of future research. There is an urgent need for a comprehensive identification of "risk factors" in DHF/DSS. This research could be approached by undertaking comparative prospective epidemiological studies in dengue-endemic areas with and without DHF/DSS. Although important progress is being made in the development of attenuated dengue vaccines for each dengue type, a clearer understanding of the pathogenesis of DHF/DSS may be required to provide guidelines for safe and lasting immunoprophylaxis in man.

Human monkeypox, 1970-79

Abstract: Increasing attention has been given to human monkeypox since the achievement of global smallpox eradication. Monkeypox, which was first described in Central Africa in 1970, resembles smallpox clinically but differs from it epidemiologically. Forty-seven cases of human monkeypox have occurred since 1970 in 5 Central and West African countries; 38 of these cases have been reported from Zaire. The evolution of the illness and the sequelae of monkeypox and smallpox are the same; monkeypox has a case-fatality rate of about 17%. Children below 10 years of age comprise 83% of the cases. All cases have occurred in tropical rainforest areas and clustering of cases has been observed in certain zones within countries and within families. Person-to-person spread may have occurred in 4 cases; the secondary attack rate among susceptible, very close family members was 7.5% (3 cases/40 contacts) and among all susceptible contacts was 3.3% (4 cases/123 contacts)-much lower than the 25-40% secondary attack rate that occurs with smallpox. Although the low transmission rate and the low frequency of disease indicate that monkeypox is not a public health problem, more data are needed.Whilst many animals near human monkeypox cases have been demonstrated to have orthopoxvirus antibodies, the natural reservoir(s) and the vector(s) of monkeypox virus are unknown. Studies are in progress to identify the natural cycle of monkeypox virus and to define better the clinical and epidemiological features of this disease.

Prevalence of markers of hepatitis B virus infection in various countries: a WHO collaborative study.

Abstract: A WHO collaborative study on viral hepatitis B in which 21 laboratories in 20 countries participated is described. The aim of the study was to define the prevalence of hepatitis B surface antigen (HBsAg), its subtypes, and its antibody (anti-HBs) by age and sex and urban or rural residence in normal populations in different parts of the world. High-risk groups in the populations and patients with various diseases were also investigated. The results of the study confirmed that HBsAg and anti-HBs prevalence rates were higher in African and Asian countries than in the Americas, Australia, and northern and central Europe. Some eastern and southern European countries, however, were also shown to have high HBsAg and anti-HBs prevalence rates, comparable with those in Africa and Asia. In countries with low HBsAg and anti-HBs prevalence, there seems to be a gradual build-up during late childhood or early adolescence, whereas in countries with high HBsAg and its antibody prevalence, they were frequently detected in preschool children. Although the trend was towards a higher frequency of HBsAg and anti-HBs in urban than in rural and in male than in female populations, the differences were in most cases not significant. On the other hand, a significantly higher prevalence of markers of hepatitis B virus infection was seen in high-risk population groups than in normal populations. This was, however, clearly defined only in areas with low HBsAg and anti-HBs prevalence in the normal population. The geographical distribution of HBsAg subtypes showed a higher prevalence of the ad subdeterminant over ay in central European countries, whereas in eastern and southern Europe the ay subtype predominated. In West Africa, ayw was the only variant found, whereas in East Africa ad occurred more frequently than ay. In Australia, both adw and ayw subtypes were detected, whereas in the Far East and South-east Asia only adw and adr were seen.

Molluscicides in schistosomiasis control

Abstract: Although mollusciciding can be a cost-effective method of controlling schistosomiasis transmission, only one organic molluscicide, niclosamide, is now being produced commercially, and only a few compounds are at present being tested in the laboratory. In future, improved cost-effective use of molluscicides will require more precise knowledge of schistosomiasis transmission patterns in each endemic area and improved application techniques. In snail control studies using controlled-release formulations only the organotins, especially tributyltin oxide (TBTO), have given satisfactory long-term results. However, large-scale field trials of organotin formulations have not been implemented and their use cannot be recommended as their chronic toxicity in mammals has not yet been determined. The development of molluscicides of indigenous plant origin deserves support. Endod, derived from the berries of the climbing plant Phytolacca dodecandra, is the most extensively tested plant molluscicide, but data on its chronic toxicity to non-target organisms are lacking. The mode of action of molluscicides has not been extensively studied, though knowledge of the properties required of molluscicidal molecules has contributed to the discovery and development of niclosamide and nicotinanilide. In general, molluscicides probably cause stress on the water balance system, which in gastropods in thought to be under neurosecretory control.

Indicators for the forecasting of malaria epidemics.

Abstract: The entomological inoculation rate is presented as a comprehensive indicator of malaria transmission level, its relative changes reflecting the risk of potential epidemic development. This rate is a known function of several epidemiological direct factors and is particularly sensitive to the survival rate and the sporogonic cycle of the vector. Although not yet fully quantifiable, relationships exist between direct factors responsible for the transmission of infection and certain meteorological and environmental indirect factors like air temperature, relative humidity, or importation of malaria parasites.The establishment of a two-stage monitoring system is suggested: the first stage would involve setting up a warning system based on the surveillance of the relevant indirect factors; at the appropriate time, this would trigger the second stage monitoring of the epidemiological direct factors having a definite bearing on the development of malaria outbreaks. It is recognized that the gain in reliability of the proposed approach depends largely on the progress still to be achieved in the quantification of the complex system of relations connecting the main direct factors with single or combined indirect factors. It is also noted that the proposed monitoring system should, in due course, provide the decision-makers with the epidemiological information required for the selection and implementation of intervention measures designed to prevent epidemic resurgences.

A controlled field trial of liver oral typhoid vaccine Ty21a.

Abstract: A controlled field trial of a live oral typhoid vaccine was carried out in Alexandria, Egypt, in 1978-79. A total of 32 388 children were included in the study. They were divided in two comparable groups, one given 3 doses of the vaccine and the other 3 doses of the placebo. Each active dose contained 1 x 10(9)-8 x 10(9) live Ty21a bacteria. From March 1978 to March 1979, the population studied was followed up and suspected typhoid cases were investigated bacteriologically and serologically. The effectiveness of the vaccine was assessed by analysis of the incidence of typhoid fever in the two groups. The results of the follow-up indicate that, in the dosage schedule used, the Ty21a mutant strain, found previously to be stable and safe, is protective against typhoid fever for at least one year.

An outbreak of type 2 dengue fever in the Seychelles, probably transmitted by Aedes albopictus (Skuse).

Abstract: Between December 1976 and September 1977 the Seychelles group of islands in the Indian Ocean was struck by an extensive epidemic of dengue fever. The peak of the epidemic was in the last week of February. Type 2 dengue virus was isolated from patients and mosquitos. Aedes albopictus was the sole vector. The clinical picture was that of classical dengue. Haemorrhagic fever and the shock syndrome were not observed.Absenteeism from schools and offices, anamnestic questioning, and prevalence of antibodies in sera collected after the epidemic was over, indicated that approximately 75% of the population had been infected. Serological evidence was obtained of an epidemic of dengue in the islands more than 40 years earlier. This was confirmed by archival records.

Is income the only constraint on child nutrition in rural Bangladesh

Abstract: The importance of family income in relation to some other socioedemographic factors that might affect the nutritional status of children in the rural areas of Bangladesh was investigated. The factors analyzed in addition to family income were: age of the children; sex of the children; birth order; ownership of land by the family; fathers occupation; housing conditions; season; sources of drinking water; fathers education; mothers education; and participation of the children in food supplementation programs. The source of data for the study was was the Campanigonj Health Project Noakhali. 517 children who were aged 3 years or younger in August 1974 were included in the study. Seasonal factors family income mothers education and sex and birth order of the children appeared to be important determinants of malnutrition. An interaction between family income and mothers education in relation to child nutrition was quite apparent. A higher family income was of relatively greater benefit to the children of literate mothers than to those of illiterate mothers in improving the nutritional status. There was a threshold point below which income appeared as the primary constraint on child nutrition. A nutrition education program might prove helpful in improving the nutritional status of children of wealtheir families. The study was undertaken at a time when there was a state of famine throughout Bangladesh.

Microbiological surveillance of intra-neighbourhood E1 Tor cholera transmission in rural Bangladesh.

Abstract: The apparent failure of handpump tubewells to reduce the incidence of cholera among users in the flooded rural area of Bangladesh has stimulated interest in defining precisely the means of Vibrio cholerae transmission during localized outbreaks. Cholera-infected neighbourhoods were placed under intensive microbiological surveillance to pinpoint contaminated sources and subsequent infections. The results show that cholera transmission was via contaminated surface water, particularly water taken into households for cooking or drinking. Infections resulted from a daily dose not exceeding 105 organisms and the frequency of exposure appeared to be a major determinant of the infection rate. The importance of these data in environmental interventions and particularly in the provision of tubewells is discussed.

Reduction of neonatal tetanus by mass immunization of non-pregnant women: duration of protection provided by one or two doses of aluminium-adsorbed tetanus toxoid

Abstract: The protection from neonatal tetanus afforded by 1-2 doses of tetanus and diphtheria toxoids was determined by analyzing neonatal mortality among infants born to the subjects 9-32 months after immunization in rural Bangladesh. The neonatal mortality rate for children whose mothers had received 2 injections of tetanus toxoid was 20/1000 births less than the rate among children whose mothers had received cholera toxoid representing a 1/3 reduction in neonatal mortality. The reduced mortality rate was attributable almost entirely to a 75% lower death rate among infants 4-14 days of age. In the period up to 20 months after vaccination the reduction in deaths among 4-14-day-old infants after a single dose of tetanus-diphtheria toxoids was about the same as that after 2 doses; however beyond 20 months a single dose did not appear to confer protection. In countries with a high rate of neonatal tetanus and with little or no prenatal care mass tetanus toxoid immunization of all women of reproductive age may be indicated. The 2 initial immunizations can be spaced 1 year apart if necessary and booster doses should be scheduled at subsequent 3-year intervals.

Drug-resistant malaria-occurrence, control, and surveillance.

Abstract: Chloroquine resistant strains of Plasmodium falciparum were initially reported during the early 1960s and are currently found in many areas of Asia and South America. The prevalence and degree of resistance are increasing in all affected areas representing a serious setback to antimalaria programs. Alternative drugs are much more expensive and frequently more cumbersome to use. Consequently it is essential that a concerted effort be made to arrest the spread of resistant strains by developing standardized national policies on drug use. The probable genetics and epidemiology of drug resistance are considered in this report and attention is directed to the problems involved in its control. Antimalarial drugs interfere with important physiological functions of the parasites. Chloroquine and mepacrine apparently block acid proteases and peptidases in the phagosomes of intraerythrocytic parasites. Circumstantial evidence from "in vitro" tests suggests that strains of P. falciparum from various parts of the world although primarily susceptible to chloroquine exhibit "a priori" different sensitivities. P. falciparum in the Sobat valley of Ethiopia and in central Sudan appears to be significantly less susceptible to chloroquine than the Uganda I strain. There are no indications yet of chloroquine resistance in P. vivax P. malariae or P. ovale. The relative prevalence of chloroquine resistant infections and the degree of resistance are still on the increase in all affected areas. The development of drug resistance in areas with previously susceptible parasites has thus far always been associated with the use of the particular medicaments. 4 main factors seem to be involved: the degree of drug pressure; the degree of host/parasite contact; the duration of drug pressure; and the type of drug used. The occurrence of chloroquine resistant falciparum malaria requires the urgent attention of the health authorities and that several operational measures be undertaken. Instructions must be provided concerning the principles of drug use in antimalaria programs in the event of the spread of drug resistance and these instructions are reviewed. The methods for the monitoring of drug sensitivity are also reviewed. The World Health Organization (WHO) has developed global monitoring program initially implemented in 1977 in the Southeast Asia Region. Program objectives are identified.

Does BCG vaccination protect the newborn and young infants

Abstract: PIP: BCG vaccination has been applied on an increasing scale during the last few decades. This vaccination is now being applied to the newborn despite the fact that there is little direct evidence concerning the degree of protection afforded to very young infants. This discussion reviews the evidence that is available regarding vaccination of the newborn from 3 controlled trials that were carried out in the 1930s and the only recent evidence that is available on this question which comes from retrospective studies. The 1st effort to examine the efficacy of BCG vaccination of young infants in a controlled trial was begun in New York City in 1926. Up to 1933, half of the infants (under 1 year old, many under 4 weeks) referred from tuberculosis homes were vaccinated, the others serving as control. There were 3 deaths from tuberculosis among 445 vaccinated children but 18 deaths among 545 controls. During the 14 years of the controlled trial in Saskatchewan Indian infants (begun in 1933), there were 53 deaths among those vaccinated with BCG and 63 among the controls. Among the 306 vaccinated children there were 6 cases of tuberculosis, 2 of whom died. Among the 303 controls, there were 29 cases, 9 of whom died. A study of BCG vaccination of the newborn by a percutaneous multiple puncture method was started by Rosenthal et al. in 1937. It comprised 3381 infants of whom about half were vaccinated during the 1st week after birth if the household members were free of tuberculosis. As regards tuberculosis, the difference in morbidity was highly significant. There were 17 cases among the 1716 vaccinated and 65 cases among the 1665 controls. An interesting analysis of morbidity statistics for different countries was made by Bjartveit and Waaler, who studied the association between the decline of tuberculosis in various age groups and the age at which vaccination was given. This association was pronounced and thus provided evidence of the efficacy of BCG vaccination. Results have been recently published of a retrospective study that concerned 6364 infants who were vaccinated at birth, in Hamburg in 1954, and 9524 who were not. Up to 1971, 9 of the vaccinated and 130 of the unvaccinated children had developed tuberculosis. Of the 30,370 children born in 1963, 27,371 were vaccinated and 2999 were not. There were 11 cases of tuberculosis among the vaccinated and 16 cases among the unvaccinated children over the 8 year follow-up period. At face value, the evidence suggests that BCG vaccination of the newborn confers considerable protection against tuberculosis in infants and young children, yet it must be remembered that the evidence is both scanty and superficial.

Pyrimethamine sensitivity in Plasmodium falciparum: determination in vitro by a modified 48-hour test.

Abstract: Four strains of Plasmodium falciparum recently isolated in culture were assessed in vitro for their response to pyrimethamine. A simple modified 48-hour test was used, which showed two strains to be sensitive to the drug in vitro, while the other two were resistant at a very high level. In the two strains for which relevant clinical information was available the in vivo response to pyrimethamine was corroborated by the in vitro findings. This modified 48-hour test is thus useful for determining patterns of drug sensitivity in laboratory-adapted strains, and would be a valuable asset if found to be equally applicable under field conditions.

Resistance to antimicrobial agents of Vibrio cholerae E1 Tor strains isolated during the fourth cholera epidemic in the United Republic of Tanzania.

Abstract: Isolates of Vibrio cholerae obtained immediately after the outbreak of the fourth recorded epidemic of cholera in the United Republic of Tanzania were sensitive to tetracycline, but after five months of its extensive therapeutic and prophylactic use, 76% of the isolates were observed to be resistant to this and other antimicrobial agents. The appearance of resistance was found to be due to the rapid spread of antibiotic resistance plasmids belonging to the C incompatibility complex. Although most plasmid incompatibility groups have been shown to be unstable in V. cholerae, the strains found in the present epidemic seem to carry a plasmid belonging to one of the few relatively stable groups. These findings emphasize the importance of monitoring any emergence of bacterial resistance that may occur when mass prophylaxis programmes are in operation and also the importance of determining the genetic basis of the resistance mechanism.

Vaccination against poliomyelitis in economically underdeveloped countries.

Abstract: Poliomyelitis lameness surveys in children of school age recently reported from Burma, Egypt, Ghana, and the Philippines have indicated an estimated, average annual endemic incidence of paralytic poliomyelitis similar to or higher than the overall average annual rate in the USA during the peak years in the prevaccine era. Contrary to oft-expressed dogma, high rates of paralytic poliomyelitis are occurring annually in regions with high infant mortality rates, continuing undernutrition, and absence of basic sanitary facilities. Recent data indicate that prolonged breast feeding does not impede the effectiveness of oral poliovirus vaccine (OPV). A high prevalence of nonpoliovirus enteric infections can modify, delay, and lower the frequency of seroconversion after OPV, but these effects are overcome by multiple doses. The problem of eliminating paralytic poliomyelitis from economically underdeveloped countries depends on administrative rather than immunological or epidemiological factors, although a specially concentrated effort is needed in countries where most of the cases occur during the first two years of life and where paralytic polioviruses are propagating throughout the year in a large proportion of the infant population. Under such circumstances, expanded routine infant immunization programmes, which include OPV but reach at best only 20-40% of the total infant population, who receive only one or a few doses of vaccines requiring multiple doses, cannot be expected to eliminate paralytic poliomyelitis as an important public health problem. Injections of multiple doses of quadruple vaccine (DPT + inactivated poliomyelitis vaccine) would not only greatly increase the cost of routine immunizations but would not achieve more or as much as feeding OPV at the time of the DPT injections. Mass administration of OPV each year on 2 days of the year 2 months apart, to all children under 2, 3, or 4 years of age (depending on the epidemiological situation), without reference to the number of OPV doses they may have had before, can be expected to yield optimum results in countries with small numbers of professional health personnel and many other year-round problems.

Cost-benefit analysis and immunization programmes in developing countries.

Abstract: Cost-benefit analysis can provide strong evidence of the viability of immunization programs. This form of analysis involves the identification valuation and summation of the costs and benefits in each year of the program. The main components of immunization program costs are the wages of the immunizing and supervisory staff transport costs and the cost of the vaccine. Major benefits include savings in treatment costs following reduced incidence of disease reductions in mortality and morbidity avoidance of suffering to children and their families and spillover benefits. Although cost-benefit analyses tend to underestimate the benefits of immunization there is evidence of very high rates of return on investments in this area. This benefit would become even more evident if the benefits derived from a rural infants immunization were weighted higher than those associated with immunization of urban infants. Moreover this approach would bring the welfare function in cost-benefit analysis more in line with the aims of policy makers to address inequity in access to health care. Also needing to be addressed are the inadequacies of the human capital approach of life valuation especially in rural areas of developing countries.

Clinical survey techniques to estimate prevalence and annual incidence of poliomyelitis in developing countries.

Abstract: Recent epidemiological data suggest that poliomyelitis is a more important public health problem in developing countries than was originally suspected. Because of the availability of a cheap, effective, but labile oral vaccine, it is important that countries determine the incidence of poliomyelitis in order to determine the necessity and speed with which a vaccination programme should be introduced.Sequelae of poliomyelitis are distinctive and can be used to study the incidence of residual paralysis in children above the age of 5 years. Prevalence data for lameness due to poliomyelitis can then be translated into rates of annual incidence of paralytic disease. Lameness surveys can be efficiently done in schools and data are reliable as long as a similar search for lame children is done amongst children of the same age group who do not attend school but are in the geographical area served by the school. House-to-house surveys, while more time-consuming, are more reliable.

The Queensland cholera incident of 1977. 2. The epidemiological investigation.

Abstract: In 1977 the first case of cholera known to be contracted in Australia during the seventh pandemic occurred in southeastern Queensland. Toxigenic isolates of Vibrio cholerae, biotype eltor, serotype Inaba, phage-type 2, were obtained from the index case, a companion of the patient, the reticulated water supply of their place of residence, and a stretch of the neighbouring river that was being used to supplement fully treated water piped from Brisbane. Treatment of the auxiliary supply consisted solely of chlorination. A section of another river was later shown to contain V. cholerae. No source of pollution was identified for either river. From the persistence of the microorganism in the first river over a two-month period, despite increases in river flow following significant rainfall, it seems that the cholera vibrio can not only survive for a long period but can also grow in the river water. This strongly suggests that certain surface, and possibly subsurface, waters may serve as potential silent foci of V. cholerae. Hence the importance of providing bacteriologically safe water supplies, and the possible need to expand the definition of a 'cholera-receptive area'.

Antigens of Setaria digitata: cross-reaction with surface antigens of Wuchereria bancrofti microfilariae and serum antibodies of W. bancrofti-infected subjects.

Abstract: Extracts of Setaria digitata have been fractionated by DEAE-Sephadex A50 chromatography and the fractions obtained were used in the inhibition of indirect immunofluorescence of Wuchereria bancrofti microfilariae. The fractions were also tested by an enzyme-linked immunosorbent assay (ELISA) technique for reactivity against antibodies in the serum of patients with W. bancrofti infections. The results indicate that S. digitata contains several antigenic fractions that show cross-reactivity against filariasis sera; two of these fractions cross-reacted with surface antigens of W. bancrofti microfilariae but, when tested by the ELISA technique, these antigens did not show the highest reactivity against serum antibodies.

A longitudinal study of Plasmodium falciparum malaria in the West African savanna using the ELISA technique.

Abstract: Malarial antibody levels were measured by the enzyme-linked immunosorbent assay (ELISA) in two West African populations, one exposed to intense malaria transmission and the other protected The results reflected the transmission of maternal antibody and, in the unprotected population, the subsequent increase of the ELISA values with age reflected the development of the immune response to malaria Malaria control activities reduced ELISA values in the protected population The limitations of the ELISA test used in this study are shown by the fact that numerous infants with previous proven parasitaemia were ELISA-negative Purified antigens are needed to improve the ELISA test for use in serological surveys of malaria

Advances in epidemiology survey methodology and techniques in schistosomiasis.

Abstract: Quantitative techniques are now recognized to contribute to the validity and comparability of data from epidemiological studies in schistosomiasis. These methods have been developed and tested in field investigations in areas where Schistosoma mansoni is endemic and, to a lesser extent, S. haematobium endemic areas. Carefully planned epidemiological investigations using standardized and quantitative methods have contributed to our understanding of the relationships between intensity of infection and morbidity, as well as to the development of improved control strategies relevant to these areas. This article reviews the newer parasitological techniques, methods of morbidity assessment, and data analysis procedures employed in current epidemiological studies in schistosomiasis, as well as the analytical questions involved in research on the epidemiology of schistosomiasis.

Routine enterovirus diagnosis in a human rhabdomyosarcoma cell line.

Abstract: For many years a substitute cell line has been sought to replace monkey kidney cell cultures for the diagnosis of enterovirus infections. Reports by various workers have shown that the RD cell line, derived from a human rhabdomyosarcoma, will support the replication of most of the prototype strains of enterovirus. The present study shows that, with the exception of the group B coxsackieviruses, RD cells are more sensitive than cynomolgus monkey kidney cultures for the isolation of a wide variety of enteroviruses from clinical specimens. Since regular access by many diagnostic laboratories to supplies of primary cell cultures is often difficult because of distance from source or cost factors, a simple cell culture system is proposed which should prove useful for the diagnosis of most of the important enterovirus infections.

Evaluation of the enzyme-linked immunosorbent assay (ELISA) and other serological tests for the diagnosis of toxoplasmosis.

Abstract: The enzyme-linked immunosorbent assay (ELISA) was evaluated in human toxoplasmosis in three laboratories using their own procedures. The same batch of serum samples was investigated in the three laboratories. ELISA results were compared by statistical analysis both with one another and with those of the dye test (DT), immunofluorescence (IF), complement fixation test (CFT), and indirect haemagglutination (IHA). Highly significant correlations were obtained between the three laboratories with ELISA using two different antigens and enzyme conjugates. The correlations between ELISA and the other serological tests showed the following sequence: CFT>IF>IHA>DT. Highly significant correlations were obtained between ELISA using anti-γ-chain and anti-total immunoglobulin conjugates. The agreement in discrimination between sera with low and high antibody levels was good for all the different ELISA techniques but discrimination between positive and negative sera depended rather on the ELISA procedure used.

The world's last endemic case of smallpox: surveillance and containment measures

Abstract: On 31 October 1977, the world's last known case of endemic smallpox was discovered in Merca, Somalia. The source of infection was quickly identified; 19 days previously, the male patient had been in contact with two other cases for not more than 15 minutes, but the surveillance activities surrounding these cases did not identify him as a contact. The patient was isolated and containment and surveillance activities and a vaccination campaign were rapidly instituted; 161 contacts were identified, 41 of whom had not been vaccinated within the last three years. The patient recovered and fortunately no other cases occurred.

Relationship between ABO blood groups and malaria.

Abstract: A total of 736 patients with fever was tested for malaria and classified according to ABO blood group. Of these, 476 cases had patent parasitaemia at the time of investigation. The distribution of blood groups in this group was significantly different from that in 1300 controls from the same area. While group A was found to be more common in malaria cases than in normals, the reverse situation was found for group O. Possible explanations for this are discussed.

Epidemiological studies of rubella virus in a tropical African community.

Abstract: The single-radial-haemolysis test for antibody to rubella virus provides a simple rapid method for carrying out large serological surveys. The availability of a collection of sequential serum samples from inhabitants of two Gambian villages, Manduar and Keneba, made it possible to determine the pattern of rubella epidemics in these communities between 1966 and 1976. The serological findings indicated that an epidemic had occurred approximately two years before the commencement of the study. There was no further evidence of rubella infection until approximately 1973 when a large-scale epidemic occurred. Although the communities were monitored throughout the period of study there was no clinical evidence of infection and no cases of congenital rubella syndrome.

The Queensland cholera incident of 1977. 1. The index case.

Abstract: The first known case of cholera to be contracted in Australia during the seventh pandemic occurred in Queensland in 1977. There was no record of recent travel abroad by the patient, or of her having been in contact with persons suffering from gastroenteritis. Vibrio cholerae, biotype eltor, serotype Inaba, phage-type 2, was the causative microorganism. This case is unique in that the microbiological diagnosis was based on the identification of an isolate from venous blood. This indicates that the patient was bacteraemic, an observation not previously reported. The incident shows the importance of routine screening of faecal specimens for V. cholerae, as well as other enteropathogens.

The genetics of drug resistance in malaria parasites.

Abstract: The available experimental data on the genetics of drug resistance in malaria parasites are reviewed. Seven possible mechanisms for the origin of drug resistance are considered, and it is pointed out that spontaneous gene mutation is probably the most important. Experiments on the production of pyrimethamine-resistant and chloroquine-resistant strains of rodent Plasmodium species, and on the inheritance of such drug resistance, are reviewed. Relevant biochemical data are also considered in relation to the genetics of drug resistance. Studies on competition between drug-sensitive and drug-resistant parasites in mixed populations of rodent plasmodia are described. The implications of these findings for drug resistance in P. falciparum are discussed.