The effect of malaria control on Plasmodium falciparum in Africa between 2000 and 2015.

Since the year 2000, a concerted campaign against malaria has led to unprecedented levels of intervention coverage across sub-Saharan Africa. Understanding the effect of this control effort is vital to inform future control planning. However, the effect of malaria interventions across the varied epidemiological settings of Africa remains poorly understood owing to the absence of reliable surveillance data and the simplistic approaches underlying current disease estimates. Here we link a large database of malaria field surveys with detailed reconstructions of changing intervention coverage to directly evaluate trends from 2000 to 2015, and quantify the attributable effect of malaria disease control efforts. We found that Plasmodium falciparum infection prevalence in endemic Africa halved and the incidence of clinical disease fell by 40% between 2000 and 2015. We estimate that interventions have averted 663 (542-753 credible interval) million clinical cases since 2000. Insecticide-treated nets, the most widespread intervention, were by far the largest contributor (68% of cases averted). Although still below target levels, current malaria interventions have substantially reduced malaria disease incidence across the continent. Increasing access to these interventions, and maintaining their effectiveness in the face of insecticide and drug resistance, should form a cornerstone of post-2015 control strategies.

Divergent isoenzyme profiles of sylvatic and domiciliary Trypanosoma cruzi in the eastern plains, piedmont, and highlands of Colombia.

Fifty-four stocks of Trypanosoma cruzi from vectors, mammalian reservoirs, and infected humans were characterized by enzyme electrophoresis in starch gels using Brazilian zymodeme reference strains (Z1, X-10; Z2, ESM; Z3, CAN-3) as standards. Colombian stocks were collected in three ecologically and epidemiologically distinct settings. Thirteen enzymes were included in the evaluation. Sixteen different phenotypic profiles or "zymodemes" were evident and generated three groups of closely related stocks: a sylvatic Z1-like group, a domiciliary Z1-like group, and a sylvatic Z3-like group. The number of zymodemes observed in foci of sylvatic transmission was greater than in foci of domiciliary transmission. Modified ecologic conditions associated with agriculture and the consequent reduction of biologic diversity may account for the observed pattern of zymodeme distribution and heterogeneity. The phenotypic similarity between the principal sylvatic group of stocks and domiciliary stocks contrasts with the extensive differences observed between the domestic Z2 zymodeme and sylvatic Z1 and Z3 zymodemes in Brazil and Chile.

Onchocerca volvulus: enzyme polymorphism in relation to the differentiation of forest and savannah strains of this parasite.

Isozyme analysis was carried out on Onchocerca volvulus worms collected from Liberia, Ivory Coast, Burkina Faso and Sudan to see whether this technique could detect differences between forest and savannah populations of this parasite. A total of 243 forest and 189 savannah individual female worms were electrophoresed and stained for seven enzymes. Four showed some polymorphism, LDH, MDH, PGM and MPI and the other three, GAPDH, PEP and GPI were invariant. Statistical analysis of the results showed that the relative proportions of genotypes from within the different countries conformed to Hardy-Weinberg expectations. Pairwise comparisons of allele frequencies between countries showed that populations from Liberia and Ivory Coast had a very similar composition; there was some divergence between all the other pairs of populations and the genetic distance was calculated to summarize the degree of divergence. The number of loci examined was small and the genetic distances were within the range expected for separate geographical populations of the same species. The usefulness of this technique in worm identification is discussed.

Leishmania in the Old World: 5. Numerical analysis of isoenzyme data.

Numerical analysis of 59 zymodemes of Old World Leishmania, based on the enzyme profiles of 280 stocks, revealed several distinct clusters. Some of these clusters corresponded with traditional taxonomic groupings: L. major, L. tropica, L. aethiopica and L. donovani sensu lato, but hitherto unrecognized groups were also indicated. The analysis provided an overview of the interrelationships between the Leishmania zymodemes.

Analysing isoenzyme band patterns using similarity coefficients: a personal computer program.

A computer program in Fortran 77 was developed to analyse the isoenzyme patterns of trypanosomes isolated from African sleeping sickness patients, to allow biochemical relationships between populations of trypanosomes from different hosts and geographic areas to be elucidated. However, the generality of the design allows it to be used with presence/absence data from a variety of sources, including DNA fingerprints. The program reads in isoenzyme band patterns from an ASCII file and calculates a matrix of similarity coefficients. Four different similarity measures are offered, suitable for presence/absence data from a range of organisms and experimental procedures. The matrix of similarity values produced is suitable for analysis by ordination methods including principal coordinates analysis, and the production of dendrograms and icicle plots using SPSS/PC+.

Quality circles and their potential application to rural health care in Papua New Guinea.

A quality circle is a group of service providers who meet regularly to solve problems relating to the quality of their work. This is an example of bottom-up rather than top-down management which has found considerable success in the industries of the developed world. This article describes the principles which govern the operation of quality circles, the expected benefits and how best to introduce them. The problems relating to the provision of quality health care in rural areas and the potential application of the quality circle methodology are discussed.

PIP: The process of documenting poor quality services is easier than devising strategies to assure high standards of quality. The usual approach is to set standards, undertake measurements, and make recommendations; the disadvantages are that quality control units are reactive and do nothing to prevent problems; selected indicators may not be sufficiently comprehensive or sensitive measures; monitoring may be intermittent; and quality of control people may not be in a position to correct the problem. One strategy, the quality circle, is a means to assure high standards of quality. It is a group of 4-10 people from the same work area who meet regularly to solve workplace problems. Quality circles originated in Japan and have been used in the USA and the United Kingdom. The underlying principle is that most individuals can contribute to the efficient and effective running of their organization; the method contrasts with a top-down manager's approach with imposition of regulations from above. The individuals involved in a quality circle are the circle members, the circle leader, the circle facilitator, and the circle coordinator. The circle functions according to principles identified and discussed, such as voluntariness of circle participation, keeping one's own house in order, ownership, systematic problem-solving, and training requirements. The expected benefits are improved staff morale, improved communication, improved supervisory roles, and improved quality of outputs. When quality circles fail, it may be not the concept, but the application. Success may be dependent on the commitment from senior management throughout the life of the program. There must eventually be organized problem-solving in a systematic way. The bottom-up approach is best introduced on a small scale at first, until experience is gained. Quality circles must conform with existing organizational structures. Time and expense for training must be committed to the quality circle program. Adequate resources and management are also necessary. If these six preconditions are satisfied, there is still no guarantee of success, because of personalities or problems unrelated to the work situation. Quality circles could be applied in Papua New Guinea in hospitals, aide posts, and health centers. User confidence in health centers must not be overlooked, as it is one of the most influential factors in outcome of treatment.

Origins and organization of genetic diversity in natural populations of Trypanosoma brucei.

Experimental work has established that a sexual process can occur in African trypanosomes (Jenni, Marti, Schweizer, Betschart, Le Page, Wells, Tait, Paindavoine, Pays & Steinert, 1986; Paindavoine, Zampetti-Bosseler, Pays, Schweizer, Guyaux, Jenni & Steinert, 1986; Tait, personal communication). However, the role of the process in natural populations of trypanosomes is poorly understood. This paper considers what information can be gained from analyses of isoenzyme polymorphism. A cladistic approach is used to help determine whether trypanosome diversity could have been produced by mutation alone. When applied to three East African populations of Trypanosoma brucei it provides evidence that some diversity has arisen through a sexual process; this explains the variation observed within a locality and can account for the evolution of differences between localities. However, the extent to which genetic exchange currently operates is less clear. Analysis of genotype frequencies indicates that agreements with Hardy-Weinberg expectations can be obtained even if genetic exchange exerted no influence over genotype frequencies. Moreover, analysis of joint locus frequencies reveals disequilibrium between loci and that trypanosome populations may be lacking several genotype combinations. Thus, genetic exchange may not occur sufficiently frequently, or in such a way as to break up associations between loci. The relevance of these observations to the evolution of strain differences within T. brucei is discussed.

Genetic variation in Trypanosoma brucei and the epidemiology of sleeping sickness in the Lambwe Valley, Kenya.

A contingency table approach was used to explore the influence of location, host species and time on the genetic composition of a Trypanosoma brucei population in Lambwe Valley, Kenya. Significant differences in zymodeme frequencies were noticed over comparatively short geographical distances suggesting that transmission of T. brucei is somewhat localized. A significant association was observed between zymodeme and the mammalian host from which T. brucei was derived. The association was consistent in different localities in Lambwe valley and remained stable for at least 32 months. These observations indicate that zymodemes are adapted to different host species and that genetic exchange has not disrupted host associations over this time-scale. A major change in the composition of the T. brucei population during a sleeping sickness outbreak in 1980 was confirmed. But while new zymodemes emerged, a decline in overall diversity was noted during times of high sleeping sickness incidence. The results can be explained by selection of T. brucei zymodemes for particular transmission cycles. Although it is not necessary to invoke genetic exchange, sex may help T. brucei to adapt to changes in selection pressures. Such a hypothesis helps to explain why T. brucei appears largely clonal in the short term, even though population studies indicate that sex is responsible for much genetic diversity in the long term. It also explains why neighbouring populations of T. brucei are composed of a different range of zymodemes formed from the same alleles. Such a view implies that genetic exchange has an important role in the microevolution of T. brucei populations.

Information systems for health sector monitoring in Papua New Guinea.

This paper describes (i). how a national health information System was designed, tested and implemented in Papua New Guinea, (ii). how the system was integrated with other management information systems, and (iii). how information has been used to support decision-making. It concludes that central coordination of systems design is essential to make sure that information systems are aligned with government priorities and can deliver the information required by managers. While there is often scope for improving the performance of existing information systems, too much emphasis can be placed on revising data collection procedures and creating the perfect information system. Data analysis, even from imperfect systems, can stimulate greater interest in information, which can improve the quality and completeness of reporting and encourage a more methodical approach to planning and monitoring services. Our experience suggests that senior decision-makers and political leaders can play an important role in creating a culture of information use. By demanding health information, using it to formulate policy, and disseminating it through the channels open to them, they can exert greater influence in negotiations with donors and other government departments, encourage a more rational approach to decision-making that will improve the operation of health services, and stimulate greater use of information at lower levels of the health system. The ability of information systems to deliver these benefits is critical to their sustainability.

Initial experience of using a knowledge based system for monitoring immunization services in Papua New Guinea.

A knowledge based system (KBS) which helps health service managers to interpret immunization coverage rates was installed in two provinces of Papua New Guinea. It was assessed over a period of 4 months to determine whether it was a potentially useful management tool. One province used the system but did not adjust its activities significantly because it was meeting its targets for immunization. In the other province the KBS helped provincial managers to detect problems and respond to them. Consequently, improvements in performance indicators were detected. It is difficult to attribute the improvements entirely to the KBS but several actions were taken to strengthen immunization services and the KBS appeared to support these. It appears that interventions which make routinely collected data more understandable and readily usable by health service managers can lead to improvements in the delivery of health services.

PIP: Since 1986 the Department of Health in Papua New Guinea has undertaken a nationwide program to computerize its health information systems at the provincial level. The computerized information system, based on IBM-compatible PCs, generates monthly reports on various health programs. A knowledge based system (KBS) for analyzing immunization coverage rates in the provincial health information system has been developed using the expert system shell CRYSTAL. The KBS is a menu driven program that reads data in the existing system and attempts to make interpretations for health service managers. It points out problems in delivering immunization services, suggests why they might occur and what could be done about them. To ensure that the KBS would be relevant to its potential users, the KBS was installed in two provinces, Manus and New Ireland, so that comments on the system could be obtained and a preliminary assessment made. The two provinces were visited in July 1992 and the software installed on provincial microcomputers. A follow-up visit was made early in November 1992 to see what use was made of the system. The KBS helped staff to recognize several problems and successes: 1) immunization results in the second quarter were generally poor; 2) some immunization reports had not been submitted by certain health centers; 3) ranking of health centers showed that some health centers were performing well and others poorly; 4) particular problems were being experienced at individual health centers, e.g., high drop-out rates from first to third doses of triple antigen; and 5) problems occurring with supplies could be followed up. During the four months that the KBS was installed the average number of attenders for final doses rose from 306 to 453 per month (p = 0.037). The KBS appeared to be of potential benefit in helping health service managers make use of routinely collected data for the monitoring and evaluation of health services.