Is there a correlation between malaria incidence and IRS coverage in western Zambezi region, Namibia?

Setting: A comparison of routine Namibia National Malaria Programme data (reported) vs. household survey data (administrative) on indoor residual spraying (IRS) in western Zambezi region, Namibia, for the 2014-2015 malaria season. Objectives: To determine 1) IRS coverage (administrative and reported), 2) its effect on malaria incidence, and 3) reasons for non-uptake of IRS in western Zambezi region, Namibia, for the 2014-2015 malaria season. Design: This was a descriptive study. Results: IRS coverage in western Zambezi region was low, ranging from 42.3% to 52.2% for administrative coverage vs. 45.9-66.7% for reported coverage. There was no significant correlation between IRS coverage and malaria incidence for this region (r = -0.45, P = 0.22). The main reasons for households not being sprayed were that residents were not at home during spraying times or that spray operators did not visit the households. Conclusions: IRS coverage in western Zambezi region, Namibia, was low during the 2014-2015 malaria season because of poor community engagement and awareness of times for spray operations within communities. Higher IRS coverage could be achieved through improved community engagement. Better targeting of the highest risk areas by the use of malaria surveillance will be required to mitigate malaria transmission.

Contexte : Une comparaison des données de routine du programme national de lutte centre le paludisme de Namibie (rapportées) et des données d'enquête dans les foyers (administratives) relatives à la pulvérisation d'insecticide à effet rémanent (IRS) dans la région ouest du Zambèze, en Namibie, pour la saison 2014­2015 du paludisme.Objectifs : Déterminer 1) la couverture de l'IRS (administrative et rapportée), 2) son effet sur l'incidence du paludisme, et 3) les raisons de la non couverture de l'IRS dans la région ouest du Zambèze, Namibie, pendant la saison 2014­2015 du paludisme.Schéma : Une étude descriptive.Résultats : La couverture de l'IRS dans la région ouest du Zambèze a été faible, allant de 42,3% à 52,2% pour la couverture administrative contre 45,9% à 66,7% pour la couverture rapportée. Il n'y a pas eu de corrélation significative entre couverture de l'IRS et incidence du paludisme dans cette région (r = −0,45 ; P = 0,22). Les raisons majeures pour lesquelles les foyers n'ont pas bénéficié de pulvérisations ont été l'absence des résidents à leur domicile lors de la pulvérisation ou, inversement, la non-venue des opérateurs de pulvérisation dans les foyers.Conclusions : La couverture de l'IRS dans la région ouest du Zambèze, Namibie, a été faible pendant la saison 2014­2015 du paludisme en raison de l'engagement médiocre de la communauté et de la méconnaissance des dates d'opérations de pulvérisation dans les communautés. Une couverture plus élevée de l'IRS pourrait être obtenue avec une meilleur engagement de la communauté. Un meilleur ciblage des zones à risque les plus élevés en utilisant la surveillance du paludisme sera requis pour atténuer la transmission du paludisme.

Marco de referencia: Una comparación de los datos corrientes del Programa Nacional contra el Paludismo de Namibia (notificados), con los datos de una encuesta domiciliaria (administrativos) sobre la fumigación de interiores con insecticidas de efecto residual (IRS) en la región occidental de Zambezi en Namibia, durante la temporada de paludismo del 2014­2015.Objetivos: Determinar 1) la cobertura de la IRS (administrativa y notificada), 2) su efecto sobre la incidencia de paludismo, y 3) las razones de la falta de IRS en la región occidental de Zambezi, en Namibia, durante la temporada de paludismo del 2014­2015.Método: Un estudio descriptivo.Resultados: La cobertura de la IRS en la región occidental de Zambezi fue baja, del 42,3% al 52,2% según la cobertura administrativa, en comparación con el 45,9% al 66,7% según la cobertura notificada. paludismo en la región (r = −0,45; P = 0,22). Las principales razones por las cuales no se fumigaron los domicilios fueron que los residentes no se encontraban presentes en el momento de la fumigación o que los operadores de fumigación no visitaron los hogares.Conclusiónes: La cobertura de la fumigación de interiores con insecticidas de efecto residual en la región occidental de Zambezi, en Namibia, fue baja durante la temporada de paludismo del 2014­2015 por falta de participación comunitaria y de conocimiento de los horarios de fumigación en las comunidades. La cobertura se puede ampliar si se fomenta el compromiso comunitario y es necesario dirigir mejor las campañas a las zonas de mayor riesgo, según lo indiquen los datos de la vigilancia del paludismo, con el propósito de disminuir la transmisión de la enfermedad.

Burden of asymptomatic malaria among a tribal population in a forested village of central India: a hidden challenge for malaria control in India.

OBJECTIVE: Chhattisgarh in India is a malaria-endemic state with seven southern districts that contributes approximately 50-60% of the reported malaria cases in the state every year. The problem is further complicated due to asymptomatic malaria cases which are largely responsible for persistent transmission. This study was undertaken in one of the forested villages of the Keshkal subdistrict in Kondagaon district to ascertain the proportion of the population harbouring subclinical malarial infections. STUDY DESIGN: Community-based cross-sectional study. METHODS: Mass blood surveys were undertaken of the entire population of the village in the post-monsoon seasons of 2013 and 2014. Fingerprick blood smears were prepared from individuals of all ages to detect malaria infections in their blood. Individuals with fever at the time of the survey were tested with rapid diagnostic tests, and parasitaemia in thick blood smears was confirmed by microscopy. Malaria-positive cases were treated with anti-malarials in accordance with the national drug policy. RESULTS: Peripheral blood smears of 134 and 159 individuals, including children, were screened for malaria infection in 2013 and 2014, respectively. Overall, the malaria slide positivity rates were 27.6% and 27.7% in 2013 and 2014, respectively, and the prevalence rates of asymptomatic malaria were 20% and 22.8%. This study showed that, for two consecutive years, the prevalence of asymptomatic malaria infection was significantly higher among children aged ≤14 years (34.4% and 34.1% for 2013 and 2014, respectively) compared with adults (15.2% and 18.2% for 2013 and 2014, respectively; P = 0.023 and 0.04, respectively). CONCLUSION: The number of asymptomatic malaria cases, especially Plasmodium falciparum, is significant, reinforcing the underlying challenge facing the malaria elimination programme in India.

Trends in the selection of insecticide resistance in Anopheles gambiae s.l. mosquitoes in northwest Tanzania during a community randomized trial of longlasting insecticidal nets and indoor residual spraying.

Anopheles gambiae s.l. (Diptera: Culicidae) in Muleba, Tanzania has developed high levels of resistance to most insecticides currently advocated for malaria control. The kdr mutation has almost reached fixation in An. gambiae s.s. in Muleba. This change has the potential to jeopardize malaria control interventions carried out in the region. Trends in insecticide resistance were monitored in two intervention villages using World Health Organization (WHO) susceptibility test kits. Additional mechanisms contributing to observed phenotypic resistance were investigated using Centers for Disease Control (CDC) bottle bioassays with piperonylbutoxide (PBO) and S,S,S-tributyl phosphorotrithioate (DEF) synergists. Resistance genotyping for kdr and Ace-1 alleles was conducted using quantitative polymerase chain reaction (qPCR). In both study villages, high phenotypic resistance to several pyrethroids and DDT was observed, with mortality in the range of 12-23%. There was a sharp decrease in mortality in An. gambiae s.l. exposed to bendiocarb (carbamate) from 84% in November 2011 to 31% in December 2012 after two rounds of bendiocarb-based indoor residual spraying (IRS). Anopheles gambiae s.l. remained susceptible to pirimiphos-methyl (organophosphate). Bendiocarb-based IRS did not lead to the reversion of pyrethroid resistance. There was no evidence for selection for Ace-1 resistance alleles. The need to investigate the operational impact of the observed resistance selection on the effectiveness of longlasting insecticidal nets and IRS for malaria control is urgent.

Epidemiology of malaria in South Africa: from control to elimination.

Locally specific epidemiological understanding is pivotal to the success of malaria elimination in South Africa. Here, we focus on how the host, vector, parasite and environment and their interactions have influenced malaria incidence in South Africa between 1995 and 2012. Broad environmental considerations are necessary, including the physical (temperature and humidity), social (migration patterns), economic (quality of housing stock) and political (regional collaboration). 

What will move malaria control to elimination in South Africa?

In this supplement, several authors have shared lessons from the past and identified factors that led to the significant reductions in malaria morbidity and mortality during the past half-century in South Africa. In addition, strategies for achieving malaria elimination have been proposed. Here, we highlight the gaps that have been identified and make proposals for taking South Africa from malaria control to elimination.

Malaria control aimed at the entire population in KwaZulu-Natal negates the need for policies to prevent malaria in pregnancy.

BACKGROUND: South Africa has no policy to prevent malaria in pregnancy, despite the adverse effects of the disease in pregnancy. However, malaria control measures consisting of indoor residual spraying and specific antimalarial treatment have been in place since the 1970s. Information on the burden of malaria in pregnancy in South Africa is needed to indicate whether a specific policy for malaria prevention in pregnancy is necessary. OBJECTIVE: To determine the burden of malaria in pregnancy in KwaZulu-Natal (KZN) province, South Africa. METHODS: Pregnant women were enrolled at their first antenatal care visit to three health facilities in Umkhanyakude health district in northern KZN during May 2004 - September 2005 and followed up until delivery. Data collection included demographic details, current and previous malaria infection during pregnancy, haemoglobin concentrations and birth outcomes. RESULTS: Of the 1 406 study participants, more than a quarter were younger than 20 years of age, and more than 90% were unemployed and unmarried. Although 33.2% of the women were anaemic, this was not related to malaria. The prevalence and incidence of malaria were very low, and low birth weight was only weakly associated with malaria (1/10). CONCLUSION: The low burden of malaria in these pregnant women suggests that they have benefited from malaria control strategies in the study area. The implication is that additional measures specific for malaria prevention in pregnancy are not required. However, ongoing monitoring is needed to ensure that malaria prevalence remains low.

Incidence of epilepsy: a systematic review and meta-analysis.

OBJECTIVE: To estimate the pooled incidence of epilepsy from published studies and investigate sources of heterogeneity in the estimates. METHODS: We searched online databases for incidence studies and used meta-analytic methods to analyze the data. RESULTS: Thirty-three articles met the entry criteria. The median incidence of epilepsy was 50.4/100,000/year (interquartile range [IQR] 33.6-75.6), while it was 45.0 (IQR 30.3-66.7) for high-income countries and 81.7 (IQR 28.0-239.5) for low- and middle-income countries. Population-based studies had higher incidence estimates than hospital-based studies (p = 0.02) while retrospective study design was associated with lower estimates than prospective studies (p = 0.04). CONCLUSION: We provide data that could potentially be used to assess the burden and analyze the trends in incidence of epilepsy. Our results support the need for large population-based incidence studies of epilepsy.

Effects of deworming during pregnancy on maternal and perinatal outcomes in Entebbe, Uganda: a randomized controlled trial.

BACKGROUND: Helminth infections during pregnancy may be associated with adverse outcomes, including maternal anemia, low birth weight, and perinatal mortality. Deworming during pregnancy has therefore been strongly advocated, but its benefits have not been rigorously evaluated. METHODS: In Entebbe, Uganda, 2507 pregnant women were recruited to a randomized, double-blind, placebo-controlled trial investigating albendazole and praziquantel in a 2 x 2 factorial design [ISRCTN32849447]. Hematinics and sulphadoxine-pyrimethamine for presumptive treatment of malaria were provided routinely. Maternal and perinatal outcomes were recorded. Analyses were by intention to treat. RESULTS: At enrollment, 68% of women had helminths, 45% had hookworm, 18% had Schistosoma mansoni infection; 40% were anemic (hemoglobin level, <11.2 g/dL). At delivery, 35% were anaemic; there was no overall effect of albendazole (odds ratio [OR], 0.95; 95% confidence interval [CI], 0.79-1.15) or praziquantel (OR, 1.00; 95% CI, 0.83-1.21) on maternal anemia, but there was a suggestion of benefit of albendazole among women with moderate to heavy hookworm (OR, 0.45; 95% CI, 0.21-0.98; P=.15 for interaction). There was no effect of either anthelminthic treatment on mean birth weight (difference in mean associated with albendazole: -0.00 kg; 95% CI, -0.05 to 0.04 kg; difference in mean associated with praziquantel: -0.01 kg; 95% CI, -0.05 to 0.04 kg) or on proportion of low birth weight. Anthelminthic use during pregnancy showed no effect on perinatal mortality or congenital anomalies. CONCLUSIONS: In our study area, where helminth prevalence was high but infection intensity was low, there was no overall effect of anthelminthic use during pregnancy on maternal anemia, birth weight, perinatal mortality, or congenital anomalies. The possible benefit of albendazole against anemia in pregnant women with heavy hookworm infection warrants further investigation.

Is sexual risk taking behaviour changing in rural south-west Uganda? Behaviour trends in a rural population cohort 1993-2006.

OBJECTIVE: To describe sexual behaviour trends in a rural Ugandan cohort in the context of an evolving HIV epidemic, 1993-2006. METHODS: Sexual behaviour data were collected annually from a population cohort in which HIV serological surveys were also conducted. Behaviour trends were determined using survival analysis and logistic regression. Trends are reported based on the years in which the respective indicators were collected. RESULTS: Between 1993 and 2006, median age at first sex increased from 16.7 years to 18.2 years among 17-20-year-old girls and from 18.5 years to 19.9 years among boys. Both sexes reported a dip in age at sexual debut between 1998 and 2001. One or more casual partners in the past 12 months among men rose from 11.6% in 1997 to 12.7% in 2004 and then declined to 10.2% in 2006. Among women it increased from 1.4% in 1997 to 3.7% in 2004 and then reduced to 1.4% in 2006. The rise in casual partners between 1997 and 2004 was driven mainly by older age groups. Trends in condom use with casual partners varied by age, increasing among those aged 35+ years, declining in the middle age groups and presenting a dip and then a rise in the youngest aged group (13-19 years). CONCLUSION: Among youth, risky behaviour declined but increased in the late 1990s/early 2000s. Among those aged 35+ years, condom use rose but casual partners also rose. Several indicators portrayed a temporary increase in risk taking behaviour from 1998 to 2002.

Exploring 30 years of malaria case data in KwaZulu-Natal, South Africa: part I. The impact of climatic factors.

Large parts of Africa are prone to malaria epidemics. Advance epidemic warning would give health services an opportunity to prepare. Because malaria transmission is largely limited by climate, climate-based epidemic warning systems are a real possibility. To develop and test such a system, good long-term malaria and climate data are needed. In KwaZulu-Natal (KZN), South Africa, 30 years of confirmed malaria case data provide a unique opportunity to examine short- and long-term trends. We analysed seasonal case totals and seasonal changes in cases (both log-transformed) against a range of climatic indicators obtained from three weather stations in the highest malaria incidence districts, using linear regression analysis. Seasonal changes in case numbers (delta log cases, dlc) were significantly associated with several climate variables. The two most significant ones were mean maximum daily temperatures from January to October of the preceding season (n=30, r2=0.364, P=0.0004) and total rainfall during the current summer months of November-March (n=30, r2=0.282, P=0.003). These two variables, when entered into the same regression model, together explained 49.7% of the total variation in dlc. We found no evidence of association between case totals and climate. In KZN, where malaria control operations are intense, climate appears to drive the interannual variation of malaria incidence, but not its overall level. The accompanying paper provides evidence that overall levels are associated with non-climatic factors such as drug resistance and possibly HIV prevalence.

Exploring 30 years of malaria case data in KwaZulu-Natal, South Africa: part II. The impact of non-climatic factors.

Malaria transmission is a multifactorial phenomenon. Climate is a major limiting factor in the spatial and temporal distribution of malaria, but many non-climatic factors may alter or override the effect of climate. Thirty years of monthly malaria incidence data from KwaZulu-Natal province, South Africa, reveal strong medium and long-term trends, which were not present in the climate data. This paper explores various non-climatic factors that may have contributed towards the observed trends. The development of antimalarial drug resistance, available information on human immunodeficiency virus (HIV) prevalence, cross-border people movements, agricultural activities, emergence of insecticide resistance and the case reporting system are reviewed and their potential effect on malaria transmission examined. Single-variable linear regression analysis showed significant association between seasonal case totals (log-transformed) and the measured level of drug resistance (log-transformed) (r2=0.558, n=10, P=0.013) as well as relative measures of HIV infection since 1990 (r2=0.846, n=11, P=0.001). The other factors appear to have affected the level of malaria transmission at certain periods and to some degree. The importance of surveillance and inclusion of non-climatic variables in analysis of malaria data is demonstrated.

Spatial patterns of infant mortality in Mali: the effect of malaria endemicity.

A spatial analysis was carried out to identify factors related to geographic differences in infant mortality risk in Mali by linking data from two spatially structured databases: the Demographic and Health Surveys of 1995-1996 and the Mapping Malaria Risk in Africa database for Mali. Socioeconomic factors measured directly at the individual level and site-specific malaria prevalence predicted for the Demographic and Health Surveys' locations by a spatial model fitted to the Mapping Malaria Risk in Africa database were examined as possible risk factors. The analysis was carried out by fitting a Bayesian hierarchical geostatistical logistic model to infant mortality risk, by Markov chain Monte Carlo simulation. It confirmed that mother's education, birth order and interval, infant's sex, residence, and mother's age at infant's birth had a strong impact on infant mortality risk in Mali. The residual spatial pattern of infant mortality showed a clear relation to well-known foci of malaria transmission, especially the inland delta of the Niger River. No effect of estimated parasite prevalence could be demonstrated. Possible explanations include confounding by unmeasured covariates and sparsity of the source malaria data. Spatial statistical models of malaria prevalence are useful for indicating approximate levels of endemicity over wide areas and, hence, for guiding intervention strategies. However, at points very remote from those sampled, it is important to consider prediction error.

Temperature-suitability maps for schistosomiasis in South Africa.

The results of parasitological surveys have shown that both urinary and intestinal schistosomiasis occur widely among the human residents of South Africa. The national data on both diseases have now been incorporated into a geographical information system, to develop new maps based on defined temperature constraints. The disease data, obtained from a 'hard-copy' atlas of schistosomiasis, were used as a template to select temperature regimes that were (1) suitable and (2) unsuitable for the transmission of schistosomes to humans in South Africa. The regimes were derived from the published results of investigations in which the biology of larval schistosomes (i.e. schistosome transmission) was related to temperature in South Africa. Those regimes that were based on the estimated temperature minima for transmission corresponded more closely to the disease-distribution data than those based on the corresponding maxima. An estimate of the number of children living in the climate-suitable areas was made but, within the context of the spatial methodology used and the limitations of the available disease data, it was not possible to predict the prevalences of schistosomiasis.

An epidemiological perspective of substance use among high school pupils in rural KwaZulu-Natal.

OBJECTIVES: To investigate prevalence and the factors influencing substance use among rural high school pupils in KwaZulu-Natal in order to develop and implement intervention programmes. DESIGN: Cross-sectional study. SETTING: Twenty-eight high schools in southern KwaZulu-Natal. SUBJECTS: One thousand three hundred and eighteen grade 10 pupils. OUTCOME MEASURES: An anonymous self-reporting questionnaire was used to investigate the use of alcohol, tobacco (cigarettes), cannabis and solvents. RESULTS: Of the male scholars, 52.9% (95% confidence interval (CI): 45.4-60.3) reported ever using alcohol, 16.9% (CI: 11.5-24.0) reported using cannabis, and 13.1% (CI: 7.2-22.5) had smoked more than one cigarette daily. Among male pupils 45.5% (CI: 38.6-52.6) had inhaled benzine and 34.6% (CI: 28.0-41.8), thinners; 7.4% (CI: 3.4-15.2) had used cocaine and 4.1% (CI: 1.0-10.6), crack. Female pupils reported significantly less use of alcohol (25.5%, CI: 17.6-35.3), cannabis (2.3%, CI: 1.3-4.1), cigarettes (more than one daily) (2.0%, CI: 1.0-4.1), and inhalation of benzine (18.8%, CI: 13.8-25.2) and thinners (10.8%, CI: 7.2-16). Logistical regression indicated that the odds of smoking cigarettes increased significantly (p < 0.0005) with use of the other substances. CONCLUSION: The results of this study confirm the prevalence of multi-substance use among pupils at the majority of rural high schools in this district and the need for targeted interventions to reduce/prevent this.

Prevalence, incidence, and mother-to-child transmission of HIV-1 in rural South Africa.

Simple, robust approaches are needed to monitor prevalence, incidence, and mother-to-child transmission of HIV-1 in rural Africa. We have designed a method that uses antibody and viral RNA testing of dried blood spots obtained from mother-infant pairs attending routine immunisation clinics. In our study, prevalence and incidence of HIV-1 was highest in young women in their late teens and early twenties. In children born to infected mothers, prevalence increased from 14% in infants younger than 6 weeks of age to 24% at 3-6 months. The blood-spot approach is an effective method for surveillance of HIV-1 in women and children, and for early identification of incidence of this infection in women of child-bearing age.

Field and laboratory comparative evaluation of ten rapid malaria diagnostic tests.

The paper reports on a comparative evaluation of 10 rapid malaria tests available in South Africa in 1998: AccuCheck (AC, developmental), Cape Biotech (CB), ICT Malaria Pf (ICT1) and Pf/Pv (ICT2), Kat Medical (KAT), MakroMal (MM), OptiMAL (OP), ParaSight-F (PS), Quorum (Q), Determine-Malaria (DM). In a laboratory study, designed to test absolute detection limits, Plasmodium falciparum-infected blood was diluted with uninfected blood to known parasite concentrations ranging from 500 to 0.1 parasites per microlitre (P/microL). The 50% detection limits were: ICT1, 3.28; ICT2, 4.86; KAT, 6.36; MM, 9.37; CB, 11.42; DM, 12.40; Q, 16.98; PS, 20; AC, 31.15 and OP, 91.16 P/microL. A field study was carried out to test post-treatment specificity. Blood samples from malaria patients were tested with all products (except AC and DM) on the day of treatment and 3 and 7 days thereafter, against a gold standard of microscopy and polymerase chain reaction (PCR). OP and PS produced fewer false-positive results on day 7 (18 and 19%, respectively) than the other rapid tests (38-56%). However, microscopy, PCR, OP and PS disagreed largely as to which individuals remained positive. The tests were further compared with regard to general specificity, particularly cross-reactivity with rheumatoid factor, speed, simplicity, their ability to detect other species, storage requirements and general presentation.

The use of spatial analysis in mapping the distribution of bancroftian filariasis in four West African countries.

The geographical distribution of human infection with Wuchereria bancrofti was investigated in four West African countries (Benin, Burkina Faso, Ghana and Togo), using a commercial immunochromatographic test for filarial antigen. Efforts were made to cover each health-system implementation unit and to ensure no sampling point was >50 km from another, but otherwise the 401 study communities were selected at random. The aim was to enable spatial analysis of the data, to provide a prediction of the overall spatial relationships of the infection. The results, which were subjected to an independent random validation in Burkina Faso and Ghana, revealed that prevalence in the adult population of some communities exceeded 70% and that, over large areas of Burkina Faso, community prevalences were between 30% and 50%. Most of Togo, southern Benin and much of southern Ghana appeared completely free of the infection. Although there were foci on the Ghanaian coast with prevalences of 10%-30%, such high prevalences did not extend into coastal Togo or costal Benin. The prevalence map produced should be useful in prioritizing areas for filariasis control, identifying potential overlap with ivermectin-distribution activities undertaken by onchocerciasis-control programmes, and enabling inter-country and sub-regional planning to be initiated. The results indicate that bancroftian filariasis is more widely distributed in arid areas of Burkina Faso than hitherto recognized and that the prevalences of infection have remained fairly stable for at least 30 years. The campaign to eliminate lymphatic filariasis as a public-health problem in Africa will require significantly more resources (human, financial, and logistic) than previously anticipated.

Patterns in age-specific malaria incidence in a population exposed to low levels of malaria transmission intensity.

The population of the northern part of the province of KwaZulu Natal in South Africa has experienced low levels of malaria transmission intensity for many years. We investigated the widely held assumption that individuals in this population do not develop clinical tolerance to infection with Plasmodium falciparum. We calculated malaria incidence rates by 5-year age groups from a comprehensive small area malaria reporting system and from national census data for the period from mid-1990 to mid-1999. Incidence rates were plotted against age groups for each of the nine malaria seasons, and by quintile of crude incidence rate. These show that age-specific incidence varied considerably in areas of high incidence and in years of high incidence. In these areas malaria incidence rose with age until the late teens, and either remained constant or decreased in young adults. This finding appears to be consistent with results from settings of much higher transmission intensities which show that clinical tolerance to infection with P. falciparum in adults may be acquired as a result of a small number of infective bites in early childhood and implies that even in this relatively low transmission area, there is an asymptomatic reservoir of infection in older people. The results also show that in high incidence subregions the lowest incidences are reported for children under 5 years of age, which may be the result of greater protection offered to this age group by malaria vector control through indoor house spraying.

An empirical malaria distribution map for West Africa.

The objective of this study was to produce a malaria distribution map that would constitute a useful tool for development and health planners in West Africa. The recently created continental database of malaria survey results (MARA/ARMA 1998) provides the opportunity for producing empirical models and maps of malaria distribution at a regional and eventually at a continental level. This paper reports on the mapping of malaria distribution for sub-Saharan West Africa based on these data. The strategy was to undertake a spatial statistical analysis of malaria parasite prevalence in relation to those potential bio-physical environmental factors involved in the distribution of malaria transmission intensity which are readily available at any map location. The resulting model was then used to predict parasite prevalence for the whole of West Africa. We also produced estimates of the proportion of population of each country in the region exposed to various categories of risk to show the impact that malaria is having on individual countries. The data represent a very large sample of children in West Africa. It constitutes a first attempt to produce a malaria risk map of the West African region, based entirely on malariometric data. We anticipate that it will provide useful additional guidance to control programme managers, and that it can be refined once sufficient additional data become available.

Invasive cervical cancer and human immunodeficiency virus (HIV) infection: a South African perspective.

The aim of this study was to compare the prevalence and presentation of cervical cancer in HIV-positive and HIV-negative women in our local population. Six hundred and seventy-two patients with cervical cancer presented to the gynecology oncology unit of King Edward VIII Hospital, South Africa. The HIV seroprevalence among these patients was 21%. There was an increase in the background prevalence of HIV infection (1.6-32.5%) as well as a quadrupling in the prevalence of HIV infection among patients with invasive cervical cancer (5-21%) over a 10-year period. The mean ages of the HIV-negative patients and HIV-positive patients were 55.2 and 39.8 years, respectively. Most of the HIV-positive patients were in the 30- to 40-year-old age group (51%), whereas the majority of patients who were HIV negative were in the 50- to 60-year-old age group (36%). The majority of patients, irrespective of HIV status, were more likely to have late stage disease than early stage disease. There was an increase in HIV infection in patients with both types of background prevalence and among patients with invasive cervical cancer. The mean age of HIV-positive patients was 15 years younger than that of the HIV-negative patients. The majority of patients, irrespective of HIV status, presented with late stage disease.