Malaria Admissions Research Articles

Chloroquine-resistant Plasmodium falciparum cerebral malaria in a chloroquine-susceptible area.

Chloroquine-resistant Plasmodium falciparum is endemic in many areas. Saudi Arabia was considered to have chloroquine-susceptible P. falciparum. During the 1997-1998 season, an outbreak of malaria occurred in the southwestern region. Over a 4-month period, 32 cases (6.2%) of 520 malaria admissions met the World Health Organization criteria for cerebral malaria. The mean patient age was 28 years. Thirteen male and 19 female patients were admitted in coma. The mean duration of coma was 4.3 days; the case fatality rate was 41%. Compared with those who recovered, patients who died had a lower mean admission diastolic blood pressure and hemoglobin level, higher mean blood urea nitrogen and blood glucose levels, and thrombocytopenia. Logistic regression analysis identified treatment with quinine rather than chloroquine to be associated with survival. These findings show the potential of P. falciparum to emerge as chloroquine resistant in previously susceptible areas, resulting in significant morbidity and mortality in spite of sophisticated medical care.

The cost of treating paediatric malaria admissions and the potential impact of insecticide-treated mosquito nets on hospital expenditure.

To calculate the costs at Kilifi District Hospital (KDH) and Malindi Sub-district Hospital (MSH) of treating paediatric malaria admissions including three common presentations of severe paediatric malaria, i.e. cerebral malaria, severe malaria anaemia and malaria-associated seizures; and to estimate the implications for hospital expenditure of a reduction in paediatric malaria admissions. Patient data were obtained from hospital records. All costs were allocated to departments that provided direct patient care by a four-stage step-down procedure. Laboratory and drug costs of treating paediatric malaria admissions were separately identified. Unit recurrent costs per admission in KDH ranged from US $57 for 'other' paediatric malaria to US $105 for cerebral malaria, and in MSH from US $33 to US $44 for the same categories. The annual recurrent cost of treating all paediatric malaria admissions to KDH prior to the trial was estimated at US $78 900. Adjusting for preintervention differences in malaria admission rates and age between intervention and control areas, the ITBN trial found a 41% reduction in paediatric malaria admissions. The reduction in admissions resulted in an estimated saving of US $6240 in the cost of treating paediatric malaria admissions from the intervention area. There would be a substantial reduction in costs of treating paediatric malaria admissions if the intervention were introduced in the whole catchment area of the hospital. Actual savings would depend on the proportion of potential savings that can in practice be realised, and on the effectiveness of the intervention when routinely implemented.

Predicting malaria seasons in Kenya using multitemporal meteorological satellite sensor data

This article describes research that predicts the seasonality of malaria in Kenya using remotely sensed images from satellite sensors. The predictions were made using relationships established between long-term data on paediatric severe malaria admissions and simultaneously collected data from the Advanced Very High Resolution Radiometer (AVHRR) on the National Oceanic and Atmospheric Administrations (NOAA) polar-orbiting meteorological satellites and the High Resolution Radiometer (HRR) on the European Organization for the Exploitation of Meteorological Satellites' ( eumetsat) geostationary Meteosat satellites. The remotely sensed data were processed to provide surrogate information on land surface temperature, reflectance in the middle infra-red, rainfall, and the normalized difference vegetation index (NDVI).These variables were then subjected to temporal Fourier processing and the fitted Fourier data were compared with the mean percentage of total annual malaria admissions recorded in each month. The NDVI in the preceding month correlated most significantly and consistently with malaria presentations across the 3 sites (mean adjusted r 2 = 0 · 71, range 0·61–0·79). Regression analyses showed that an NDVI threshold of 0·35–0·40 was required for more than 5% of the annual malaria cases to be presented in a given month. These thresholds were then extrapolated spatially with the temporal Fourier-processed NDVI data to define the number of months, in which malaria admissions could be expected across Kenya in an average year, at an 8 × 8 km resolution. The resulting maps were compared with the only existing map (Butler's) of malaria transmission periods for Kenya, compiled from expert opinion. Conclusions are drawn on the appropriateness of remote sensing techniques for compiling national strategies for malaria intervention.

Management of severe malarial anaemia in Gambian children

The optimum management of children with severe malarial anaemia is still uncertain. Hence, we have undertaken a study to determine whether iron treatment is as effective at restoring haemoglobin levels one month after presentation as blood transfusion without iron treatment in children with moderately severe malarial anaemia. Two hundred and eighty-seven children with a packed cell volume (PCV) <15% and malaria infection were recruited into the study; 173 children were assigned to receive blood transfusion because they had a PCV <12% and/or signs of respiratory distress and the remaining 114 children were allocated at random to receive either blood transfusion (58) or treatment with oral iron (56) for 28 d. Twenty-four children died, 23 in the most severely anaemic group. Fifteen children (65%) died before transfusion was given and most deaths occurred within the first 4 h of admission. One child died in the iron treatment group and 10 subsequently required transfusion. Among the severely anaemic children, those with respiratory distress were at greater risk of death than those without respiratory distress. After 28 d, haematological restoration was significantly better in children who had received iron than in those treated by blood transfusion ( P = 0·02). Children who received malaria chemoprophylaxis after discharge from hospital had fewer episodes of malaria and subsequent admissions to a hospital or health centre than those who did not. Children with severe anaemia and clinical signs of respiratory distress must be identified quickly and transfused as soon as possible. However, for less severely anaemic children who are clinically stable, iron therapy offers an alternative to transfusion provided such children can be kept under surveillance and transfused subsequently should this become necessary.

Absence of malaria-specific mortality in children in an area of hyperendemic malaria

We conducted a prospective community-based malaria surveillance study on a cohort of children <10 years old living in an area of hyperendemic malaria (spleen rates >50% in children aged 2–9 years) in Vanuatu, Melanesia, supported by a concurrent prospective descriptive study of malaria admissions to the local hospital. The incidence of clinical malaria in children <10 years old was 1·9 episodes/year. The annual incidence of severe malaria (severe malarial anaemia and cerebral malaria) was only 2 1000 in children aged <5 years. The only manifestation of severe malaria seen in indigenous children was anaemia. No death could be attributed to malaria. While the incidence of uncomplicated clinical malaria in this population was comparable to that in many parts of Africa, the incidence of severe forms of the disease was significantly lower. This could not be attributed to differing rates of malaria transmission, chloroquine resistance, or to host protective or behavioural factors. These findings suggest that studies which compare disease patterns in geographically disparate populations may be instrumental in developing a better understanding of the determinants of clinical outcome in Plasmodium falciparum malaria and that such regional differences must be considered when planning or interpreting the effects of malaria interventions.

Relation between severe malaria morbidity in children and level of Plasmodium falciparum transmission in Africa

Malaria remains a major cause of mortality and morbidity in Africa. Many approaches to malaria control involve reducing the chances of infection but little is known of the relations between parasite exposure and the development of effective clinical immunity so the long-term effect of such approaches to control on the pattern and frequency of malaria cannot be predicted. We have prospectively recorded paediatric admissions with severe malaria over three to five years from five discrete communities in The Gambia and Kenya. Demographic analysis of the communities exposed to disease risk allowed the estimation of age-specific rates for severe malaria. Within each community the exposure to Plasmodium falciparum infection was determined through repeated parasitological and serological surveys among children and infants. We used acute respiratory-tract infections (ARI) as a comparison. 3556 malaria admissions were recorded for the five sites. Marked differences were observed in age, clinical spectrum and rates of severe malaria between the five sites. Paradoxically, the risks of severe disease in childhood were lowest among populations with the highest transmission intensities, and the highest disease risks were observed among populations exposed to low-to-moderate intensities of transmission. For severe malaria, for example, admission rates (per 1000 per year) for children up to their 10th birthday were estimated as 3.9, 25.8, 25.9, 16.7, and 18.0 in the five communities; the forces of infection estimated for those communities (new infections per infant per month) were 0.001, 0.034, 0.050, 0.093, and 0.176, respectively. Similar trends were noted for cerebral malaria and for severe malaria anaemia but not for ARI. Mean age of disease decreased with increasing transmission intensity. We propose that a critical determinant of life-time disease risk is the ability to develop clinical immunity early in life during a period when other protective mechanisms may operate. In highly endemic areas measures which reduce parasite transmission, and thus immunity, may lead to a change in both the clinical spectrum of severe disease and the overall burden of severe malaria morbidity.

Nature's experiment: what implications for malaria prevention?

Snow et al. reported, on the basis of hospital admissions from five defined African communities exposed to very different intensities of malaria transmission, a decline in the severity of malaria from areas of low-to-moderate to areas of high transmission. They found, among children aged 0-9 years, a decline in admission rates for all-cause malaria and more so for cerebral malaria, a levelling-off or slight decline in the admission rate for severe malarial anemia, and a lowering of the mean age of all-cause malaria admissions. There are problems, however, with using the intensity of transmission as the independent variable and malaria mortality or the incidence of life-threatening malaria as the dependent variable. Nonetheless, Snow et al.'s observation does not justify withholding preventive measures from people in malaria situations. What Snow et al. have shown, however, is the need for a new synthesis of the epidemiology of malaria. Meanwhile, the choice of preventive measure should depend upon the benefits expected from the strategy and take into consideration that in areas of intense transmission, partial prevention may lead to an increased incidence of cerebral malaria.

THE MALARIA PROBLEM TODAY

In dealing with present day problems of malaria, attention in this paper will be centered on potential benefits forthcoming as a result of wartime experience and wartime research. From this experience and research, important advances in the field of malariology have followed. In particular, they have contributed to improved methods in the treatment of malaria and to new approaches in regard to prevention. CLINICAL MALARIA Army and Navy statistics 1 for World War II reveal a total of 572,950 reported admissions for malaria. Actually, it is probable that, had complete reporting been possible, the total would have more nearly approximated a million admissions. Whatever the exact figure, clinical experience on an unprecedented scale was gained, and as a result many interesting and exceedingly important developments took place in the field of clinical malaria. Substitution of Quinacrine Hydrochloride for Quinine.— A development of foremost importance is that during World War II