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Severe anemia is one of the major complications of malaria in Africa. We studied 2 populations, one in a village and the second in a periurban area in Mali, to understand the preventable factors in the disease. The 2 correlates of disease were parasitemia above 100 000 parasitized red blood cells per microliter (0.1 x 10(12)/L) and a low baseline hemoglobin level. All cases of moderate to severe anemia occurred in children under 3.2 years of age. Raising the baseline hemoglobin level and lowering peak parasitemia in infants and young children may reduce the incidence of severe anemia resulting from malarial infection.

Seven repeated cross-sectional parasitological surveys, collecting a total of 13,912 blood samples, were carried out from September 1995 to February 1998 in three irrigated rice growing villages and three villages without irrigated agriculture in the area surrounding Niono, Mali. Parasite prevalence varied according to season and agricultural zone, but showed similar patterns for villages within the same zone. Overall, malaria prevalence was 47% in the villages without irrigated agriculture and 34% in the irrigated rice growing villages. In a village in the irrigated zone, and a village in the non-irrigated zone, 1067 and 608 children up to the age of 14 years, respectively, were followed in a passive malariological study for the period of 13 months. Fevers were attributed to malaria using a statistical method, taking into account the parasitaemia in afebrile controls from the cross-sectional surveys. The incidence of malaria fevers differed markedly between the two zones and over time. In the village in the irrigated zone, the incidence of malaria fevers was fairly constant over the year at 0.7 per 1000 children per day. In the village without irrigated agriculture, incidence was low during the dry season (at 0.6 per 1000 children per day), whereas it was high during the rainy season (at 3.2 per 1000 children per day). These results correspond well to the malaria transmission observed in a concurrent entomological survey. Rice cultivation in the semi-arid sub-Saharan environment altered the transmission pattern from seasonal to perennial, but reduced annual incidence more than two-fold.

Malaria infection and anemia during pregnancy are the primary causes of maternal and fetal morbidity and mortality. The aims of this study were to identify risk factors for malaria infection and to assess the relationship between malaria infection and anemia in pregnant women. Two cross-sectional surveys were conducted in September 1993 and then again in May 1994 (the end of the rainy and dry seasons respectively). A total of 235 pregnant women were randomly selected from both the rural and urban areas of Bandiagara, Mali. According to results from multivariate analysis, the risk of malaria infection was significantly higher during the rainy season (OR= 4.85, 95% CI 2.42-9.75) the first trimester of gestation (OR= 2.21, 95% CI 1.00-4.87, in younger women (OR= 2.48, 95% CI 1.19-5.16), and in women living in the rural area (2.49, 95% CI 0.99-6.27). The risk of anemia was also higher during the rainy season (OR= 1.93, 95% CI 1.10-3.39, in the rural area (OR= 3.55, 95% CI 1.46-8.62). The risk of anemia was lower during the first trimester of gestational age (OR= 0.45, 95% CI 0.22-0.92). The relationship between malaria infection and anemia also varied with season. During the rainy season, the risk for anemia was similar among malaria-infected and non-infected pregnant women. In contrast, the risk was higher among infected pregnant women during the dry season (OR= 3.43, 95% CI 1.09-10.07). In conclusion, the data suggest, that earlier gestation age, living in the rural area, and young age rather than parity are important risk factors for malaria infection in pregnant women. Further, malaria infection is strongly associated with anemia in pregnant women particularly during the dry season and is most likely the cause of anemia. Thus, control measures against malaria infection should target younger rural women in their first trimester of pregnancy.

In areas of intense malaria parasite transmission, preliminary studies of the rate of reinfection after curative therapy suggest that small sample size studies of vaccine efficacy are feasible. However, the effect of transmission rate, which may vary considerably between transmission seasons, on reinfection rate has not been assessed in areas of mesoendemicity with seasonal transmission. To address this question, the Plasmodium falciparum reinfection rate after curative therapy was measured in Sotuba, a Malian village with historically low transmission rates, as estimated by the entomological inoculation rate (EIR). The reinfection rate after curative Fansidar (sulfadoxine-pyrimethamine) treatment was 80.7% (88/109). The EIR during the 13-week study period (seasonal transmission) varied between 1 and 4.5 infected bites/person/month. The finding that reinfection rates were high despite low EIRs suggests that a low EIR may be sufficient to support small sample size vaccine efficacy trials in mesoendemic areas.

Complement receptor 1 (CR1) has been implicated in rosetting of uninfected red blood cells to Plasmodium falciparum-infected cells, and rosette formation is associated with severe malaria. The Knops blood group (KN) is located on CR1 and some of these antigens, ie, McCoy (McC) and Swain-Langley (Sl(a)), show marked frequency differences between Caucasians and Africans. Thus, defining the molecular basis of these antigens may provide new insight into the mechanisms of P falciparum malaria. Monoclonal antibody epitope mapping and serologic inhibition studies using CR1 deletion constructs localized McC and Sl(a) to long homologous repeat D of CR1. Direct DNA sequencing of selected donors identified several single nucleotide polymorphisms in exon 29 coding for complement control protein modules 24 and 25. Two of these appeared to be blood group specific: McC associated with K1590E and Sl(a) with R1601G. These associations were confirmed by inhibition studies using allele-specific mutants. A sequence-specific oligonucleotide probe hybridization assay was developed to genotype several African populations and perform family inheritance studies. Concordance between the 1590 mutation and McC was 94%; that between Sl(a) and 1601 was 88%. All but 2 samples exhibiting discrepancies between the genotype and phenotype were found to be due to low red cell CR1 copy numbers, low or absent expression of some alleles, or heterozygosity combined with low normal levels of CR1. These data further explain the variability observed in previous serologic studies of CR1 and show that DNA and protein-based genetic studies will be needed to clarify the role of the KN antigens in malaria.

Patients with gastrointestinal obstruction caused by peritonitis carcinomatosa suffer from chronic nausea, abdominal distension and inability to ingest food. Patients can receive home care only in rare cases. We performed a gastrostomy for the purpose of reducing gastrointestinal pressure in three patients with gastrointestinal obstruction caused by peritonitis carcinomatosa. The three patients had decreased mental and physical suffering and were able to be discharged from the hospital. We report the efficacy of gastrostomy because of the improvements in the three patients QOL at home.