Associations between mild-to-moderate anaemia in pregnancy and helminth, malaria and HIV infection in Entebbe, Uganda

It is suggested that helminths, particularly hookworm and schistosomiasis, may be important causes of anaemia in pregnancy. We assessed the associations between mild-to-moderate anaemia (haemoglobin >8.0 g/dl and <11.2 g/dl) and helminths, malaria and HIV among 2507 otherwise healthy pregnant women at enrolment to a trial of deworming in pregnancy in Entebbe, Uganda. The prevalence of anaemia was 39.7%. The prevalence of hookworm was 44.5%, Mansonella perstans 21.3%, Schistosoma mansoni 18.3%, Strongyloides 12.3%, Trichuris 9.1%, Ascaris 2.3%, asymptomatic Plasmodium falciparum parasitaemia 10.9% and HIV 11.9%. Anaemia showed little association with the presence of any helminth, but showed a strong association with malaria (adjusted odds ratio (AOR) 3.22, 95% CI 2.43-4.26) and HIV (AOR 2.46, 95% CI 1.90-3.19). There was a weak association between anaemia and increasing hookworm infection intensity. Thus, although highly prevalent, helminths showed little association with mild-to-moderate anaemia in this population, but HIV and malaria both showed a strong association. This result may relate to relatively good nutrition and low helminth infection intensity. These findings are pertinent to estimating the disease burden of helminths and other infections in pregnancy. [Clinical Trial No. ISRCTN32849447].     

Predictors of antimalarial treatment failure in an area of unstable malaria transmission in eastern Sudan

The factors that identify patients at risk of malaria treatment failure were evaluated in an area of unstable malaria transmission in eastern Sudan. We analyzed data from 471 patients who had been enrolled in six previous clinical antimalarial trials for uncomplicated Plasmodium falciparum malaria. Thirty-four (7.3%) had treatment failure (crude). In logistic regression models, an age of < or =5 years (odds ratio [OR]=3.7; 95% CI 1.5-8.6; P=0.002) and parasitaemia that took 3 days to clear (OR=2.4; 95% CI 1.0-5.9; P=0.04) were found to be predictors for treatment failure. Presenting temperature (OR=1.4; 95% CI 0.9-2.2; P=0.1), level of parasitaemia (OR=1.0; 95% CI 1.0-1.0; P=0.8) and presence of gametocytes (OR=0.3; 95% CI 0.9-1.2; P=0.1) were not associated with treatment failure. Thus, these factors might be used to identify those in whom treatment might fail in the future.     

Haemoglobin-E in the presence of oxidative substances from fava bean may be protective against Plasmodium falciparum malaria.

A case-control study was carried out at a community hospital in eastern Thailand in order to study the association between haemoglobin E and Plasmodium falciparum malaria; 271 P. falciparum cases and 271 controls were enrolled. After adjusting for age, sex, time since last malaria attack, history of mosquito net use, and history of fava bean consumption in the previous month, neither heterozygous nor homozygous haemoglobin E provided significant protection against P. falciparum infection, with odds ratios (OR) = 0.91 (95% confidence limits = 0.61, 1.36) and 0.78 (0.34, 1.82) respectively when compared to persons with haemoglobin A who were not consumers of fava beans. However, haemoglobin E carriers who ate fava beans were significantly protected against P. falciparum malaria with OR = 0.26 (0.09, 0.76) and OR = 0.001 (0.00, 1120.59) for subjects with heterozygous and homozygous haemoglobin E, respectively. The study suggests a possible synergistic protective effect of haemoglobin E on the risk of P. falciparum malaria in subjects who have consumed fava beans.     

Schistosoma mansoni in pregnancy and associations with anaemia in northwest Tanzania

Schistosomiasis among pregnant women has been inadequately investigated. In order to determine the importance of Schistosoma mansoni in this subgroup, we conducted a cross-sectional survey of 972 women in Tanzania and investigated the prevalence of Schistosoma mansoni, hookworm and malaria and their associations with anaemia. Overall, 63.5% of women were infected with S. mansoni, with prevalence highest among younger women and decreasing with increasing age. The prevalence of hookworm was 56.3%, and 16.4% of women had malaria parasitaemia. Overall, 66.4% of women were anaemic. Increased risk of anaemia was associated with heavy infection with S. mansoni but not hookworm or Plasmodium falciparum parasitaemia.     

Spleen enlargement and genetic diversity of Plasmodium falciparum infection in two ethnic groups with different malaria susceptibility in Mali, West Africa

The high resistance to malaria in the nomadic Fulani population needs further understanding. The ability to cope with multiclonal Plasmodium falciparum infections was assessed in a cross-sectional survey in the Fulani and the Dogon, their sympatric ethnic group in Mali. The Fulani had lower parasite prevalence and densities and more prominent spleen enlargement. Spleen rates in children aged 2-9 years were 75% in the Fulani and 44% in the Dogon (P<0.001). There was no difference in number of P. falciparum genotypes, defined by merozoite surface protein 2 polymorphism, with mean values of 2.25 and 2.11 (P=0.503) in the Dogon and Fulani, respectively. Spleen rate increased with parasite prevalence, density and number of co-infecting clones in asymptomatic Dogon. Moreover, splenomegaly was increased in individuals with clinical malaria in the Dogon, odds ratio 3.67 (95% CI 1.65-8.15, P=0.003), but not found in the Fulani, 1.36 (95% CI 0.53-3.48, P=0.633). The more susceptible Dogon population thus appear to respond with pronounced spleen enlargement to asymptomatic multiclonal infections and acute disease whereas the Fulani have generally enlarged spleens already functional for protection. The results emphasize the importance of spleen function in protective immunity to the polymorphic malaria parasite.     

Efficacy of artesunate plus chloroquine for the treatment of uncomplicated malaria in children in Burkina Faso: a double-blind, randomized, controlled trial

Chloroquine (CQ)-resistant Plasmodium falciparum is compromising malaria control in Africa. Combining artesunate (AS) with standard antimalarial drugs increases cure rates and may delay drug resistance. We compared the safety and efficacy of CQ alone and CQ combined with AS (CQ-AS) for treating uncomplicated P. falciparum malaria in Burkina Faso between August 1999 and August 2000. Chloroquine (25 mg/kg over 3 d) combined with AS or placebo (4 mg/kg/d for 3 d) was administered to 300 children aged 6 to 59 months in a randomized, double-blind study. Follow-up extended over 28 d. No adverse drug reactions were recorded. By day 14, parasites were cleared in 120/147 (81.6%) CQ AS-treated children compared with 53/143 (37.1%) CQ-treated children (odds ratio [OR] = 7.55, 95% CI 4.27-13.43, P < 0.001). Corresponding rates for day 28 were 71/145 (49.0%) vs. 27/142 (19.0%) (OR= 4.09, 95% CI 2.33-7.21, P < 0.001). Children who received CQ-AS had significantly faster parasite and fever clearance. Despite the beneficial effects of adding AS, the high failure rate at day 28 of CQ-AS precludes its use as the first-line regimen for treating CQ-resistant P. falciparum in Burkina Faso.     

The relationship between malaria parasitaemia and availability of healthcare facility in Mpwapwa district, central Tanzania

A study was carried out in six villages located at different altitudes in Mpwapwa district of central Tanzania to determine malaria parasitaemia and transmission levels in villages with or without health care facilities. A total of 1119 schoolchildren (age = 5.9-12.3 years) were examined for malaria parasitaemia. Plasmodiumfalciparum was the predominant malaria species accounting for 92.8% of all species. The average malaria prevalence rate among schoolchildren was 25.8% (range 1.5-53.8%). The geometric mean parasite densities for P.falciparum was 361 (N = 286). Higher malaria prevalence was observed in villages at lower (< 1000 m) than at intermediate (1000-1500m) or higher (> 1500m) altitudes. Schoolchildren in areas with health care facilities were less at risk of acquiring malaria by 33.4% as compared with those living in areas without health facilities. Mean packed cell volume in schoolchildren was 38.5% (range = 35.2-41.0%). Splenomegaly was observed in 18.1% (0-40.2%) of the schoolchildren examined and it was higher among those in villages without health care facilities. Anopheles gambiae sensu lato was the only malaria vector found in the district and was found in all villages and at all altitudes. Sporozoite rate in An. gambiae s.l. ranged from 0-10.5%, with the lowland villages recording the highest rates. This study indicates that altitude and geographical accessibility to healthcare service are important determinants of malaria infection among rural communities in Tanzania.     

Blood group phenotypes A and B are risk factors for cerebral malaria in Odisha, India

There is increasing evidence that the ABO blood group phenotypes modulates Plasmodium falciparum rosetting and may influence the clinical manifestation of severe malaria. Whether blood group phenotypes are associated with risk of severe falciparum malaria in Odisha, we analyzed 343 adult malaria patients. The results showed high prevalence of blood group B in both mild (n=110) and severe malaria (cerebral malaria [CM]; n=130 and non-cerebral severe malaria [NCSM]; n=103) categories among the non-O group and while type O is significantly associated with protection against CM, patients with type A and B group had increased risk for developing CM. Further, the strength of association for B group (p=< 0.0001) was high and has double the risk of (OR=5.0) of developing CM compared to blood group A (OR=2.5). Such findings may probably be due to strain specific blood group preferences of P. falciparum and high prevalence of B group. However, the ABO blood group distribution of mild malaria was comparable with that of the NCSM group of patients. The lack of association of ABO phenotypes with NCSM is evidence for the hypothesis that the underlying pathogenesis cascades are different in CM and NCSM clinical presentations.     

Associations of peak shifts in age--prevalence for human malarias with bednet coverage

Effects of bednet coverage (C) on prevalence of malaria were analysed using data from 1990-92 from 9 Papua New Guinean villages. Effects of coverage varied by age, resulting in a shift in age of peak prevalence from 4.7 (C = 0%) to 11.6 (C = 100%) years for Plasmodium falciparum, from 3.4 to 4.9 years for P. vivax and from 11.0 to 16.8 years for P. malariae. In small areas with no bednets the age distribution of P. falciparum parasitaemia was like that of a holoendemic area. Where coverage was complete the pattern corresponded to mesoendemicity. Thus, protracted use of bednets can result in profound changes in the endemicity of malaria even when coverage is incomplete and without insecticide treatment. Average entomological inoculation rates (EIRs) estimated from indoor landing rates on individuals without bednets were 35, 12 and 10 infectious bites per person per annum for P. falciparum, P. vivax and P. malariae, respectively. Logistic regression analyses indicated that the EIR estimate for P. falciparum was related to prevalence of this species independently of effects of bednet coverage. However, the recent EIR still accounted for much less variation than did the bednets. A similar pattern was seen for P. malariae, while there were no significant relationships between the recent EIR and the parasite positivity for P. vivax. It is concluded that short-term variations in inoculation rate are not important determinants of parasite prevalence in this population.     

A stable, oligosymptomatic malaria focus in Thailand

Blood from most of the 250 residents of a non-migratory farming village in south-eastern Thailand was visually examined for malaria parasites monthly for 2 years. Nearly 97% of the population had at least one (median = 5) patent Plasmodium falciparum infection per year; 72% had one due to P. vivax (median = 1). This contrasted with a slide positivity rate of 17% calculated from 12 months of passive case detection before the study began. Children 1-9 years old had the highest mean monthly prevalence (51%) and highest geometric mean density (10/500 white blood cells) of P. falciparum. Fewer than half the expected number of mixed infections were found but these were more common at high densities of P. falciparum. Individuals over 19 years old comprised 52% of the population but accounted for only 18% of P. vivax and 32% of P. falciparum gametocytaemias. Fever rates were marginally higher in those below 10 years old (8%) but occurred with equal frequency in those with patent infections or negative. The spleen rate (89% stage 1) was 24% in those under 15 years old and 7% in those older. No malaria mortality was seen P. falciparum cases treated for 10 d with quinine+tetracycline (QT) cleared the infection as often as those given one dose of mefloquine+sulfadoxine+pyrimethamine (MSP); both treatments reduced densities in cases not cured. Apparently unsupervised compliance was no better with MSP than with QT. The role played by hyperendemic, cryptic foci in Asian epidemics of malaria may have been underestimated.     

Haematinic treatment of anaemia increases the risk of Plasmodium vivax malaria in pregnancy

Nutritional deficiency and malaria are 2 major causes of anaemia during pregnancy in tropical areas. The relationship between anaemia, its treatment with iron and folate, and malaria was studied in a prospective cohort of 2112 pregnant Karen women on the north-western border of Thailand between 1993 and 1997. The development of Plasmodium vivax malaria was associated with a past mean haematocrit > 30% (hazard ratio = 1.5, 95% CI 1.2-2, P = 0.001) and recent (< or = 30 d) iron and folate supplementation (hazard ratio = 1.7, 95% CI 1.1-2.6, P = 0.01). There were no associations with P. falciparum infections. Plasmodium vivax has a predilection for young erythrocytes, and these results suggest that pregnant women with larger numbers of circulating young red cells are at greater risk of developing P. vivax malaria. In P. vivax-endemic areas, systematic iron and folate supplementation confers both benefit and risk in pregnancy.     

Seasonal variation in hyperparasitaemia and gametocyte carriage in patients with Plasmodium falciparum malaria on the Thai-Burmese border

Between January 2000 and December 2002 monthly rainfall was correlated with the proportion of patients with hyperparasitaemic Plasmodium falciparum malaria and with the proportion of patients with P. falciparum gametocytes. During the observation period 6953 cases of P. falciparum malaria were treated at the Shoklo Malaria Research Unit in Maela refugee camp on the Thai-Burmese border. Three hundred and seventy-five of these patients had >/=4% of parasitized red blood cells. Although there were more monthly malaria cases in the rainy season, rainfall was negatively correlated with the proportion of patients with hyperparasitaemia (Spearman's rho = -0.59, P < 0.001 ), and the proportion of gametocyte carriers among P. falciparum cases, (Spearman's rho = -0.39, P = 0.018). After controlling for age and the origin of the patient, the odds ratio for developing hyperparasitaemia during the dry season was 1.6 (95% CI 1.14-2.2; P = 0.006). The adjusted odds ratio for gametocyte carriage during the dry season was 1.3 (95% CI 1.03-1.6; P = 0.02). Migrations, changes in transmission patterns, the haematological burden of cumulative infections, and ultraviolet immunosuppression are discussed as potential explanations for these observations.     

Population dynamics of Anopheles culicifacies and malaria in the tribal area of central India.

A longitudinal study (1993-94) on malaria was conducted in Dungaria, a typical forest fringe tribal village in Mandla district of central India (Madhya Pradesh). Our initial objective was to obtain in-depth baseline data on malaria transmission in the tribal village to elucidate the factors responsible for persistent malaria in the area and thereby to help in formulating an improved malaria control program. Anopheles culicifacies Giles was the predominant vector of malaria, although Anopheles fluviatilis James were recorded in small numbers. The transmission season was from May to November. Analysis of the malaria cases revealed hyperendemic malaria, with Plasmodium falciparum the predominant species. The prevalence of Plasmodium vivax was mainly in the summer and that of P. falciparum in autumn. The study suggested that a number of factors were responsible for the continuation of malaria transmission in the village.     

杭州市1990-2009前后十年疟疾流行病学特征比较分析

目的对杭州市达到基本消灭疟疾标准后,1990-1999年与2000-2009年前后十年疟疾疫情的流行特点进行比较分析,为制定今后的疟疾防治策略提供依据。方法对1990-2009年血检阳性确诊疟疾病例的个案调查资料进行统计分析,采用SPSS 11.5统计软件,采用χ2检验对1990-1999年和2000-2009年的流行特点进行比较分析,P<0.05为差异有统计学意义。结果 1990-2009年平均年发病率0.2/10万,1990-1999年疟疾发病呈高度散发,2000-2009年出现疟疾局部暴发疫情;前后十年疟疾病人在不同性别、职业及年龄组中的构成比差异均有统计学意义(P均<0.05);前后十年本地、外出感染、外来患者在构成上差异有统计学意义(χ2=47.74,P<0.05);2000-2009年本地病人发病高峰(8~10月份)明显滞后外来病人(6~9月份);1990-2009年疟疾病人627例,其中共检出间日疟598例,恶性疟29例,分别占95.37%和4.63%,前后十年间日疟和恶性疟构成比差异无统计学意义(χ2=3.54,P=0.06)。结论 2000-2009年大量外来病人的输入使杭州市疟疾发病总人数明显上升,出现局部暴发疫情,不断加强对来自高疟区流动人口的监测,提高医疗单位疟疾诊治和镜检能力,从源头上控制传染源,是今后杭州市疟疾防治工作的重点。     

Epidemiology of malaria in pregnancy in central India.

Analysis of three years of data from a malaria clinic operated by the Indian Council of Medical Research (ICMR) in the Government Medical College Hospital in Jabalpur, central India, showed a high malaria prevalence among pregnant women, which was statistically highly significant (P < 0.0001) compared with the situation among nonpregnant women. Cerebral malaria was a common complication of severe Plasmodium falciparum infection, with a high mortality during pregnancy, requiring immediate attention. The study also showed that malaria infection was more frequent in primigravidae, falling progressively with increasing parity. Mean parasite densities were significantly higher in pregnant women compared with nonpregnant women for both P. falciparum (P < 0.001; df = 137) and P. vivax (P < 0.05; df = 72) infection. Pregnant women with falciparum or vivax malaria were significantly more anaemic than noninfected pregnant women or infected nonpregnant women. The average weight of 155 neonates from infected mothers was 350 g less than that of 175 neonates from noninfected mothers. This difference in birth weight was statistically significant for both P. falciparum (P < 0.0001; df = 278) and P. vivax (P < 0.0001; df = 223) infection. Congenital malaria was not recorded. We conclude that pregnant women from this geographical area require systematic intervention owing to their high susceptibility to malaria during pregnancy and the puerperium.     

Malaria in southern Mozambique: malariometric indicators and malaria case definition in Manhiça district

A total of 2057 children aged <10 years were selected at random from a demographic surveillance system and enrolled in 4 malariometric cross-sectional surveys in different seasons in Manhi?a district in southern Mozambique. Plasmodium falciparum accounted for 90% of all malaria infections and the prevalence of asexual P. falciparum ranged from 13.7-21.7% at the end of the dry season to 30.5-34.0% at the end of rainy season. In order to determine the malaria attributable fraction (MAF) of fever, 1021 children from a nearby hospital acted as fever cases and from this separate case-control study the crude MAF was 36%, showing a marked age dependency. Plasmodium falciparum is the most common malaria species in Manhi?a. This malaria-mesoendemic area has year-round transmission. The importance of other non-malarial fever-causing conditions among infants was highlighted. Malaria appeared to be a major contributory factor to anaemia in the area.     

Intestinal parasitic infections in adolescent girls from two boarding schools in southern Benin

Intestinal parasitic infections (IPI), especially helminths, represent a major public health problem that increase iron deficiency anaemia in developing countries. This study investigated the prevalence, risk factors and nutritional consequences of IPIs in 180 adolescent girls aged 12-17 years living in two boarding schools in southern Benin. Data were collected using a structured questionnaire and laboratory analysis of blood and faecal samples. The relationships between socioeconomic indicators, IPIs and iron status were analysed using logistic regression analysis. Fifty percent of the subjects were infected with at least one IPI: 2% with helminths, 41% with protozoa and 7% with two or more intestinal parasites. Adolescent girls from a large family and those whose mothers were manual workers showed a higher risk of intestinal parasitism (odds ratio (OR)=3.5, 95% CI 2.5-5.2 (P=0.02) and OR=2.4, 95% CI 2.0-3.0 (P=0.03), respectively). Likewise, drinking untreated water was also a high risk factor for infection (OR=2.3, 95% CI 1.5-2.4; P=0.03). No significant association was observed between IPIs and iron deficiency or iron deficiency anaemia, which can be explained by the low wormload observed. These findings reinforce the need to involve mothers in health initiatives to control intestinal parasitism in Benin.     

The effect of Plasmodium falciparum infection on expression of monocyte surface molecules

Plasmodium falciparum infection may result in severe malaria in susceptible individuals. The pathogenesis of severe disease is probably a combination of the sequestration of infected erythrocytes and overstimulation of the immune response. Monocytes are a key source of many of the pro-inflammatory agents implicated but also are found sequestered in blood vessels. However, little is known about the monocyte phenotype in malaria disease. Flow cytometry was performed on fresh whole blood to determine surface expression of four receptors during acute severe and non-severe malaria and again during convalescence when uninfected. Three hundred and fifty-six children with P. falciparum infection were studied and were found to show increased expression of intercellular adhesion molecule-1 (ICAM-1), urokinase plasminogen activator receptor (uPAR), CD23 and chemokine receptor 5 (CCR5) (P<0.001) during acute disease compared with convalescent levels. Using multivariate analysis, it was found that large increases in expression of ICAM-1 (odds ratio (OR) 2.44, 95% CI 1.80-3.32) and uPAR (OR 3.14, 95% CI 1.93-5.09) but small increases in expression of CD23 (OR 0.82, 95% CI 0.68-0.96) were independently associated with severe malaria. These results give an insight into the cellular processes occurring in severe malaria and suggest that pathology is based on a complex repertoire of pro- and anti-inflammatory processes.     

Risk factors for Plasmodium vivax infection in the Lacandon forest, southern Mexico.

A study was conducted to characterize the risk of Plasmodium vivax infection in the Lacandon forest, southern Mexico. Blood samples and questionnaire data were collected in 1992. Malaria cases (n = 137) were identified by the presence of symptoms and a positive thick blood smear. The control group included individuals with negative antibody titres and no history of malaria (n = 4994). From 7628 individuals studied, 1006 had anti-P. vivax antibodies. Seroprevalence increased with age. Risk factors associated with infection included: place of birth outside the village of residence (odds ratio, OR 11.67; 95% CI 5.21-26.11); no use of medical services (OR 4.69, 95% CI 3.01-7.29), never using bed-nets (OR 3.98, 95 % CI 1.23-12.86) and poor knowledge of malaria transmission, prevention and treatment (OR 2.30, 95 % CI 1.30-4.07). Health education represents the best recommendation for controlling the disease in the area.     

Malaria control using permethrin applied to tents of nomadic Afghan refugees in northern Pakistan.

Malaria control among nomadic populations has, in the past, posed serious logistic difficulties. Presented in this article are the results of a pilot study in which permethrin was sprayed on the tents of over 26000 nomadic Afghan refugees in an area of Pakistan where seasonal malaria outbreaks occur. In this area Anopheles culicifacies and A. stephensi are the malaria vectors. Population surveys in the year of the study, before and at the end of the transmission season, showed that the increase in the Plasmodium falciparum prevalence among the Afghan nomads was on average significantly less (increase from 6.4% to 15.3%) than that among the resident Pakistani population (from 3.2% to 45.6%). Surveys at the end of the transmission season among primary schoolchildren the year before and the year of the permethrin trial showed that the P. falciparum prevalence among nomadic children decreased significantly (from 46.9% to 16.3%), whereas an increase was observed among the local Pakistani children. The results show that spraying tents with permethrin was a safe and culturally acceptable intervention for the Afghan refugees and that the findings warrant further investigation.