Distinct pattern of class and subclass antibodies in immune complexes of children with cerebral malaria and severe malarial anaemia

Plasmodium falciparum infection can lead to deadly complications such as severe malaria-associated anaemia (SMA) and cerebral malaria (CM). Children with severe malaria have elevated levels of circulating immune complexes (ICs). To further investigate the quantitative differences in antibody class/subclass components of ICs in SMA and CM , we enrolled 75 children with SMA and 32 children with CM from hospitals in western Kenya and matched them to 74 and 52 control children, respectively, with uncomplicated symptomatic malaria. Total IgG IC levels were always elevated in children with malaria upon enrolment, but children with CM had the highest levels of any group. Conditional logistic regression showed a borderline association between IgG4-containing IC levels and increased risk of SMA (OR = 3·11, 95% CI 1·01–9·56, P  = 0·05). Total IgG ICs (OR = 2·84, 95% CI 1·08–7·46, P  = 0·03) and IgE-containing ICs (OR = 6·82, OR 1·88–24·73, P  ≤ 0·01) were associated with increased risk of CM. These results point to differences in the contribution of the different antibody class and subclass components of ICs to the pathogenesis of SMA and CM and give insight into potential mechanisms of disease.     

Travellers returning to Sweden with falciparum malaria: pre-travel advice, behaviour, chemoprophylaxis and diagnostic delay

We have investigated pre-travel advice, behaviour, chemoprophylaxis and diagnostic delay in travellers returning to Sweden with falciparum malaria. Questionnaires were distributed to patients having been notified with falciparum malaria from 1994 to 2001. Of 408 notified patients, 237 (58%) returned the questionnaires; 62% were males and 43% above the age of 45 y. Africa was the travel destination in 90% of the cases, and 27% had travelled to Kenya. 69% had spent more than 1 night in the countryside, and 6% had stayed in modern urban areas only. 40% took an adequate dose of chemoprophylaxis, although this proportion decreased from 55% to 12% during the study period. Nine per cent used both bed nets and mosquito repellents regularly. The median time from onset of symptoms to contact with health care professionals was 2 d, and from that contact to start of malaria treatment the median time was less than 24 h.     

Plasmodium falciparum: use of a NANP19 antibody-test for the detection of infection in non-immune travellers

Circumsporozoite (CS) antibodies are a reliable serological marker for the infection of Plasmodium falciparum. The purpose of this investigation was to construct and evaluate an enzyme-linked immunosorbent assay test for the detection of CS antibodies. While the sensitivity of the newly developed test reached 78%, the specificity was 99%. In addition, the optimized kit was used to test for infection with P. falciparum in 1903 travellers that were recruited from a prospective study for malaria chemoprophylaxis. Sixty-six of the 1903 patients (3.5%) showed elevated CS antigen antibody titres. However, seroconversion could only be demonstrated in 18 (0.95%) patients. Among those seroconverting, there was a significantly higher percentage of male travellers (1.28%) than female travellers (0.56%). Positive reactions were more frequent among returnees from West and East Africa (1.49 and 1.14%, respectively) than among those from other endemic areas, e.g. South America (n=0). Despite its limited sensitivity, this newly developed kit for CS antibody testing may be a valuable tool for the estimation of the risk for travellers in malarious regions to acquire an infection with P. falciparum. It may also be useful for the determination of the efficacy of malaria chemoprophylaxis for inhibiting outbreak of disease.     

Effectiveness of intermittent preventive treatment with sulphadoxine-pyrimethamine for control of malaria in pregnancy in western Kenya: a hospital-based study

OBJECTIVE: To monitor the effectiveness of intermittent preventive treatment (IPT) with sulphadoxine-pyrimethamine (SP) for the control of malaria in pregnancy at delivery in the Provincial Hospital in Kisumu, Kenya, and to assess the effect of IPT in participants in a cohort study. METHODS: Between June 1999 and June 2000, information on IPT and birth outcome was collected in 2302 consecutive deliveries. A group of 889 women, who were enrolled in a cohort to assess the interaction between malaria and HIV, were analysed separately because of the enrollment criteria and different access to health care. RESULTS: The prevalence of placental malaria was 13.8% and of low birthweight (LBW) was 12.2%. In multivariable analysis, IPT (> or =1 dose of SP) was associated with a reduction in placental malaria and LBW [adjusted odds ratio (OR) 0.56, 95% confidence interval (CI) 0.39-0.83 and OR 0.65, 95% CI 0.45-0.95, respectively]. An adjusted mean increase in birthweight of 61 g was seen (95% CI 22-101 g) for each increment in number of SP doses (> or =2 doses grouped together). IPT was associated with a reduction in placental malaria in HIV-seronegative women (OR 0.49, 95% CI 0.28-0.86) but this was not significant among HIV-seropositive women (OR 0.45, 95% CI 0.20-1.05). A significant effect on birthweight could not be detected among participants in the HIV-cohort. CONCLUSIONS: This evaluation confirms that IPT with SP is effective in reducing placental malaria and LBW. It will be important to increase coverage of IPT and to extend IPT to antenatal clinics in peri-urban and rural areas.     

Cross-border malaria control for internally displaced persons: observational results from a pilot programme in eastern Burma/Myanmar

Objectives  To document the feasibility of a cross-border community based integrated malaria control programme implemented by internally displaced persons in eastern Burma/Myanmar.
Methods  This pilot study was conducted from February 2003 through January 2005 in seven villages of displaced ethnic Karen. Interventions comprised early diagnosis of Plasmodium falciparum and treatment with mefloquine and artesunate, distribution of long-lasting insecticide treated nets (LLITNs), and educational messages. The primary outcome measure was P. falciparum prevalence during bi-annual universal screenings with the Paracheck-Pf^® (Orchid Biomedical Systems, Goa, India) device. Secondary outcomes were P. falciparum incidence and process indicators related to net use and malaria knowledge, attitudes and practices (KAP).
Results  P. falciparum prevalence in original programme areas declined from 8.4% [95% confidence interval (CI) 8.3–8.6] at baseline to 1.1% (95% CI 1.1–1.2) in the final screening. Annual incidence in original areas declined from 232 to 70 cases/1000/year [incidence rate ratio 0.30 (95% CI 0.24–0.39)]. The proportion of household members sleeping under a LLITN improved from 0% to 89% and malaria KAP improved in all areas.
Conclusions  Integrated malaria control organized and implemented by displaced persons is feasible in eastern Burma/Myanmar. The decline in P. falciparum prevalence and incidence suggest that it may be possible to reduce the burden of disease and the reservoir of malaria in eastern Burma/Myanmar, with implications for malaria control in the greater Mekong region.     

Risk factors for presentation to hospital with severe anaemia in Tanzanian children: a case-control study

In malaria endemic areas anaemia is a usually silent condition that nevertheless places a considerable burden on health services. Cases of severe anaemia often require hospitalization and blood transfusions. The objective of this study was to assess risk factors for admission with anaemia to facilitate the design of anaemia control programmes. We conducted a prospective case-control study of children aged 2-59 months admitted to a district hospital in southern Tanzania. There were 216 cases of severe anaemia [packed cell volume (PCV) < 25%] and 234 age-matched controls (PCV > or = 25%). Most cases [55.6% (n = 120)] were < 1 year of age. Anaemia was significantly associated with the educational level of parents, type of accommodation, health-seeking behaviour, the child's nutritional status and recent and current medical history. Of these, the single most important factor was Plasmodium falciparum parasitaemia [OR 4.3, 95% confidence interval (CI) 2.9-6.5, P < 0.001]. Multivariate analysis showed that increased recent health expenditure [OR 2.2 (95% CI 1.3-3.9), P = 0.005], malnutrition [OR 2.4 (95%CI 1.3-4.3), P < 0.001], living > 10 km from the hospital [OR 3.0 (95% CI 1.9-4.9), P < 0.001], a history of previous blood transfusion [OR 3.8 (95% CI 1.7-9.1), P < 0.001] and P. falciparum parasitaemia [OR 9.5 (95% CI 4.3-21.3), P < 0.001] were independently related to risk of being admitted with anaemia. These findings are considered in terms of the pathophysiological pathway leading to anaemia. The concentration of anaemia in infants and problems of access to health services and adequate case management underline the need for targeted preventive strategies for anaemia control.     

Compliance with malaria chemoprophylaxis and preventative measures against mosquito bites among Dutch travellers.

Summary Self-reported compliance with a malaria chemoprophylaxis regimen of proguanil (PG) plus chloroquine (CQ) was assessed in a cohort of 547 Dutch travellers who visited a single travel clinic when travelling to various areas endemic for falciparum malaria. 503 (92%) had taken PG/CQ prophylaxis, but only 326 (60%) reported regular and uninterrupted use throughout the journey and 4 weeks afterwards. Compliance differed by travel destination and was 45% in South America, 52% in West Africa, 53% in South-east Asia, 60% in the Indian Subcontinent and 78% in East Africa. Parasitologically confirmed falciparum malaria occurred in 5 travellers (0.9%), including 3 of 24 non-compliant travellers to West Africa (12.5%). Apart from destination, independent risk factors for non-compliance were young age, extensive travel experience and adventurous travel. Compliance with protection against mosquito bites was 80% for wearing long-sleeved shirts and long-legged trousers after sunset, 73% for use of repellents, 56% for sleeping under bednets and 37% for keeping the sleeping quarters free of mosquitoes. Although 440 travellers (80%) reported to have taken two or more of these measures at least once, only 88 (16%) had done so on a daily basis. Daily use of bednets was reported more frequently among subjects who were non-compliant with chemoprophylaxis. Compliance regarding malaria chemoprophylaxis should be improved, particularly in high-risk areas such as Sub-saharan Africa, with extra attention to young, adventurous travellers. More emphasis should be placed on prevention of Anopheles bites.     

Epidemiology of malaria in an area of low transmission in central India

A longitudinal study on malaria was carried out from 2003 to 2005 in an area of unstable malaria in the Panna district in central India. Both Plasmodium vivax and P. falciparum were prevalent; however, the risk of P. falciparum malaria was 31.6% (95% confidence interval [CI] = 29.6-33.6%), which is four times higher compared with that of P. vivax malaria (7.8%, 95% CI = 6.7-9%). An increasing trend was recorded in malaria prevalence from 30.2% in 2003 to 46.6% in 2004 (odds ratio [OR] = 2.0, 95% CI = 1.6-2.5) that increased to 58.6% in 2005 (OR = 1.6, 95% CI = 1.2-2.1). This increase was statistically significant (chi(2) = 120.5, degrees of freedom = 2, P < 0.0001). Anopheles culicifacies was the dominant vector of malaria and showed partial (< 50%) resistance to DDT, which indicated that DDT can still be used. Improved access to treatment facilities, combination therapy, and vector control appears to be the most promising method for controlling malaria in this region.     

Tolerability of doxycycline monohydrate salt vs. chloroquine-proguanil in malaria chemoprophylaxis

The resistance of Plasmodium falciparum to the chloroquine-proguanil association (C/P) as antimalarial chemoprophylaxis is becoming increasingly common in Africa. Daily oral doxycycline hyclate 100 mg is effective as malaria prophylaxis. But the hyclate salt's adverse effects combined with the capsule's galenic form are incompatible with good chemoprophylaxis compliance. We conducted a randomized group study of 522 French soldiers deployed in Gabon and Chad for 4 months to determine the tolerability of short-term malaria chemoprophylaxis with a 100-mg daily tablet of a monohydrate doxycycline salt compared with a daily C/P capsule. At days 7 and 120, compliance was better in the doxycycline group [respectively 98.5%vs. 73.9% (P < 0.001) and 90.5%vs. 74% (P < 0.001)]. No major event (evacuation, hospitalization) was related to the medications. Epigastralgia, diarrhoea, urticaria, mouth ulcers, sun sensitization and desquamation were significantly more frequent in the C/P group (P < 0.05). There was no statistical difference for malaria incidence, vertigo, nausea and hair loss. These results suggest that doxycycline monohydrate may be safely used in short-term malaria chemoprophylaxis. With the same efficacy as a hyclate doxycycline, doxycycline monohydrate could be a good chemoprophylaxis for short-term travellers at particular risk of C/P resistant P. falciparum malaria.     

Exchange transfusion as an adjunct to the treatment of severe falciparum malaria

Summary
objective   To compare the efficacy of exchange transfusion as the adjunct to quinine treatment (21 patients) with quinine therapy alone (29 patients).
method   A retrospective study of 50 patients with severe falciparum malaria was conducted at Chumphorn Hospital, Southern Thailand.
results   Clinical characteristics in both treatment groups were not significantly different although in the exchange transfusion group, the admission geometric mean parasitaemia (18 (5%), and the proportion of patients with more than 10% parasitaemia was higher (76%, P = 0.03) than in the group who received quinine alone (10 ± 4%; 38%, P = 0.1). The mortality rate of patients who received exchange transfusion was 48%; that of the remainder, 69%. ( P = 0.3). ARDS ( P = 0.01) and oliguric renal failure ( P = 0.04) were significant risk factors for death in these patients.
conclusion   Exchange transfusion was safe and well tolerated. Results of our study revealed a 20% reduction in mortality when exchange transfusion was used as an adjunct to quinine treatment. It should therefore be considered in patients with severe falciparum malaria when possible.     

Microscopic and sub-microscopic Plasmodium falciparum infection, but not inflammation caused by infection, is associated with low birth weight

Pregnancy-associated malaria is one of the leading causes of low birth weight in malaria endemic areas. In this study, 145 parturient women residing in areas endemic for Plasmodium falciparum in Lambaréné, Gabon, were recruited into the study after delivery, and the association of maternal P. falciparum infection, inflammatory response, and birth weight was studied. At delivery, 10% (15) of the mothers (12 were positive in both peripheral and placental blood smears, 1 was positive in peripheral blood only, and 2 were positive in placenta blood only) were positive for P. falciparum by microscopy and 23% (30) by real-time polymerase chain reaction (PCR). The level of C-reactive protein (CRP) was significantly elevated in microscopically P. falciparum-positive pregnant women (34 mg/L; 95% CI: 3-458) but not in those with sub-microscopic infections (6 mg/L; 95% CI: 1-40) compared with those free of P. falciparum infection (7 mg/L; 95% CI: 1-43). In a multivariate analysis, the presence of microscopic (adjusted OR = 28.6, 95% CI = 4.8-169.0) or sub-microscopic (adjusted OR = 13.2, 95% CI = 2.4-73.0) P. falciparum infection in pregnant women and age of mothers < 21 years (adjusted OR = 9.7 CI = 1.0-89.7), but not CRP levels, were independent predictors for low birth weight. This finding may have important operational implications and emphasizes the need for appropriate diagnostic methods in studies evaluating the outcome of pregnancy-associated malaria.     

Reduced prevalence of Plasmodium falciparum infection and of concomitant anaemia in pregnant women with heterozygous G6PD deficiency

Glucose-6-phosphate dehydrogenase (G6PD) deficiency confers protection against malaria in children, yet its role in malaria in pregnancy is unknown. In a cross-sectional study among 529 pregnant Ghanaian women, Plasmodium falciparum infection, anaemia and G6PD genotypes were assessed. Of these, 30.4% were heterozygous and 2.6% were homozygous for G6PD deficiency. The prevalence of P. falciparum infection decreased from 66% in G6PD-normal women to 58% in heterozygotes, and to 50% in individuals with homozygous G6PD deficiency (Chi2(trend) = 4.4, P = 0.04). Multivariate analysis revealed that in multigravid women but not in primigravidae, heterozygous G6PD deficiency was associated with a reduced risk of P. falciparum infection (Odds ratio (OR), 0.6; 95% confidence interval (95% CI), [0.4-0.9]). This protection against infection was limited to the third trimenon of pregnancy. In addition, heterozygous G6PD deficiency was associated with a reduced risk of anaemia among infected multigravidae (OR, 0.5 [0.3-1.0]). Pregnancy is a period of high vulnerability to malaria. The results of this study provide evidence for protection against malaria in pregnancy caused by heterozygous G6PD deficiency. This advantage, even if confined to multigravid women, may contribute to the selection of G6PD variants in malaria-endemic regions.     

Cattle, other domestic animal ownership, and distance between dwelling structures are associated with reduced risk of recurrent Plasmodium falciparum infection in southern Zambia

Objectives  To examine the associations between household Plasmodium falciparum infection and a number of factors including domestic animal ownership, potential mosquito breeding sites, indoor darkness, density of people, distance between dwelling structures, and insecticide-treated bed net use.
Methods  Analyses were based on data collected from a household survey conducted in Macha, Zambia. Thirty-four households with recurrent malaria infection in 2005–2008 were selected as case households and compared with 37 control households with no malaria infection randomly selected from the same geographic area. Logistic regression models were used to identify factors associated with household P. falciparum infection.
Results  In multivariate analysis, cattle ownership was associated with reduced risk of P. falciparum infection (adjusted odds ratio = 0.19; 95% CI = 0.05–0.69), as was increased distance between dwelling structures (aOR = 0.26; 95% CI = 0.07–0.98). Ownership of the highest category of cattle, goats, dogs, or cats dramatically reduced the risk of P. falciparum infection (aOR = 0.13; 95% CI = 0.03–0.56).
Conclusion  Domestic animal, in particular cattle, ownership and greater distance between dwelling structures were associated with reduced risk of recurrent P. falciparum infection at the household level. These factors should be further investigated as supplemental measures for malaria control in rural African settings.     

Performance of OptiMAL-IT® compared to microscopy, for malaria detection in Burkina Faso

Objective  To compare the performance of OptiMAL-IT^®, a rapid diagnostic test for malaria, with that of microscopy in Burkina Faso.
Method  Finger-prick blood samples of 464 children attending hospital for suspected malaria were tested for malaria by microscopy and OptiMAL-IT^®.
Results  The sensitivity and specificity of OptiMAL-IT^® were 98.7% (CI 95% = 97.6–99.8) and 96.2% (CI 95% = 94.3–98.1) respectively, with a high positive likelihood ratio (25.97).
Conclusion  OptiMAL-IT^® can be considered a good method to diagnose malaria in Burkina Faso, particularly in remote areas with little or no access to microscopy services.     

Low frequency of complications in imported falciparum malaria: a review of 222 cases in south-eastern Norway.

We performed a retrospective study of 222 cases of falciparum malaria diagnosed in Oslo and Akerhus counties, Norway, from January 1988 to December 1997. Except for 12 cases, all had acquired the disease in sub-Saharan Africa. Sixty-four (28.8%) cases occurred in assumed non-immune individuals; of these, 41 (64.1%) were compliant to recommended antimalarial chemoprophylaxis. The mean time lag from first symptom to diagnosis (total diagnosis delay) was 4.6 d (median 3 d, range 0-30 d) and the mean time from presentation to diagnosis (doctor's delay) was 1.3 d (median 0 d, range 0-25 d). There were no fatal cases, and only 8 (3.6%) had a complicated course. The following factors were significantly associated with development of complicated disease: higher age, non-immunity combined with chemoprophylaxis non-compliance, prolonged doctor's delay and prolonged total diagnosis delay (p < or = 0.05). Our data suggest that complicated disease in imported falciparum malaria may largely be prevented by high chemoprophylaxis compliance rates in non-immune travellers and a high index of suspicion in physicians evaluating febrile travellers.     

In-vivo efficacy of amodiaquine-artesunate in children with uncomplicated Plasmodium falciparum malaria in western Kenya

Objectives  To assess the efficacy of amodiaquine-artesunate in an area with high chloroquine resistance in western Kenya.
Methods  Twenty-eight day in-vivo efficacy trial of amodiaquine-artesunate in 103 children aged 6–59 months in western Kenya with smear-confirmed uncomplicated Plasmodium falciparum malaria.
Results  The 28-day uncorrected adequate clinical and parasitological response (ACPR) was 69.0%, with 15.5% Late Clinical Failure and 15.5% Late Parasitologic Failure rates. The PCR-corrected 28-day ACPR was 90.2%. Clinical risk factors for recurrent infection (recrudescences and reinfections) were lower axillary temperature at enrolment and low weight-for-age Z-score. The presence of single nucleotide polymorphisms pfcrt 76T and pfmdr1 86Y at baseline was associated with increased risk of recurrent infections, both reinfections and recrudescences.
Conclusion  Although artemether-lumefantrine (Coartem^®) is the first line ACT in Kenya, amodiaquine-artesunate is registered as an option for treatment of uncomplicated P. falciparum and remains an effective alternative to Coartem^® in western Kenya. Continued amodiaquine monotherapy in the private sector may jeopardise the future use of amodiaquine-artesunate as an alternative artemisinin-based combination therapy.     

Severe malaria and concomitant bacteraemia in children admitted to a rural Mozambican hospital

Objectives  To describe the prevalence, aetiology and prognostic implications of coexisting invasive bacterial disease in children admitted with severe malaria in a rural Mozambican Hospital.
Methods  Retrospective study of data systematically collected from June 2003 to May 2007 in a rural Mozambican hospital, from all children younger than 5 years admitted with severe malaria.
Results  Seven thousand and forty-three children were admitted with a diagnosis of malaria. 25.2% fulfilled the criteria for severe malaria. 5.4% of the children with severe malaria and valid blood culture results had a concomitant bacteraemia. Case fatality rates of severe malaria cases rose steeply when bacteraemia was also present (from 4.0% to 22.0%, P  < 0.0001), and bacteraemia was an independent risk factor for death among severe malaria patients (adjusted OR 6.2, 95% CI 2.8–13.7, P  = 0.0001). Streptococcus pneumoniae , Gram-negative bacteria, Staphilococcus aureus and non-typhoid Salmonella (NTS) were the most frequently isolated microorganisms among severe malaria cases. Their frequency and associated case fatality rates (CFR) varied according to age and to syndromic presentation. Streptococcus pneumoniae had a relatively low CFR, but was consistently associated with severe malaria syndromes, or anaemia severity groups. No clear-cut relationship between malarial anaemia and NTS bacteraemia was found.
Conclusions  The coexistence of malaria and invasive bacterial infections is a frequent and life-threatening condition in many endemic African settings. In Mozambique, S. pneumoniae is the leading pathogen in this interaction, possibly as a consequence of the high HIV prevalence in the area. Measures directed at reducing the burden of both those infections are urgently needed to reduce child mortality in Africa.     

Insecticide-treated bednets for the prevention of Plasmodium falciparum malaria in Cambodia: a cluster-randomized trial

OBJECTIVES: To validate and quantify the impact of insecticide-treated bednets (ITN) on malaria morbidity and mortality in Cambodia. METHODS: A paired, cluster-randomized trial of ITN was conducted in Rattanakiri, North East Cambodia. Thirty-four villages with a total population of 10,726 were randomized to receive deltamethrin-impregnated bednets or to control (no net provision). Cross-sectional surveys measured Plasmodium falciparum prevalence at baseline and 10 months after ITN distribution. Village malaria volunteers in control and intervention villages treated dipstick-positive P. falciparum cases with artesunate and mefloquine. The resulting passive surveillance data were used as an estimate of the incidence of clinical P. falciparum infections. RESULTS: There was a protective efficacy of 28% in P. falciparum incidence (adjusted rate ratio 0.72, 95% CI 0.47-1.08) and 9% in P. falciparum prevalence (adjusted prevalence ratio 0.91, 95% CI 0.65-1.28) in ITN relative to control villages; however, neither of these estimates reached statistical significance. Individual-level analysis indicated a greater reduction in P. falciparum prevalence among under 5-year-olds (adjusted OR = 0.63, 95% CI 0.26-1.53) compared to older individuals (interaction P = 0.042). The protective efficacy of 35% (95% CI -28, 67%) with respect to clinical P. falciparum incidence in under 5-year-olds was more pronounced than the corresponding estimates for prevalence but was again not significant. CONCLUSIONS: Lack of statistical significance in the results is likely to be due to a lack of power. The analysis provides further evidence for ITN effectiveness in South East Asia, particularly among individuals under 5 years of age.     

Prevention of malaria in Afghanistan through social marketing of insecticide-treated nets: evaluation of coverage and effectiveness by cross-sectional surveys and passive surveillance

Malaria is often a major health problem in countries undergoing war or conflict owing to breakdown of health systems, displacement of vulnerable populations, and the increased risk of epidemics. After 23 years of conflict, malaria has become prevalent in many rural areas of Afghanistan. From 1993 to the present, a network of non-governmental organizations, co-ordinated by HealthNet International, has operated a programme of bednet sales and re-treatment in lowland areas. To examine whether a strategy based on insecticide-treated nets (ITN) is a viable public health solution to malaria, communities were given the opportunity to buy nets and then monitored to determine population coverage and disease control impact. This was carried out using two contrasting methods: cross-sectional surveys and passive surveillance from clinics using a case-control design. Nets were purchased by 59% of families. Cross-sectional surveys demonstrated a 59% reduction in the risk of Plasmodium falciparum infection among ITN users compared with non-users (OR 0.41; 95% CI 0.25-0.66). The passive surveillance method showed a comparable reduction in the risk of symptomatic P. falciparum malaria among ITN users (OR 0.31; 95% CI 0.21-0.47). The cross-sectional method showed a 50% reduction in risk of P. vivax infection in ITN users compared with non-users (OR 0.50; 95% CI 0.17-1.49) but this effect was not statistically significant. The passive surveillance method showed a 25% reduction in the risk of symptomatic P. vivax malaria (OR 0.75; 95% CI 0.66-0.85). ITN appeared to be less effective against P. vivax because of relapsing infections; hence an effect took more than one season to become apparent. Passive surveillance was cheaper to perform and gave results consistent with cross-sectional surveys. Untreated nets provided some protection. Data on socioeconomic status, a potential confounding factor, was not collected. However, at the time of net sales, there was no difference in malaria prevalence between buyers and non-buyers. The abundance of Anopheles stephensi, the main vector, did not appear to be affected by ITN. ITN constitute one of the few feasible options for protection against malaria in chronic emergencies.     

Clinical features of children hospitalized with malaria--a study from Bikaner, northwest India

Severe Plasmodium vivax malaria in adults has been reported from Bikaner (northwestern India) but the reports on children are scanty. This prospective study was done on 303 admitted children of malaria. The diagnosis was done by peripheral blood smear and rapid diagnostic test. Further confirmation of severe P. vivax monoinfection was done by polymerase chain reaction (PCR). The proportion of P. falciparum, P. vivax, and mixed (P. falciparum and P. vivax) infection was 61.01%, 33.99%, and 4.95%, respectively. Severe disease was present in 49.5% (150/303) children with malaria, with the risk greatest among P. vivax monoinfection (63.1% [65/103]) compared with P. falciparum, either alone (42.7% [79/185]; odds ratio [OR] = 2.3 [95% confidence interval (CI) = 1.40-3.76], P = 0.001) or mixed infections (40% [6/15]; OR = 2.57 [95% CI = 0.88-7.48]). In children < 5 years of age, the proportion of severe malaria attributable to P. vivax rose to 67.4% (31/46) compared with 30.4% (14/46) of P. falciparum (OR = 4.7 [95% CI = 2.6-8.6], P < 0.0001) and 2.2% (1/46) of mixed infection (OR = 92 [95% CI = 24.6-339.9], P < 0.0001). The proportion of patients having severe manifestations, which included severe anemia, thrombocytopenia, cerebral malaria, acute respiratory distress syndrome, hepatic dysfunction, renal dysfunction, abnormal bleeding was significantly high in association with P. vivax monoinfection in 0-5 year age group, while the same was significantly high in association with P. falciparum monoinfection in 5-10 year age group. Similarly P. vivax monoinfection had greatest propensity to cause multiorgan dysfunction in 0-5 year age group (34.1% [17/41], P < 0.0001) in comparison to P. falciparum monoinfection, which had similar propensity in 5-10 year age group (36.8% [35/95], P = 0.039). Plasmodium vivax monoinfection was almost equally serious to cause significant mortality in comparison to P. falciparum (case fatality rate of severe P. vivax was 3.9% versus 3.2% of severe P. falciparum malaria; P = 1.0). This study reaffirms the evidence of severe P. vivax malaria in children in Bikaner.