Effects of acute Plasmodium falciparum malaria on body weight in children in an endemic area

A model of pregnancy-associated malaria for inducing adverse pregnancy outcomes in ICR mouse

BACKGROUND

Based on understanding of placental pathological features and safe medication in pregnancy-associated malaria (PAM), establishment of a stable pregnant mouse infection model with Plasmodium was urgently needed.

METHODS

ICR mice with vaginal plugs detected were randomly divided into post-pregnancy infection (Malaria+) and uninfected pregnancy (Malaria-) cohorts. Age-matched mice that had not been mated were infected as pre-pregnancy infection group (Virgin control), which were subsequently mated with ICR males. All mice were inoculated with 1 × 106Plasmodium berghei ANKA-infected RBCs by intraperitoneal injection, and the same amount of saline was given to Malaria- group. We recorded the incidence of adverse pregnancy outcomes and the amounts of offspring in each group.

RESULTS

The Virgin group mice were unable to conceive normally, and vaginal bleeding, abortion, or stillbirth appeared in the Malaria+ group. The incidence of adverse pregnancy outcomes was extremely high and statistically significant compared with the control (Malaria-) group (P < 0.05), of which placenta exhibited pathological features associated with human gestational malaria.

CONCLUSIONS

The intraperitoneal injection of 1 × 106Plasmodium berghei ANKA-infected RBCs could establish a model of pregnancy-associated malaria in ICR mouse.

Malaria prevalence in asymptomatic and symptomatic children in Kiwangwa, Bagamoyo district, Tanzania

BACKGROUND

Malaria prevalence continues to decline across sub-Saharan Africa as a result of various intervention strategies. However, the diseases still poses a public health concern in the region. While symptomatic malaria is recognized and treated, asymptomatic infections become increasingly important for interrupting transmission. A cross-sectional survey was conducted to assess malaria prevalence in symptomatic and asymptomatic children in Kiwangwa ward in Bagamoyo District in Tanzania.

METHODS

Four hundred school-aged children in Kiwanga ward were recruited in the study; 200 from Kiwangwa dispensary and 200 from nearby schools. Primary health parameters were examined and blood samples collected and examined for Plasmodium falciparum prevalence using rapid diagnostic test (RDT), light microscopy (LM) and reverse transcription quantitative PCR (RT-qPCR) targeting transcripts of A-type 18s rRNA of P. falciparum. Gametocytes were detected by LM and RT-qPCR targeting transcripts of gametocyte specific marker, Pfs25.

RESULTS

Overall P. falciparum prevalence was 73.3, 40.8 and 36.3% by RT-qPCR, RDT and LM in the study area, respectively (P < 0.001). As expected symptomatic children had a significantly higher prevalence of 89, 67.5 and 64.5% by qPCR, RDT and LM, compared to 57.5, 14 and 8% in the asymptomatic group, respectively. However, gametocyte prevalence in asymptomatic individuals was higher by both LM (2%) and qPCR (14%) than in symptomatic individuals LM (0.5%) and qPCR (3%).

CONCLUSIONS

A substantial difference in prevalence of symptomatic and asymptomatic infections observed in Kiwangwa ward underpins the use of molecular tools in malaria surveillance aiming at estimating prevalence and transmission. Notably, the higher gametocytaemia observed in asymptomatic children indicates the reservoir infections and points to the need for detection and treatment of both asymptomatic and symptomatic malaria.

Asiatic acid influences parasitaemia reduction and ameliorates malaria anaemia in P. berghei infected Sprague-Dawley male rats

BACKGROUND

Current malaria treatment is either "anti-parasitic", "anti-infectivity" or both without addressing the pathophysiological derangement (anti-disease aspect) associated with the disease. Asiatic acid is a natural phytochemical with oxidant, antioxidant and anti-inflammatory properties whose effect on malarial and accompanying pathophysiology are yet to be investigated. Asiatic acid influence in P. berghei-infected Sprague Dawley rats on %parasitaemia and malarial anaemia were investigated.

METHODS

Plasmodium berghei-infected rats (90-120 g) were orally administered with Asiatic acid (5, 10, 20 mg/kg) and 30 mg/kg chloroquine as a positive control. Changes in %parasitaemia and haematological parameters in Asiatic acid administered rats were monitored in a 21 day study and compared to controls.

RESULTS

All animals developed stable parasitaemia (15-20 %) by day 7. Asiatic acid doses suppressed parasitaemia, normalised haematological measurements and influenced biophysical characteristics changes. Most positive changes were associated with intragastric administration of 10 mg/kg Asiatic acid dose. Peak %parasitaemia in Asiatic acid administration occurred at days 12 with a shorter time course compared to day 9 for chloroquine (30 mg/kg) treatment with a longer time course.

CONCLUSIONS

Oral Asiatic acid administration influenced %parasitaemia suppression, ameliorated malarial anaemia and increased biophysical properties on infected animals. Asiatic acid may be a replacement alternative for chloroquine treatment with concomitant amelioration of malaria pathophysiology. Due to different action time courses, Asiatic acid and chloroquine may be possible candidates in combination therapy.

Could Plasmodium vivax malaria trigger malnutrition? Revisiting the Bradford Hill criteria to assess a causal relationship between two neglected problems

The benign characteristics formerly attributed to Plasmodium vivax infections have recently changed owing to the increasing number of reports of severe vivax malaria resulting in a broad spectrum of clinical complications, probably including undernutrition. Causal inference is a complex process, and arriving at a tentative inference of the causal or non-causal nature of an association is a subjective process limited by the existing evidence. Applying classical epidemiology principles, such as the Bradford Hill criteria, may help foster an understanding of causality and lead to appropriate interventions being proposed that may improve quality of life and decrease morbidity in neglected populations. Here, we examined these criteria in the context of the available data suggesting that vivax malaria may substantially contribute to childhood malnutrition. We found the data supported a role for P. vivax in the etiology of undernutrition in endemic areas. Thus, the application of modern causal inference tools, in future studies, may be useful in determining causation.

Effect of Short-Term Supplementation with Ready-to-Use Therapeutic Food or Micronutrients for Children after Illness for Prevention of Malnutrition: A Randomised Controlled Trial in Uganda

BACKGROUND

Globally, Médecins Sans Frontières (MSF) treats more than 300,000 severely malnourished children annually. Malnutrition is not only caused by lack of food but also by illnesses and by poor infant and child feeding practices. Breaking the vicious cycle of illness and malnutrition by providing ill children with nutritional supplementation is a potentially powerful strategy for preventing malnutrition that has not been adequately investigated. Therefore, MSF investigated whether incidence of malnutrition among ill children <5 y old could be reduced by providing a fortified food product or micronutrients during their 2-wk convalescence period. Two trials, one in Nigeria and one in Uganda, were conducted; here, we report on the trial that took place in Kaabong, a poor agropastoral region of Karamoja, in east Uganda. While the region of Karamoja shows an acute malnutrition rate between 8.4% and 11.5% of which 2% to 3% severe malnutrition, more than half (58%) of the population in the district of Kaabong is considered food insecure.

METHODS AND FINDINGS

We investigated the effect of two types of nutritional supplementation on the incidence of malnutrition in ill children presenting at outpatient clinics during March 2011 to April 2012 in Kaabong, Karamoja region, Uganda, a resource-poor region where malnutrition is a chronic problem for its seminomadic population. A three-armed, partially-blinded, randomised controlled trial was conducted in children diagnosed with malaria, diarrhoea, or lower respiratory tract infection. Non-malnourished children aged 6 to 59 mo were randomised to one of three arms: one sachet/d of ready-to-use therapeutic food (RUTF), two sachets/d of micronutrient powder (MNP), or no supplement (control) for 14 d for each illness over 6 mo. The primary outcome was the incidence of first negative nutritional outcome (NNO) during the 6 mo follow-up. NNO was a study-specific measure used to indicate progression to moderate or severe acute malnutrition; it was defined as weight-for-height z-score <-2, mid-upper arm circumference (MUAC) <115 mm, or oedema, whichever came first. Of the 2,202 randomised participants, 51.2% were girls, and the mean age was 25.2 (±13.8) mo; 148 (6.7%) participants were lost to follow-up, 9 (0.4%) died, and 14 (0.6%) were admitted to hospital. The incidence rates of NNO (first event/year) for the RUTF, MNP, and control groups were 0.143 (95% confidence interval [CI], 0.107-0.191), 0.185 (0.141-0.239), and 0.213 (0.167-0.272), respectively. The incidence rate ratio was 0.67 (95% CI, 0.46-0.98; p = 0.037) for RUTF versus control; a reduction of 33.3%. The incidence rate ratio was 0.86 (0.61-1.23; p = 0.413) for MNP versus control and 0.77 for RUTF versus MNP (95% CI 0.52-1.15; p = 0.200). The average numbers of study illnesses for the RUTF, MNP, and control groups were 2.3 (95% CI, 2.2-2.4), 2.1 (2.0-2.3), and 2.3 (2.2-2.5). The proportions of children who died in the RUTF, MNP, and control groups were 0%, 0.8%, and 0.4%. The findings apply to ill but not malnourished children and cannot be generalised to a general population including children who are not necessarily ill or who are already malnourished.

CONCLUSIONS

A 2-wk nutrition supplementation programme with RUTF as part of routine primary medical care to non-malnourished children with malaria, LRTI, or diarrhoea proved effective in preventing malnutrition in eastern Uganda. The low incidence of malnutrition in this population may warrant a more targeted intervention to improve cost effectiveness.

TRIAL REGISTRATION

clinicaltrials.gov NCT01497236.

Association between anthropometry-based nutritional status and malaria: a systematic review of observational studies

BACKGROUND

Multiple studies in various parts of the world have analysed the association of nutritional status on malaria using anthropometric measures, but results differ due to the heterogeneity of the study population, species of the parasite, and other factors involved in the host and parasite relationship. The aim of this study was to perform a systematic review on the inter-relationship of nutritional status based on anthropometry and malarial infection.

METHODS

Two independent reviewers accessed the MEDLINE and LILACS databases using the same search terms related to malaria and anthropometry. Prospective studies associating anthropometry and malaria (incidence or severity) were selected. References from the included studies and reviews were used to increase the review sensitivity. Data were extracted using a standardized form and the quality of the prospective studies was assessed. Selected articles were grouped based on exposures and outcomes.

RESULTS

The search identified a total of 1688 studies: 1629 from MEDLINE and 59 from LILACS. A total of 23 met the inclusion criteria. Five additional studies were detected by reading the references of the 23 included studies and reviews, totaling 28 studies included. The mean sample size was 662.1 people, ranging from 57 to 5620. The mean follow-up was 365.8 days, ranging from 14 days to 1 year and 9 months, and nine studies did not report the follow-up period. Prospective studies assessing the relationship between malaria and malnutrition were mostly carried out in Africa. Of the 20 studies with malarial outcomes, fifteen had high and five had average quality, with an average score of 80.5 %. Most anthropometric parameters had no association with malaria incidence (47/52; 90.4 %) or parasite density (20/25; 80 %). However, the impact of malnutrition was noted in malaria mortality and severity (7/17; 41.2 %). Regarding the effects of malaria on malnutrition, malaria was associated with very few anthropometric parameters (8/39; 20.6 %).

CONCLUSIONS

This systematic review found that most of the evidence associating malaria and malnutrition comes from P. falciparum endemic areas, with a significant heterogeneity in studies' design. Apparently malnutrition has not a great impact on malaria morbidity, but could have a negative impact on malaria mortality and severity. Most studies show no association between malaria and subsequent malnutrition in P. falciparum areas. In Plasmodium vivax endemic areas, malaria was associated with malnutrition in children. A discussion among experts in the field is needed to standardize future studies to increase external validity and accuracy.

Factors contributing to anaemia after uncomplicated Plasmodiumfalciparum malaria in children

The factors contributing to anaemia in falciparum malaria were characterized in 1261 prospectively studied children in an endemic area of southwestern Nigeria. Of these, 487 (39%) presented with anaemia (haematocrit <30%). The following were found to be independent risk factors for anaemia at presentation: age <5 years, history of illness >3 days before presentation, presence of fever, a palpable liver, >parasitaemia 10,000/microl blood, and gametocytaemia. The mean maximum fractional fall in haematocrit (FFH) after treatment was 13.8% (95% confidence interval [CI] 13-14.6) of the baseline value. This occurred 3 days after treatment began and correlated positively with enrolment haematocrit. In children whose haematocrit was >30% at enrolment, the following were found to be independent risk factors associated with subsequent development of anaemia during follow-up: age <5 years and parasitaemia > or =100,000 parasites/microl. Haematological recovery was usually complete by 4-5 weeks, but was slower in children who were anaemic at enrolment and in those with recrudescence of their infections. Half of the children with recrudescence were still anaemic at 4 weeks. These findings have implications for the control of the burden of malarial anaemia in children in sub-Saharan African countries.