Therapeutic efficacies of artemisinin-based combination therapies in Nigerian children with uncomplicated falciparum malaria during five years of adoption as first-line treatments

Declining responsiveness of childhood Plasmodium falciparum infections to artemisinin-based combination treatments ten years following deployment as first-line antimalarials in Nigeria

Background

The development and spread of artemisinin-resistant Plasmodium falciparum malaria in Greater Mekong Subregion has created impetus for continuing global monitoring of efficacy of artemisinin-based combination therapies (ACTs). This post analyses is aimed to evaluate changes in early treatment response markers 10 years after the adoption of ACTs as first-line treatments of uncomplicated falciparum malaria in Nigeria.

Methods

At 14 sentinel sites in six geographical areas of Nigeria, we evaluated treatment responses in 1341 children under 5 years and in additional 360 children under 16 years with uncomplicated malaria enrolled in randomized trials of artemether-lumefantrine versus artesunate-amodiaquine at 5-year interval in 2009–2010 and 2014–2015 and at 2-year interval in 2009–2010 and 2012–2015, respectively after deployment in 2005.

Results

Asexual parasite positivity 1 day after treatment initiation (APPD1) rose from 54 to 62% and 2 days after treatment initiation from 5 to 26% in 2009–2010 to 2014–2015 (P = 0.002 and P <  0.0001, respectively). Parasite clearance time increased significantly from 1.6 days (95% confidence interval [CI]: 1.55–1.64) to 1.9 days (95% CI, 1.9–2.0) and geometric mean parasite reduction ratio 2 days after treatment initiation decreased significantly from 11 000 to 4700 within the same time period (P <  0.0001 for each). Enrolment parasitaemia > 75 000 μl^− 1, haematocrit > 27% 1 day post-treatment initiation, treatment with artemether-lumefantrine and enrolment in 2014–2015 independently predicted APPD1. In parallel, Kaplan-Meier estimated risk of recurrent infections by day 28 rose from 8 to 14% (P = 0.005) and from 9 to 15% (P = 0.02) with artemether-lumefantrine and artesunate-amodiaquine, respectively. Mean asexual parasitaemia half-life increased significantly from 1.1 h to 1.3 h within 2 years (P <  0.0001).

Conclusions

These data indicate declining parasitological responses through time to the two ACTs may be due to emergence of parasites with reduced susceptibility or decrease in immunity to the infections in these children.

Trial registration

Pan African Clinical Trial Registration PACTR201508001188143, 3 July 2015; PACTR201508001191898, 7 July 2015 and PACTR201508001193368, 8 July 2015 PACTR201510001189370, 3 July 2015; PACTR201709002064150, 1 March 2017; https://www.pactr.samrca.ac.za

Electronic supplementary material

The online version of this article (10.1186/s40249-019-0577-x) contains supplementary material, which is available to authorized users.

Parasite reduction ratio one day after initiation of artemisinin-based combination therapies and its relationship with parasite clearance time in acutely malarious children

BACKGROUND

In acute falciparum malaria, asexual parasite reduction ratio two days post-treatment initiation (PRRD2) ≥ 10 000 per cycle has been used as a measure of the rapid clearance of parasitaemia and efficacy of artemisinin derivatives. However, there is little evaluation of alternative measures; for example, parasite reduction ratio one day after treatment initiation (PRRD1) and its relationship with parasite clearance time (PCT) or PRRD2. This study evaluated the use of PRRD1 as a measure of responsiveness to antimalarial drugs.

METHODS

In acutely malarious children treated with artesunate-amodiaquine (AA), artemether-lumefantrine (AL) or dihydroartemisinin-piperaquine (DHP), the relationships between PRRD1 or PRRD2 and PCT, and between PRRD1 and PRRD2 were evaluated using linear regression. Agreement between estimates of PCT using PRRD1 and PRRD2 linear regression equations was evaluated using the Bland-Altman analysis. Predictors of PRRD1 > 5000 per half cycle and PRRD2 ≥ 10 000 per cycle were evaluated using stepwise multiple logistic regression models. Using the linear regression equation of the relationship between PRRD1 and PCT previously generated in half of the DHP-treated children during the early study phase, PCT estimates were compared in a prospective blinded manner with PCTs determined by microscopy during the later study phase in the remaining half.

RESULTS

In 919 malarious children, PRRD1 was significantly higher in DHP- and AA-treated compared with AL-treated children (P <  0.0001). PRRD1 or PRRD2 values correlated significantly negatively with PCT values (P <  0.0001 for each) and significantly positively with each other (P <  0.0001). PCT estimates from linear regression equations for PRRD1 and PRRD2 showed insignificant bias on the Bland-Altman plot (P = 0.7) indicating the estimates can be used interchangeably. At presentation, age > 15 months, parasitaemia > 10 000/μl and DHP treatment independently predicted PRRD1 > 5000 per half cycle, while age > 30 months, haematocrit ≥31%, body temperature > 37.4 °C, parasitaemia > 100 000/μl, PRRD1 value > 1000 and no gametocytaemia independently predicted PRRD2 ≥ 10 000 per cycle. Using the linear regression equation generated during the early phase in 166 DHP-treated children, PCT estimates and PCTs determined by microscopy in the 155 children in the later phase were similar in the same patients.

CONCLUSIONS

PRRD1 and estimates of PCT using PRRD1 linear regression equation of PRRD1 and PCT can be used in therapeutic efficacy studies.

TRIAL REGISTRATION

Pan African Clinical Trial Registration PACTR201709002064150, 1 March 2017, http://www.pactr.org.

Efficacy of Artemisinin-Based Combination Treatments of Uncomplicated Falciparum Malaria in Under-Five-Year-Old Nigerian Children Ten Years Following Adoption as First-Line Antimalarials

The efficacies of 3-day regimens of artemether-lumefantrine (AL), artesunate-amodiaquine (AA), and dihydroartemisinin-piperaquine (DHP) were evaluated in 910 children < 5 years old with uncomplicated malaria from six geographical areas of Nigeria. Parasite positivity 1 day and Kaplan-Meier estimated risk of persistent parasitemia 3 days after therapy initiation were both significantly higher, and geometric mean parasite reduction ratio 1 day after treatment initiation (PRRD1) was significantly lower in AL-treated children than in AA- and DHP-treated children. No history of fever, temperature > 38°C, enrollment parasitemia > 75,000 μL-1, and PRRD1 < 5,000 independently predicted persistent parasitemia 1 day after treatment initiation. Parasite clearance was significantly faster and risk of reappearance of asexual parasitemia after initial clearance was significantly lower in DHP-treated children. Overall, day 42 polymerase chain reaction-corrected efficacy was 98.3% (95% confidence interval [CI]: 96.1-100) and was similar for all treatments. In a non-compartment model, declines of parasitemias were monoexponential with mean terminal elimination half-life of 1.3 hours and unimodal frequency distribution of half-lives. All treatments were well tolerated. In summary, all three treatments evaluated remain efficacious treatments of uncomplicated malaria in young Nigerian children, but DHP appears more efficacious than AL or AA.

Sustained Effectiveness of a Fixed-Dose Combination of Artesunate and Amodiaquine in 480 Patients with Uncomplicated Plasmodium falciparum Malaria in Côte d'Ivoire

The objective of this study was to monitor the effectiveness of artesunate-amodiaquine fixed-dose combination tablets (ASAQ Winthrop®) in the treatment of uncomplicated Plasmodium falciparum malaria in Côte d'Ivoire. Two enrolment periods (November 2009 to May 2010 and March to October 2013) were compared using an identical design. Subjects with proven monospecific P. falciparum infection according to the WHO diagnostic criteria were eligible. 290 patients during each period received a dose of ASAQ Winthrop tablets appropriate for their age. The primary outcome measure was PCR-corrected adequate clinical and parasitological response at Day 28 in the per protocol population (255 in Period 1 and 240 in Period 2). This was achieved by 95.7% of patients during Period 1 and 96.3% during Period 2. Over 95% of patients were afebrile at Day 3 and complete parasite clearance was achieved at Day 3 in >99% of patients. Nineteen adverse events in nineteen patients were considered as possibly related to treatment, principally vomiting, abnormal liver function tests, and pruritus. There was no evidence for loss of effectiveness over the three-year period in spite of strong drug pressure. This trial was registered in the US Clinical Trials Registry (clinical.trials.gov) under the identifier number NCT01023399.

Therapeutic efficacy and effects of artemisinin-based combination treatments on uncomplicated Plasmodium falciparum malaria -associated anaemia in Nigerian children during seven years of adoption as first-line treatments

BACKGROUND

Artemisinin-based combination treatments (ACTs) are the first-line treatments of uncomplicated Plasmodium falciparum malaria in many endemic areas but there are few evaluation of their efficacy in anaemic malarious children.

METHODS

Therapeutic efficacy of 3-day regimens of artesunate-amodiaquine and artemether-lumefantrine was evaluated in 437 anaemic and 909 non-anaemic malarious children following treatment during a seven-year period (2008-2014). Patterns of temporal changes in haematocrit were classified based on haematocrit values <30% and ≥30%. Kinetics of the disposition of the deficit in haematocrit from 30% following treatment were evaluated using a non-compartment model.

RESULTS

PCR-corrected parasitological efficacy 28 days after start of treatment was significantly higher in artesunate-amodiaquine- compared to artemether-lumefantrine-treated children [97% (95%CI: 92.8-100) versus 96.4% (95%CI: 91.3-99.4), P = 0.02], but it was similar in non-anaemic and anaemic children. Fall in haematocrit/1 000 asexual parasites cleared from peripheral blood was significantly greater at lower compared to higher parasitaemias (P < 0.0001), and in non-anaemic compared to anaemic children (P = 0.007). In anaemic children at presentation, mean anaemia recovery time (AnRT) was 15.4 days (95%CI: 13.3-17.4) and it did not change over the years. Declines in haematocrit deficits from 30% were monoexponential with mean estimated half-time of 1.4 days (95%CI: 1.2-1.6). Anaemia half-time (t½anaemia) correlated positively with AnRT in the same patients (r = 0.69, P < 0.0001). Bland-Altman analysis of 10 multiples of t½anaemia and AnRT showed narrow limit of agreement with insignificant bias (P = 0.07) suggesting both can be used interchangeably in the same patients.

CONCLUSIONS

Artesunate-amodiaquine and artemether-lumefantrine remain efficacious treatments of uncomplicated P. falciparum infections in non-anaemic and anaemic Nigerian children in the last 7 years of adoption as first-line treatments. These ACTs may also conserve haematocrit at high parasitaemias and in anaemic children.

TRIALS REGISTRATION

Pan African Clinical Trial Registry PACTR201508001188143 , 3 July 2015; PACTR201510001189370 , 3 July 2015; PACTR201508001191898 , 7 July 2015 and PACTR201508001193368 , 8 July 2015.

Early rising asexual parasitaemia in Nigerian children following a first dose of artemisinin-based combination treatments of falciparum malaria

Background

Early rising asexual parasitaemia (ERAP), initially defined as ‘an increase in the parasite count over the baseline pre-treatment level during the first 24 h of treatment’ of falciparum malaria with artemisinin derivatives is well documented, but there is no characterization of its risk factors, kinetics, molecular features or relationship to late-appearing anaemia (LAA) in acute falciparum malaria in African children following oral artemisinin-based combination therapies (ACTs).

Methods

ERAP was defined as ≥5% increase in pre-treatment parasitaemia within 8 h of initiating treatment. Parasitaemia was quantified pre-treatment and 1–2 hourly for 8 h, and less frequently thereafter for 6 weeks following randomized treatment of acutely malarious children with artesunate-amodiaquine, artemether-lumefantrine or dihydroartemisinin-piperaquine. Risk factors were determined by stepwise multiple logistic regression model. Kinetics of release into and of elimination of asexual parasites and DNA clones from peripheral blood were evaluated by method of residuals and non-compartment model, respectively. Parasite population changes were evaluated morphologically and by molecular genotyping.

Results

ERAP occurred in 205 of 416 children. A parasitaemia <100,000/μL and parasitaemia 1 day post-treatment initiation were independent predictors of ERAP. In children with ERAP: mean and peak time of increase in parasitaemia were 105.6% (95% CI 81–130.1) and 2.5 h (95% CI 2.2–2.7), respectively. Mean lag time, half-time and rate constant of release were 0.2 h (95% CI 0.2–0.3), 1 h (95% CI 0.9–1.1), and 0.9 h⁻¹ (95% CI 0.8–1), respectively. Schizonts and young gametocytes were seen only in peripheral blood of few children with ERAP. In age-, gender-, baseline parasitaemia- and treatment-matched children with and without ERAP, parasite DNA clearance time and area under curve of number of DNA clones versus time were significantly higher in children with ERAP indicating peripheral retention of released parasites followed by elimination. DNA clone elimination was monoexponential.

Conclusion

ERAP is common, occurs rapidly as first order process and may be due to mobilization of parasites from deep tissue following a first dose of ACTs of acute childhood falciparum malaria.

Trials registration

Pan African Clinical Trial Registry PACTR201508001188143, 3 July 2015; PACTR201510001189370, 3 July 2015; PACTR201508001191898, 7 July 2015 and PACTR201508001193368, 8 July 2015.

Therapeutic efficacy and effects of artesunate-amodiaquine and artemether-lumefantrine on malaria-associated anaemia in Nigerian children aged two years and under

BACKGROUND

Artemisinin-based combination therapies are recommended as first-line treatments for uncomplicated falciparum malaria, but there is little evaluation of their efficacy and effects on uncomplicated malaria-associated anaemia in children aged 2 years and under.

METHODS

Parasitological efficacy and effects on malaria-associated anaemia were evaluated in 250 malarious children aged 2 years and under, and efficacy was evaluated in 603 malarious children older than two but younger than 5 years of age following treatment with artesunate-amodiaquine (AA) or artemether-lumefantrine (AL). Kinetics of the disposition of parasitaemia following treatment were evaluated using a non-compartment model. Late-appearing anaemia (LAA) was diagnosed using the following criteria: clearance of parasitaemia, fever and other symptoms occurring within 7 days of starting treatment, adequate clinical and parasitological response on days 28-42, haematocrit (HCT) ≥ 30 % at 1 and/or 2 weeks, a fall in HCT to < 30 % occurring at 3-6 weeks, absence of concomitant illness at 1-6 weeks, and absence of asexual parasitaemia detected using both microscopy and polymerase chain reaction (PCR) at 1-6 weeks.

RESULTS

Overall, in children aged 2 years and under, the PCR-corrected parasitological efficacy was 97.2 % (95 % CI 92.8-101.6), which was similar for both treatments. In children older than 2 years, parasitological efficacy was also similar for both treatments, but parasite prevalence 1 day after treatment began was significantly higher, and fever and parasite clearance times were significantly faster in the AA-treated children compared with the AL-treated children. Declines in parasitaemia were monoexponential with an estimated elimination half-time of 1 h. Elimination half-times were similar for both treatments. In children aged 2 years and under who were anaemic at presentation, the mean anaemia recovery time was 12.1 days (95 % CI 10.6-13.6, n = 127), which was similar for both treatments. Relatively asymptomatic LAA occurred in 11 children (4.4 %) aged 2 years and under, the recovery from which was uneventful.

CONCLUSION

This study showed that AA and AL are efficacious treatments for uncomplicated falciparum malaria in Nigerian children aged 2 years and under, and that AA clears parasitaemia and fever significantly faster than AL in children older than 2 years. Both treatments may cause a relatively asymptomatic LAA with uneventful recovery in a small proportion of children aged 2 years and under.

TRIALS REGISTRATION

Pan African Clinical Trial Registry PACTR201508001188143, 3 July 2015; PACTR201510001189370, 3 July 2015; PACTR201508001191898, 7 July 2015 and PACTR201508001193368, 8 July 2015  http://www.pactr.org .

Provider compliance to artemisinin-based combination therapy at primary health care facilities in the middle belt of Ghana

BACKGROUND

In 2004, Ghana implemented the artemisinin-based combination therapy (ACT) policy. Health worker (HW) adherence to the national malaria guidelines on case-management with ACT for children below 5 years of age and older patients presenting at health facilities (HF) for primary illness consultations was evaluated 5 years post-ACT policy change.

METHODS

Cross-sectional surveys were conducted from 2010 to 2011 at HFs that provide curative care as part of outpatient activities in two districts located in the middle belt of Ghana to coincide with the periods of low and high malaria transmission seasons. A review of patient medical records, HW interviews, HF inventories and finger-pricked blood obtained for independent malaria microscopy were used to assess HW practices on malaria case-management.

RESULTS

Data from 130 HW interviews, 769 patient medical records at 20 HFs over 75 survey days were individually linked and evaluated. The majority of consultations were performed at health centres/clinics (68.3 %) by medical assistants (28.6 %) and nurse aids (23.5 %). About 68.4 % of HWs had received ACT-specific training and 51.9 %, supervisory visits in the preceding 6 months. Despite the availability of malaria diagnostic test at most HFs (94 %), only 39.8 % (241) out of 605 (78.7 %) patients who reported fever were investigated for malaria. Treatment with ACT in line with the guidelines was 66.7 %; higher in <5 children compared to patients ≥5 years old. Judged against reference microscopy, only 44.8 % (107/239) of ACT prescriptions that conformed to the guidelines were "truly malaria". Multivariate logistic regression analysis showed that HW were significantly more likely to comply with the guidelines if treatment were by low cadre of health staff, were for children below 5 years of age, and malaria test was performed.

CONCLUSION

Although the majority of patients presenting with malaria received treatment according to the national malaria guidelines, there were widespread inappropriate treatment with ACT. Compliance with the guidelines on ACT use was low, 5 years post-ACT policy change. The Ghana NMCP needs to strengthen HW capacity on malaria case-management through regular training supported by effective laboratory quality control measures.

The emerging threat of artemisinin resistance in malaria: focus on artemether-lumefantrine

The development of artemisinin resistance in the Greater Mekong Subregion poses a significant threat to malaria elimination. Artemisinin-based combination therapies including artemether-lumefantrine (AL) are recommended by WHO as first-line treatment for uncomplicated Plasmodium falciparum malaria. This article provides a comprehensive review of the existing and latest data as a basis for interpretation of observed variability in parasite sensitivity to AL over the last 5 years. Clinical efficacy and preclinical data from a range of endemic countries are summarized, including potential molecular markers of resistance. Overall, AL remains effective in the treatment of uncomplicated P. falciparum malaria in most regions. Establishing validated molecular markers for resistance and strict efficacy monitoring will reinforce timely updates of treatment policies.

Efficacy of artemisinin-based combination treatments of uncomplicated falciparum malaria in under-five-year-old Nigerian children

The efficacy of 3-day regimens of artemether-lumefantrine and artesunate-amodiaquine were evaluated in 747 children < 5 years of age with uncomplicated malaria from six geographical areas of Nigeria. Fever clearance was significantly faster (P = 0.006) and the proportion of children with parasitemia 1 day after treatment began was significantly lower (P = 0.016) in artesunate-amodiaquine-compared with artemether-lumefantrine-treated children. Parasite clearance times were similar with both treatments. Overall efficacy was 96.3% (95% confidence interval [CI] 94.5-97.6%), and was similar for both regimens. Polymerase chain reaction-corrected parasitologic cure rates on Day 28 were 96.9% (95% CI 93.9-98.2%) and 98.3% (95% CI 96.1-99.3%) for artemether-lumefantrine and artesunate-amodiaquine, respectively. Gametocyte carriage post treatment was significantly lower than pretreatment (P < 0.0001). In anemic children, mean time to recovery from anemia was 10 days (95% CI 9.04-10.9) and was similar for both regimens. Both treatments were well tolerated and are safe and efficacious treatments of uncomplicated falciparum malaria in young Nigerian children.

Monitoring the efficacy and safety of three artemisinin based-combinations therapies in Senegal: results from two years surveillance

Background

Malaria remains a major public health problem in developing countries. Then in these countries prompt access to effective antimalarial treatment such as Artemisinin based-Combination Therapies (ACT) proves to be an essential tool for controlling the disease. In Senegal, since 2006 a nationwide scaling up program of ACT is being implemented. In this context it has become relevant to monitor ACT efficacy and provide recommendations for the Senegalese national malaria control program.

Methods

An open randomized trial was conducted during two malaria transmission seasons (2011 and 2012) to assess the efficacy and safety of three combinations: dihydro-artemisinin-piperaquine (DHAPQ), artemether-lumefantrine (AL) and artesunate-amodiaquine (ASAQ). The primary end point of the study was represented by a PCR adjusted adequate clinical and parasitological response (ACPR) at day 28. Secondary end points included: (i) a ACPR at days 35 and 42, (ii) a parasite and fever clearance time, (iii) ACTs safety and tolerability. The 2003 WHO’s protocol for antimalarial drug evaluation was used to assess each outcome.

Results

Overall, 534 patients were randomized selected to receive, either ASAQ (n = 180), AL (n = 178) or DHAPQ (n = 176). The PCR adjusted ACPR at day 28 was 99.41% for the group ASAQ, while that was 100% in the AL and DHAPQ groups (p = 0.37). The therapeutic efficacy was evaluated at 99.37% in the ASAQ arm versus 100% in AL and DHAPQ arm at day 35 (p = 0.37). At day 42, the ACPR was 99.27% in the ASAQ group versus 100% for both AL and DHAPQ groups, (p = 0.36). No serious adverse event was noted during the study period. Also a similar safety profile was noted in the 3 study groups.

Conclusion

In the context of scaling up of ACTs in Senegal, ASAQ, AL and DHAPQ are highly effective and safe antimalarial drugs. However, it’s remains important to continue to monitor their efficacy.

Trial registration

PACTR 201305000552290.

Open-label trial of three dosage regimens of fixed-dose combination of artemisinin and naphthoquine for treating uncomplicated falciparum malaria in Calabar, Nigeria

BACKGROUND

The use of anti-malarial drug combinations with artemisinin, or with one of its derivatives, is now widely recommended to overcome drug resistance in falciparum malaria. Fixed-dose combination of artemisinin and naphthoquine is a new generation artemisinin combination therapy (ACT) offered as a single dose therapy. The aim of the study was to assess the therapeutic efficacy, safety and tolerability of three dosage schedules of fixed-dose combination of artemisinin (125 mg) and naphthoquine (50 mg) for treating uncomplicated Plasmodium falciparum malaria among adolescents and adults in Calabar, South-east Nigeria.

METHOD

A total of 121 patients aged ≥15 years with uncomplicated P. falciparum malaria were enrolled and randomly assigned to three dosage schedules: (A) 700 mg (four tablets) single dose; (B) 700 mg 12-hourly x two doses; and (C) 1,400 mg (eight tablets) single dose. Patients were observed for 28 days, with clinical, parasitological, and haematological assessments.

RESULTS

A total of 108 patients completed the study. The overall 28-day cure rate was 88.9%. Day 28-cure rates of the three dosage schedules were 85.3%, 93.1% and 88.9% for Group A, B and C respectively. Adverse events were few and mild, the commonest being weakness and headache; there was no serious adverse event.

CONCLUSION

Concerns for emergence of parasite resistance due to the use of artemisinin-naphthoquine as single dose regimen is likely to compromise the usefulness of this potentially important combination treatment. A robust multi-centre trial is recommended to evaluate a three-day regimen with potentials to achieve high cure rates while minimizing the risk of emergence of resistant parasite strains.

Scaling up impact of malaria control programmes: a tale of events in Sub-Saharan Africa and People's Republic of China

This review aims at providing synthetic information with scientific evidence on the trends in the malaria events from 1960 to 2011, with the hope that it will help policy makers to take informed decisions on public health issues and intervention designs on malaria control towards elimination in both Sub-Sahara Africa and in the People's Republic of China by highlighting the achievements, progress and challenges in research on moving malaria from epidemic status towards elimination. Our findings showed that since 1960, malaria control programmes in most countries have been disjointed and not harmonized. Interestingly, during the last decade, the causal factors of the unprecedented and substantial decline in malaria morbidity and mortality rates in most vulnerable groups in these endemic areas are multifaceted, including not only the spread of malaria and its related effects but also political and financial willingness, commitment and funding by governments and international donors. The benefits of scaling up the impact of malaria coverage interventions, improvement of health system approaches and sustained commitment of stakeholders are highlighted, although considerable efforts are still necessary in Sub-Sahara Africa. Furthermore, novel integrated control strategies aiming at moving malaria from epidemic status to control towards elimination, require solid research priorities both for sustainability of the most efficient existing tools and intervention coverage, and in gaining more insights in the understanding of the epidemiology, pathogenesis, vector dynamics, and socioeconomic aspects of the disease. In conclusion, political commitment and financial investment of stakeholders in sustaining the scaling up impact of malaria control interventions, networking between African and Chinese scientists, and their Western partners are urgently needed in upholding the recent gains, and in translating lessons learnt from the Chinese malaria control achievements and successes into practical interventions in malaria endemic countries in Africa and elsewhere.

Risk factors for Plasmodium falciparum hyperparasitaemia in malarious children

Background

Hyperparasitaemia is a feature of childhood severe malaria but there is little information on the risk factors for hyperparasitaemia in malarious children

Methods

The risk factors associated with Plasmodium falciparum hyperparasitaemia, defined as asexual parasitaemia > 250,000/μl, at presentation were evaluated in 3338 malarious children enrolled prospectively between 2008 and 2010 in an endemic area of southwestern Nigeria.

Results

At enrolment, 97 (3%) of 3338 malarious children had hyperparasitaemia. In a multiple regression model, 3 factors were found to be independent risk factors for the presence of hyperparasitaemia at enrolment: an age ≤ 11 years (Adjusted odds ratio [AOR] = 2.85, 95% confidence interval [CI] 1.23-6.61, P = 0.014), fever (AOR = 2.02, 95% CI 1.23-3.29, P = 0.005), and enrolment after year 2008 (AOR = 0.42, 95% CI 0.24-0.73, P = 0.002). Duration of illness ≤ 3 d was associated with increased risk of hyperparasitaemia. There was no association between season and hyperparasitaemia. Compared to non-hyperparasitaemia, hyperparasitaemia was associated with an increased risk of progression to cerebral malaria (P < 0.0001). The risk of progression in hyperparasitaemic children was higher in < 5-year olds (P = 0.02).

Conclusion

Young age and presence of fever are independent risk factors for hyperparasitaemia which is associated with an increased risk of progression to cerebral malaria. The findings have implications for case and community management of childhood hyperparasitaemia and for malaria control efforts in sub-Saharan Africa where severe malaria is relatively common.