BackgroundAccurate diagnosis of malaria is important for effective disease management and control. In Cameroon, presumptive clinical diagnosis, thick-film microscopy (TFM), and rapid diagnostic tests (RDT) are commonly used to diagnose cases of Plasmodium falciparum malaria. However, these methods lack sensitivity to detect low parasitaemia. Polymerase chain reaction (PCR), on the other hand, enhances the detection of sub-microscopic parasitaemia making it a much-needed tool for epidemiological surveys, mass screening, and the assessment of interventions for malaria elimination. Therefore, this study sought to determine the frequency of cases missed by traditional methods that are detected by PCR.MethodsBlood samples, collected from 551 febrile Cameroonian patients between February 2014 and February 2015, were tested for P. falciparum by microscopy, RDT and PCR. The hospital records of participants were reviewed to obtain data on the clinical diagnosis made by the health care worker.ResultsThe prevalence of malaria by microscopy, RDT and PCR was 31%, 45%, and 54%, respectively. However, of the 92% of participants diagnosed as having clinical cases of malaria by the health care worker, 38% were malaria-negative by PCR. PCR detected 23% and 12% more malaria infections than microscopy and RDT, respectively. A total of 128 (23%) individuals had sub-microscopic infections in the study population. The sensitivity of microscopy, RDT, and clinical diagnosis was 57%, 78% and 100%; the specificity was 99%, 94%, and 17%; the positive predictive values were 99%, 94%, and 59%; the negative predictive values were 66%, 78%, and 100%, respectively. Thus, 41% of the participants clinically diagnosed as having malaria had fever caused by other pathogens.ConclusionsMalaria diagnostic methods, such as TFM and RDT missed 12–23% of malaria cases detected by PCR. Therefore, traditional diagnostic approaches (TFM, RDT and clinical diagnosis) are not adequate when accurate epidemiological data are needed for monitoring malaria control and elimination interventions.

Background Despite malaria, malnutrition and anaemia being major public-health challenges in Cameroon, very little has been reported on the interaction between these interconnected health determinants. This study therefore sought to investigate the relationship between malaria, anaemia, nutritional and socio-economic status amongst under—ten children living in six localities within two health districts in the North Region of Cameroon. Methods Accordingly, a cross- sectional survey was conducted during the peak malaria season in November 2014, in Pitoa and Mayo-Oulo Health Districts. Three hundred and sixty eight children aged 6months—10 years were enrolled. Structured questionnaires were used to assess socio-economic status. Anthropometric indices were taken using standard methods and nutritional status assessed by calculating Height for Age (HA), Weight for Age (WA) and Weight for Height (WH) z-scores to determine stunting, underweight and wasting respectively. Finger-prick blood samples were used to prepare thin and thick blood smears for microscopy. Whole blood was collected to determine the PCV and blood spots on filter paper were used to extract plasmodium DNA for speciation by PCR. Results Overall prevalence rates of malaria, malnutrition and anaemia were 32.9%, 54.1% and 20.6% respectively. Stunting, underweight and wasting were detected in 56.9%, 63.5% and 34.8% of the children respectively. There was a significant association between malaria and malnutrition [OR = 1.89, (95% CI: 1.12–3.19); (p = 0.017)]. Malnutrition was also strongly associated with malaria status [OR = 2.07, (95% CI: 1.22–3.53); (p = 0.007)]. The prevalence rates of mild, moderate and severe anaemia were 8.1%, 9.2% and 3.3% respectively. Both malaria status and anaemia correlated with development index [OR = 0.75, (95% CI: 0.58–0.99); (p = 0.042)] and [OR = 1.45, (95% CI: 1.05–2.00); (p = 0.023)] respectively. Conclusion Our findings show a synergistic relationship between malaria and malnutrition. Effective collaboration between malaria control and nutrition intervention programmes is essential for proper case management and improved socio-economic status.

Background. Human immunodeficiency virus (HIV) infection reduces placental transfer of antibodies from mother to the fetus for many antigens; however, conflicting data exist for transfer of immunoglobulin G (IgG) to malarial antigens. The mechanism(s) underlying reduced placental transfer is unknown.Methods. Levels of maternal and cord total IgG, IgG subclasses, and cord-to-mother ratios (CMRs) were measured in 107 mother-cord pairs to 3 malarial antigens: circumsporozoite protein (CSP), apical membrane antigen 1 (AMA-1), merozoite surface protein 1 (MSP-1), and tetanus toxoid C-fragment (TTc).Results. Immunoglobulin G levels to CSP and TTc were lower in HIV+ mothers, and cord IgG to CSP, MSP-1, and TTc were significantly lower in neonates born to HIV+ mothers (all P values <.05). The prevalence of mothers with hypergammaglobulinemia was significantly higher among HIV+ women (68%) compared with HIV− mothers (8%) (P < .0001). Maternal hypergammaglobulinemia was associated with reduction in transplacental transfer of antibodies to CSP (P = .03), MSP-1 (P = .004), and TTc (P = .012), and CMRs <1 were found for MSP-1 (odds ratio [OR] = 6.5), TTc (OR = 4.95), and IgG1 to CSP (OR = 3.75, P = .025) in statistical models adjusted for maternal IgG.Conclusions. Data confirmed that HIV infections are associated with lower cord antibody levels to malarial antigens and that hypergammaglobulinemia may contribute to reduced antibody transfer.

Malaria endemicity in Cameroon greatly varies according to ecological environment. In such conditions, parasitaemia, which is associated with fever, may not always suffice to define an episode of clinical malaria. The evaluation of malaria control intervention strategies mostly consists of identifying cases of clinical malaria and is crucial to promote better diagnosis for accurate measurement of the impact of the intervention. We sought out to define and quantify clinical malaria cases in children from three health districts in the Northern region of Cameroon. A cohort study of 6,195 children aged between 6 and 120 months was carried out during the raining season (July to October) between 2013 and 2014. Differential diagnosis of clinical malaria was performed using the parasite density and axillary temperature. At recruitment, patients with malaria-related symptoms (fever [axillary temperature ≥ 37.5°C], chills, severe malaise, headache, or vomiting) and a malaria positive blood smear were classified under clinical malaria group. The malaria attributable fraction was calculated using logistic regression models. Plasmodium falciparum was responsible for over 91% of infections. Children from Pitoa health district had the highest number of asymptomatic infections (45.60%) compared to those from Garoua and Mayo Oulo. The most suitable cut-off for the association between parasite densities and fever was found among children less than 24 months. Overall, parasite densities that ranged above 3,200 parasites per μl of blood could be used to define the malaria attributable fever cases. In groups of children aged between 24 and 59 months and 60 and 94 months, the optimum cut-off parasite density was 6,400 parasites per μl of blood, while children aged between 95 and 120 months had a cut-off of 800 parasites per μl of blood. In the same ecoepidemiological zone, clinical malaria case definitions are influenced by age and location (health district) and this could be considered when evaluating malaria intervention strategies in endemic areas.

BackgroundSampling of saliva for diagnosing Plasmodium falciparum infections is a safe, non-invasive alternative to sampling of blood. However, the use of saliva presents a challenge because lower concentrations of parasite DNA are present in saliva compared to peripheral blood. Therefore, a sensitive method is needed for detection of parasite DNA in saliva. This study utilized two recently reported “ultra-sensitive” PCR assays based on detection of the P. falciparum mitochondrial cox3 gene and the multi-copy nuclear varATS gene. The ultra-sensitive assays have an advantage over standard 18S rRNA gene-based PCR assay as they target genes with higher copy numbers per parasite genome. Stored saliva DNA samples from 60 Cameroonian individuals with infections previously confirmed by 18S rRNA gene PCR in peripheral blood were tested with assays targeting the cox3 and varATS genes.ResultsOverall, the standard 18S rRNA gene-based PCR assay detected P. falciparum DNA in 62% of the stored saliva DNA samples, whereas 77 and 68% of the samples were positive with assays that target the cox3 and varATS genes, respectively. Interestingly, the ultra-sensitive assays detected more P. falciparum infections in stored saliva samples than were originally detected by thick-film microscopy (41/60 = 68%). When stratified by number of parasites in the blood, the cox3 assay successfully detected more than 90% of infections using saliva when individuals had > 1000 parasites/μl of peripheral blood, but sensitivity was reduced at submicroscopic parasitemia levels. Bands on electrophoresis gels were distinct for the cox3 assay, whereas faint or non-specific bands were sometimes observed for varATS and 18S rRNA that made interpretation of results difficult. Assays could be completed in 3.5 and 3 h for the cox3 and varATS assays, respectively, whereas the 18S rRNA gene assays required at least 7 h.ConclusionsThis study demonstrates that a PCR assay targeting the cox3 gene detected P. falciparum DNA in more saliva samples than primers for the 18S rRNA gene. Non-invasive collection of saliva in combination with the proposed cox3 primer-based PCR assay could potentially enhance routine testing of P. falciparum during disease surveillance, monitoring, and evaluation of interventions for malaria elimination.Electronic supplementary materialThe online version of this article (10.1186/s41182-018-0100-2) contains supplementary material, which is available to authorized users.