The association of intraleucocytic malaria pigment and disease severity in Papua New Guinean children with severe P. falciparum malaria.

BACKGROUND: Plasmodium falciparum pigment-containing leucocytes (PCLs) are associated with adverse clinical manifestations of severe malaria in African children. However, limited data exist on the association of PCLs in settings outside of Africa. METHODS: Thin films on peripheral blood slides obtained from children ages 6 months-10 y with severe malaria were examined for PCLs. The intraleucocytic pigment data were correlated with clinical phenotypic data such as severe anaemia, metabolic acidosis and coma to determine the association of PCLs with clinical phenotypes of severe malaria and outcome. RESULTS: Of the 169 children with severe P. falciparum malaria confirmed by microscopy, 76% (129/169) had PCLs. Compared with children without PCLs, the presence (adjusted odds ratio [AOR] 3.2 [95% confidence interval {CI} 1.5 to 6.9], p≤0.01) and quantity (AOR 1.0 [95% CI 1.0 to 1.1], p=0.04) of pigment-containing monocytes (PCMs) was significantly associated with severe anaemia, while the quantity of both PCMs (AOR 1.0 [95% CI 1.0 to 1.1], p≤0.01) and pigment-containing neutrophils (AOR 1.0 [95% CI 1.0 to 1.1], p=0.01) was significantly associated with metabolic acidosis. Plasma P. falciparum histidine-rich protein-2 level negatively correlated with the platelet count (r=-0.5, p≤0.01) in patients with PCLs and no PCLs. CONCLUSIONS: In Papua New Guinean children with severe P. falciparum malaria, the presence and quantity of PCLs are predictors of disease severity, severe anaemia and metabolic acidosis.

Contribution of Malaria to Inhospital Mortality in Papua New Guinean Children from a Malaria-Endemic Area: A Prospective Observational Study.

We aimed to identify clinical and laboratory predictors of mortality in children from a malaria-endemic area of Papua New Guinea hospitalized for severe illness. Children aged 0.5-10 years presenting with any WHO-defined feature of severe malarial illness were eligible for recruitment. Each child was assessed with a detailed clinical examination, blood film microscopy, malaria rapid diagnostic testing (RDT), a full blood examination, and blood glucose and lactate concentrations. Clinical care was coordinated by local medical staff in accordance with national guidelines. Daily study assessments were conducted until death or discharge. Other biochemical tests and malaria polymerase chain reaction (PCR) tests were performed subsequently. Logistic regression identified independent predictors of death. Of 787 evaluable children with severe illness, 336 had confirmed severe malaria (microscopy and PCR positive) and 58 (6.6%) died during hospitalization. The independent predictors of mortality were hyperlactatemia (adjusted odds ratio [95% CI]: 2.85 [1.24-6.41], P = 0.01), malnutrition (2.92 [1.36-6.23], P = 0.005), renal impairment (3.85 [1.53-9.24], P = 0.002), plasma albumin (0.93 [0.88-0.98] for a 1 g/L increase, P = 0.004), and Blantyre coma score (BCS) ≤ 2 (10.3 [4.77-23.0] versus a normal BCS, P < 0.0001). Confirmed severe malaria (0.11 [0.03-0.30] versus non-malarial severe illness, P < 0.0001) was independently associated with lower mortality. Although established risk factors were evident, malaria was inversely associated with mortality. This highlights the importance of accurate diagnosis through blood film microscopy, RDTs, and, if available, PCR to both guide management and provide valid epidemiological data.

Ultrasonographic assessment of splenic volume at presentation and after anti-malarial therapy in children with malarial anaemia.

BACKGROUND: Splenic enlargement is a component of the host response to malaria and may also influence the genesis and progression of malarial anaemia. Few cross-sectional and no longitudinal studies have assessed the relationship between splenic volume measured ultrasonographically and haemoglobin concentrations in children with malaria. METHODS: Fifteen Papua New Guinean children with severe malarial anaemia (SMA; haemoglobin<50 g/L) and ten with moderate malarial anaemia (MMA; 51-99 g/L) were recruited. The SMA patients were given intramuscular artemether followed by oral artemisinin combination therapy (ACT), and were transfused one unit of packed cells 0.3-4.0 days post-admission. The MMA patients were treated with ACT. Splenic enlargement (Hackett's grade, subcostal distance and ultrasonographically determined volume) and haemoglobin concentrations were measured on days 0, 1, 2, 3, 7, 14, 28, and 42. RESULTS: Associations between Hackett's grade, subcostal distance and splenic volume were modest (rs≤0.62, P<0.001). Baseline splenic volume was not associated with age or haemoglobin (P≥0.90). Mean splenic volume had fallen by approximately 50% at day 14 in children with MMA (P≤0.011 vs days 0, 1 and 2), but there was no change in the SMA group (P≥0.30). There was no change in haemoglobin in the MMA group during follow-up but a rise in the SMA group to day 7 (P≤0.05 vs days 0, 1, 2, and 3) which paralleled the packed cell volume transfused. CONCLUSIONS: Clinical assessment of splenomegaly is imprecise compared with ultrasonography. Serial splenic volumes and haemoglobin concentrations suggest that the spleen does not influence post-treatment haemoglobin, including after transfusion.

Viral pathogens in children hospitalized with features of central nervous system infection in a malaria-endemic region of Papua New Guinea.

BACKGROUND: Viral central nervous system (CNS) infections are common in countries where malaria is endemic but, due to limited laboratory facilities, few studies have systematically examined the prevalence and clinical consequences of the presence of viruses in cerebrospinal fluid (CSF) from children with suspected CNS infection. METHODS: We performed a prospective study of Papua New Guinean children hospitalized with signs and symptoms of CNS infection. CSF samples from 300 children without proven bacterial/fungal meningitis were analyzed for human herpes viruses (HHV), picornaviruses, influenza, adenoviruses, flaviviruses and bacteria. RESULTS: Fifty-five children (18%) had viral (42), bacterial (20) or both viral and bacterial (7) nucleic acids (NA) identified in their CSF. Human herpes viruses accounted for 91% of all viruses found. The identification of viral or bacterial NA was not associated with any characteristic clinical features. By contrast, malaria was associated with increased identification of viral and bacterial NA and with impaired consciousness, multiple convulsions and age. Malaria was also inversely associated with an adverse outcome. Amongst children with HHV infection, those with HHV-6 and -7 were younger, were more likely have impaired consciousness and had a higher proportion of adverse outcomes than children with CMV. Dengue and enteroviral infections were infrequent. Adenoviral and influenza infections were not identified. CONCLUSION: Infections with HHV-6, HHV-7, dengue and enterovirus have the potential to cause serious CNS disease in young PNG children. However most HHVs in this malaria-endemic setting should be considered to be the result of reactivation from a latent reservoir without clinical sequelae.

Severe anemia in Papua New Guinean children from a malaria-endemic area: a case-control etiologic study.

BACKGROUND: There are few detailed etiologic studies of severe anemia in children from malaria-endemic areas and none in those countries with holoendemic transmission of multiple Plasmodium species. METHODOLOGY/PRINCIPAL FINDINGS: We examined associates of severe anemia in 143 well-characterized Papua New Guinean (PNG) children aged 0.5-10 years with hemoglobin concentration <50 g/L (median [inter-quartile range] 39 [33]-[44] g/L) and 120 matched healthy children (113 [107-119] g/L) in a case-control cross-sectional study. A range of socio-demographic, behavioural, anthropometric, clinical and laboratory (including genetic) variables were incorporated in multivariate models with severe anemia as dependent variable. Consistent with a likely trophic effect of chloroquine or amodiaquine on parvovirus B19 (B19V) replication, B19V PCR/IgM positivity had the highest odds ratio (95% confidence interval) of 75.8 (15.4-526), followed by P. falciparum infection (19.4 (6.7-62.6)), vitamin A deficiency (13.5 (5.4-37.7)), body mass index-for-age z-score <2.0 (8.4 (2.7-27.0)) and incomplete vaccination (2.94 (1.3-7.2)). P. vivax infection was inversely associated (0.12 (0.02-0.47), reflecting early acquisition of immunity and/or a lack of reticulocytes for parasite invasion. After imputation of missing data, iron deficiency was a weak positive predictor (6.4% of population attributable risk). CONCLUSIONS/SIGNIFICANCE: These data show that severe anemia is multifactorial in PNG children, strongly associated with under-nutrition and certain common infections, and potentially preventable through vitamin A supplementation and improved nutrition, completion of vaccination schedules, and intermittent preventive antimalarial treatment using non-chloroquine/amodiaquine-based regimens.

Rapid antigen detection tests for malaria diagnosis in severely ill Papua New Guinean children: a comparative study using Bayesian latent class models.

BACKGROUND: Although rapid diagnostic tests (RDTs) have practical advantages over light microscopy (LM) and good sensitivity in severe falciparum malaria in Africa, their utility where severe non-falciparum malaria occurs is unknown. LM, RDTs and polymerase chain reaction (PCR)-based methods have limitations, and thus conventional comparative malaria diagnostic studies employ imperfect gold standards. We assessed whether, using Bayesian latent class models (LCMs) which do not require a reference method, RDTs could safely direct initial anti-infective therapy in severe ill children from an area of hyperendemic transmission of both Plasmodium falciparum and P. vivax. METHODS AND FINDINGS: We studied 797 Papua New Guinean children hospitalized with well-characterized severe illness for whom LM, RDT and nested PCR (nPCR) results were available. For any severe malaria, the estimated prevalence was 47.5% with RDTs exhibiting similar sensitivity and negative predictive value (NPV) to nPCR (≥96.0%). LM was the least sensitive test (87.4%) and had the lowest NPV (89.7%), but had the highest specificity (99.1%) and positive predictive value (98.9%). For severe falciparum malaria (prevalence 42.9%), the findings were similar. For non-falciparum severe malaria (prevalence 6.9%), no test had the WHO-recommended sensitivity and specificity of >95% and >90%, respectively. RDTs were the least sensitive (69.6%) and had the lowest NPV (96.7%). CONCLUSIONS: RDTs appear a valuable point-of-care test that is at least equivalent to LM in diagnosing severe falciparum malaria in this epidemiologic situation. None of the tests had the required sensitivity/specificity for severe non-falciparum malaria but the number of false-negative RDTs in this group was small.

Features and prognosis of severe malaria caused by Plasmodium falciparum, Plasmodium vivax and mixed Plasmodium species in Papua New Guinean children.

BACKGROUND: Mortality from severe pediatric falciparum malaria appears low in Oceania but Plasmodium vivax is increasingly recognized as a cause of complications and death. The features and prognosis of mixed Plasmodium species infections are poorly characterized. Detailed prospective studies that include accurate malaria diagnosis and detection of co-morbidities are lacking. METHODS AND FINDINGS: We followed 340 Papua New Guinean (PNG) children with PCR-confirmed severe malaria (77.1% P. falciparum, 7.9% P. vivax, 14.7% P. falciparum/vivax) hospitalized over a 3-year period. Bacterial cultures were performed to identify co-incident sepsis. Clinical management was under national guidelines. Of 262 children with severe falciparum malaria, 30.9%, 24.8% and 23.2% had impaired consciousness, severe anemia, and metabolic acidosis/hyperlactatemia, respectively. Two (0.8%) presented with hypoglycemia, seven (2.7%) were discharged with neurologic impairment, and one child died (0.4%). The 27 severe vivax malaria cases presented with similar phenotypic features to the falciparum malaria cases but respiratory distress was five times more common (P=0.001); one child died (3.7%). The 50 children with P. falciparum/vivax infections shared phenotypic features of mono-species infections, but were more likely to present in deep coma and had the highest mortality (8.0%; P=0.003 vs falciparum malaria). Overall, bacterial cultures were positive in only two non-fatal cases. 83.6% of the children had alpha-thalassemia trait and seven with coma/impaired consciousness had South Asian ovalocytosis (SAO). CONCLUSIONS: The low mortality from severe falciparum malaria in PNG children may reflect protective genetic factors other than alpha-thalassemia trait/SAO, good nutrition, and/or infrequent co-incident sepsis. Severe vivax malaria had similar features but severe P. falciparum/vivax infections were associated with the most severe phenotype and worst prognosis.

Lumbar puncture in children from an area of malaria endemicity who present with a febrile seizure.

BACKGROUND: Although routine lumbar puncture (LP) is often recommended as part of the assessment of fever-associated seizures in children, accumulating evidence questions its value and reveals a decrease in its frequency. Our primary hypothesis was that children who present with a single seizure but with no clinical signs of meningism or coma do not require LP as part of initial diagnostic assessment. METHODS: We prospectively followed up 377 children aged 2 months through 10 years who presented with at least 1 fever-associated seizure to Modilon Hospital, Madang, Papua New Guinea, from November 2007 through July 2009. Clinical management was performed by hospital staff according to national pediatric guidelines. RESULTS: Of 188 children with a single seizure and 189 children with multiple seizures, 139 (73.9%) and 154 (81.5%), respectively, underwent a LP as part of their initial assessment. Of the 130 children with a single seizure but no evidence of meningism (ie, neck stiffness, positive Kernig's or Brudzinski's sign, and bulging fontanelle) or coma (Blantyre Coma Score 2), none (95% confidence interval, 0%-3.6%) had proven or probable acute bacterial meningitis, and only 1 patient had viral encephalitis (subacute sclerosing panencephalitis). Eighty-one of these children (62.3%) had a final diagnosis of a simple febrile seizure. Proven or probable acute bacterial meningitis was more common in children with a single seizure and meningism or coma (10; 17.2%) and in those with multiple seizures without or with meningism or coma (2 [2.0%] and 30 [33.7%], respectively). CONCLUSIONS: Initial LP is unnecessary when careful clinical assessment indicates features of a simple febrile seizure.