Giemsa-stained Thick Blood Smears Research Articles

Imported Malaria in Egypt

Background: With the dramatic increase in international travel among Egyptian people, the risk of malaria importation from malaria-endemic regions threatens the achievement of the malaria elimination goal of Egypt. Patients and methods: Blood samples from 700 patients were collected from different medical laboratories in Egypt from travelers to African endemic areas either Egyptians or foreigners coming to Egypt within previous 8 weeks; during period from January to December 2016. All samples were done by direct microscopic examination of the Giemsa-stained thick and thin blood smears (“gold standard”), as well as the rapid diagnostic test (RDT) (Accurate MAL-w23, Polymed) for feverish cases as a confirmatory test. Results: A total of 25;3.57%(out of 700) imported malaria cases were recorded.P. falciparum (15 cases,60%) and P. vivax (14 cases, 56%) were the two predominant species as well as one case (4%)P ovale. From them 4 cases had mixedP.falciparum and P.vivax and one case had P. falciparum and ovale, The cases were coming from 11 African countries and their distribution was, Sudan,11; Nigeria, 5; Ghana,3; Cameroon,1; Angola,1; Congo,1; Chad,1; Guinea,1; Togo,1; South Africa,1; and Eritrea,1case. RDT was performed for feverish (300) patients and positive results were obtained among 27 cases. Twenty five of them had parasitemia while the other two had history of past infection. Conclusions: Imported malaria infections pose an increasing challenge to the malaria elimination in Egypt. The risk of potential re-introduction of malaria into inland malaria free areas of Egypt should be urgently addressed, also the rapid di­agnostic tests (RDTs), offer a useful tool for rapid diagnosis in suspected cases.

Nested PCR using thick blood smears as source of Plasmodium DNA: an alternative to study archival blood films

The study aimed to evaluate a protocol of nested PCR using archival Giemsa-stained thick blood smears (GTS)as source of Plasmodium DNA. A total of 138 GTS from patients of five municipalities from Pará State (Amazon Region, Brazil) was included in this survey. These samples were classified in three groups (group 1: 85 Plasmodium positive and negative GTS stored in plastic box during five years; group 2: 28 Plasmodium positive and negative GTS stored in wooden box during 10 years; and group 3: 25 Trypanosoma cruzi GTS negative for Plasmodium stored in plastic box during a month) and were submitted to DNA extraction with Chelex-100. Subsequently, extracted DNA samples were quantified and the integrity was verified by electrophoresis. Nested PCR protocol was performed to detect Plasmodium species. The results of nested PCR were compared to microscopy and statistic parameters were calculated by screening test. DNA samples from all groups had acceptable quantity and purity level, but the evaluation of integrity showed 19 degraded samples from group 2. By nested PCR, this group showed very low sensitivity (29.63%) and accuracy (32.14%), while nested PCR for samples from group 1 showed 100% of sensitivity and 97.65% of accuracy. The results of this research showed that samples stored until five years can be useful as Plasmodium DNA source for nested PCR to identify Plasmodium species, being an important alternative to support retrospective studies.

Chloroquine neither eliminates liver stage parasites nor delays their development in a murine Chemoprophylaxis Vaccination model.

Chemoprophylaxis Vaccination (CVac) confers long lasting sterile protection against homologous parasite strains in humans, and involves inoculation of infectious sporozoites (SPZ) under drug cover. CVac using the drug chloroquine (CQ) induces pre-erythrocytic immunity in humans that includes antibody to SPZ and T-cell responses to liver stage (LS) parasites. The mechanism by which CVac with CQ induces strong protective immunity is not understood as untreated infections do not confer protection. CQ kills blood stage parasites, but its effect on LS parasites is poorly studied. Here we hypothesized that CQ may prolong or perturb LS development of Plasmodium, as a potential explanation for enhanced pre-erythrocytic immune responses. Balb/c mice with or without CQ prophylaxis were infected with sporozoite forms of a luciferase-expressing rodent parasite, Plasmodium yoelii-Luc (Py-Luc). Mice that received primaquine, a drug that kills LS parasites, served as a positive control of drug effect. Parasite burden in liver was measured both by bioluminescence and by qRT-PCR quantification of parasite transcript. Time to appearance of parasites in the blood was monitored by microscopic analysis of Giemsa-stained thick and thin blood smears. The parasite load in livers of CQ-treated and untreated mice did not significantly differ at any of the time points studied. Parasites appeared in the blood smears of both CQ-treated and untreated mice 3 days after infection. Taken together, our findings confirm that CQ neither eliminates LS parasites nor delays their development. Further investigations into the mechanism of CQ-induced protection after CVac are required, and may give insights relevant to drug and vaccine development.

Improved Detection of Sleeping Sickness Cases by LED Fluorescence Microscopy: Evidence from a Prospective Multi-Centric Study in the Democratic Republic of the Congo

Background: Confirmatory diagnosis of Trypanosoma brucei gambiense human African trypanosomiasis (HAT) is based on demonstration of parasites by microscopy. However, the sensitivity of routine microscopy methods is very low, and many cases are missed and left untreated. A clinical study was conducted in the Democratic Republic of the Congo to evaluate the accuracy of improved microscopy methods in diagnosis of HAT. These included examination by fluorescence microscopy (FM) of acridine orange (AO) stained smears of whole blood and smears made following a new procedure for concentrating trypanosomes by selective lysis of red blood cells (RBC). Methodology/Principal Findings: Venous blood was collected from 213 HAT cases, 101 HAT suspects and 95 controls and used to determine the accuracy of four microscopy methods: bright field microscopy of Giemsa-stained thick blood smears, FM of AO-stained thick blood smears, FM of AO-stained thick blood smears prepared after RBC lysis and concentration, and FM of AO-stained thin blood smears prepared after RBC lysis and concentration. The sensitivity of FM using thick blood smears stained with AO was 3 times higher than bright field microscopy using Giemsa-stained thick blood smears [19.7% (95% CI: 14.9% - 25.6%) versus 6.1% (95% CI: 3.6% - 10.2%)]. When the RBC lysis and concentration procedure was included, sensitivity of the test was further enhanced to 23.0% (95% CI: 17.9% - 29.1%) with thick blood smears and 34.3% (95% CI: 28.2% - 40.9%) with thin blood smears. Specificity of all four microscopy methods was 100% (95% CI: 96.1% - 100.0%). However, the miniature anion exchange chromatography technique (mAECT) and capillary tube centrifugation (CTC) method remained more sensitive. Conclusions: These new methods have practical advantages, including shorter staining time, ease of demonstration of parasites, and the possibility of archiving slides. They could, therefore, be alternative methods to improve case detection where concentration procedures such as mAECT or CTC are not performed.

Malaria in Hadhramout, a southeast province of Yemen: prevalence, risk factors, knowledge, attitude and practices (KAPs).

BackgroundYemen is a Mediterranean country where 65% of its population is at risk of malaria, with 43% at high risk. Yemen is still in the control phase without sustainable reduction in the proportion of malaria cases. A cross-sectional household survey was carried out in different districts in the southeast of the country to determine malaria prevalence and identify factors that impede progress of the elimination phase.MethodsBlood specimens were collected from 735 individuals aged 1–66 years. Plasmodium species were detected and identified by microscopic examination of Giemsa-stained thick and thin blood smears. A household-based questionnaire was used to collect demographic, socioeconomic and environmental data.ResultsThe overall prevalence of malaria was 18.8% with Plasmodium falciparum as the predominant species (99.3%), with a low rate of Plasmodium vivax detected (0.7%). The infection rate was higher in Al-Raydah and Qusyer districts (21.8%) compared to Hajer district (11.8%). Fifty-two percent of the persons positive for Plasmodium were asymptomatic with low parasite density. The adults had a higher infection rate as compared to children. Univariate analysis identified those whose household’s head are fishermen (OR = 11.3, 95% CI: 3.13 – 40.5) and farmers (OR = 4.84, 95% CI: 1.73 – 13.6) as high-risk groups. A higher number of positive smears were observed in people living in houses with uncemented brick walls (OR = 2.1, 95% CI: 1.32 – 3.30), without access to toilets (OR = 1.6, 95% CI: 1.05 – 2.32), without a fridge (OR = 1. 6, 95% CI: 1.05 – 2.30), or without TV (OR = 1. 6, (95% CI: 1.05 – 2.30). People living in houses with water collection points located less than 200 meters away were also at higher risk of acquiring malaria (OR = 1.6, 95% CI: 1.05 – 2.30). Knowledge about the importance of using insecticide-treated mosquito nets (ITNs) and indoor residual spraying (IRS) for prevention of malaria was 7% and 2%, respectively.ConclusionsSeveral environmental, socioeconomic and behavioral issues were discovered to be the contributing factors to the high prevalence of malaria in southeast Yemen. Novel strategies adapted to the local situations need to be established in order to improve the effectiveness of malaria control.

The epidemiology of malaria in Bursa--2009-2012

Malaria is a common disease in many tropical and subtropical areas, which may threaten life. In this study, we examined the epidemiology of malaria in Bursa province using the data provided by the Province Health Directorate, collected over 2009 to 2012. The data include a total of 29.683 blood samples taken by active and passive surveillance. Giemsa-stained thin and thick blood smears were examined with a 100X oil immersion objective using a standard microscope. A total of 21 (0.07%) malaria cases were detected. Of these, 20 (95.2%) cases were male and 1 (4.8%) case was female, with highest rates occurring in June and September. All of the cases were imported, of whom 10 (47.6%) were caused by Plasmodium vivax and 11 (52.4%) by P. falciparum. All P. falciparum cases were found to be imported cases that traveled to African nations (Côte d'Ivoire, Sudan, Equatorial Guinea, Nigeria, Senegal, Mali, Somalia). Malaria cases were mainly observed in the 15-to-44-year-old range. We believe that these results will lead to better-targeted and more effective malaria control programs.

A rapid sensitive, flow cytometry-based method for the detection of Plasmodium vivax-infected blood cells

BackgroundPlasmodium vivax preferentially infects Duffy-positive reticulocytes and infections typically have few parasite-infected cells in the peripheral circulation. These features complicate detection and quantification by flow cytometry (FC) using standard nucleic acid-based staining methods. A simple antibody-based FC method was developed for rapid parasite detection along with simultaneous detection of other parasite and erythrocyte markers.MethodsClinical samples were collected from patients diagnosed with P. vivax at a district Malaria Clinic in Kanchanaburi, Thailand. One μL of infected blood was washed, fixed, stained with a Plasmodium pan-specific anti-PfBiP antibody conjugated with Alexa Fluor 660, and analysed by FC. Additional primary conjugated antibodies for stage-specific markers of P. vivax for late trophozoite-early schizonts (MSP1-Alexa Fluor 660), late-stage schizonts (DBP-Alexa Fluor 555), and sexual stages (Pvs16) were used to differentiate intra-erythrocytic developmental stages.ResultsThe percentages of P. vivax-infected cells determined by the FC method and manually by microscopic examination of Giemsa-stained thick blood smears were positively correlated by Spearman’s rank correlation coefficient (R 2 = 0.93843) from 0.001 to 1.00% P. vivax-infected reticulocytes.ConclusionsThe FC-based method is a simple, robust, and efficient method for detecting P. vivax-infected reticulocytes.

Plasmodium falciparum Specific IgE, IgG and Anti-GPI IgG Antibodies in Cameroonian Children with Severe and Uncomplicated Malaria

Aims: We investigated the role of antibodies in the pathogenesis of severe malaria in children by measuring and comparing plasma levels of antibodies to glycosyl phosphatidy linositol (GPI) and crude Plasmodium falciparum extract. Study Design: Cross-sectional case-control study. Place and Duration of Study: Five health institutions in two towns and seven primary schools in the South West region of Cameroon between April 2003 and December 2005. Methodology: A total of 649 children including 25, 156 and 233 cases of cerebral malaria (CM), severe malaria anaemia (SMA) and uncomplicated malaria (UM) respectively were recruited from health institutions and 233 apparently healthy controls (HC) from schools using predefined inclusion criteria. Malaria parasitaemia was determined by light microscopy using Giemsa-stained thick blood smears, haemoglobin level using a haemoglobinometer and blood cell count using a haemocytometer. The levels of total IgE,

A Case of Plasmodium ovale wallikeri Infection in a Chinese Worker Returning from West Africa

In contrast to the gradual reduction in the number of locally transmitted malaria cases in China, the number of imported malaria cases has been increasing since 2008. Here, we report a case of a 39-year-old Chinese man who acquired Plasmodium ovale wallikeri infection while staying in Ghana, West Africa for 6 months in 2012. Microscopic examinations of Giemsa-stained thin and thick blood smears indicated Plasmodium vivax infection. However, the results of rapid diagnostic tests, which were conducted 3 times, were not in agreement with P. vivax. To further check the diagnosis, standard PCR analysis of the small-subunit rRNA gene was conducted, based on which a phylogeny tree was constructed. The results of gene sequencing indicated that this malaria is a variant of P. ovale (P. ovale wallikeri). The infection in this patient was not a new infection, but a relapse of the infection from the one that he had contracted in West Africa.

Malaria and helminth co-infection and nutritional status of febrile patients in Southern Ethiopia

Because the mechanisms by which Plasmodium and helminth parasites affect nutritional status are different, these parasites likely have additive effects when they co-exist in a host. This study aimed to compare the prevalence of undernutrition in patients infected with either Plasmodium or helminths and those co-infected with the two types of parasites. Acute febrile patients suspected of having malaria who attended the outpatient clinic at Dore Bafeno Health Center between December 2010 and February 2011 were examined for Plasmodium parasites using Giemsa-stained thick and thin blood smears and for helminths using the thick Kato-Katz method. Nutritional status was determined using anthropometric indices generated from height and weight measurements. Of the 702 patients examined, 34.5% were infected with helminths alone, 12.3% were infected with Plasmodium alone, and 19.4% co-infected with Plasmodium and intestinal helminths. Out of the patients examined, 44.9% were undernourished. The prevalence of undernutrition was not significantly different between those patients not infected with Plasmodium or helminth species and those infected with Plasmodium or helminth species. The differences in the odds of undernutrition were also not significant between patients who were co-infected with different Plasmodium and helminth species and those with single infections with Plasmodium or helminth species in our multivariable logistic regression model adjusted for the confounding effects of age and sex. The prevalence of undernutrition was comparable in patients infected with Plasmodium or helminths alone and those co-infected with Plasmodium and helminths in Dore Bafeno Health Center, Southern Ethiopia. However, further studies are needed in areas of intense transmission where both parasites are endemic to elucidate whether the impact of Plasmodium and helminth co-infection on undernutrition is additive or multiplicative.

AP-1/Fos-TGase2 Axis Mediates Wounding-induced Plasmodium falciparum Killing in Anopheles gambiae

Anopheline mosquitoes are the only vectors of human malaria worldwide. It is now widely accepted that mosquito immune responses play a crucial role in restricting Plasmodium development within the vector; therefore, further dissection of the molecular mechanisms underlying these processes should inform new vector control strategies urgently needed to roll back the disease. Here, using genome-wide transcriptional profiling, bioinformatics, and functional gene analysis, we identify a new axis of mosquito resistance to monoclonal Plasmodium falciparum infections that includes the AP-1 transcription factor Fos and the transglutaminase 2 (TGase2), a cross-linking enzyme with known roles in wound responses. We demonstrate that Fos regulates induction of TGase2 expression after wounding but does not affect expression of the components of the well characterized complement-like system. Silencing of Fos or of TGase2 aborts the wounding-induced mosquito killing of P. falciparum. These results reveal multiple signaling pathways that are required for efficient Plasmodium killing in Anopheles gambiae.

Prevalence of congenital malaria in high-risk Ghanaian newborns: a cross-sectional study

BackgroundCongenital malaria is defined as malaria parasitaemia in the first week of life. The reported prevalence of congenital malaria in sub-Saharan Africa is variable (0 - 46%). Even though the clinical significance of congenital malaria parasitaemia is uncertain, anti-malarial drugs are empirically prescribed for sick newborns by frontline health care workers. Data on prevalence of congenital malaria in high-risk newborns will inform appropriate drug use and timely referral of sick newborns.MethodsBlood samples of untreated newborns less than 1 week of age at the time of referral to Korle Bu Teaching hospital in Accra, Ghana during the peak malaria seasons (April to July) of 2008 and 2010 were examined for malaria parasites by, i) Giemsa-stained thick and thin blood smears for parasite count and species identification, ii) histidine-rich protein- and lactic dehydrogenase-based rapid diagnosis tests, or iii) polymerase chain reaction amplification of the merozoite surface protein 2 gene, for identification of sub-microscopic parasitaemia. Other investigations were also done as clinically indicated.ResultsIn 2008, nine cases of Plasmodium falciparum parasitaemia were diagnosed by microscopy in 405 (2.2%) newborns. All the nine newborns had low parasite densities (≤50 per microlitre). In 2010, there was no case of parasitaemia by either microscopy or rapid diagnosis tests in 522 newborns; however, 56/467 (12%) cases of P. falciparum were detected by polymerase chain reaction.ConclusionCongenital malaria is an uncommon cause of clinical illness in high-risk untreated newborns referred to a tertiary hospital in the first week of life. Empirical anti-malarial drug treatment for sick newborns without laboratory confirmation of parasitaemia is imprudent. Early referral of sick newborns to hospitals with resources and skills for appropriate care is recommended.

The epidemiology of HIV seropositive malaria infected pregnant women in Akure Metropolis, Southwestern Nigeria

Background: HIV increases the risks of malaria in pregnant women, while maternal human immunodeficiency virus (HIV) viral load also facilitates perinatal transmission to neonates. Malaria and HIV coinfection has been shown to exacerbate adverse pregnancy complications. Our study was designed to determine the HIV prevalence of pregnant women at an antenatal clinic in Akure in southwestern Nigeria, investigate the relationship between dual HIV and malaria infection and HIV viral load and CD4+ T cell counts. The study also estimated the risks of adverse pregnancy outcomes in a selected cohort of 74 pregnant women. Materials and Methods: We evaluated the HIV serostatus of 3,225 pregnant women, who attended the antenatal clinic between August 2012 and April 2013. A cohort of 74 pregnant women was selected for the investigation of the relationship between coinfection of HIV and malaria and HIV viral load and CD4+ cell counts. Their HIV status was determined during three trimesters of pregnancy by both HIV-1/2 strips and confirmatory enzyme-linked immunosorbent assay (ELISA) method. Malaria parasitemia was determined by Giemsa-stained thin and thick blood smears. CD4 cell count was by flow cytometry using the CyFlow Counter (Partec, Germany). Viral load estimated by Amplicor HIV-I monitor assay. Results: We found 3.53% prevalence of HIV serostatus among the 3,225 pregnant women who were screened. Forty-four of the 74 subjects were HIV positive and 30 were HIV negative controls. The results show HIV infection among the pregnant women reduced the CD4 cells from a mean of 750 cells/ml for HIV negative women to a mean of 363 cells/ml for HIV seropositive women. Additionally the presence of malaria more than doubled the HIV viral load from a mean of 7,270 ribonucleic acid (RNA) copies/ml for HIV positive women without malaria to 15,148 RNA copies/ml for HIV positive women with malaria. Conclusion: In this study, HIV infection significantly increased risk of acquiring malaria in pregnant women (odds ratio (OR) = 2.27). Dual HIV/malaria infections exacerbated adverse pregnancy outcomes

Asymptomatic Carriage of Plasmodium in Urban Dakar: The Risk of Malaria Should Not Be Underestimated

IntroductionThe objective of this study was to measure the rate of asymptomatic carriage of plasmodium in the Dakar region two years after the implementation of new strategies in clinical malaria management.MethodologyBetween October and December 2008, 2952 households selected in 50 sites of Dakar area, were visited for interviews and blood sampling. Giemsa-stained thick blood smears (TBS) were performed for microscopy in asymptomatic adult women and children aged 2 to 10 years. To ensure the quality of the microscopy, we performed a polymerase chain reaction (PCR) with real time qPCR in all positive TBS by microscopy and in a sample of negative TBS and filter paper blood spots.ResultsThe analysis has concerned 2427 women and 2231 children. The mean age of the women was 35.6 years. The mean age of the children was 5.4 years. The parasite prevalence was 2.01% (49/2427) in women and 2.15% (48/2231) in children. Parasite prevalence varied from one study site to another, ranging from 0 to 7.41%. In multivariate analysis, reporting a malaria episode in 2008 was associated with plasmodium carriage (OR = 2.57, P = 0.002) in women; in children, a malaria episode (OR = 6.19, P<0.001) and a travel out of Dakar during last 3 months (OR = 2.27, P = 0.023) were associated with plasmodium carriage.Among the positive TBS, 95.8% (93/97) were positive by plasmodium PCR. Among the negative TBS, 13.9% (41/293) were positive by PCR. In blood spots, 15.2% (76/500) were positive by PCR. We estimated at 16.5% the parasite prevalence if PCR were performed in 4658 TBS.ConclusionParasite prevalence in Dakar area seemed to be higher than the rate found by microscopy. PCR may be the best tool for measuring plasmodium prevalence in the context of low transmission. Environmental conditions play a major role in the heterogeneity of parasite prevalence within sites.

Assessment of LED fluorescence microscopy for the diagnosis of Plasmodium falciparum infections in Gabon

BackgroundRapid and accurate diagnosis of malaria is central to clinical management and the prevention of drug-overuse, which may lead to resistance development, toxicity and economic losses. So far, light microscopy (LM) of Giemsa-stained thick blood smears is the gold standard. Under optimal conditions the procedure is fast and reliable; nevertheless a gain in speed would be a great advantage. Rapid diagnosis tests are an alternative, although they cost more and give qualitative instead of quantitative results. Light-emitting diode (LED) fluorescence microscopy (ledFM 400 ×, 1000 ×) may offer a reliable and cheap alternative, which can be used at the point of care.MethodsLedFM and conventional fluorescence microscopy (uvFM) were compared to LM in 210 samples from patients with history of fever in the last 24 hours admitted to the Albert Schweitzer Hospital in Lambaréné, Gabon.ResultsSensitivities were 99.1% for ledFM and 97.0% for uvFM, specificities 90.7% for ledFM 400 × and 92.6% for ledFM 1000 × and uvFM. High agreement was found in Bland-Altman-plot and Kappa coefficient (ledFM 1000 ×: 0.914, ledFM 400 × and uvFM: 0.895). The time to diagnosis for both FM methods was shorter compared to LM (LM: 43 min, uvFM: 16 min, ledFM 1000 ×: 14 min, ledFM 400 ×: 10 min).ConclusionledFM is a reliable, accurate, fast and inexpensive tool for daily routine malaria diagnosis and may be used as a point of care diagnostic tool.

Evaluation of the performance of CareStart™ Malaria Pf/Pv Combo rapid diagnostic test for the diagnosis of malaria in Jimma, southwestern Ethiopia

Objective To evaluate the diagnostic performance of CareStart™ Malaria Pf/Pv Combo test relative to microscopy, for the diagnosis of falciparum and vivax malaria in Ethiopia. Methods Two hundred and forty febrile patients visiting the Serbo health center in Jimma zone, southwestern Ethiopia, were involved in this study in 2008. Giemsa-stained thin and thick blood smears were prepared and microscopically examined under a 100× oil immersion microscope objective for Plasmodium species identification and determination of parasitemia respectively. CareStart™ Malaria Pf/Pv Combo test was performed as per the manufacturers’ instruction. Findings The validity of CareStart™ Malaria Pf/Pv Combo test for the diagnosis of Plasmodium was very good with a sensitivity of 95.8%, specificity of 100%, positive predictive value of 100% and negative predictive value of 96%. The test performed equally well for the identification of Plasmodium falciparum and P. vivax. The diagnostic performance of this CareStart™ test is comparable to light microscopy of thin and thick blood smears. Conclusion Although CareStart™ Malaria Pf/Pv Combo test and blood microscopy have comparable diagnostic performance for Plasmodium detection, the CareStart™ test has the added advantage of being simple to interpret, cost-efficient, and hence it is preferable to use this rapid diagnostic test for malaria diagnosis in areas where microscopy is not accessible and during times of malaria epidemics that are observed approximately every 4–5 years in Ethiopia.

Evaluation of the performance of CareStart™ Malaria Pf/ Pv Combo and Paracheck Pf ® tests for the diagnosis of malaria in Wondo Genet, southern Ethiopia

Objective To evaluate the diagnostic performance of CareStart™ Malaria Pf/Pv Combo test relative to microscopy for the diagnosis of falciparum and vivax malaria in Ethiopia. Methods 668 febrile patients visiting two health centers in Wondo Genet, southern Ethiopia, involved in this study in 2008. Giemsa-stained thin and thick blood smears were prepared and microscopically examined under a 100× oil immersion microscope objective for Plasmodium species identification and determination of parasitaemia, respectively. CareStart™ Malaria Pf/Pv Combo test and Paracheck Pf ® test were performed as per the manufacturers’ instruction. Findings The diagnostic validity of CareStart™ Malaria Pf/Pv Combo test for the diagnosis of Plasmodium falciparum were very good with sensitivity of 99.4%, specificity of 98%, positive predictive value of 94.4% and negative predictive value of 99.8%. Sensitivity, specificity, positive predictive value and negative predictive value of the test for the diagnosis of P. vivax were 99.4%, 98.2%, 94.5% and 99.8%, respectively. The diagnostic performance of CareStart™ Malaria Pf/Pv Combo test is comparable to that of Paracheck Pf ® test for the diagnosis of P. falciparum (sensitivity 99.4%, specificity 98.2%). Conclusion Although CareStart™ Malaria Pf/Pv Combo test and Paracheck Pf ® test have comparable diagnostic performance for the diagnosis of P. falciparum, CareStart™ Malaria Pf/Pv Combo test has the added advantage of diagnosing P. vivax. Hence, it is preferable to use CareStart™ Malaria Pf/Pv Combo test for the diagnosis of malaria in areas where microscopy is not accessible and where malaria due to P. falciparum and P. vivax are co-endemic as in Ethiopia.

Comparison of blood smear microscopy to a rapid diagnostic test for &lt;i&gt;in-vitro&lt;/i&gt; testing for &lt;i&gt;P. Falciparum&lt;/i&gt; malaria in Kenyan school children

To compare the diagnostic performance of microscopy using Giemsa-stained thick and thin blood smears to a rapid malaria dipstick test (RDT) in detecting P. falciparum malaria in Kenyan school children. Randomised, controlled feeding intervention trial from 1998-2001. Rural Embu district, Kenya. The area is considered endemic for malaria, with four rainy seasons per year. Chloroquine resistance was estimated in 80% of patients. Children had a spleen rate of 45%. A sample of 515 rural Kenyan primary school children, aged 7-11 years, who were enrolled in a feeding intervention trial from 1998-2001. Percent positive and negative P. falciparum malaria status, sensitivity, specificity and positive and negative predictive values of RDT. For both years, the RDT yielded positive results of 30% in children compared to microscopy (17%). With microscopy as the "gold standard", RDT yielded a sensitivity of 81.3% in 1998 and 79.3% in 2000. Specificity was 81.6% in 1998 and 78.3% in 2000. Positive predictive value was 47.3% in 1998 and 42.6% in 2000, and negative predictive value was 95.6% in 1998 and 94.9% in 2000. Rapid diagnostic testing is a valuable tool for diagnosis and can shorten the interval for starting treatment, particularly where microscopy may not be feasible due to resource and distance limitations.

Evaluation and optimization of membrane feeding compared to direct feeding as an assay for infectivity

BackgroundMalaria parasite infectivity to mosquitoes has been measured in a variety of ways and setting, includind direct feeds of and/or membrane feeding blood collected from randomly selected or gametocytemic volunteers. Anopheles gambiae s.l is the main vector responsible of Plasmodium falciparum transmission in Bancoumana and represents about 90% of the laboratory findings, whereas Plasmodium malariae and Plasmodium ovale together represent only 10%.Materials and methodsBetween August 1996 and December 1998, direct and membrane feeding methods were compared for the infectivity of children and adolescent gametocyte carriers to anopheline mosquitoes in the village of Bancoumana in Mali. Gametocyte carriers were recruited twice a month through a screening of members of 30 families using Giemsa-stained thick blood smears. F1 generation mosquitoes issued from individual female wild mosquitoes from Bancoumana were reared in a controlled insectary conditions and fed 5% sugar solution in the laboratory in Bamako, until the feeding day when they are starved 12 hours before the feeding experiment. These F1 generation mosquitoes were divided in two groups, one group fed directly on gametocyte carriers and the other fed using membrane feeding method.ResultsResults from 372 Plasmodium falciparum gametocyte carriers showed that children aged 4–9 years were more infectious than adolescents (p = 0.039), especially during the rainy season. Data from 35 carriers showed that mosquitoes which were used for direct feeding were about 1.5 times more likely to feed (p < 0.001) and two times more likely to become infected, if they fed (p < 0.001), than were those which were used for membrane feeding. Overall, infectivity was about three-times higher for direct feeding than for membrane feeding (p < 0.001).ConclusionAlthough intensity of infectivity was lower for membrane feeding, it could be a surrogate to direct feeding for evaluating transmission-blocking activity of candidate malaria vaccines. An optimization of the method for future trials would involve using about three-times more mosquitoes than would be used for direct feeding.

Spatial heterogeneity of malaria in Indian reserves of Southwestern Amazonia, Brazil

BackgroundMalaria constitutes a major cause of morbidity in the Brazilian Amazon where an estimated 6 million people are considered at high risk of transmission. Indigenous peoples in the Amazon are particularly vulnerable to potentially epidemic disease such as malaria; notwithstanding, very little is known about the epidemiology of malaria in Indian reservations of the region. The aim of this paper is to present a spatial analysis of malaria cases over a four-year time period (2003–2006) among indigenous peoples of the Brazilian State of Rondônia, southwestern Amazon, by using passive morbidity data (results from Giemsa-stained thick blood smears) gathered from the National Malaria Epidemiologic Surveillance System databank.ResultsA total of 4,160 cases of malaria were recorded in 14 Indian reserves in the State of Rondônia between 2003 and 2006. In six reservations no cases of malaria were reported in the period. Overall, P. vivax accounted for 76.18 of malaria cases reported in the indigenous population of Rondônia. The P. vivax/P. falciparum ratio for the period was 3.78. Two reserves accounted for over half of the cases reported for the total indigenous population in the period – Roosevelt and Pacaas Novas – with a total of 1,646 (39.57%) and 1,145 (27.52%) cases, respectively. Kernel mapping of malaria mean Annual Parasite Index – API according to indigenous reserves and environmental zones revealed a heterogeneous pattern of disease distribution, with one clear area of high risk of transmission comprising reservations of west Rondônia along the Guaporé-Madeira River basins, and another high risk area to the east, on the Roosevelt reserve.ConclusionBy means of kernel mapping, it was shown that malaria risk varies widely between Indian reserves and environmental zones defined on the basis of predominant ecologic characteristics and land use patterns observed in the southwestern Brazilian Amazon. The geographical approach in this paper helped to determine where the greatest needs lie for more intensively focused malaria control activities in Indian reserves in the region. It also provided a reference to assess the effectiveness of control measures that have been put in place by Brazilian public health authorities.