MalariaWorld journal最新文献

Background: In Nigeria, decline in the sensitivity of Plasmodium falciparum to Artemisinin Combination Therapy (ACT) has prompted the unofficial use of chloroquine (CQ) for self-medication. This study was designed to determine the prevalence and distribution of CQ resistant/susceptible alleles of CQ resistance transporter (Pfcrt) and P. falciparum multidrug resistance gene 1 (Pfmdr1) in view of the possible re-introduction of CQ for malaria treatment.

Materials and methods: Four hundred and sixty six (466) P. falciparum positive samples were randomly collected from five states of northwest Nigeria. The samples were amplified using RT- PCR at codon 76 for Pfcrt and codon 86 for Pfmdr1. Data was analysed using chi-square, odds ratios and paired t-tests.

Results: Drug susceptible alleles (N86) were most prevalent in the study population (47.9%; 223/466), followed by the drug resistance alleles 86Y (28.3%; 132/466), followed by the drug susceptible alleles K76 (17.4%; 81/466), the resistant alleles 76T (12.4%; 58/466) and finally the mixed infection mutation K76T (3.6%; 17/466). Differences between the distributions of the Pfmdr1 and Pfcrt alleles were significant (P<0.05). There were significant differences (P<0.05) between N86 and 86Y alleles, but no significant differences between K76 and 76T alleles, including the prevalence of the various alleles across the different age groups.

Conclusion: The results of this study suggest the possibility of (re)introducing CQ for malaria treatment in north-western Nigeria and provide insight in the genetic background of P. falciparum in the study area.

Background: Antimalarial drug-resistant Plasmodium falciparum strains have been a major obstacle to the global efforts of controlling and eliminating malaria. The hope of reintroducing chloroquine for the treatment of uncomplicated malaria follows recent reports on decreases in the prevalence of chloroquine-resistant P. falciparum in several countries and recently, its total disappearance in Malawi and Zambia. In Nigeria, the discontinued use of chloroquine for malaria treatment was officially announced in 2005. A few available reports have shown a persistent high prevalence of the major biomarker of chloroquine resistance in southwest Nigeria. However, information on its prevalence in rural and urban areas is scanty. We investigated possible factors associated with the prevalence of a biomarker for chloroquine-resistance in Ogun State, southwest Nigeria.

Materials and methods: Parasite DNA was extracted from dried blood spots collected by finger-prick in malaria symptomatic and asymptomatic subjects attending the urban-based State General Hospital and a rural-based Primary Health Centre. A structured questionnaire was used to collect data on malaria/fever treatment history. Nested Polymerase Chain Reaction (PCR) followed by Restriction Fragment Length Polymorphisms (RFLP) analysis was used to detect mutations in the P. falciparum chloroquine resistance transporter (Pfcrt).

Results: Of the 243 participants recruited for this study, 56 were found to harbour P. falciparum parasites, of which 62.5% (35/56) showed symptoms of malaria. Prevalence of P. falciparum chloroquine-resistant strains (Pfcrt K76T) was 69.6%. The prevalence of Pfcrt K76T recorded in the rural area (91.7%) was significantly higher (P<0.05) than that in the urban area (53.1%). There was no correlation between prevalence of chloroquine-resistant strains and malaria symptoms in the rural area. However, prevalence of chloroquine-resistant strains was significantly higher in malaria-symptomatic subjects from the urban area.

Conclusions: Drug-resistant P. falciparum strains recorded in the rural area were associated with self-medication and patronage of drug vendors who continue to sell chloroquine. These findings present the importance of continuous surveillance of biomarkers indicating drug resistance especially now that antimalarial drug resistance is a threat to malaria eradication.

Background: Eave tubes are novel mosquito control devices that help to protect households against malaria vectors and other mosquitoes. They are installed in the upper walls of human habitations after the eaves have been closed. Mosquitoes trying to enter through these tubes are intercepted by electrostatic netting that can be treated with a variety of insecticides. Using video, mosquito behaviour and duration of contact with netting in eave tubes was recorded and analysed to assess contamination with insecticides under semi-field and field conditions.

Materials and methods: Off-the-shelf action cameras were used to observe behaviour of mosquitoes in eave tubes near Ifakara, Tanzania. In an experimental hut in a screen house, we observed Anopheles arabiensis females on electrostatic eave tube netting treated with bendiocarb powder or with Beauveria bassiana spores, both in comparison to untreated netting. In village houses that had been equipped with eave tubes we observed the behaviour of wild mosquitoes towards electrostatic netting treated with bendiocarb. Results were evaluated using a short-contact assay (5 second exposure).

Results: In the semi-field setup, the median contact time of An. arabiensis on bendiocarb-powdered eave tube nets was 276.4 sec (n=56), compared to 26.3 sec on the control (n=59). Of all the mosquitoes observed on the treated net, 94.6% had contact times of more than 5 seconds on the bendiocarb-powdered netting. The median time on nets powdered with B. bassiana spores was 34.4 sec (n=26), compared 37.1 sec in the untreated control (n=22). 88.5% of the mosquitoes spent more than 5 seconds on the treated nets. In the field we recorded 106 individual mosquitoes of unknown species inside tubes. They spent a median time of 70.9 sec on the bendiocarb-treated netting, with 90.6% remaining there for more than 5 seconds.

Conclusions: We have found no indication that the behaviour of mosquitoes on electrostatic eave tube netting, treated either with bendiocarb powder or with B. bassiana spores, interferes with successful transfer of lethal doses of these insecticidal actives. The videographic set-up used in this study is simple, sturdy and reliable enough to observe and analyse mosquito behaviour under field conditions.

Background: Initiation of specific antimalarial treatment within 24 hrs of fever onset at home and before presentation to the hospital is one of the strategies to reduce mortality from malaria in sub-Saharan Africa. In order to determine whether this strategy is being implemented we describe the use and factors associated with the use of pre-hospital medications among children admitted with malaria in one of the tertiary hospitals in Uganda.

Materials and methods: Use of pre-hospital medications was assessed in 205 children aged 6-59 months and diagnosed with malaria at admission in Mulago hospital. Data were obtained on the type, source, and dose adequacy of medicines used before presentation to the hospital as well as the socio-demographical characteristics of the children. The proportion of children using pre-hospital medication was determined and logistic regression analysis used to determine factors associated with use of pre-hospital medication.

Results: Overall, 147/205 (72%) of the children were given some medication for their illness before presentation to the hospital. The common pre-hospital medicines used were paracetamol (107/147, 72.8 %) and antimalarial medicines (91/147, 61.9 %). Antibiotics were used in only 12 (8.2 %) of the cases. The majority (62/91, 68%) of the cases got medicines from a health facility but only 41/91 (45%) received an adequate dose. Having fever for more than three days was significantly associated with use of pre-hospital medicines (OR = 2.2; 95% CI 1.12-4.35; p = 0.02).

Conclusions: The pre-hospital use of medicines is common amongst children presenting with malaria to this tertiary Ugandan hospital. The practice is, however, associated with use of inadequate doses of antimalarials and delay in presentation to the hospital. More effort is therefore needed to educate communities on the importance of proper home management of malaria.

Background: During pregnancy, malaria poses a great health risk to both mother and foetus. In Kenya, to prevent and control infections, mothers receive intermittent preventive treatment during pregnancy (IPTp) and are provided with a bednet (ITN). Uptake of these control strategies, however, is not optimal. In Kajiado County, for instance, only ITNs are given to pregnant women, without IPTp. We assessed utilisation of health facilities and WHO-recommended maternal malaria control strategies in Kajiado County.

Materials and methods: A total of eleven health facilities were recruited, in which 6899 pregnant women were divided in three groups. Group 1 were women attending a clinic and used ITNs, group 2 did not attend a clinic but used ITNs and group 3, which did neither. 86% Of deliveries were assessed; 84% of these in clinics and 16% at home. Throughout pregnancy, data on abortion and premature births were collected. Upon delivery, data on stillbirths, birth weight and neonatal mortality was noted. Mother's cord and placental blood was examined for malaria parasites and parasitaemia using microscopy; haemoglobin levels were determined.

Results: 86% Of the women visited a health facility, 97% used an ITN. Only 3% went without visits or bednet usage. Although the number of cases was low, attending a clinic and using a bednet increased maternal Hb and reduced maternal mortality. Use of nets decreased maternal malaria cases and mortality due to malaria whilst maternal Hb increased. Across the study groups, infant outcomes improved, with fewer abortions, premature births, still births, neonatal mortality and an increase in mean body weight at birth.

Conclusion: Women should be sensitised to visit clinics and use ITNs for better maternal and new-born health outcomes.

Background: Microscopic diagnosis of Giemsa-stained thick and thin blood films has remained the standard laboratory method for diagnosing malaria. High quality performance of microscopists that examine blood slides in health facilities remains critically important.

Materials and methods: A cross-sectional study was conducted to assess the performance of 107 malaria microscopists working at 23 malaria rechecking laboratories in Ethiopia. A set of 12 blood film slides was distributed to each microscopist. Data was collected and exported to SPSS version 20 for analysis. Chi-square, sensitivity, specificity, percent agreement, and kappa scores were calculated to assess performance in detecting and identification of Plasmodium species.

Results: The mean age of the participants was 30 ± 5 yrs and most of them (54; 50.5%) were working at regional reference laboratories. Overall, the sensitivity of participants in detecting and identifying malaria parasite species was 96.8% and 56.7%, respectively. The overall agreement on detection and identification of malaria species was 96.8% (Kappa = 0.9) and 64.8% (Kappa = 0.33), respectively. The least accurately identified malaria parasite species was P. malariae (3/107; 2.8%) followed by P. ovale (35/107; 32.7%). Participants working at hospital laboratories had the highest percentage (72.3 %, Kappa=0.51) of accurate species identification. Study participants that had participated in malaria microscopy and quality assurance trainings were significantly better at quantifying parasite densities (P<0.001).

Conclusion: The accuracy of parasite identification and quantification differed strongly between participants and expert microscopists. Therefore, regular competency assessment and training for malaria microscopists should be mandatory to assure proper diagnosis and management of malaria in Ethiopia.

Background: Asymptomatic malaria parasitaemia remains an effective transmission pool for malaria during pregnancy, which can result in placenta parasitaemia and adverse pregnancy outcomes. This study examined asymptomatic malaria parasitaemia among pregnant women in the antenatal clinic in General Hospital, Nassarawa-Eggon, Nasarawa State, Nigeria.

Materials and methods: A cross-sectional hospital based survey was carried out among 242 apparently healthy pregnant women presenting for booking in an antenatal clinic between June and August 2014. An interviewer-administered semi-structured questionnaire was used to obtain information on socio-demographic data and possible risk factors for asymptomatic malaria parasitaemia. These women should not have taken antimalarial medicines two weeks prior to the interview. Microscopy was used to identify malaria parasites and haemoglobin levels were estimated. Data was analysed using Epi Info 3.5.3. Descriptive statistics such as means, standard deviations, proportions, and range were used to summarise the data and the Chi square test was used to test association between categorical explanatory variables and outcome variables.

Results: Mean age (± SD) was 25.5 ± 5.5 years, 118 (48.8%) of the women were in the 25-34 years age group, while 153 (63.2%) were multigravidae. Asymptomatic Plasmodium falciparum infection was found in 55 women (22.7%; 95% CI: 18.0-28.7%) Among these, 36 (65.5%) were anaemic [OR: 2.0, CI: 1.1-3.8]. Long lasting insecticidal net (LLIN) was not used by 17 (30.9%) of the respondents. Younger age group (below 25 years) [AOR: 2.4, CI: 1.2-4.9] and non-usage of LLIN [AOR: 2.4, CI: 1.1-5.1] were significant predictors of asymptomatic malaria parasitaemia.

Conclusion: Asymptomatic malaria parasitaemia is a health challenge among pregnant women, especially in the younger age group and can predispose them to maternal anaemia. The supply and appropriate use of LLIN should be intensified.

Background: Establishment of an in vitro model to study placental malaria is essential for understanding the biology and pathogenesis of placental malaria. We defined experimental variables for obtaining responses of BeWo cells to placental binding Plasmodium falciparum infected erythrocytes (IE, CS2 parasites).

Materials and methods: Experimental variables included i) concentration of forskolin, a cyclic adenosine monophosphate inducer important in the induction of syncytialisation of BeWo, ii) suitable period of incubating BeWo with forskolin, and iii) ratio of IE to BeWo cells and length of incubation to induce physiological changes in BeWo cells, including the vasculogenic factors vascular endothelial growth factor A (VEGFA), endoglin, and angiopoietin-2; an anti-angiogenic factor (inhibin A); a regulator of cell growth, mammalian target of rapamycin (mTOR); a chemokine (IL-8); and the cytokine macrophage inhibition factor. The human hormone, chorionic gonadotrophin was used as a marker for syncytialisation.

Results: We showed that 72 hrs incubation of BeWo with 10 μm forskolin resulted in higher levels of syncytialisation and hCG secretion. Overall, the best condition was to co-culture syncytialised BeWo with a 10:1 ratio of IE for 48 hours. Under these conditions, when co-cultured with IE, BeWo produced increased amounts of IL-8 (p=0.0001), VEGF (p=0.001) and endoglin (p=0.001).

Conclusion: The model can be used to evaluate the impact of IE, inflammatory cytokines and other factors associated with placental malaria on syncytiotrophoblast function.

Background: We evaluated the association between the use of intermittent preventive treatment with sulphadoxine-pyrimethamine (IPTp-SP) on pregnancy outcomes among women who delivered at a secondary hospital in Nsukka, Enugu State, Nigeria.

Materials and methods: Relevant obstetric data (e.g. IPTp-SP use), matched against pregnancy outcome data such as delivery method, stillbirth, maternal haematocrit test results and babies' birth weights, were collected retrospectively from antenatal care (ANC) case files of women who delivered within a one-year period (2013).

Results: The prevalence of adverse pregnancy outcomes recorded out of the 500 ANC case files analysed were: low birth weight (LBW) 3.6% (15), anaemia 54.3% (114), caesarean section 31.6% (156) and stillbirth 3.6% (67). A total of 342 (68.4%) of the women received IPTp-SP during ANC and the receipt of IPTp-SP was significantly associated with reductions in the following events: LBW [OR = 0.26, 95% CI = 0.09 - 0.75], moderate anaemia [OR = 0.33, 95% CI = 0.17 - 0.63], caesarean section [OR = 0.36, 95% CI = 0.24 - 0.53] and stillbirth [OR = 0.10, 95% CI = 0.06 - 0.18].

Conclusion: In this area of high malaria transmission we demonstrated significant reductions in unfavourable maternal and infant health outcomes when using IPT-SP.

Background: Malaria is the most common life-threatening infectious disease among travellers and chemoprophylaxis is recommended. The overall effectiveness, medication types and cost of malaria chemoprophylaxis in Accra are not well documented. This study investigated the use of chemoprophylaxis for malaria prevention in air travellers departing from Kotoka International Airport (KIA) in Accra, Ghana.

Materials and methods: A cross-sectional study was conducted in the departure lounge of the KIA between February and May 2012. A total of 424 respondents voluntarily completed a semi-structured questionnaire, which included socio-demographic characteristics, duration of stay, nationality, country of permanent residence, chemoprophylaxis used, number of doses missed, cost and side effects experienced, and cost of treatment.

Results: The mean age of respondents was 37 ± 0.84 years with a male:female ratio of 1.2:1.The mean duration of stay in Ghana was 47.9 days [SD 56.8] and 73.5% had made one trip to the country in the preceding year. Of the respondents, 50.7% were from Europe, 24.1% from North America and 17.5% from Africa. The most popular malaria prevention method used was prophylactics (37%) with atovaquone/proguanil used most frequently (34.9%), followed by mefloquine (11.6%) and doxycycline (7.8%). Compliance was high: 73.8% of respondents did not miss a single dose. The most commonly reported side effects were dreams, abdominal discomfort and headaches. Malaria incidence was 7.1% with 80% of them receiving treatment in a hospital or clinic; incurring a cost of up to $30 to treat a person.

Conclusions: Most air travellers from Accr a take atovaquone/pr oguanil. Malaria incidence was low and most travellers were compliant with their chemoprophylaxis with very few side effects. The cost of chemoprophylaxis is low and is thus recommended for all travellers to Accra, Ghana.