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The MalariaWorld Journal

Research: Household ownership and use of insecticide-treated bednets among school children in Ibadan, Oyo State, Nigeria

July 3, 2016 - 10:06 -- MalariaWorld Journal
Author(s): 
Justina U. Onwuka, Joshua O. Akinyemi, IkeOluwapo O. Ajayi
Reference: 
MWJ2016, 7, 9
 
This study was conducted to explore school children’s report of household ownership and use of ITNs in Oyo State, Nigeria. A cross-sectional survey was conducted. A three-stage sampling technique was used to select 611 pupils from 15 out of 88 primary schools. Information on pupils’ socio-demographics, report of household ownership and use of ITNs were obtained using a semi-structured interviewer-administered questionnaire. Data was analysed using descriptive statistics and Chi-square tests at 5% level of significance. Respondents’ mean age was 10.5±1.7 yrs; 52.7% were females, 84.6% were Yoruba and 65.3% lived with children below 5 yrs of age in their households. Most of the respondents (81.7%) reported household ownership of at least one ITN. The majority (76.4%) obtained nets through mass distribution campaigns. Most of the respondents (89%) reported use of ITNs by a household member the night preceding the survey. More than half of the respondents (51.6%) reported ITN use by children below 5 yrs of age. Class was significantly associated with reported household ownership of ITNs (χ2= 9.217, p <0.010). The majority of the pupils reported household ownership and use of ITNs. They should be considered a potential source of information in monitoring and evaluation activities related to ITN ownership and use.

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Research: Larval environment influences vector competence of the malaria mosquito Anopheles gambiae

June 29, 2016 - 09:34 -- MalariaWorld Journal
Author(s): 
Antoine M.G. Barreaux, Priscille Barreaux, Kevin Thievent, Jacob C. Koella
Reference: 
MWJ2016, 7, 8
 
While environmental factors such as temperature can influence the vector competence of mosquitoes directly, for example by affecting the longevity of the mosquito and the development of the malaria parasite they may also have an indirect impact on the parasite’s transmission. By influencing larval development, they may affect the adult traits that are important for the parasite’s development and transmission. We studied the influence of two larval environmental factors, food availability and temperature, on the probability that mosquitoes infected with the malaria parasite survived to harbour sporozoites in their salivary glands. Anopheles gambiae larvae were reared at 21oC, 25oC or 29oC, and fed either a standard larval diet or half of it. Adults could blood feed on mice harbouring the infectious gametocytic stage of Plasmodium berghei ANKA transformed with green fluorescent protein (GFP). Survival was assessed every 24 hrs up to 21 days post infection, when surviving mosquitoes were dissected to check the salivary glands for sporozoites with a fluorescent microscope sensitive to GFP. Using a binomial GLM we analysed ‘vector competence’, i.e. if mosquitoes survived until dissection and harboured sporozoites in their salivary glands. Vector competence dropped by about a third if we fed larvae half the standard food regime. The effect of temperature during the larval period depended strongly on the food regime. At low food, increasing temperature from 21oC to 29oC increased vector competence from about 0.18 to 0.48, whereas at standard food, vector competence dropped from about 0.67 at 21oC to 0.56 at 29oC. Thus, perceptions and models about the role of environmental change on the transmission of malaria should include how the environment changes adult life-history by influencing larval development.

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Research: Prevalence of submicroscopic Plasmodium falciparum infections in asymptomatic children in low transmission settings in Bagamoyo, Tanzania

June 17, 2016 - 16:38 -- MalariaWorld Journal
Author(s): 
Deborah Sumari, Joseph Mugasa, Majige Selemani, Seif Shekalaghe, Kefas Mugittu, Paul Gwakisa
Reference: 
MWJ 2016, 7, 6
 
Falciparum malaria in endemic areas continues to occur in asymptomatic cases, which contribute to the persistence of transmission as well as the size of the parasite reservoirs. Recent successes in malaria control have resulted in renewed interest in malaria eradication and identification of the human infectious reservoir is essential for this. In this study, we evaluated prevalence of microscopic and submicroscopic gametocytes that were obtained from asymptomatic primary school children from Bagamoyo rural in Tanzania. Samples were collected from 501 asymptomatic primary school children (6-14 years of age) from 7 villages in Bagamoyo district. Participants were screened for malaria in the field using RDT, and samples were brought to the laboratory for microscopy and molecular analysis. Parasite density was determined by microscopy, and gametocyte carriage identification was performed by RT-qPCR targeting gametocyte-specific genes. Asymptomatic infection was found to be 45.1% (95%: CI=40.7-49.6) by RT-qPCR, followed by RDT, 14.2% (95%: CI=11.2-17.5) and microscopy 6.8% (95%: CI=4.7-9.4). Parasite prevalence by microscopy was 12% (23/191) in boys compared to 3.6% (11/310) in girls (p<0.001). Gametocytes were detected in 12.6% (226/501) of the asymptomatic school children by RT-qPCR compared to only 0.8% (4/501) of the children by microscopy (P=0.008). Asymptomatic infection and submicroscopic gametocyte carriage were high in the study area. The detection of asymptomatic cases with circulating submicroscopic P. falciparum gametocytes in school children indicates that these form a substantive gametocyte reservoir that sustains malaria transmission. Asymptomatic carriers and submicroscopic infections should therefore be considered when implementing elimination strategies of the disease.

 

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Research: Comparison of malaria diagnostic methods in four hospitals in the Volta region of Ghana

June 10, 2016 - 06:41 -- MalariaWorld Journal
Author(s): 
Bismarck Dinko, Reuben Ayivor-Djanie, James Abugri, Eric Agboli, Gideon Kye-Duodu, Senyo Tagboto, John Tampuori, Festus Adzaku, Fred N. Binka, Gordon A. Awandare
Reference: 
MWJ2016, 7, 5
 
We compared diagnostic methods and tested the sensitivities of different malaria diagnostic methods against PCR.
 Study participants from four hospitals with a suspicion of malaria donated finger-prick blood for RDT and blood film examination. In addition, a blood spot was collected for PCR analysis, prior to treatment. Retrospective species-specific PCR was performed on all samples collected. Using PCR we found an overall malaria prevalence of 39% among the 211 evaluable blood spots (83/211) and this ranged between 6-61% across the four hospitals. Of the 164 participants with RDT data, malaria prevalence was 57% (94/164), ranging from 3-100% from the four hospitals. Microscopy was the least sensitive with a parasite prevalence of 21% (25/119) of the evaluable 119 participants, varying from 9 to 35% across three health facilities. By comparison, we found the sensitivities and specificities of RDT results when compared to PCR to be slightly higher than microscopy compared to PCR. These were 56.4% versus 41.7% and 90% versus 81.9%, respectively, but generally lower than expected. Ninety-five percent of the PCR-detected infections were P. falciparum, while 4% were mixed species infections of P. falciparum and P. malariae, with the remaining being a mono-infection of P. malariae. While using PCR as a gold standard, we found RDT to be more reliable in diagnosing malaria than microscopy. In addition, a majority of malaria-treated cases were not supported by PCR diagnosis, leading to possible overtreatment. Pragmatic strategies are needed to ensure suspected malaria cases are accurately diagnosed before treatment.

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Research: ABO/Rhesus blood group systems and malaria prevalence among students of the University of Dschang, Cameroon

April 14, 2016 - 08:22 -- Open Access
Author(s): 
Roland Bamou, Silas L. Sevidzem
Reference: 
MWJ2016, 7, 4

 

A study was carried out on students of the University of Dschang, Cameroon, to examine the relationship between ABO blood group, rhesus factor and prevalence of Plasmodium falciparum infection. Blood group and rhesus factor were typed by agglutination using antisera while malaria infection was determined using Rapid Diagnostic Test CareStart malaria HRP2 pf. Out of 620 students 582 were screened for ABO blood group and Rhesus factor, and 276 were tested for P. falciparum infection. Faculty of Science (FS) members and male students were highly represented, with 356 (61.2%) and 303 (52.1%) participants, respectively. Blood group O was most common (48.8%), followed by blood group A (25.8%), B (23.0%) and AB (2.4%). Total percentage of rhesus positive was 92.4%, and its distribution varied across ABO blood groups. Of the 276 students examined for malaria infection, 27 were found positive (9.8%). Except for blood group AB individuals, of which none were infected, malaria infection did not vary among blood groups. Rhesus factor and blood group did not impact on malaria infection in the hypo-endemic highland area of Dschang, Cameroon.

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Research: Knowledge, attitude and practice on malaria prevention and sulfadoxine- pyrimethamine utilisation among pregnant women in Badagry, Lagos State, Nigeria

March 25, 2016 - 12:46 -- Open Access
Author(s): 
Josephine N. Chukwurah, Emmanuel T. Idowu, Adeniyi K. Adeneye, Oluwagbemiga O. Aina, Philip U. Agomo, Adetoro O. Otubanjo
Reference: 
MWJ2016, 7, 3
 
We studied the knowledge, attitude and practices of pregnant women on malaria prevention, assessed their knowledge of sulfadoxine-pyrimethamine (SP) for intermittent preventive therapy in pregnancy (IPTp-SP), and used the outcomes to create awareness on malaria prevention with IPTp-SP. A structured questionnaire on malaria prevention and SP utilisation was administered to 450 pregnant women attending antenatal clinics in both government and private health facilities in Badagry, Lagos State, Nigeria. 355 (78.8%) of the pregnant women perceived malaria as a serious illness. Other responses by the respondents included: parasitic disease (13; 2.9%); caused by mosquito (5; 1.9%), while 77 (17%) said they did not know. The signs and symptoms of malaria mentioned included headache (109; 24.2%), weakness (77; 17.1%), fever (77; 17.1%) and body pains (44; 10%). 174 (58%) women indicated that they would go to a hospital when having malaria, 54 (17%) indulged in self-medication, while 32 (11%) took herbs. 43 (14%) did nothing. Malaria prevention was performed by taking herbs (134; 30%); artemisinin-based combination therapy (ACT) (123; 27%); daraprim (104; 23%); blood tonic (51; 11%); paracetamol (21; 5%) and SP (17; 4%). Mosquito control was mainly carried out by the use of insecticide spray (215; 47.7%), followed by anti-mosquito coils (95; 21%). Out of the 450 pregnant women interviewed, 350 (84.5%) said that SP was for the treatment of malaria, while 69 (15.2%) said that it was for malaria prevention. Knowledge of SP was influenced by both education (P<0.05) and parity (P<0.001). The majority of the pregnant women had knowledge of SP but did not know that it is used for malaria prevention. Most of the respondents took malaria-preventive measures by taking herbs but preferred to go to the hospital when suspecting that they had malaria. 

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Research: Knowledge, attitudes and practices on malaria in relation to its transmission among primary school children in Bagamoyo district, Tanzania

February 19, 2016 - 08:21 -- Open Access
Author(s): 
Deborah Sumari, Angel Dillip, Vitalis Ndume, Joseph P. Mugasa, Paul S. Gwakisa
Reference: 
MWJ2016, 7, 2
 
We investigated the knowledge and understanding of primary school children on malaria transmission, recognition of symptoms, treatment seeking behaviour, preventive measures and practices in order to potentially include this group in Tanzania’s malaria control efforts. 125 children were recruited from three purposively selected primary schools in Bagamoyo district, Tanzania. A semi-structured interview guide, including both closed and open-ended questions, was used to collect information from the participants to obtain their knowledge and understanding on malaria transmission, treatment and prevention. More than half of the school children (79/125; 63.2%) had knowledge on malaria as a disease and its transmission; 101/125 (80.8%) of the respondents reported that going to the hospital was their immediate care-seeking behaviour once they felt malaria symptoms, while 14/125 (11.2%) opted for self-medication. With regard to malaria prevention and control, 115/125 (92.0%) of the respondents reported using bednets as their main malaria prevention strategy, while 6/125 (4.8%) preferred the use of medicine, mostly artemether lumefantrine, as prophylaxis. Narratives obtained were able to explain clearly the rationale behind different options children took to treat and to protect themselves against malaria. Findings indicated that primary school children in Bagamoyo district are aware of malaria, its symptoms and preventive measures, although some had misconceptions and could not associate the disease with its transmission. We conclude that inclusion of school children on malaria control educational programmes could yield substantial benefits towards malaria elimination.

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Research: Plasmodium falciparum malaria in northern Côte d’Ivoire: prevalence in the general hospital of Tanda sanitary district

January 7, 2016 - 15:46 -- Bart G.J. Knols
Author(s): 
Thomas Y. Aba, Raoul Moh, Lassina Cissé, Gisele C. Yapo-Kouadio, Frederic N. Ello, Chrysostome Mossou, Zelica Diallo, Ouffoue Kra, Emmanuel Bissagnené
Reference: 
MWJ2016, 7, 1
 
Until about 2010, the majority of data collected on malaria in Côte d’Ivoire were based on presumptive cases, particularly in the northern part of the country, where parasitological research had rarely been carried out. The purpose of this study was to determine the actual malaria prevalence amongst presumptive cases admitted to one of the general hospitals in the Northern part of the country, where malaria diagnosis is suboptimal. A cross-sectional study was conducted in the general medicine, maternity and paediatric wards between January and August 2010. Patients of all ages, suspected of having malaria, were included after giving their informed oral consent. Several parameters were investigated: the presence of Plasmodium using thick blood film, HIV/ Plasmodium co-infection, signs of severity, aspects of malaria treatment and other associated factors. Of 379 patients included, with a median age of 4 yrs [range 1 month - 71 yrs], 9% were HIV-positive, 74% were ≤ 15 yrs of age, 60% were urbanised and 23% were using long-lasting insecticide-treated nets. Malaria prevalence was 67.5% and was significantly associated with the rainy season (p < 0.001), age ≤ 5 yrs (p = 0.004) and no cotrimoxazole chemoprophylaxis in HIV-infected patients (p = 0.04). Only P. falciparum was detected, with a mean density of 12,523 trophozoites/μl of blood, but with 12,610 trophozoites/μl of blood in HIV-positive patients and 7,055 trophozoites/μl of blood in HIV-negative patients (p < 0.001). Severe malaria accounted for 77% of cases. Prescribed antimalarial drugs were: IM artemether (56%), quinine (28%), artemether + lumefantrine (10%) and artesunate + amodiaquine (6%). Apyrexia and parasite clearance were observed at day 2-3 post treatment in 87% of patients. Adverse events were reported among 60 patients (17%). The outcome was marked by: a healing rate of 90%, a rate of 5% lost to follow-up and a 7% lethality for severe malaria, significantly associated with the age ≤ 5 yrs (p=0.02), hyperparasitaemia >20% (p=0.004), neurological disorders (p < 0.001) and respiratory distress (p=0.007). Malaria prevalence in the general hospital of Tanda remains high, with a predominance of severe malaria affecting children under the age of 5 yrs. 

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Research: Mosquito control via inbuilt net hoisting windows: the inverted S/O channel/grip device option

December 9, 2015 - 20:22 -- Bart G.J. Knols
Author(s): 
Francis S.O. Ugwu
Reference: 
MWJ2015, 6, 14
 
Effective control of in-house mosquitoes, due to entry prevention, takes advantage of the behavioural preferences of endophagy and endophily of mosquitoes. Insecticide-treated nets (ITN) adopt this, but is burdened with challenges, which result in dwindling adoption of the methodology in the tropics. An alternative is prevention of vector-human contact through house modifications, which adopts S/O channel/grip devices that form attachments to existing windows. Inverted S/O channel/grip frame (ISOWF) was therefore devised as an integrated window frame, which could be used for direct net attachment and housing shutters. The ISOWF is a lightweight material weighing 1/6 of the equivalent size of wood. Appropriate dies were employed to form channels from thin iron sheets in the preferred shape and size of a laterally inverted letter ‘S’ (ƨ). The upper half was minimised to form and facilitate the ‘O’ griping of nets, while the remaining half was bloated to house window shutters. Net hoisting or de-hoisting periods were determined by timing. A room screened with a net was attached to the device and situated next to a mosquito breeding room. This was used to evaluate the effectiveness of the method. The time taken to hoist the net was measured. The frame was constructed like a metal/ wooden frame, except that the anterior view had two steps. The average time taken to hoist or de-hoist a net across a 60 cm x 120 cm window, formed by the frame, was 5.96 and 1.68 minutes, respectively. The nets retained their integrity. Mixed mosquito populations numbering 1,341 in total could not gain access to a room with carbon dioxide attractant, and the ISOWF screen prevented passage.
 The ISOWF acts as a potential mosquito entry-prevention device, which further provides reinforcement to house screening. It forms an effective mosquito control device, which brands house screening as a sustainable environment for mosquito control, and subsequently, malaria control. This will also control the overall indoor densities of nuisance mosquitoes and other insect vectors.

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Research: Modelling the impact of declining insecticide resistance with mosquito age on malaria transmission

November 14, 2015 - 16:33 -- Bart G.J. Knols
Author(s): 
Adam Saddler, Jacob C Koella
Reference: 
MWJ2015, 6, 13
 
The evolution of insecticide resistance can lead to an increase in the entomological indicators of malaria transmission, such as mosquito survival and blood feeding rates, thus threatening efforts to control malaria. Yet, there is little evidence from the field that malaria control programmes are failing due to insecticide resistance. One explanation for this apparent contradiction is the growing evidence that insecticide resistance declines with mosquito age. Once a mosquito is first infected by Plasmodium parasites, it will not be able to transmit those parasites until they have undergone development, which lasts around 10 days. Thus, although the evolution of resistance in a population will enhance the survival of young mosquitoes, the insecticide may still kill old, and thus potentially infectious, mosquitoes, and thereby maintaining its efficacy in controlling malaria. The current evidence for age-related insecticide resistance is reviewed. A mathematical model is then described that predicts how the decline of resistance with the age of a mosquito will affect the intensity of transmission of malaria. The model combines the behavioural response of the mosquitoes to insecticides with an epidemiological model of malaria. It was found that phenotypic resistance decreases between 1.37% to 9.71% per day, independent of the mosquito species or strain. The models suggest that a decline in resistance within this range strongly diminishes the predicted impact of insecticide resistance on the effectiveness of malaria transmission-controlling interventions.
 Our model can be used to assess the threat of insecticide-resistance for the control of malaria. The model confirms observations from the field suggesting that, even where genetically insecticide-resistant mosquitoes dominate populations, insecticides can substantially reduce the transmission of malaria.

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