Malaria Infection Rates Research Articles

Malaria Prevalence Investigation among Pregnant Women in Relation to Their Social Well Being: A Case Study of Lugbe and Gosa, Abuja, Nigeria

Aim: This research aim was to investigate the impact of living conditions (Socio demographic characteristics) of pregnant women on their malarial status.
 Study Design: In order to achieve the objectives of the study, Cross sectional survey was used. This is because only a subsect of the population was used. Descriptive designs was utilised in the Questionnaire aspect of the study.
 Place and Duration of Study: The Presidential Malarial initiative PMI/USAID - funded Insectary Laboratory at Nasarawa State University, Keffi/six (6) Months.
 Methodology: Blood samples were collected from the participating pregnant women by pricking their thumb and the blood droplet was examined using a direct thin and thick blood smear preparation stained with giemsa for the presence of the ring form stages of the parasites in the blood of the individuals in the laboratory. Qualitative data were sourced through Questionnaire administration to 589 pregnant women in Antenatal care clinics (ANC) in the area and their malaria status was also determined.
 Results: Study results showed a high prevalence rate of malaria in pregnancy (70.5%), the greater number of occurrences being in Lugbe (42.3%) than in Gosa (28.2%). Those living in houses built with wood recorded more positive cases of malaria and are at greater risk of infection (odds = 1.866%).
 Conclusion: This study has shown an increased rate of malaria infection amongst pregnant women living in wood and mud houses. The result also shows high rate of malaria occurrences due to low living conditions amongst pregnant women domiciled in this area of study. Hence, pregnant women should as a routine be placed on malaria prophylaxis and periodically checked as they can be asymptomatic, only exhibiting symptoms when its already late.

Invivo Impact of Malaria and HIV Co-Infection on CD4 Cell Count of Infected Patients of Niger Delta Extraction

The study evaluated the impact of co-infection of malaria parasitaemia, and HIV positive indices on the CD4 cell count of 120 HIV infected subjects, who were already diagnosed and visiting Braithwaite Memorial Specialist Hospital Port Harcourt for routine Medical check-up. Also, a control group of 40 HIV negative were included as part of the study control group. The subjects were between the age ranges of ≤10–79 years respectively. A double check laboratory assay was conducted to detect the presence of antibody to HIV as confirmed using immunocomb 11 and Determine for HIV status. A thick Blood film stained with field stain (A and B) was used to detect the presence of malaria parasite in the subject’s blood. Furthermore, CD4 cell count was assayed using Partec cyflow counter (Partec, Germany). Excel and Graphpad statistical software were used for analysis of the data generated. The result among the HIV positive subjects and control subjects revealed that the highest positive for malaria infection was observed among ≤10 years age group as 2 (100%) and 11 (84.61%) respectively. In the HIV positive subjects, the distribution of malaria infection among sex revealed a high rate in male 42(77.78%) than in female 44 (66.67%). Similarly, the control recorded a high rate of malaria infection in male 11 (57.89%) than in female 7 (33.33%). However, 86 (71.67%) had malaria and HIV co-infection while 34 (65%) had only HIV mono infection. The positive HIV subjects who had CD4 cells count below 200 cells/mm3 were 15%, above 200-499cells/mm3 were 58.3% while 500 cells/mm3 and above had normal CD4 cells counts for 26%. Nonetheless, for the control subjects, no CD4 cells count of below 200cells/ mm was observed, 2.5% fell within the moderate category while 75% had normal CD4 cells count. Statistical analysis using ANOVA and t-test showed that there is significant difference between CD4 of seropositive and seronegative subjects infected with or without malaria (p=0.00). In addition, a t-test further demonstrated Comparison of Mean CD4 Cell Count among HIV and Malaria Infected and Non-Infected Subjects. MP/HIV Co-Infection and Mono Infection with No Infection showed strong mean difference (p=0.00) in the various CD4 counts while HIV Mono-Infection and others only had a non significant (p=0.44) mean difference between HIV Mono-Infection and No HIV or Malaria Infection. A robust and effective malaria and HIV control management programme should be strongly underpinned; so as to improve the quality of life of patients and HIV patients should be encouraged to live a healthy life style, through the provision of antiretroviral drugs and regular health education engagement, even as the provision of antimalarial treated net would be helpful to the subjects.

Evaluation of mosquito electrocuting traps as a safe alternative to the human landing catch for measuring human exposure to malaria vectors in Burkina Faso

BackgroundMeasuring human exposure to mosquito bites is a crucial component of vector-borne disease surveillance. For malaria vectors, the human landing catch (HLC) remains the gold standard for direct estimation of exposure. This method, however, is controversial since participants risk exposure to potentially infected mosquito bites. Recently an exposure-free mosquito electrocuting trap (MET) was developed to provide a safer alternative to the HLC. Early prototypes of the MET performed well in Tanzania but have yet to be tested in West Africa, where malaria vector species composition, ecology and behaviour are different. The performance of the MET relative to HLC for characterizing mosquito vector population dynamics and biting behaviour in Burkina Faso was evaluated.MethodsA longitudinal study was initiated within 12 villages in Burkina Faso in October 2016. Host-seeking mosquitoes were sampled monthly using HLC and MET collections over 14 months. Collections were made at 4 households on each night, with METs deployed inside and outside at 2 houses, and HLC inside and outside at another two. Malaria vector abundance, species composition, sporozoite rate and location of biting (indoor versus outdoor) were recorded.ResultsIn total, 41,800 mosquitoes were collected over 324 sampling nights, with the major malaria vector being Anopheles gambiae sensu lato (s.l.) complex. Overall the MET caught fewer An. gambiae s.l. than the HLC (mean predicted number of 0.78 versus 1.82 indoors, and 1.05 versus 2.04 outdoors). However, MET collections gave a consistent representation of seasonal dynamics in vector populations, species composition, biting behaviour (location and time) and malaria infection rates relative to HLC. As the relative performance of the MET was somewhat higher in outdoor versus indoor settings, this trapping method slightly underestimated the proportion of bites preventable by LLINs compared to the HLC (MET = 82.08%; HLC = 87.19%).ConclusionsThe MET collected proportionately fewer mosquitoes than the HLC. However, estimates of An. gambiae s.l. density in METs were highly correlated with HLC. Thus, although less sensitive, the MET is a safer alternative than the HLC. Its use is recommended particularly for sampling vectors in outdoor environments where it is most sensitive.

Prevalence of malaria parasites in children at Vom Christian Hospital, Jos South, Plateau State, Nigeria

Malaria is the most prevalent tropical disease in the world today. This study aimed to determine the prevalence of malaria parasites in children examined at Vom Christian Hospital. Blood samples were collected by finger prick and venipuncture and examined using thick and thin blood film under x100 objective. Out of the 360 children examined, 31(8.6%) were found infected with malaria parasites. The male children (9.8%) were more infected than the females (7.7%) there was no significant difference in prevalence of malaria in relation to gender (p=0.8575). Plasmodium falciparum (71.0%) was the most prevalent malaria parasite encountered in the study-area while P. malariae (29.0%) was least encountered. There was no significant difference of species encountered in relation to gender (p = 0.4985). Children aged between 7-9 years old (20.7%) were significantly (p<0.0001) more infected with malaria parasites, while those aged between 13-15 years old (3.7%) were least infected. Children aged <12 months old were not infected in the study-area. Children with blood Group O, 14(45.1%) had the highest rate of malaria infection, followed by those with blood Group A, 9(29.0%) while blood Group B had the lowest rate, with 3 (9.7%) of the infection. The various blood groups were mostly infected with P. falciparum, but there was no significant difference (p=0.08402) in the prevalence of malaria infection in relation to species and blood group. Children whose parents were farmers, 24(12.0%) were significantly (p<0.0001) more infected with malaria parasites, while those whose parents were civil servants, 2(4.0%) were the least infected. To this end, effective malaria control strategies need to be indoctrinated and public health campaigns carried out to increase awareness in the community and to further reduce the prevalence of malaria in the study- area.Keywords: Malaria parasites; children; gender; blood group.

The risk of transfusion transmitted malaria and the need for malaria screening of blood donors in Abuja, Nigeria

Background: Blood transfusion saves life but it is also a major risk factor in the transmission of certain infections such as malaria, which remains a public health problem in tropical and sub-Saharan Africa. Methodology: This study investigated the prevalence of malaria among 550 blood donors aged 18 to 60 years from blood bank units of some selected hospitals in Federal Capital Territory (FCT), Abuja, using gold standard microscopy for malaria parasite detection. Results: Two hundred and fifty two (45.8%) donors were positive for malaria parasites. Replacement donors had higher prevalence rate of malaria compared to voluntary donors. The distribution of infection on the basis of age revealed the highest prevalence rate of malaria among the 20- 29yrs age group. The rate of infection among the males and the females was not significantly different ( p >0.05). No association was observed between the blood group types and the rate of malaria infection ( p > 0.05). Conclusion: A high prevalence of malaria parasitaemia was observed among blood donors in FCT, Abuja, Nigeria in this study. The introduction of malaria screening as part of routine screening for blood donation and the provision of modern blood screening equipment within healthcare facilities are highly advocated. Keywords: Blood, Malaria, Microscopy, ABO Blood group

Malaria infection rates in Anopheles albimanus (Diptera: Culicidae) at Ipetí-Guna, a village within a region targeted for malaria elimination in Panamá

The Panamá Canal construction encompassed one of the first examples of malaria elimination. Nevertheless, malaria has uninterruptedly persisted in Native American populations living within a few kilometers of the Panamá Canal. Here, we present results from a monthly longitudinal study (May 2016 to March 2018), whose goal was to quantitatively describe seasonal patterns of Plasmodium spp. infection in Anopheles albimanus Wiedemann, and its association with environmental covariates, at Ipetí-Guna, a village within a region targeted for malaria elimination in Panamá. To detect Plasmodium spp. infections we employed a standard nested PCR on DNA extracts from mosquito pools of varying size, which were then used to estimate monthly infection rates using a maximum likelihood method. The infection rate estimates (IR) were analyzed using time series analysis methods to study their association with changes in rainfall, temperature, NDVI (a satellite derived vegetation index), malaria cases and human biting rates (HBR). We found that mosquitoes were infected by Plasmodium vivax mainly from September to December, reaching a peak in December. Time series modeling showed malaria IR in An albimanus increased, simultaneously with HBR, and IR in the previous month. These results suggest that elimination interventions, such as mass drug administration, are likely to be more effective if deployed from the middle to the end of the dry season (March and April at Ipetí-Guna), when the likelihood of malaria infection in mosquitoes is very low and when curtailing human infections driving infections in mosquitoes can reduce malaria transmission, and increase the chance for elimination.

Malaria among foreign migrant workers in Savannakhet Province, Lao People\u2019s Democratic Republic

BackgroundAlthough mobile and migrant populations are considered an important group in malaria elimination settings, there is currently a lack of understanding about foreign migrant workers in the Lao People’s Democratic Republic (Lao PDR). The present study aimed to document the migration characteristics, positive rate of malaria infection, and preventive and treatment-seeking behavior for malaria among foreign migrant workers in the malaria-endemic districts of Savannakhet province, Lao PDR.MethodsA community-based survey was undertaken in four districts of Savannakhet province between February and June, 2015. Questionnaire-based interviews and blood examinations, including rapid diagnostic tests and PCR assays, were conducted with 391 migrant workers who were registered at local police departments.ResultsMost of the study participants were men (75.7%) and Vietnamese (92.6%). The median age (interquartile range) was 31 (25 to 41) years old. Most common occupation was factory worker (47.6%), followed by trader/shopkeeper (21.5%) and plantation worker/farmer (16.4%). The median length of stay (interquartile range) in the districts was 405 (183 to 1207) days. The majority of the participants (85.9%) had not worked in a province other than the study province, nor had the majority (92.6%) worked in a foreign country other than the Lao PDR. Although most of the participants (62.7%) reportedly used a bed net daily, these nets were mostly conventional untreated ones. No one tested positive for malaria. However, 10.0% of the participants reported a malaria-like illness episode that had occurred in the Lao PDR. The most common measure taken for the episode was to visit a hospital/health center in the Lao PDR, followed by conducting self-medication alone. Forty-one participants reported an experience of working in the forest while living in the Lao PDR.ConclusionsForeign migrant workers who are registered at local police departments are unlikely to play a major role in maintaining local transmissions and spreading drug-resistant malaria in the study province. However, some of them were involved in forest-related activities, suggesting that these workers are potentially at risk of malaria. The Lao National Malaria Control Program should educate foreign migrant workers about the risk of malaria when living in Lao PDR.

Malaria infection among children under-five: the use of large-scale interventions in Ghana

BackgroundDespite the significant investments to control malaria infection rates over the past years, infection rates remain significant in sub-Saharan Africa. This study investigates the association with use of large-scale malaria interventions such as: Indoor Residual Spraying (IRS), Insecticide Treated bed-Nets (ITN), and Behaviour Change Communication (BCC) strategies, and the prevalence of malaria among children under-five in Ghana.MethodsCross-sectional data on 2, 449 children aged 6 to 59 months who were tested for malaria, through Rapid Diagnostic Test (RDT), are drawn from the recent wave of the Ghana Demographic and Health Surveys (GDHS 2014). We use a logit model to analyse the heterogeneous association between control measures and malaria infection among under five children of different age cohorts and household poverty statuses.ResultsOur estimates suggest that IRS offers much more protection than ITN use. The odds of malaria infection among children who sleep in IRS is significantly lower (odds ratio [OR] = 0.312; 95% CI -1.47 -0.81; p = 0.00) compared to those who are not protected. This association is even high (odds ratio [OR] = 0.372; 95% CI -1.76 -1.02; p = 0.00) among children in poor households protected by IRS compared to those who have no IRS protection. ITN use did not have a significant association with malaria infection among children, except among children whose mothers have at least secondary education. For such children, the odds of malaria infection are significantly lower ([OR] =0.545; 95% CI = − 0.84 -0.11; p = 0.011) compared to those who are not protected. Regarding BCC strategies, we found that malaria education through television is the best strategy to covey malaria education as it significantly reduces the odds of malaria infection ([OR] =0.715; 95% CI = − 0.55 -0.10; p = 0.005) compared to those who do not received malaria education via television. BCC strategy via print media has a significant but limited protection for children of educated mothers.ConclusionPolicy makers should direct more resources to IRS, especially in communities where the use of ITN is less likely to be effective, such as poor and rural households. The distribution of ITNs needs to be accompanied with education programs to ensure its best protection.

Obstetric and Haematological Determinants of Malaria Parasitaemia among Pregnant Women in Kano State, Nigeria

Malaria during pregnancy has serious health consequences, and poses substantial risk to the mother, her fetus, and the new born. This study was carried out to assess the relationships between malaria parasitaemia and some obstetric, haematological and clinical characteristics of pregnant women of various parities in the study area, with the hope to better understanding the local malaria situation. The laboratory techniques employed were: preparation of thick and thin blood smears, by Giemsa staining, for malaria parasite screening; measurement of blood haemoglobin, for detection of anaemia by Cyanmethaemoglobin method; alkaline pH electrophoresis of haemoglobin, for detection of haemoglobin variance. Parity was found to be significantly associated with malarial infection, with high prevalence seen in nulliparous and primiparous women, and the rate of infection decreasing with increasing parity. Likewise the sickle cell trait was found to influence the prevalence of malaria infection, with pregnant women who had the sickle cell condition (Hb SS) and those with normal haemoglobin (Hb AA) being more at risk for malaria infection than those individuals with the sickle cell trait (Hb AS and SC). A strong association was also found between anaemia and malaria parasitaemia, with individuals that were anaemic being more infected than those that were not anaemic. However, history of fever and previous chemoprophylaxis were not found to have any impact on the rate of malaria infection. Health education programs on the management of malaria in pregnancy should be intensified.&#x0D;

Evaluation of rapid PfHRP-2/pLDH-based tests in diagnosing microscopy-confirmed falciparum malaria in Hodeidah governorate, Yemen

Along with the determination of malaria infection rate among suspected patients attending hospitals in Hodeidah governorate, the present study evaluated the accuracy of Plasmodium falciparum histidine-rich protein-2 (PfHRP-2)/parasite-specific lactate dehydrogenase (pLDH)-based rapid diagnostic test (RDT) for the diagnosis of microscopy-confirmed falciparum malaria. An overall malaria infection rate of 19.3% (57/295) among suspected patients attending hospitals was microscopically confirmed. The sensitivity of thin blood films for the detection of malaria parasites was 79.0% compared to thick films and was greatly affected by the parasite density, being 65.0% or less at parasite densities of ≤1000 parasites/μl of blood. Compared to light microscopy, the present study revealed sensitivity levels of 100.0% (95% CI: 92.0–100.0) vs. 94.7% (95% CI: 84.2–98.6), specificity levels of 97.3% (95% CI: 89.8–99.5) vs. 100.0% (95% CI: 93.9–100.0), positive predictive values of 89.9% (95% CI: 88.3–99.0) vs. 100.0 (95% CI: 91.6–100.0) and negative predictive values of 100.0% (95% CI: 93.9–100.0) vs. 98.7% (95% CI: 89.3–98.7) for the PfHRP-2 and pLDH components of SD BIOLINE® RDT, respectively, for falciparum malaria diagnosis. Therefore, the overall accuracy levels of the PfHRP-2 and pLDH components of the investigated RDT for the diagnosis of microscopy-confirmed falciparum malaria are 98.5% (95% CI: 94.6–99.6) and 97.7% (95% CI: 93.5–99.2), respectively.

Spatio-Temporal Dynamics of Asymptomatic Malaria: Bridging the Gap Between Annual Malaria Resurgences in a Sahelian Environment.

.In areas of seasonal malaria transmission, the incidence rate of malaria infection is presumed to be near zero at the end of the dry season. Asymptomatic individuals may constitute a major parasite reservoir during this time. We conducted a longitudinal analysis of the spatio-temporal distribution of clinical malaria and asymptomatic parasitemia over time in a Malian town to highlight these malaria transmission dynamics. For a cohort of 300 rural children followed over 2009–2014, periodicity and phase shift between malaria and rainfall were determined by spectral analysis. Spatial risk clusters of clinical episodes or carriage were identified. A nested-case-control study was conducted to assess the parasite carriage factors. Malaria infection persisted over the entire year with seasonal peaks. High transmission periods began 2–3 months after the rains began. A cluster with a low risk of clinical malaria in the town center persisted in high and low transmission periods. Throughout 2009–2014, cluster locations did not vary from year to year. Asymptomatic and gametocyte carriage were persistent, even during low transmission periods. For high transmission periods, the ratio of asymptomatic to clinical cases was approximately 0.5, but was five times higher during low transmission periods. Clinical episodes at previous high transmission periods were a protective factor for asymptomatic carriage, but carrying parasites without symptoms at a previous high transmission period was a risk factor for asymptomatic carriage. Stable malaria transmission was associated with sustained asymptomatic carriage during dry seasons. Control strategies should target persistent low-level parasitemia clusters to interrupt transmission.

Malaria Infection and Gametocyte Carriage Rates in Preparation for Transmission Blocking Vaccine Trials in Bancoumana, Mali.

The epidemiological characterization of transmission reservoirs is a critical step in preparation for interventional trials for malaria elimination/eradication. Using cluster sampling and households/compounds as units of sampling, we recruited and followed monthly, from June 2011 to June 2012, 250 volunteers 3 months to 50 years of age in Bancoumana, Mali. In July 2012, only participants 5-35 years of age (N = 121) were reenrolled and followed for an additional year. Malaria infection prevalence was highest in October in both 2011 (21.5%, 50/233) and 2012 (38.2%, 26/68). During both years, malaria infection prevalence was highest in children 5-14 years of age (P = 0.01 and P = 0.02, respectively). The gametocyte carriage prevalence was highest in November 2011 (7.6%, 17/225) and in October 2012 (16.2%, 11/68). Gametocyte carriage rates by age did not significantly differ in 2011 and 2012. In Bancoumana, the asexual and sexual parasite carriage rates are relatively high and highly seasonal. Seasonal variation and age differences in parasite and gametocyte carriage provide essential knowledge for the design of transmission blocking assay and vaccine studies in the field.

Fine scale mapping of malaria infection clusters by using routinely collected health facility data in urban Dar es Salaam, Tanzania.

This study investigated whether passively collected routine health facility data can be used for mapping spatial heterogeneities in malaria transmission at the level of local government housing cluster administrative units in Dar es Salaam, Tanzania. From June 2012 to January 2013, residential locations of patients tested for malaria at a public health facility were traced based on their local leaders' names and geo-referencing the point locations of these leaders' houses. Geographic information systems (GIS) were used to visualise the spatial distribution of malaria infection rates. Spatial scan statistics was deployed to detect spatial clustering of high infection rates. Among 2407 patients tested for malaria, 46.6% (1121) could be traced to their 411 different residential housing clusters. One small spatially aggregated cluster of neighbourhoods with high prevalence was identified. While the home residence housing cluster leader was unambiguously identified for 73.8% (240/325) of malaria-positive patients, only 42.3% (881/2082) of those with negative test results were successfully traced. It was concluded that recording simple points of reference during routine health facility visits can be used for mapping malaria infection burden on very fine geographic scales, potentially offering a feasible approach to rational geographic targeting of malaria control interventions. However, in order to tap the full potential of this approach, it would be necessary to optimise patient tracing success and eliminate biases by blinding personnel to test results.

Bionomics of Anopheles fluviatilis and Anopheles culicifacies (Diptera: Culicidae) in Relation to Malaria Transmission in East-Central India.

The southern districts of Odisha State in east-central India have been highly endemic for falciparum malaria for many decades. However, there is no adequate information on the abundance of the vector species or their bionomics in relation to space and time in these districts. Therefore, a study was carried out on the entomological aspects of malaria transmission to generate such information. Collections of mosquitoes were made once during each of the three seasons in 128 villages selected from eight districts. Villages within the foot-hill ecotype had a significantly greater abundance of Anopheles fluviatilis James s. l., whereas the abundance of Anopheles culicifacies Giles s. l. was significantly greater in the plain ecotype. The abundance of An. fluviatilis was maximum during the cold season, whereas An. culicifacies abundance was highest during summer and rainy seasons. The maximum likelihood estimation of the malaria infection rate in An. fluviatilis was 1.78%, 6.05%, and 2.6% in Ganjam, Kalahandi, and Rayagada districts, respectively. The infection rate of An. culicifacies was 1.39% only in Kandhamal district; infected females were not detected elsewhere. Concurrently, the annual malaria parasite incidence (MPI) was significantly higher in hill-top (17.6) and foot-hill (14.4) villages compared to plain villages (4.1). The districts with more villages in hill-top and foot-hill ecotypes also had a greater abundance of An. fluviatilis, the major malaria vector, and exhibited a higher incidence of malaria than villages within the plain ecotype, where An. culicifacies was the most abundant vector.

Disparities between malaria infection and treatment rates: Evidence from a cross-sectional analysis of households in Uganda.

BackgroundIn Sub-Saharan Africa, both under-treatment and over-treatment of malaria are common since illnesses are often diagnosed and treated on the basis of symptoms. We investigate whether malaria treatment rates among febrile individuals correspond to observed patterns of malaria infection by age and by local prevalence.Methods and findingsWe use data on treatment of febrile illnesses from a household survey that was conducted between March and May 2012 in 92 villages in six districts in Eastern Uganda. All household members were also tested for malaria using a rapid diagnostic test. We show that both the age of the febrile individual and the village prevalence rate are strongly associated with the odds that a febrile patient was infected with malaria, but not with the odds of ACT treatment. Compared to individuals who were aged 15 or above, febrile individuals aged 5–14 had 3.21 times the odds of testing positive for malaria (95% CI: [2.36 4.37], P<0·001), and febrile individuals who were under age 5 had 2.66 times the odds of testing positive for malaria (95% CI: [1.99 3.56], P<0·001). However, ACT treatment rates for febrile illnesses were not significantly higher for either children ages 5–14 (Unadjusted OR: 1.19, 95% CI: [0.88 1.62], P = 0.255) or children under the age of 5 (Unadjusted OR: 1.24, 95% CI: [0.92 1.68], P = 0·154). A one standard deviation increase in the village malaria prevalence rate was associated with a 2.03 times higher odds that a febrile individual under the age of five tested positive for malaria (95% CI: [1.63 2.54], p<0·001), but was not significantly associated with the odds of ACT treatment (Un-adjusted OR: 0.83, 95% CI: [0.66 1.05], P = 0·113). We present some evidence that this discrepancy may be because caregivers do not suspect a higher likelihood of malaria infection, conditional on fever, in young children or in high-prevalence villages.ConclusionOur findings suggest that households have significant mis-perceptions about malaria likelihood that may contribute to the under-treatment of malaria. Policies are needed to encourage caregivers to seek immediate diagnostic testing and treatment for febrile illnesses, particularly among young children.

Retraction: How the Malaria Vector Anopheles gambiae Adapts to the Use of Insecticide-Treated Nets by African Populations.

Background Insecticide treated bed nets have been recommended and proven efficient as a measure to protect African populations from malaria mosquito vector Anopheles spp. This study evaluates the consequences of bed nets use on vectors resistance to insecticides, their feeding behavior and malaria transmission in Dielmo village, Senegal, were LLINs were offered to all villagers in July 2008. Methods Adult mosquitoes were collected monthly from January 2006 to December 2011 by human landing catches (HLC) and by pyrethroid spray catches (PCS). A randomly selected sub-sample of 15–20% of An. gambiae s.l. collected each month was used to investigate the molecular forms of the An. gambiae complex, kdr mutations, and Plasmodium falciparum circumsporozoite (CSP) rate. Malaria prevalence and gametocytaemia in Dielmo villagers were measured quarterly. Results Insecticide susceptible mosquitoes (wild kdr genotype) presented a reduced lifespan after LLINs implementation but they rapidly adapted their feeding behavior, becoming more exophageous and zoophilic, and biting earlier during the night. In the meantime, insecticide-resistant specimens (kdr L1014F genotype) increased in frequency in the population, with an unchanged lifespan and feeding behaviour. P. falciparum prevalence and gametocyte rate in villagers decreased dramatically after LLINs deployment. Malaria infection rate tended to zero in susceptible mosquitoes whereas the infection rate increased markedly in the kdr homozygote mosquitoes. Conclusion Dramatic changes in vector populations and their behavior occurred after the deployment of LLINs due to the extraordinary adaptative skills of An. gambiae s. l. mosquitoes. However, despite the increasing proportion of insecticide resistant mosquitoes and their almost exclusive responsibility in malaria transmission, the P. falciparum gametocyte reservoir continued to decrease three years after the deployment of LLINs.

Distribution of malaria vectors and incidence of vivax malaria at Korean army installations near the demilitarized zone, Republic of Korea.

BackgroundAs a result of the reintroduction of malaria in the Republic of Korea (ROK) in 1993 and the threat to military and civilian populations, the Korea Military National Defense (MND) increased emphasis on vector control in 2012 at ROK Army (ROKA) installations located near the DMZ, while decreasing chemoprophylaxis, fearing potential drug resistance. Mosquito surveillance demonstrated a need for continuous monitoring of disease patterns among ROKA soldiers and vector malaria infection rates to ensure positive outcomes.MethodsAnopheles spp. were collected from May–October at three ROKA installations in three locations near the DMZ. Each of the areas included one installation <2 km and two installations 11–12 km from the DMZ in Paju and Yeoncheon counties, Gyeonggi Province. Anopheles spp. were identified by polymerase chain reaction (PCR) techniques and then assayed for the presence of vivax malaria sporozoites. The ROK MND reported vivax malaria patients monthly to Korea Centers for Disease Control and Prevention. Correlations for the incidence of Plasmodium vivax patients and infected Anopheles species were analysed using the Wilcoxon rank sum test, Pearson correlation test and liner regression analysis.ResultsA total of 4282 Anopheles spp. were collected. Anopheles kleini (69.5 %) was the most commonly collected, followed by Anopheles pullus (17.3 %), Anopheles belenrae (4.5 %), Anopheles sineroides (4.2 %), Anopheles sinensis sensu stricto (2.7 %), and Anopheles lesteri (1.9 %). Overall, 21 malaria patients were reported by the ROK MND. The monthly incidence of the malaria patients correlated with the monthly number of Plasmodium vivax sporozoite positive Anopheles spp. The monthly numbers of An.kleini demonstrated the highest correlations to the numbers of ROKA malaria patients throughout the mosquito season (P < 0.01). Anopheles spp. positive for P. vivax and malaria patients at ROKA installations located <2 km from the DMZ were higher than for ROKA installations located 11–12 km from DMZ.ConclusionThe number of Anopheles spp. positive for P. vivax sporozoites correlated with the monthly number of malaria cases and exposure of ROKA soldiers from May–October to P. vivax malaria infections. Malaria vector surveillance and vector control is warranted as part of an effective malaria management program at ROKA installations located near DMZ.

Malaria infection negatively affects feather growth rate in the house sparrow Passer domesticus

Birds often face various stressors during feather renewing, for example, enduring infection with blood parasites. Because nutritional resources are typically limited, especially for wild animals, when an individual allocates energy to one physiological system, there is subsequently less for other processes, thereby requiring a trade‐off. Surprisingly, potential trade‐offs between malaria infection and feather growth rate have not been experimentally considered yet. Here, we conducted three studies to investigate whether a trade‐off occurs among feather growth rate, malaria infection and host health conditions. First, we explored whether naturally infected and uninfected house sparrows differed in feather growth rate in the wild. Second, we asked whether experimental inoculation of malaria parasites and/or forcing the renewal of a tail feather. Lastly, we evaluated whether individual condition was affected by experimentally‐induced feather regrowth and/or malaria experimental infection. Our findings showed that feather growth rate was negatively affected by natural malaria infection status in free‐living birds and by experimental infection in captive birds. Furthermore, birds that did not increase body mass or hematocrit during the experimental study had slower feather growth. Together our results suggest that infection with blood parasites has more negative health effects than the growth of tail feathers and that these two processes (response to blood parasite infection and renewal of feathers) are traded‐off against each other. As such, our results highlight the role of malaria parasites as a potential mechanism driving other trade‐offs in wild passerines.

Declining malaria, rising of dengue and Zika virus: insights for mosquito vector control.

The fight against mosquito-borne diseases is a challenge of huge public health importance. To our mind, 2015 was an extraordinary year for malaria control, due to three hot news: the Nobel Prize to Youyou Tu for the discovery of artemisinin, the development of the first vaccine against Plasmodium falciparum malaria [i.e. RTS,S/AS01 (RTS,S)], and the fall of malaria infection rates worldwide, with special reference to sub-Saharan Africa. However, there are major challenges that still deserve attention, in order to boost malaria prevention and control. Indeed, parasite strains resistant to artemisinin have been detected, and RTS,S vaccine does not offer protection against Plasmodium vivax malaria, which predominates in many countries outside of Africa. Furthermore, the recent outbreaks of Zika virus infections, occurring in South America, Central America and the Caribbean, represent the most recent of four arrivals of important arboviruses in the Western Hemisphere, over the last 20years. Zika virus follows dengue (which slyly arrived in the hemisphere over decades and became more aggressive in the 1990s), West Nile virus (emerged in 1999) and chikungunya (emerged in 2013). Notably, there are no specific treatments for these arboviruses. The emerging scenario highlights that the effective and eco-friendly control of mosquito vectors, with special reference to highly invasive species such as Aedes aegypti and Aedes albopictus, is crucial. The concrete potential of screening plant species as sources of metabolites for parasitological purposes is worthy of attention, as elucidated by the Y. Tu's example. Notably, plant-borne molecules are often effective at few parts per million against Aedes, Ochlerotatus, Anopheles and Culex young instars, can be used for the rapid synthesis of mosquitocidal nanoformulations and even employed to prepare cheap repellents with low human toxicity. In addition, behaviour-based control tools relying to the employ of sound traps and the manipulation of swarming behaviour (i.e. "lure and kill" approach) are discussed. The importance of further research on the chemical cues routing mosquito swarming and mating dynamics is highlighted. Besides radiation, transgenic and symbiont-based mosquito control approaches, an effective option may be the employ of biological control agents of mosquito young instars, in the presence of ultra-low quantities of nanoformulated botanicals, which boost their predation rates.

Entomological aspects and the role of human behaviour in malaria transmission in a highland region of the Republic of Yemen.

BackgroundThe Republic of Yemen has the highest incidence of malaria in the Arabian Peninsula, yet little is known of its vectors or transmission dynamics.MethodsA 24-month study of the vectors and related epidemiological aspects of malaria transmission was conducted in two villages in the Taiz region in 2004–2005.ResultsCross-sectional blood film surveys recorded an overall malaria infection rate of 15.3 % (250/1638), with highest rates exceeding 30 % in one village in May and December 2005. With one exception, Plasmodium malariae, all infections were P.falciparum. Seven Anopheles species were identified among 3407 anophelines collected indoors using light traps (LT) and pyrethrum knockdown catches (PKD): Anopheles arabiensis (86.9 %), An. sergentii (9 %), An. azaniae, An. dthali, An. pretoriensis, An. coustani and An. algeriensis. Sequences for the standard barcode region of the mitochondrial COI gene confirmed the presence of two morphological forms of An. azaniae, the typical form and a previously unrecognized form not immediately identifiable as An. azaniae. ELISA detected Plasmodium sporozoites in 0.9 % of 2921 An. arabiensis (23 P. falciparum, two P. vivax) confirming this species as the primary malaria vector in Yemen. Plasmodium falciparum sporozoites were detected in An. sergentii (2/295) and a single female of An. algeriensis, incriminating both species as malaria vectors for the first time in Yemen. A vector in both wet and dry seasons, An. arabiensis was predominantly anthropophilic (human blood index = 0.86) with an entomological inoculation rate of 1.58 infective bites/person/year. Anopheles sergentii fed on cattle (67.3 %) and humans (48.3; 20.7 % mixed both species), but only 14.7 % were found in PKDs, indicating predominantly exophilic behaviour. A GIS analysis of geographic and socio-economic parameters revealed that An. arabiensis were significantly higher (P < 0.001) in houses with televisions, most likely due to the popular evening habit of viewing television collectively in houses with open doors and windows.ConclusionsThe predominantly indoor human biting vectors recorded in this study could be targeted effectively with LLINs, indoor residual spraying and/or insecticide-treated window/door curtains reinforced by education to instil a perception that effective and affordable malaria prevention is achievable.Electronic supplementary materialThe online version of this article (doi:10.1186/s12936-016-1179-8) contains supplementary material, which is available to authorized users.