Christen M. Fornadel

Analysis of Anopheles arabiensis Blood Feeding Behavior in Southern Zambia during the Two Years after Introduction of Insecticide-Treated Bed Nets

Anopheles arabiensis mosquitoes are the primary vector responsible for Plasmodium falciparum transmission in Macha, Zambia. Because insecticide-treated bed nets (ITNs) have the potential to alter host feeding behavior, the extent of the zoophilic and exophagic tendencies of the vector was evaluated during the two rainy seasons after ITN introduction. Centers for Disease Control light traps, paired indoor/outdoor human landing catches, and outdoor cattle-baited collections were used to assess potential changes in host preference. Results support the hypothesis that An. arabiensis mosquitoes in Macha remain highly anthropophilic despite high ITN use. Anopheles arabiensis mosquitoes in Macha appear to be relatively exophagic and have been caught biting outdoors immediately after sunset and before sunrise, potentially circumventing some of the protective effects of ITNs.

Centers for Disease Control Light Traps for Monitoring Anopheles arabiensis Human Biting Rates in an Area with Low Vector Density and High Insecticide-Treated Bed Net Use

Human landing catches (HLCs) are currently the preferred method to determine vector human biting rates (HBRs), which are key determinants of entomologic inoculation rates and important measures for assessing the impact of vector control efforts. Although HLCs are the most direct means of establishing HBRs, they are labor-intensive, and their use is facing increasing ethical concerns. The relationship between Centers for Disease Control (CDC) light traps and HLC collections was evaluated in Macha, Zambia during the 2007-2008 and 2008-2009 rainy seasons. A CDC light trap captured on average 1.91 (95% confidence interval = 1.16-2.28) times as many An. arabiensis per night as an indoor HLC. Additionally, nets treated with deltamethrin did not affect the numbers of An. arabiensis collected. Our results suggest that in regions where use of vector control interventions is high and vector densities are low, CDC light traps can be used to monitor An. arabiensis HBRs.

Unexpected Anthropophily in the Potential Secondary Malaria Vectors Anopheles coustani s.l. and Anopheles squamosus in Macha, Zambia

Anopheles coustani s.l. and Anopheles squamosus are sub-Saharan mosquito species that have been implicated in malaria transmission. Although generally believed to be of negligible importance due to their overwhelmingly zoophilic behavior, An. coustani s.l. and An. squamosus made up a large proportion of the anophelines collected by human landing catches during the 2007-2008 and 2008-2009 rainy seasons in Macha, Zambia. Further, polymerase chain reaction-based blood meal identification showed that the majority of blood meals from these mosquito species caught in human-baited Centers for Disease Control light traps were from human hosts. Although no An. coustani s.l. or An. squamosus were found to be positive for Plasmodium, the demonstrated anthropophilic tendencies of these mosquitoes in southern Zambia suggest their potential as secondary malaria vectors.

Frequency of Multiple Blood Meals Taken in a Single Gonotrophic Cycle by Anopheles arabiensis Mosquitoes in Macha, Zambia

Anopheles arabiensis is a major vector of Plasmodium falciparum in southern Zambia. This study aimed to determine the rate of multiple human blood meals taken by An. arabiensis to more accurately estimate entomologic inoculation rates (EIRs). Mosquitoes were collected in four village areas over two seasons. DNA from human blood meals was extracted and amplified at four microsatellite loci. Using the three-allele method, which counts > or = 3 alleles at any microsatellite locus as a multiple blood meal, we determined that the overall frequency of multiple blood meals was 18.9%, which was higher than rates reported for An. gambiae in Kenya and An. funestus in Tanzania. Computer simulations showed that the three-allele method underestimates the true multiple blood meal proportion by 3-5%. Although P. falciparum infection status was not shown to influence the frequency of multiple blood feeding, the high multiple feeding rate found in this study increased predicted malaria risk by increasing EIR.

Detection of Rickettsia massiliae in Rhipicephalus sanguineus from the Eastern United States

We report the first evidence of Rickettsia massiliae in the brown dog tick, Rhipicephalus sanguineus, from the East Coast of the United States. As part of routine pathogen surveillance, DNA samples from ixodid ticks were tested for spotted fever group rickettsiae by nested PCR. A R. massiliae-positive tick was collected off a beagle mix recently rescued from North Carolina. Infection was confirmed by partial sequence analysis of the htrA, gltA, ompB, ompA, and sca4 genes, which had 100% identity to a R. massiliae isolate from Arizona.

ANOSPEX: A Stochastic, Spatially Explicit Model for Studying Anopheles Metapopulation Dynamics

Anopheles mosquitoes transmit malaria, a major public health problem among many African countries. One of the most effective methods to control malaria is by controlling the Anopheles mosquito vectors that transmit the parasites. Mathematical models have both predictive and explorative utility to investigate the pros and cons of different malaria control strategies. We have developed a C++ based, stochastic spatially explicit model (ANOSPEX; Ano phelesSpatially-Explicit) to simulate Anopheles metapopulation dynamics. The model is biologically rich, parameterized by field data, and driven by field-collected weather data from Macha, Zambia. To preliminarily validate ANOSPEX, simulation results were compared to field mosquito collection data from Macha; simulated and observed dynamics were similar. The ANOSPEX model will be useful in a predictive and exploratory manner to develop, evaluate and implement traditional and novel strategies to control malaria, and for understanding the environmental forces driving Anopheles population dynamics.

Single-Nucleotide Polymorphisms for High-Throughput Genotyping of Anopheles arabiensis in East and Southern Africa

ABSTRACT Anopheles arabiensis Patton is one of the principal vectors of malaria in sub-Saharan Africa, occupying a wide variety of ecological zones. This species is increasingly responsible for malaria transmission in Africa and is becoming the dominant vector species in some localities. Despite its growing importance, little is known about genetic polymorphisms in this species. Multiple sequences of various gene fragments from An. arabiensis isolates from Cameroon were obtained from GenBank. In total, 20 gene fragments containing single-nucleotide polymorphisms (SNPs) at moderate density were selected for direct sequencing from field collected specimens from Tanzania and Zambia. We obtained 301 SNPs in total from the 20 gene fragments, 60 of which were suitable for Illumina GoldenGate SNP genotyping. A greater number of SNPs (n = 185) was suitable for analysis using Sequenom iPLEX, an alternative high-throughput genotyping technology using mass spectrometry. An SNP was present every 59 (± 44.5) bases on average. Overall, An. arabiensis from Tanzania and Zambia are genetically closer (mean FST = 0.075) than either is to populations in Cameroon (FST TZ-CM = 0.250, FST,ZA-CM = 0.372). A fixed polymorphism between East/southern and Central Africa was identified on AGAP000574, a gene on the X chromosome. We have identified SNPs in natural populations of An. arabiensis. SNP densities in An. arabiensis were higher than Anopheles gambiae s.s., suggesting a greater challenge in the development of high-throughput SNP analysis for this species. The SNP markers provided in this study are suitable for a high-throughput genotyping analysis and can be used for population genetic studies and association mapping efforts.

Targeting indoor residual spraying for malaria using epidemiological data: a case study of the Zambia experience

BackgroundIn Zambia and other sub-Saharan African countries affected by ongoing malaria transmission, indoor residual spraying (IRS) for malaria prevention has typically been implemented over large areas, e.g., district-wide, and targeted to peri-urban areas. However, there is a recent shift in some countries, including Zambia, towards the adoption of a more strategic and targeted IRS approach, in coordination with increased emphasis on universal coverage of long-lasting insecticidal nets (LLINs) and effective insecticide resistance management. A true targeted approach would deliver IRS to sub-district areas identified as high-risk, with the goal of maximizing the prevention of malaria cases and deaths.ResultsTogether with the Government of the Republic of Zambia, a new methodology was developed applying geographic information systems and satellite imagery to support a targeted IRS campaign during the 2014 spray season using health management information system data.Discussion/ConclusionThis case study focuses on the developed methodology while also highlighting the significant research gaps which must be filled to guide countries on the most effective strategy for IRS targeting in the context of universal LLIN coverage and evolving insecticide resistance.

Feasibility and Effectiveness of mHealth for Mobilizing Households for Indoor Residual Spraying to Prevent Malaria: A Case Study in Mali

Sending voice and/or text messages to mobilize households for spraying was more costly per structure and less effective at preparing structures than traditional door-to-door mobilization approaches supplemented with radio and town hall announcements. Challenges included: Lack of familiarity with mobile phones and with public health mobile messaging Lack of face-to-face communication with mobilizers, making it easier to ignore mobilization messages and preventing trust-building Low literacy levels Gender differentials in access to mobile phones Sending voice and/or text messages to mobilize households for spraying was more costly per structure and less effective at preparing structures than traditional door-to-door mobilization approaches supplemented with radio and town hall announcements. Challenges included: Lack of familiarity with mobile phones and with public health mobile messaging Lack of face-to-face communication with mobilizers, making it easier to ignore mobilization messages and preventing trust-building Low literacy levels Gender differentials in access to mobile phones ABSTRACT Components of mHealth are increasingly being added to development interventions worldwide. A particular case of interest is in Mali where the U.S. President’s Malaria Initiative (PMI) Africa Indoor Residual Spraying (AIRS) Project piloted a mobile mass-messaging service in Koulikoro District in August 2014 to determine whether voice and/or text messages received on cell phones could effectively replace door-to-door mobilization for an indoor residual spraying (IRS) campaign. To measure the pilot’s effectiveness, we evaluated structure preparedness (all household and food items removed) in 3 pilot intervention villages compared with 3 villages prepared for spray through door-to-door mobilization that was modified by incorporating town hall meetings and radio spots. Structure preparedness was significantly lower in households mobilized through the mobile-messaging approach compared with the door-to-door approach (49% vs. 75%, respectively; P = .03). Spray coverage of targeted households also was significantly lower among the mobile-messaging villages than the door-to-door mobilization villages (86% vs. 96%, respectively; P = .02). The mobile-messaging approach, at US

Nationwide insecticide resistance status and biting behaviour of malaria vector species in the Democratic Republic of Congo

8.62 per structure prepared, was both more costly and less effective than the door-to-door approach at US