Desmond H. Foley

The AFHSC-Division of GEIS Operations Predictive Surveillance Program: a multidisciplinary approach for the early detection and response to disease outbreaks

The Armed Forces Health Surveillance Center, Division of Global Emerging Infections Surveillance and Response System Operations (AFHSC-GEIS) initiated a coordinated, multidisciplinary program to link data sets and information derived from eco-climatic remote sensing activities, ecologic niche modeling, arthropod vector, animal disease-host/reservoir, and human disease surveillance for febrile illnesses, into a predictive surveillance program that generates advisories and alerts on emerging infectious disease outbreaks. The program’s ultimate goal is pro-active public health practice through pre-event preparedness, prevention and control, and response decision-making and prioritization. This multidisciplinary program is rooted in over 10 years experience in predictive surveillance for Rift Valley fever outbreaks in Eastern Africa. The AFHSC-GEIS Rift Valley fever project is based on the identification and use of disease-emergence critical detection points as reliable signals for increased outbreak risk. The AFHSC-GEIS predictive surveillance program has formalized the Rift Valley fever project into a structured template for extending predictive surveillance capability to other Department of Defense (DoD)-priority vector- and water-borne, and zoonotic diseases and geographic areas. These include leishmaniasis, malaria, and Crimea-Congo and other viral hemorrhagic fevers in Central Asia and Africa, dengue fever in Asia and the Americas, Japanese encephalitis (JE) and chikungunya fever in Asia, and rickettsial and other tick-borne infections in the U.S., Africa and Asia.

Insight into Global Mosquito Biogeography from Country Species Records

Abstract To advance our limited knowledge of global mosquito biogeography, we analyzed country occurrence records from the Systematic Catalog of the Culicidae (http://www.mosquitocatalog. org/main.asp), and we present world maps of species richness and endemism. A latitudinal biodiversity gradient was observed, with species richness increasing toward the equator. A linear log-log species (y)–area (x) relationship (SAR) was found that we used to compare observed and expected species densities for each country. Brazil, Indonesia, Malaysia, and Thailand had the highest numbers of species, and Brazil also had the highest taxonomic output and number of type locations. Brazil, Australia, the Philippines, and Indonesia had the highest numbers of endemic species, but excluding small island countries, Panama, French Guiana, Malaysia, and Costa Rica had the highest densities of total species and endemic species. Globally, 50% of mosquito species are endemic. Island countries had higher total number of species and higher number of endemic species than mainland countries of similar size, but the slope of the SAR was similar for island and mainland countries. Islands also had higher numbers of publications and type locations, possibly due to greater sampling effort and/or species endemism on islands. The taxonomic output was lowest for some countries in Africa and the Middle East. A consideration of country estimates of past sampling effort and species richness and endemism is proposed to guide mosquito biodiversity surveys. For species groups, we show that the number of species of Anopheles subgenus Anopheles varies with those of subgenus Cellia in a consistent manner between countries depending on the region. This pattern is discussed in relation to hypotheses about the historical biogeography and ecology of this medically important genus. Spatial analysis of country species records offers new insight into global patterns of mosquito biodiversity and survey history.

MosquitoMap and the Mal-area calculator: new web tools to relate mosquito species distribution with vector borne disease

BackgroundMosquitoes are important vectors of diseases but, in spite of various mosquito faunistic surveys globally, there is a need for a spatial online database of mosquito collection data and distribution summaries. Such a resource could provide entomologists with the results of previous mosquito surveys, and vector disease control workers, preventative medicine practitioners, and health planners with information relating mosquito distribution to vector-borne disease risk.ResultsA web application called MosquitoMap was constructed comprising mosquito collection point data stored in an ArcGIS 9.3 Server/SQL geodatabase that includes administrative area and vector species x country lookup tables. In addition to the layer containing mosquito collection points, other map layers were made available including environmental, and vector and pathogen/disease distribution layers. An application within MosquitoMap called the Mal-area calculator (MAC) was constructed to quantify the area of overlap, for any area of interest, of vector, human, and disease distribution models. Data standards for mosquito records were developed for MosquitoMap.ConclusionMosquitoMap is a public domain web resource that maps and compares georeferenced mosquito collection points to other spatial information, in a geographical information system setting. The MAC quantifies the Mal-area, i.e. the area where it is theoretically possible for vector-borne disease transmission to occur, thus providing a useful decision tool where other disease information is limited. The Mal-area approach emphasizes the independent but cumulative contribution to disease risk of the vector species predicted present. MosquitoMap adds value to, and makes accessible, the results of past collecting efforts, as well as providing a template for other arthropod spatial databases.

Potential Distribution of Two Species in the Medically Important Anopheles minimus Complex (Diptera: Culicidae)

Abstract Anopheles minimus Theobald (=An. minimus A) and possibly Anopheles harrisoni Harbach & Manguin (=An. minimus C) are important malaria vector species in the Minimus Complex in Southeast Asia. The distributions of these species are poorly known, although detailed information could benefit malaria vector incrimination and control. We used published collection records of these species and environmental geospatial data to construct consensus ecological niche models (ENM) of each species’ potential geographic distribution. The status of the Indian taxon An. fluviatilis S as a species distinct from An. harrisoni has been debated in the literature, so we tested for differentiation in ecological niche characteristics. The predicted potential distribution of An. minimus is more southerly than that of An. harrisoni: Southeast Asia is predicted to be more suitable for An. minimus, and China and India are predicted more suitable for An. harrisoni, so An. harrisoni seems to dominate under cooler conditions. The distribution of An. minimus is more continuous than that of An. harrisoni: disjunction in the potential distribution of the latter is suggested between India and Southeast Asia. Anopheles fluviatilis S occurrences are predicted within the An. harrisoni ecological potential, so we do not document ecological differentiation that might reject conspecificity. Overall, model predictions offer a synthetic view of the distribution of this species complex across the landscapes of southern and eastern Asia.

The value of georeferenced collection records for predicting patterns of mosquito species richness and endemism in the Neotropics

Abstract 1. Determining large‐scale distribution patterns for mosquitoes could advance knowledge of global mosquito biogeography and inform decisions about where mosquito inventory needs are greatest.

Geographic distribution and ecology of potential malaria vectors in the Republic of Korea.

ABSTRACT Environmental geospatial data and adult and larval mosquito collection data for up to 106 sites throughout the Republic of Korea (ROK) were used to develop ecological niche models (ENMs) of the potential geographic distribution for eight anopheline species known to occur there. The areas predicted suitable for the Hyrcanus Group species were the most extensive for Anopheles sinensis Wiedemann, An. kleini Rueda, An. belenrae Rueda, and An. pullus Yamada, intermediate for An. sineroides Yamada, and the most restricted for An. lesteri Baisas and Hu and the non-Hyrcanus Group species An. koreicus Yamada and Watanabe and An. lindesayi Yamada. The relative vectorial importance of these species is unknown, and all, except An. koreicus and An. lindesayi, are predicted to occur widely in the northwest of the ROK where malaria transmission has been sporadic since its resurgence in 1993. Our ENMs suggest that it is unlikely that An. koreicus and An. lindesayi are vectors, but we do not document consistent geographic differentiation that might incriminate any of the other species as vectors. Because all species are predicted to occur in North Korea, we also cannot reject the hypothesis that malaria infected mosquitoes from North Korea may have been the cause of the resurgence of malaria in the ROK. Ecological differentiation of the eight species is inferred from collection locations and 34 environmental layers based on remote sensing and global climatic averages. Interspecific differences were noted, and characterizing mosquito habitats by ground-based and remote sensing methods is proposed.

Importance of the"What, "" When,"and"Where"of Mosquito Collection Events

ABSTRACT There is increasing need to apply established standards for recording data on mosquito collection events, because of the diversity of potential data providers, and the growth and interoperability of online databases designed to host these collection records. In particular, adequate taxonomic and georeference data are needed for geodatabases such as Mosquitomap (http://www.mosquitomap.org/) that map and compare these collection points with other spatial information in a geographical information system (GIS) setting. Accurately georeferenced collection data are crucial for understanding mosquito biogeography, ecology, and the impact of environmental changes, as well as for species distribution modeling, planning mosquito surveys, and for determining disease risk. We sampled representative published reports of new mosquito species records from 1980 in North America to the present to ascertain the quality of georeference information. Our results show that authors have increased the frequency of reporting georeferences but that they vary in the precision of the georeference, and some information, such as the source, date, and datum of the georeference, are usually not given. We discuss recently established standards for recording collection events, some relevant online resources available to researchers to assist them in their georeferencing, and the data input schema developed for the Mosquitomap database. We propose that the mosquito research community adopt data standards for recording and reporting the results of mosquito collection events to increase the value of these data. In particular, we recommend authors lodge voucher specimens and use a GPS set to the WGS84 datum.

A Spatiotemporal Database to Track Human Scrub Typhus Using the VectorMap Application

Scrub typhus is a potentially fatal mite-borne febrile illness, primarily of the Asia-Pacific Rim. With an endemic area greater than 13 million km2 and millions of people at risk, scrub typhus remains an underreported, often misdiagnosed febrile illness. A comprehensive, updatable map of the true distribution of cases has been lacking, and therefore the true risk of disease within the very large endemic area remains unknown. The purpose of this study was to establish a database and map to track human scrub typhus. An online search using PubMed and the United States Armed Forces Pest Management Board Literature Retrieval System was performed to identify articles describing human scrub typhus cases both within and outside the traditionally accepted endemic regions. Using World Health Organization guidelines, stringent criteria were used to establish diagnoses for inclusion in the database. The preliminary screening of 181 scrub typhus publications yielded 145 publications that met the case criterion, 267 case records, and 13 serosurvey records that could be georeferenced, describing 13,739 probable or confirmed human cases in 28 countries. A map service has been established within VectorMap (www.vectormap.org) to explore the role that relative location of vectors, hosts, and the pathogen play in the transmission of mite-borne scrub typhus. The online display of scrub typhus cases in VectorMap illustrates their presence and provides an up-to-date geographic distribution of proven scrub typhus cases.

Distribution and larval habitats of Anopheles species in northern Gyeonggi Province, Republic of Korea.

ABSTRACT: A total of 180 larval collection sites (e.g., rice paddies, marshes, ground pools, ponds, stream margins, and irrigation and drainage ditches) was surveyed within a 2 km radius from Warrior Base training area, 5 km south of Panmunjeom (Joint Security Area, demilitarized zone), Gyeonggi Province, Republic of Korea (ROK), from May through October, 2007 to characterize larval habitat distributions of members of the Anopheles Hyrcanus Group (An. sinensis, An. lesteri, An. pullus, An. belenrae, An. kleini, and An. sineroides). A total of 5,859 anopheline larvae was collected from 84.4% of the sites surveyed, of which 4,071 were identified to species by polymerase chain reaction (PCR) using the ribosomal DNA internal transcribed spacer 2 (rDNA ITS2). Anopheles sinensis (52.6%) was the most frequently collected, followed by An. kleini (29.4%), An. sineroides (9.8%), An. pullus (6.7%), An. belenrae (1.1%), and An. lesteri (0.5%). Anopheles pullus and An. kleini were collected in greater proportions in May and from May – July, respectively. Few An. sinensis were collected from May – June, but it was the predominant species collected by August, and accounted for >80% of all larvae from September – October. Anopheles kleini was found in all habitats sampled; however, it was collected most frequently in young growth rice paddies, while An. sinensis was collected more frequently in mature and post-harvest paddies. Anopheles pullus was associated with pre-cultivated rice paddies, including water-filled tire ruts left from the previous falls harvest.

Mosquito bisection as a variable in estimates of PCR-derived malaria sporozoite rates

BackgroundHighly sensitive polymerase chain reaction (PCR) methods offer an alternative to the light microscopy examination of mosquito salivary glands for the determination of malaria sporozoite rates in wild caught female Anopheles. Removal of mosquito abdomens is assumed to eliminate false positives caused by malaria oocyst DNA in the midgut. This assumption has not been tested with current gold standard PCR assays, and for the variety of conditions that specimens could encounter in the laboratory and field.MethodsLaboratory Anopheles stephensi were used that had been infected with Plasmodium falciparum 6–7 days and 14 days post infection (p.i.), when oocysts only and oocysts + sporozoites, respectively, are developed. Mosquitoes were killed and immediately frozen, air dried before being frozen, or stored under humid conditions overnight before being frozen, to simulate a range of conditions in the field. Additionally, abdomens were removed anterior to, at, or posterior to the junction of the abdomen and thorax, and both portions were processed using a standard nested PCR of the small sub-unit nuclear ribosomal genes (ssrDNA) with products visualized on agarose gels.ResultsOverall, 4.1 % (4/97) of head + thorax samples that were 6–7 days p.i. gave apparent false positives for sporozoites, compared to 9.3 % (9/97) that were positive for abdomens. No positives (0/52) were obtained when similar specimens were bisected anterior to the junction of the thorax and abdomen, compared to 21.2 % (11/52) that were positive for posterior portions. Multiple bands were noted for positives from the ‘Frozen’ treatment and the rate of false negatives due to DNA degradation appears higher under the ‘Humid’ treatment. Reproducibility of results for the ‘Frozen’ treatment was 90 %.ConclusionsDespite the importance of specimen condition and the bisection step in determining sporozoite rates, little attention has been paid to them in the literature. Recommendations from this study are that: 1) care needs to be taken to reduce DNA degradation in the field; 2) mosquito abdomens be separated anterior to the junction of the thorax and abdomen; and 3) DNA sequencing of a subsample of positive results should be undertaken if possible.