Wendy Varnado

Culex Flavivirus and West Nile Virus in Culex quinquefasciatus Populations in the Southeastern United States

ABSTRACT Little is known of the interactions between insect-only flaviviruses and other arboviruses in their mosquito hosts, or the potential public health significance of these associations. The specific aims of this study were to describe the geographic distribution, prevalence, and seasonal infection rates of Culex flavivirus (CxFV) and West Nile virus (WNV) in Culex quinquefasciatus Say in the Southeastern United States, investigate the potential association between CxFV and WNV prevalence in Cx. quinquefasciatus and describe the phylogenetic relationship among CxFV and WNV isolates from the Southeastern United States and around the world. Using ArboNET records, 11 locations were selected across Georgia, Mississippi, and Louisiana that represented a range of WNV human case incidence levels. Cx. quinquefasciatus were trapped weekly throughout the summer of 2009 and pools were screened for flavivirus RNA by reverse transcriptase polymerase chain reaction. Cx. quinquefasciatus from Georgia had significantly higher CxFV infection rates than either Mississippi or Louisiana. CxFV was not detected in Mississippi after July, and no CxFV was detected in Cx. quinquefasciatus in Louisiana. In Georgia, CxFV infection rates were variable between and within counties and over time. WNV infection rates were not significantly different across states or months, and WNV sequences from all three states were identical to each other in the envelope and NS5 gene regions. Phylogenetically, NS5 and E gene sequences from Georgia CxFV isolates clustered with CxFV from Japan, Iowa, and Texas. Multiple CxFV genetic variants were found circulating simultaneously in Georgia. No evidence was found supporting an association between WNV and CxFV infection prevalence in Cx. quinquefasciatus.

NOTES ON THE ECOLOGY OF CULEX CORONATOR DYAR AND KNAB, IN MISSISSIPPI

ABSTRACT CDC light-trap collections and larval dipping conducted during 2004 and 2005 revealed Culex coronator firmly entrenched in 10 counties in central and south Mississippi. A total of 3,307 specimens (2,200 adults, 1,107 larvae) of Cx. coronator have been collected in Mississippi. Notes on breeding sites and seasonality are presented and discussed. It is likely that the Mississippi population of Cx. coronator is contiguous with the one previously known from southern Texas, because specimens have been collected in Harris County, TX over the last few years, and were also found in Louisiana in 2004. Establishment of this population of a nonnative mosquito in Mississippi reveals how apparently easy it is for such events to happen.

An Annotated List of the Mosquitoes (Diptera: Culicidae) of Mississippi

ABSTRACT: There has been no previous systematic statewide study of mosquitoes in Mississippi. This survey, resulting in the collection of over 400,000 specimens, was conducted by the authors from 2003 to 2007 throughout much of the state using CO2-baited CDC light traps and larval dipping. In addition, a health department contract mosquito surveillance technician collected several thousand specimens from the state from 2001 to 2003. Lastly, specimens housed at the Mississippi State University Entomological Museum, obtained from previous surveys, were included as vouchers for species occurring in the state. The collection records and literature show 60 species as occurring or having occurred in Mississippi. Voucher specimens representing 57 of the 60 species discussed are deposited in the Mississippi Entomological Museum or in the U.S. National Museum of Natural History (USNM), Washington, D.C.

Abundance and Diversity of Mosquito Species Collected From a Rural Area of Central Mississippi: Implications for West Nile Virus Transmission in Mississippi

Abstract To determine abundance and seasonality of potential West Nile virus (WNV) mosquito vectors in a forested area of central Mississippi, mosquitoes were collected weekly from a wildlife management area located approximately 10 mi from a local urban area known to have numerous human WNV cases. We were particularly interested in the presence or absence of Culex quinquefasciatus, the primary vector of WNV in Mississippi, although other Culex species were assayed. Two Centers for Disease Control and Prevention light traps baited with CO2 were set once a week from 2005 through 2006 in the Pearl River Wildlife Management Area (PRWMA), which consists of 6,925 acres primarily composed of bottomland hardwood forest with wetland areas. Traps were placed midafternoon and picked up the following morning. A total of 199,222 mosquitoes were collected during the 2-year study. No Cx. quinquefasciatus were collected throughout the entire study, although other health department surveys have indicated they are abundant just a few miles away. As for other potential WNV vectors, 1,325 (0.6%) Cx. nigripalpus, 1,804 (0.9%) Cx. restuans, and 6,076 (3.1%) Cx. salinarius were collected in the PRWMA over the 2-year period. These data suggest that Cx. quinquefasciatus is not usually found in remote forested environments, but is more associated with human habitation.

New diagnostic characters for females of Psorophora (Janthinosoma) species in the United States, with notes on Psorophora mexicana (Bellardi) (Diptera: Culicidae)

Abstract The discovery of an unusual specimen of Psorophora in Mississippi led to a search for new diagnostic characters on the seven United States species of Psorophora (Janthinosoma): Psorophora cyanescens, Ps. ferox, Ps. horrida, Ps. johnstonii, Ps. longipalpus, Ps. mathesoni, and Ps. mexicana. New characters were found and diagnostic descriptions and a new key are provided for identifying female specimens. The new key stresses morphological differences other than color patterns on the hindtarsi, however, notes on hindtarsal color and other variations found on each species are also provided. The status of Ps. mexicana specimens recorded from Texas is reviewed and a list of collections of this species since the 1945 record in Texas is provided. Evidence is provided supporting the recognition of Ps. mexicana as a distinct species.

Susceptibility and Vectorial Capacity of American Aedes albopictus and Aedes aegypti (Diptera: Culicidae) to American Zika Virus Strains

Abstract The rapid expansion of Zika virus (ZIKV), following the recent outbreaks of Chikungunya virus, overwhelmed the public health infrastructure in many countries and alarmed many in the scientific community. Aedes aegypti (L.) (Diptera: Culicidae) and Aedes albopictus (Skuse) (Diptera: Culicidae) have previously been incriminated as the vectors of these pathogens in addition to dengue virus. In our study, we challenged low generation Ae. aegypti (Chiapas, Mexico) and Ae. albopictus (North Carolina, Mississippi), with three strains of ZIKV, Puerto Rico (GenBank: KU501215), Honduras (GenBank: KX694534), and Miami (GenBank: MF988743). Following an oral challenge with 107.5 PFU/ml of the Puerto Rico strain, we observed high infection and dissemination rates in both species (95%). We report estimated transmission rates for both species (74 and 33%, for Ae. aegypti (L.) (Diptera: Culicidae) and Ae. albopictus (Skuse) (Diptera: Culicidae), respectively), and the presence of a probable salivary gland barrier in Ae. albopictus to Zika virus. Finally, we calculated vectorial capacity for both species and found that Ae. albopictus had a slightly lower vectorial capacity when compared with Ae. aegypti. Second Language Abstract: La rápida expansión del virus Zika, poco después de las epidemias de chikungunya, rebaso la infraestructura de salud pública en muchos países y sorprendió a muchos en la comunidad científica. Notablemente, Aedes aegypti y Aedes albopictus transmiten estos patógenos además del virus del dengue. En este estudio se expusieron con tres cepas americanas de virus Zika a grupos de Aedes aegypti y Aedes albopictus de generación reciente. Encontramos altos porcentajes de infección y diseminación en ambas especies (95%). Se reporta, la transmisión viral en ambas especies (74 y 33%, para Aedes aegypti and Aedes albopictus, respectivamente) y una probable barrera a nivel de glándulas salivarías. Finalmente, calculamos la capacidad vectorial para ambas especies.

A Statewide Survey for Container-Breeding Mosquitoes in Mississippi

Abstract Container-breeding mosquitoes are important in public health due to outbreaks of Zika, chikungunya, and dengue viruses. This paper documents the distribution of container-breeding mosquito species in Mississippi, with special emphasis on the genus Aedes. Five sites in each of the 82 Mississippi counties were sampled monthly between May 1 and August 31, 2016, and 50,109 mosquitoes in 14 species were collected. The most prevalent and widely distributed species found was Ae. albopictus, being found in all 82 counties, especially during July. A recent invasive, Ae. japonicus, seems to be spreading rapidly in Mississippi since first being discovered in the state in 2011. The most abundant Culex species collected were Cx. quinquefasciatus (found statewide), Cx. salinarius (almost exclusively in the southern portion of the state), and Cx. restuans (mostly central and southern Mississippi). Another relatively recent invasive species, Cx. coronator, was found in 20 counties, predominantly in the southern one-third of the state during late summer. Co-occurrence data of mosquito species found in the artificial containers were also documented and analyzed. Lastly, even though we sampled extensively in 410 sites across Mississippi, no larval Ae. aegypti were found. These data represent the first modern statewide survey of container species in Mississippi, and as such, allows for better public health readiness for emerging diseases and design of more effective vector control programs.

Human nasal myiasis possibly associated with cocaine abuse.

Blow fly (Diptera: Calliphoridae) larvae have been reported previously from human nares in cases of facultative myiasis (James 1947, USDA Misc. Publ. 631; Beckendorf et al. 2002, Arch. Intern. Med. 162:638 40; Daniel et al. 1994, J. Hosp. Infect. 28:149 52; Jacobson et al. 1980, Infect. Control 1: 319 20; Magnarelli et al. 1981, Am. J. Trop. Med. Hyg. 30: 894 96; Manfrim et al. 2007, Int. Arch. Otorhinolaryngol. 11:12-16; Smith and Clevenger 1986, Arch. Pathol. Laboratory. Med. 110: 439 440). These are often hospital-acquired infestations of comatose or incapacitated patients. However, nasal myiasis is uncommon. In a review of 400 articles on myiasis which reported 137 unique cases of U.S.-acquired myiasis, only 3 of those cases involved the nasal passages (Sherman 2000, Arch. Intern. Med. 160: 2004 14). The condition apparently affects men and women equally, usually in patients over 50, and mainly those in lower social classes (Sharma et al. 1989, J. Laryngol. Otol. 103: 489 91). Nasal ulcers, damage from leprosy, rhinorrhea, atrophic rhinitis, and nasopharyngeal infections may attract ovipositing flies (Manfrim et al. 2007; Sharma et al. 1989; Rao 1929, Indian Med. Gaz. 64: 308 82;Thami et al. 1995, J. Dermatol. 22: 348 50). Herein, we present a case of nasal myiasis, at first thought to have resulted from a car accident (and subsequent environmental exposure), but later assumed to be associated with cocaine abuse.

Survey of Mosquito Control Knowledge, Attitudes, and Practices among County and Municipal Programs in Mississippi

Abstract After Hurricane Katrina, 87 qualifying communities in Mississippi were issued contracts for disbursement of

Chikungunya in Mississippi: The Health Department Response to Imported Cases.

2.8 million in federal funds for mosquito control. As part of this funding, a survey of mosquito control personnel was conducted to evaluate effectiveness of mosquito control programs at these 87 sites before and after disbursement of funds. Two nearly identical questionnaires requested information from county and municipal personnel about specifics for each of the sites, descriptions of operations and practices, information about mosquito control personnel, and information about attitudes of the respondents before and after implementation of the grant. Findings revealed that municipal mosquito control in Mississippi is conducted mostly by personnel in small town/city public works departments and not by contract to an outside agency. Also, mosquito control is composed mostly of routine spraying, based loosely on complaints, time of year, or other factors. For example, only 3% of participants in our survey utilized adult mosquito trapping surveillance data in their spray decisions, and only 11% said they dipped for larvae before treating standing water sites. In light of current environmental consciousness and chemophobia, much work remains to bring Mississippi mosquito control up to current scientific standards. The survey described herein was the first step, shedding light on specific problems encountered in mosquito control and providing public health and regulatory officials with guidance as to which issues to address first.