Philip M. Armstrong

Department of Environmental Sciences
The Connecticut Agricultural Experiment Station
123 Huntington Street
P.O. Box 1106
New Haven, CT 06504
Voice: (203) 974-8510 Fax: (203) 974-8502



Dr. Armstrong has expertise on the molecular evolution, epidemiology, and ecology of arthropod-borne viruses (arboviruses). 



B.A. Biology, University of California, Santa Cruz (1991)

S.M. Tropical Public Health, Harvard School of Public Health (1994)

Sc.D. Tropical Public Health, Harvard School of Public Health (1998)


Station career:

Agricultural Scientist-2014-present
Associate Agricultural Scientist 2008-2014
Assistant Scientist II 2004-2008

Past Research:

Dr. Armstrong has conducted research on tick- and mosquito-borne viruses for more than 25 years (see selected publications below).


Current Research:

Current research focuses on the molecular evolution and ecology of arboviruses transmitted in the northeastern U.S., including eastern equine encephalitis virus, West Nile virus, and Powassan virus.  Genetic relationships of these viruses are compared to track the origin, spread, and long-term persistence of strains involved in disease outbreaks and to identify variants associated with different ecological niches and/or disease outcomes. In addition, his group evaluates the role of different mosquito species to serve as vectors of arboviruses by determining their vector competence, host-feeding, and virus-infection patterns in nature. He also directs the Connecticut Mosquito and Arbovirus Surveillance Program that monitors mosquito populations and virus activity at more than 100 locations statewide.


Selected publications available from the author,

  • Petruff TA, McMillan JR, Shepard JJ, Andreadis TG, Armstrong PM (2020) Increased mosquito abundance and species richness in Connecticut, United States 2001-2019. Sci Reports 2020 Nov 6;10(1):19287.

  • Eastwood G, Shepard JJ, Misencik MJ, Andreadis TG, Armstrong PM (2020) Local persistence of novel regional variants of La Crosse virus in the Northeast USA. Parasit Vectors 13(1):569.

  • McMillan JR, Armstrong PM, Andreadis TG (2020) Patterns of mosquito and arbovirus community composition and ecological indexes of arboviral risk in the northeast United States. PLoS Negl Trop Dis 14(2):e0008066.

  • Eastwood G, Donnellycolt AK, Shepard JJ, Misencik MJ, Bedoukian R, Cole L, Armstrong PM, Andreadis TG (2020) Evaluation of novel trapping lures for monitoring exotic and native container-inhabiting Aedes spp. (Diptera: Culicidae) mosquitoes. J Med Entomol 57(2):534-541.

  • Kache PA, Eastwood G, Collins-Palmer K, Katz M, Falco RC, Bajwa WI, Armstrong PM, Andreadis TG, Diuk-Wasser MA (2020) Environmental determinants of Aedes albopictus abundance at a northern limit of its range in the United States. Am J Trop Med Hyg 102(2):436-447.

  • Armstrong PM, Ehrlich HY, Magalhaes T, Miller MR, Conway PJ, Bransfield A, Misencik MJ, Gloria-Soria A, Warren JL, Andreadis TG, Shepard JJ, Foy BD, Pitzer VE, Brackney DE (2020) Successive blood meals enhance virus dissemination within mosquitoes and increase transmission potential. Nat Microbiol 5(2):239-247.

  • Uraki R, Hastings AK, Brackney DE, Armstrong PM, Fikrig E (2019) AgBR1 antibodies delay lethal Aedes aegypti-borne West Nile virus infection in mice. NPJ Vaccines. 4:23.

  • Keyel AC, Elison Timm O, Backenson PB, Prussing C, Quinones S, McDonough KA, Vuille M, Conn JE, Armstrong PM, Andreadis TG, Kramer LD (2019) Seasonal temperatures and hydrological conditions improve the prediction of West Nile virus infection rates in Culex mosquitoes and human case counts in New York and Connecticut. PLoS One. 14(6):e0217854.

  • Weger-Lucarelli J, Rückert C, Grubaugh ND, Misencik MJ, Armstrong PM, Stenglein MD, Ebel GD, Brackney DE (2018) Adventitious viruses persistently infect three commonly used mosquito cell lines. Virology 2018 521:175-180.

    Tan Y, Tsan-Yuk Lam T, Heberlein-Larson LA, Smole SC, Auguste AJ, Hennigan S, Halpin RA, Fedorova N, Puri V, Stockwell TB, Shilts MH,

  • Andreadis T, Armstrong, PM, Tesh RB, Weaver SC, Unnasch TR, Ciota AT, Kramer LD, Das SR (2018) Large scale complete genome sequencing and phylodynamic analysis of eastern equine encephalitis virus reveal source-sink transmission dynamics in the United States. J Virol  92:e00074-18

  • Anderson JF, Armstrong PM, Misencik MJ, Bransfield AB, Andreadis TG, and Molaei G (2018) Seasonal distribution, blood feeding habits, and viruses of mosquitoes in an open-faced quarry in Connecticut, 2010 and 2011.   J Am Mosq Cont Assoc 34(1):1-10.

  • Yang F, Chan K, Marek PE, Armstrong PM, Liu P, Bova JE, Bernick JN, McMillan BE, Weidlich BG, Paulson SL (2018) Cache Valley Virus in Aedes japonicus japonicus mosquitoes, Appalachian Region, United States. Emerg Infect Dis. 24(3):553-557.

  • Skaff NK, Armstrong PM, Andreadis TG, and Cheruvelil (2017) Wetland characteristics linked to broad-scale patterns in Culiseta melanura abundance and eastern equine encephalitis virus infection. Parasit Vectors 10:501.

  • Gloria-Soria A, Armstrong PM, Powell JF, and Turner PE (2017) Infection rate of Aedes aegypti mosquitoes with dengue virus depends on the interaction between temperature and mosquito genotype. Proc Biol Sci 284: 20171506.

  • Armstrong PM, Andreadis TG, Shepard JJ, and Thomas MC (2017) Northern range expansion of the Asian tiger mosquito (Aedes albopictus): Analysis of mosquito data form Connecticut USA. PLoS Negl Trop Dis 11(5): e0005623.

  • Cahill ME, Yao Y, Nock D, Armstrong PM, Andreadis TG, Diuk-Wasser MA, Montgomery RR (2017) West Nile Virus Seroprevalence, Connecticut, USA, 2000-2014. Emerg Infect Dis 23(4):708-710.

  • Grubaugh ND, Rückert C, Armstrong PM, Bransfield A, Anderson JF, Ebel GD, and Brackney DE (2016) Transmission bottlenecks and RNAi collectively influence tick-borne flavivirus evolution. Virus Evol 2(2):vew033.

  • Brackney DE and Armstrong PM (2016) Transmission and evolution of tick-borne viruses.  Curr Opin in Virol 21:67-74.

  • Misencik MJ, Grubaugh ND, Andreadis TG, Ebel GD, and Armstrong PM (2016) Isolation of a novel insect-specific flavivirus from Culiseta melanura in the northeastern United States.  Vector-Borne Zoonotic Dis 16(33): 181-190.

  • Molaei G, Thomas MC, Muller T, Medlock J, Shepard JJ, Armstrong PM, and Andreadis TG (2016) Dynamics of vector-host interactions in avian communities in four eastern equine encephalitis virus foci in the northeastern U.S.  PLoS Negl Trop Dis 10(1):e0004347.

  • Nelson R, Esponda-Morrison B, Armstrong P, and Shepard J (2015) West Nile virus- Connecticut, 2015.  Conn Epidemiol 35(7): 25-26.

  • Molaei G, Armstrong PM, Graham AC, Kramer LD, and Andreadis TG (2015) Insights into the recent emergence and expansion of eastern equine encephalitis virus in a new focus in the Northern New England USA.  Parasit Vectors 8: 516.

  • Molaei G, Armstrong PM, Abadam CF, Akaratovic KI, Kiser JP, and Andreadis TG (2015) Vector-host interactions of Culiseta melanura in a focus of eastern equine encephalitis virus activity in southeastern Virginia.  PLoS One 10(9): e0136743.

  • Armstrong PM, Andreadis TG, and Anderson JF (2015) Emergence of a new lineage of Cache Valley virus (Bunyaviridae: Orthobunyavirus) in the northeastern United States.  Am J Trop Med Hyg 93: 11-17.

  • Anderson JF, Main AJ, Armstrong PM, Andreadis TG, and Ferrandino FJ (2015) Arboviruses in North Dakota, 2003-2006.  Am J Trop Med Hyg 92: 377-93.

  • Andreadis TG, Armstrong PM, Anderson JF, and Main AJ (2014) Spatial-temporal analysis of Cache Valley virus infection in Anopheline and Culicine mosquitoes in the northeastern United States, 1997-2012. Vector-Borne Zoonotic Dis 14: 763-73.

  • Nelson R, Ciesielski T, Andreadis T, and Armstrong P (2014) Human case of eastern equine encephalitis- Connecticut, 2013.  Conn Epidemiol 34(3): 9-10.

  • Nelson R, Esponda B, Andreadis T, and Armstrong P (2014) West Nile virus Connecticut, 2000-2013. Conn Epidemiol 34(2):5-7.

  • Armstrong PM, Anderson JF, Farajollahi A, Healy SP, Unlu I, Crepeau TN, Gaugler R, Fonseca DM, Andreadis TG (2013) Isolations of Cache Valley virus from Aedes albopictus (Diptera: Culicidae) in New Jersey and evaluation of its role as a regional arbovirus vector. J Med Entotomol 50(6): 1310-14.

  • Armstrong PM and Andreadis TG. (2013) Eastern equine encephalitis virus--old enemy, new threat.  N Engl J Med 368:1670-3.

  • Molaei G, Andreadis TG, Armstrong PM, Thomas MC, Deschamps T, Cuebas-Incle E, Montgomery W, Osborne M, Smole S, Matton P, Andrews W, Best C, Cornine F 3rd, Bidlack E, Texeira T (2013) Vector-host interactions and epizootiology of eastern equine encephalitis virus in Massachusetts. Vector Borne Zoonotic Dis 13:312-23.

  • Anderson JF and PM Armstrong (2012) Prevalence and genetic characterization of Powassan virus strains infecting Ixodes scapularis in Connecticut. Am J Trop Med Hyg 87:754-9.

  • Armstrong PM, N Prince, TG Andreadis (2012) Development of a multi-target TaqMan assay to detect eastern equine encephalitis virus variants in mosquitoes.  Vector Borne Zoonotic Dis 12:872-6.

  • Armstrong PM, CR Vossbrinck, TG Andreadis,  JF Anderson, KN Pesko, RM Newman, NJ Lennon, BW Birren, GD Ebel, and MR Henn (2011) Molecular evolution of West Nile virus in a northern temperate region: Connecticut, USA 1999-2008. Virology 417:203-10.

  • Armstrong PM, TG Andreadis, SL Finan, JJ Shepard, MC Thomas (2011) Detection of infectious virus from field-collected mosquitoes by Vero cell culture assay. J Vis Exp 52: pii: 2889. doi: 10.3791/2889.30.

  • Molaei G, RF Cummings, T Su, PM Armstrong, GA Williams, ML Chen, JP Webb and TG Andreadis (2010) Vector-host interactions governing epidemiology of West Nile virus in southern California.  Am J Trop Med Hyg 83: 1269-1282.

  • Armstrong PM and TG Andreadis (2010) Eastern equine encephalitis virus in mosquitoes and their role as bridge vectors.  Emerg Infect Dis 16:1869-1874.

  • Andreadis TG, PM Armstrong, and WI Bajwa (2010) Studies on hibernating populations of Culex pipiens from a West Nile virus endemic focus in New York City: parity rates and isolation of West Nile virus. J Am Mosq Cont Assoc 26: 257-64.

  • Diuk-Wasser MA, G Molaei, JE Simpson, CM Folsom-O’Keefe, PM Armstrong and TG Andreadis (2010) Avian communal roosts as amplification foci for West Nile virus in urban areas in northeastern United States. Am J Trop Med Hyg 82:337-43.

  • Molaei G, A Frajollahi, PM Armstrong, J Oliver, JJ Howard, TG Andreadis (2009) Identification of blood meals in Anopheles quadrimaculatus and Anopheles    punctipennis from eastern equine encephalitis virus foci in northeastern U.S.A. Med Vet Entomol 23:350-6.

  • Armstrong PM, TG Andreadis, JF Anderson, JW Stull, CN Mores (2008) Tracking eastern equine encephalitis virus perpetuation in northeastern U.S. by phylogenetic analysis. Am J Trop Med Hyg 79:291-6.

  • Molaei G, TG Andreadis, PM Armstrong, M Diuk-Wasser (2008) Host-feeding patterns of mosquito vectors of arboviral agents in Connecticut, USA: molecular analysis of blood meals from twenty-three species of Aedes, Anopheles, Culex, Coquillettidia, Psorophora, and Uranotaenia. J Med Entomol 45:1143-51.

  • Andreadis TG, JF Anderson, PM Armstrong, and AJ Main (2008) Isolations of Jamestown Canyon virus (Bunyaviridae: Orthobunyavirus) from field collected mosquitoes (Diptera: Culicidae) in Connecticut, USA: a ten-year analysis, 1997-2006. Vector Borne Zoonotic Dis 8:175-88.

  • Armstrong PM and TG Andreadis (2007) Genetic relationships of Jamestown Canyon virus strains (Bunyaviridae: Orthobunyavirus) infecting Connecticut mosquitoes. Am J Trop Med Hyg 77: 1157-62.

  • Molaei G, TG Andreadis, PM Armstrong, R Bueno, J Dennett, SV Real, C Sargent, A Bala, Y Randle, H Guzman, A, Travassos Da Rosa, T Wuithiranyagool, and RB Tesh (2007) Host feeding pattern of Culex quinquefasciatus and its role in transmission of West Nile virus in Harris County, Texas. Am J Trop Med 77: 73-81.

  • Andreadis TG and PM Armstrong (2007) A two-year evaluation of elevated canopy trapping for Culex mosquitoes and West Nile virus in an operation surveillance program in the northeastern United States. J Am Mosq Cont Assoc 23: 137-148.

  • Molaei G, J Oliver, TG Andreadis, PM Armstrong, JJ Howard (2006) Molecular identification of blood-meal sources in Culiseta  melanura and Culiseta morsitans from an endemic focus of eastern equine encephalitis virus in New York.  Am  J Trop Med Hyg 75: 1140-1147.

  • Armstrong PM and TG Andreadis (2006) A new genetic variant of La Crosse virus isolated from New England. Am J Trop Med Hyg 75: 491-496.

  • Molaei G, TG Andreadis, PM Armstrong, JF Anderson, CR Vossbrinck (2006) Host feeding patterns of Culex mosquitoes and West Nile virus transmission, northeastern United States. Emerg Infect Dis 12: 468-474.

  • Armstrong PM, TG Andreadis, JF Anderson, AJ Main (2005) Isolations of Potosi virus from mosquitoes collected in Connecticut. J Med Entomol 42: 875-881.