Philip M. Armstrong

Department of Environmental Sciences
The Connecticut Agricultural Experiment Station
123 Huntington Street
New Haven, CT 06511
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 T. A., McMillan J. R., Shepard J. J., Andreadis T. G., Armstrong, P. M. (2020). Increased mosquito abundance and species richness in Connecticut, United States 2001-2019. Sci Reports, 10(1), 19287.

  • Eastwood G., Shepard J. J., Misencik M. J., Andreadis T. G., Armstrong, P. M. (2020). Local persistence of novel regional variants of La Crosse virus in the Northeast USA. Parasit Vectors, 13(1), 569.

  • McMillan J. R., Armstrong, P. M., Andreadis T. G. (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 A. K., Shepard J. J., Misencik M. J., Bedoukian R., Cole L., Armstrong, P. M., Andreadis T. G. (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 P. A., Eastwood G., Collins-Palmer K., Katz M., Falco R. C., Bajwa W. I., Armstrong, P. M., Andreadis T. G., Diuk-Wasser M. A. (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, P. M. , Ehrlich H. Y., Magalhaes T., Miller M. R., Conway P. J., Bransfield A., Misencik M. J., Gloria-Soria A., Warren J. L., Andreadis T. G., Shepard J. J., Foy B. D., Pitzer V. E., Brackney D. E. (2020). Successive blood meals enhance virus dissemination within mosquitoes and increase transmission potential. Nat. Microbiol. 5(2), 239-247.

  • Uraki R., Hastings A. K., Brackney, D. E., Armstrong, P. M., Fikrig E. (2019). AgBR1 antibodies delay lethal Aedes aegypti-borne West Nile virus infection in mice. NPJ Vaccines, 4, 23.

  • Keyel A. C., Elison Timm, O., Backenson, P. B., Prussing, C., Quinones, S., McDonough, K. A., Vuille, M., Conn, J. E., Armstrong, P. M., Andreadis, T. G., Kramer, L. D. (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, N. D., Misencik, M. J., Armstrong, P. M., Stenglein, M. D., Ebel, G. D., Brackney, D. E. (2018). Adventitious viruses persistently infect three commonly used mosquito cell lines. Virology521, 175-180.

  • Tan, Y., Tsan-Yuk Lam, T., Heberlein-Larson, L. A., Smole, S. C., Auguste, A. J., Hennigan, S., Halpin, R. A., Fedorova, N., Puri, V., Stockwell, T. B., Shilts, M. H., Andreadis, T., Armstrong, P. M., Tesh, R. B., Weaver, S. C., Unnasch, T. R., Ciota, A. T., Kramer, L. D., Das, S. R. (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, J. F., Armstrong, P. M., Misencik, M. J., Bransfield, A. B, Andreadis, T. G., 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, P. E., Armstrong, P. M., Liu, P., Bova, J. E., Bernick, J. N., McMillan, B. E., Weidlich, B. G., Paulson, S. L. (2018). Cache Valley Virus in Aedes japonicus japonicus mosquitoes, Appalachian Region, United States. Emerg Infect Dis., 24(3), 553-557.

  • Skaff, N. K., Armstrong, P. M., Andreadis, T. G., and Cheruvelil, K. S. (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, P. M., Powell, J. F., and Turner P. E. (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, P. M., Andreadis T. G., Shepard J. J., and Thomas, M. C. (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, M. E., Yao, Y., Nock, D., Armstrong, P. M., Andreadis T. G., Diuk-Wasser, M. A., Montgomery, R. R. (2017). West Nile Virus Seroprevalence, Connecticut, USA, 2000-2014. Emerg. Infect. Dis. 23(4), 708-710.

  • Grubaugh, N. D., Rückert, C., Armstrong, P. M., Bransfield, A., Anderson, J. F., Ebel, G. D., and Brackney, D. E. (2016). Transmission bottlenecks and RNAi collectively influence tick-borne flavivirus evolution. Virus Evol., 2(2), vew033.

  • Brackney, D. E.and Armstrong, P. M. (2016). Transmission and evolution of tick-borne viruses. Curr. Opin. in Virol., 21, 67-74.

  • Misencik M. J., Grubaugh, N. D., Andreadis, T. G., Ebel, G. D., and Armstrong, P. M. (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, M. C., Muller, T., Medlock, J., Shepard, J. J., Armstrong, P. M., and Andreadis, T. G. (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, P. M., Graham, A. C., Kramer, L. D., and Andreadis, T. G. (2015). Insights into the recent emergence and expansion of eastern equine encephalitis virus in a new focus in the Northern New England USA. Parasites & Vectors, 8, 516.

  • Molaei, G., Armstrong, P. M., Abadam, C. F., Akaratovic, K. I., Kiser, J. P., and Andreadis, T. G. (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, P. M., Andreadis T. G., and Anderson, J. F. (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, J. F., Main A. J., Armstrong, P. M., Andreadis, T. G., and Ferrandino, F. J. (2015). Arboviruses in North Dakota, 2003-2006.  Am. J. Trop. Med. Hyg., 92, 377-93.

  • Andreadis T. G., Armstrong, P. M., Anderson, J. F., and Main, A. J. (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, P. M., Anderson, J. F., Farajollahi, A., Healy, S. P., Unlu, I., Crepeau, T. N., Gaugler, R., Fonseca, D. M., Andreadis, T. G. (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, P. M. and Andreadis T. G. (2013). Eastern equine encephalitis virus--old enemy, new threat.  N. Engl. J. Med., 368, 1670-3.

  • Molaei, G., Andreadis T. G., Armstrong, P. M., Thomas, M. C., Deschamps, T., Cuebas-Incle, E., Montgomery, W., Osborne, M., Smole, S., Matton, P., Andrews, W., Best, C., Cornine, F. III, 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, J. F. and P. M. Armstrong (2012). Prevalence and genetic characterization of Powassan virus strains infecting Ixodes scapularis in Connecticut. Am. J. Trop. Med. Hyg., 87, 754-9.

  • Armstrong, P. M., N. Prince, T. G. 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, P. M., C. R. Vossbrinck, T. G. Andreadis,  J. F. Anderson, K. N. Pesko, R. M. Newman, N. J. Lennon, B. W. Birren, G. D. Ebel, and M. R. Henn (2011). Molecular evolution of West Nile virus in a northern temperate region: Connecticut, USA 1999-2008. Virology, 417, 203-10.

  • Armstrong, P. M., T. G. Andreadis, S. L. Finan, J. J. Shepard, M. C. 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., R. F. Cummings, T. Su, P. M. Armstrong, G. A. Williams, M. L. Chen, J. P. Webb and T. G. Andreadis (2010). Vector-host interactions governing epidemiology of West Nile virus in southern California.  Am. J. Trop. Med. Hyg., 83, 1269-1282.

  • Armstrong, P. M. and T. G. Andreadis (2010). Eastern equine encephalitis virus in mosquitoes and their role as bridge vectors.  Emerg. Infect. Dis. 16,1869-1874.

  • Andreadis T. G., P. M. Armstrong, and W. I. 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, M. A., G. Molaei, J. E. Simpson, C. M. Folsom-O’Keefe, P. M. Armstrong and T. G. 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, P. M. Armstrong, J. Oliver, J. J. Howard, T. G. 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, P. M., T. G. Andreadis, J. F. Anderson, J. W. Stull, C. N. 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., T. G. Andreadis, P. M. 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 T. G., J. F. Anderson, P. M. Armstrong, and A. J. 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, P. M. and T. G. Andreadis (2007). Genetic relationships of Jamestown Canyon virus strains (Bunyaviridae: Orthobunyavirus) infecting Connecticut mosquitoes. Am. J. Trop. Med. Hyg., 77, 1157-62.

  • Molaei, G., T. G. Andreadis, P. M. Armstrong, R. Bueno, J. Dennett, S. V. Real, C. Sargent, A. Bala, Y. Randle, H. Guzman, A., Travassos Da Rosa, T. Wuithiranyagool, and R. B. 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 T. G. and P. M. 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, T. G. Andreadis, P. M. Armstrong, J. J. 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, P. M. and T. G. Andreadis (2006). A new genetic variant of La Crosse virus isolated from New England. Am. J. Trop. Med. Hyg. 75, 491-496.

  • Molaei, G., T. G. Andreadis, P. M. Armstrong, J. F. Anderson, C. R. Vossbrinck (2006). Host feeding patterns of Culex mosquitoes and West Nile virus transmission, northeastern United States. Emerg. Infect. Dis. 12, 468-474.

  • Armstrong, P. M., T. G. Andreadis, J. F. Anderson, A. J. Main (2005). Isolations of Potosi virus from mosquitoes collected in Connecticut. J. Med. Entomol. 42, 875-881.