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Weather, host and vector – their interplay in the spread of insect-borne animal virus diseases

Published online by Cambridge University Press:  15 May 2009

R. F. Sellers
R. F. Sellers
Affiliation:
Animal Virus Research Institute, Pirbright, Woking, Surrey
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Summary

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The spread of insect-borne animal virus diseases is influenced by a number of factors. Hosts migrate, move or are conveyed over long distances: vectors are carried on the wind for varying distances in search of hosts and breeding sites; weather and climate affect hosts and vectors through temperature, moisture and wind. As parasites of host and vector, viruses are carried by animals, birds and insects, and their spread can be correlated with the migration of hosts and the carriage of vectors on winds associated with the movements of the Intertropical Convergence Zone (ITCZ) and warm winds to the north and south of the limits of the ITCZ. The virus is often transmitted from a local cycle to a migratory cycle and back again.

Examples of insect-borne virus diseases and their spread are analysed. Japanese, Murray Valley, Western equine, Eastern equine and St Louis encephalitis represent viruses transmitted by mosquito–bird or pig cycles.

The areas experiencing infection with these viruses can be divided into a number of zones: A, B, C, D, E and F. In zone A there is a continuous cycle of virus in host and vector throughout the year; in zone B, there is an upsurge in the cycle during the wet season, but the cycle continues during the dry season; there is movement of infected vectors between and within zones A and B on the ITCZ and the virus is introduced to zone C by infected vectors on warm winds; persistence may occur in zone C if conditions are right. In zone D, virus is introduced each year by infected vectors on warm winds and the arrival of the virus coincides with the presence of susceptible nestling birds and susceptible piglets. The disappearance of virus occurs at the time when migrating mosquitoes and birds are returning to warmer climates. The virus is introduced to zone E only on occasions every 5–10 years when conditions are suitable. Infected hosts introduced to zone F do not lead to circulation of virus, since the climate is unsuitable for vectors. Zones A, B and C correspond to endemic and zones D and E to epidemic conditions.

Similar zones can be recognized for African horse sickness, bluetongue, Ibaraki disease and bovine ephemeral fever – examples of diseases transmitted in a midge-mammal cycle. In zones A and B viruses are transported by infected midges carried on the wind in association with the movement of ITCZ and undergo cycles in young animals. In these zones and in zone C there is a continual movement of midges on the warm wind between one area and another, colonizing new sites or reinforcing populations of midges already present. Virus is introduced at times into fringe areas (zones D and E) and, as there is little resistance in the host, gives rise to clinical signs of disease. In some areas there is persistence during adverse conditions; in others, the virus is carried back to the endemic zones by infected midges or vectors.

Examples of viruses maintained in a mosquito/biting fly–mammal cycle are Venezuelan equine encephalitis and vesicular stomatitis. These viruses enter a migratory cycle from a local cycle and the vectors in the migratory cycle are carried over long distances on the wind. Further examples of virus spread by movement of vectors include West Nile, Rift Valley fever, yellow fever, epizootic haemorrhagic disease of deer and Akabane viruses.

In devising means of control it is essential to decide the relationship of host, vector and virus and the nature of the zone in which the area to be controlled lies. Because of the continual risk of reintroduction of infected vectors, it is preferable to protect the host by dipping, spraying or by vaccination rather than attempting to eliminate the local population of insects.

Type
Research Article
Information
Journal of Hygiene , Volume 85 , Issue 1 , August 1980 , pp. 65 - 102
Copyright
Copyright © Cambridge University Press 1980

References

Aitken, T. H. G., Tesh, R. B., Beaty, B. J. & Rosen, L. (1979). Transovarial transmission of yellow fever virus by mosquitoes (Aedes aegypti). American Journal of Tropical Medicine and Hygiene 28, 119–21.CrossRefGoogle ScholarPubMed
Anderson, S. G. (1954). Murray Valley encephalitis and Australian X disease. Journal of Hygiene 52, 447–68.Google ScholarPubMed
Aphis (1973). The Origin and Spread of Venezuelan Equine Encephalomyelitis, pp. 25–9. U.S. Department of Agriculture, Hyattsville.Google Scholar
Arakawa, H. & Taga, S. (1969). Climate of Japan. Chapter 2 (pp. 119–58) in World Survey of Climatology, vol. 8. Amsterdam: Elsevier.Google Scholar
Arora, R. R. & Singh, N. N. (1974). Epidemiological study of an epidemic of Japanese encephalitis in Bankura district of West Bengal during 1973. Journal of Communicable Diseases 6, 310–19.Google Scholar
Asahina, S. (1970). Transoceanic flight of mosquitoes on the northwest Pacific. Japanese Journal of Medical Science and Biology 23, 255–8.CrossRefGoogle ScholarPubMed
Barnard, B. J. H. & Botha, M. J. (1977). An inactivated Rift Valley fever vaccine. Journal of the South African Veterinary Association 48, 45–8.Google Scholar
Bartlett, M. S. (1960). The critical community size for measles in the United States. Journal of the Royal Statistical Society A 123, 37–44.CrossRefGoogle Scholar
Berdonneau, R., Sérié, C., Panthier, R., Hannoun, C., Papaioannou, S. C. & Georgieff, P. (1961). Sur l'épidémie de fievre jaune do l'année 1959 en Ethiopie. Bulletin de la Société de Pathologie Exotique 54, 276–83.Google Scholar
Best, J. R., Abegunde, A. & Taylor, W. P. (1975). An outbreak of African horse sickness in Nigeria. Veterinary Record 97, 394.CrossRefGoogle ScholarPubMed
Bevan, L. E. W. (1907). Preliminary report on the so-called ‘stiff sickness’ or ‘three-day-sickness’ of cattle in Rhodesia. Journal of Comparative Pathology and Therapeutics 20, 104–13.CrossRefGoogle Scholar
Bigler, W. J., Lassing, E. B., Buff, E. E., Prather, E. C., Beck, E. C. & Hoff, G. L. (1976). Endemic eastern encephalomyelitis in Florida: a twenty year analysis, 1955–1974. American Journal of Tropical Medicine and Hygiene 25, 884–90.CrossRefGoogle ScholarPubMed
Black, F. L. (1966). Measles endemicity in insular populations. Critical community size and its evolutionary implication. Journal of Theoretical Biology 11, 207–11.CrossRefGoogle ScholarPubMed
Boucher, K. (1975). Global Climate. London. English Universities Press.Google Scholar
Bowden, J. (1973). Migration of pests in the tropics. Mededelingen-Fakulteit Landbouwwe tenschappen, Gent 38, 785–96.Google Scholar
Bowden, J. (1976). Weather and phenology of some African Tabanidae. Journal of the Entomological Society of South Africa 39, 207–45.Google Scholar
Bowden, J. & Gibbs, D. G. (1973). Light-trap and suction-trap catches of insects in the northern Gezira, Sudan, in the season of southward movement of the Inter-Tropical Front. Bulletin of Entomological Research 62, 577–96.CrossRefGoogle Scholar
Brown, E. S., Betts, E. & Rainey, R. C. (1969). Seasonal changes in distribution of the African Armyworm Spodoptera exempta (Wlk) (Lep. Noctuidae), with special reference to Eastern Africa. Bulletin of Entomological Research 58, 661–728.CrossRefGoogle Scholar
Buescher, E. L. & Scherer, W. F. (1959). Ecologic studies of Japanese encephalitis virus in Japan. IX. Epidemiologic correlations and conclusions. American Journal of Tropical Medicine and Hygiene 8, 719–22.CrossRefGoogle ScholarPubMed
Chiykowski, L. N. & Chapman, R. K. (1965). Migration of the six-spotted leafhopper Macrosteles fascifrons (Stol). 2. Migration of the six-spotted leafhopper in central North America. Research Bulletin of the Agricultural Experimental Station. University of Wisconsin, no. 261, pp. 21–45.Google Scholar
Creech, W. B. (1977). From the Center for Disease Control. St Louis encephalitis in the United States, 1975. Journal of Infectious Diseases 135, 1014–6.CrossRefGoogle Scholar
Dalarymple, J. M., Young, O. P., Eldridge, B. F. & Russell, P. K. (1972). Ecology of arboviruses in a Maryland freshwater Swamp. III. Vertebrate hosts. American Journal of Epidemiology 96, 129–40.CrossRefGoogle Scholar
Davies, F. G. & Walker, A. R. (1974). The isolation of ephemeral fever virus from cattle and Culicoides midges in Kenya. Veterinary Record 95, 63–4.CrossRefGoogle ScholarPubMed
Dipeolu, O. O. (1977). Potential vectors of bluetongue in Nigeria. Bulletin of Animal Health and Production in Africa 25, 17–23.Google Scholar
Doherty, R. L. (1974). Arthropod-borne viruses in Australia and their relation to infection and disease. Progress in Medical Virology 17, 136–92.Google ScholarPubMed
Douglass, J. R. & Cook, W. C. (1954). The beet leafhopper. Circular United States Department of Agriculture, no. 942, 21 pp.Google Scholar
Duviard, P. (1977). Migrations of Dysdercus spp. (Hemiptera: Pyrrhocoridae) related to movements of the Inter-Tropical Convergence Zone in West Africa. Bulletin of Entomological Research 67, 185–204.CrossRefGoogle Scholar
Eisa, M. (1974). The isolation and identification of type 9 African horse sickness virus in the Sudan. British Veterinary Journal 130, 606–9.CrossRefGoogle ScholarPubMed
French, E. L. (1973). A review of arthropod-borne virus infections affecting man and animals in Australia. Australian Journal of Experimental Biology and Medical Science 51, 131–58.CrossRefGoogle ScholarPubMed
Fukumi, H., Hayashi, K., Mifune, K., Shichijo, A., Matsuo, S., Omori, N., Wada, Y., Oda, T., Mogi, M. & Mori, A. (1975). Ecology of Japanese encephalitis in Japan. I. Mosquito and pig infection with the virus in relation to human incidences. Tropical Medicine 17, 97–110.Google Scholar
Gayral, P. H. & Cavier, R. (1971). Données entomologiques et écologiques actuelles surles vecteurs de la fièvre jaune en Afrique de l'Ouest. Bulletin de la Société de Pathologie Exotique 64, 701–8.Google Scholar
Gilyard, R. T. (1945). A clinical study of Venezuelan virus equine encephalomyelitis in Trinidad, B.W.I. Journal of the American Veterinary Medical Association 106, 267–77.Google Scholar
Glick, P. A. (1939). The distribution of insects, spiders and mites in the air. Technical Bulletin U.S. Department of Agriculture, no. 673.Google Scholar
Gutierrez, E., Monath, T. P., Alava, A., Uriguen, D., Arzube, M. & Chamberlain, R. W. (1975). Epidemiologic investigations of the 1969 epidemic of Venezuelan encephalitis in Ecuador. American Journal of Epidemiology 102, 400–413.CrossRefGoogle Scholar
Haddow, A. J., Dick, G. W. A., Lumsden, W. H. R. & Smithburn, K. C. (1951). Monkeys in relation to the epidemiology of yellow fever in Uganda. Transactions of the Royal Society of Tropical Medicine and Hygiene 45, 189–224.CrossRefGoogle Scholar
Haggis, M. J. (1971). Light trap captures of Spodoptera exempta (Walk.) in relation to wind direction. East African Agricultural and Forestry Journal 37, 100–108.CrossRefGoogle Scholar
Hanson, R. P. (1952). The natural history of vesicular stomatitis. Bacteriological Reviews 16, 179–204.CrossRefGoogle ScholarPubMed
Hanson, R. P. (1968). Discussion of the natural history of vesicular stomatitis. American Journal of Epidemiology 87, 264–5.CrossRefGoogle ScholarPubMed
Hanson, R. P. (1972). Virology and epidemiology of eastern and western arboviral encephalomyelitis of horses. Proc. 3rd International Conference of Equine Infectious Diseases, Paris. pp. 110–14. (Basel: Karger, 1973.)Google Scholar
Hardy, A. C. & Milne, P. S. (1938). Aerial drift of insects. Nature, London 141, 602.CrossRefGoogle Scholar
Hayashi, K., Mifune, K. & Shichijo, A. (1965). Problems of overwintering of Japanese encephalitis virus in Japan. Endemic Diseases Bulletin, Nagasaki University 7, 99–106.Google Scholar
Hayashi, K., Mifune, K., Matsuo, S., Shichijo, A., Suzuki, H., Ura, M., Makino, Y., Wada, Y., Oda, T., Mogi, M. & Mori, A. (1978 a). Ecology of Japanese encephalitis virus in Japan, particularly the results of surveys in every interepidemic season from 1964 to 1976. Tropical Medicine 20, 81–96.Google Scholar
Hayashi, K., Suzuki, H. & Asahina, S. (1978 b). Notes on the transoceanic insects captured on East China sea in 1977. Tropical Medicine 20, 131–42.Google Scholar
Hayes, C. G. & Wallis, R. C. (1977). Ecology of western equine encephalomyelitis viruses in the eastern United States. Advances in Virus Research 21, 37–83.CrossRefGoogle ScholarPubMed
Hayes, R. O., Francy, D. B., Lazuick, J. S., Smith, G. C. & Jones, R. H. (1976). Arbovirus surveillance in six states during 1972. American Journal of Tropical Medicine and Hygiene 25, 463–76.CrossRefGoogle ScholarPubMed
Hess, A. D. & Hayes, R. O. (1967). Seasonal dynamics of western encephalitis virus. American Journal of Medical Sciences 253, 333–48.CrossRefGoogle ScholarPubMed
Hinman, A. R., McGowan, J. E. Jr & Henderson, B. E. (1971). Venezuelan equine encephalomyelitis: surveys of human illness during an epizootic in Guatemala and EI Salvador. American Journal of Epidemiology 93, 130–36.CrossRefGoogle Scholar
Holden, P., Hayes, R. O., Mitchell, C. J., Francy, D. B., Lazuick, J. S. & Hughes, T. B. (1973). House sparrows, Passer domesticus (L.), as hosts of arboviruses in Hale County, Texas. I. Field studies 1965–1969. American Journal of Tropical Medicine and Hygiene 22, 244–53.CrossRefGoogle ScholarPubMed
Inaba, Y. (1975). Ibaraki disease and its relationship to bluetongue. Australian Veterinary Journal 51, 178–85.CrossRefGoogle ScholarPubMed
Inaba, Y., Tanaka, Y., Sato, K., Ito, H., Omori, T. & Matumoto, M. (1968). Bovine epizootic fever. I. Propagation of the virus in suckling hamster, mouse and rat, and hamster kidney BHK21-W12 cells. Japanese Journal of Microbiology 12, 457–69.CrossRefGoogle Scholar
Ishida, N., Yamamoto, H., Endo, K., Konno, J. & Karoji, Y. (1976). Epidemiology of Japanese encephalitis: factor analysis of obvious decline of Japanese encephalitis infection in recent years. Japanese Journal of Bacteriology 31, 375–86.Google Scholar
Jenney, E. W. (1968). Vesicular stomatitis in the United States during the last five years (1963–1967). Proceedings of the United States Livestock Sanitary Association 71, 371–85.Google Scholar
Johnson, C. G. (1969). Migration and Dispersal of Insects by Flight. London: Methuen.Google Scholar
Johnson, K. M. & Martin, D. H. (1974). Venezuelan equine encephalitis. Advances in Veterinary Science and Comparative Medicine 18, 79–116.Google ScholarPubMed
Kanamitsu, M., Taniguchi, K., Urusawa, S., Ogata, T., Wada, Y., Wada, Y. & Saroso, J. S. (1979). Geographic distribution of arbovirus antibodies in indigenous human populations in the Indo-Australian Archipelago. American Journal of Tropical Medicine and Hygiene 28, 351–63.CrossRefGoogle ScholarPubMed
Kirk, R. (1941). An epidemic of yellow fever in the Nuba Mountains, Anglo-Egyptian Sudan. Annals of Tropical Medicine and Parasitology 33, 225–31.Google Scholar
Kisimoto, R. (1971). Long distance migration of plant hoppers Sogatella furcifera and Nilaparvata lugens. Proceedings of Symposium on Rice Insects, Toyko 1971, 201–16.Google Scholar
Kono, R. & Kim, K. H. (1969). Comparative epidemiological features of Japanese encephalitis in the Republic of Korea, China (Taiwan) and Japan. Bulletin of the World Health Organization 40, 263–77.Google ScholarPubMed
Lauerman, L. (1967). Vesicular stomatitis in temperate and tropical America. Ph.D. thesis, University of Wisconsin, Madison.Google Scholar
Levy, J. S., Carver, H. D., Moseley, I. K., Calisher, C. H., Francy, D. B. & Monath, T. P. (1978). St Louis encephalitis in Memphis–Shelby County, Tennessee, 1975: epidemiologic aspects of human cases. Southern Medical Journal 71, 633–7.CrossRefGoogle ScholarPubMed
Li, Kuang-Po, Wong, Hong-Hsiang, & Woo, Wan Sei (1964). Route of the seasonal migration of the Oriental Armyworm Moth in the eastern part of China as indicated by a three-year result of releasing and recapturing marked moths. Acta phytophylacica Sinica 3, 101–10.Google Scholar
Lillie, L. E., Wong, F. C. & Drysdale, R. A. (1976). Equine epizootic of western encephalomyelitis in Manitoba–1975. Canadian Journal of Public Health 67, Suppl. 1, 21–7.Google ScholarPubMed
Lord, R. D. & Calisher, C. H. (1970). Further evidence of southward transport of arboviruses by migratory birds. American Journal of Epidemiology 92, 73–8.CrossRefGoogle ScholarPubMed
Luby, J. P., Sulkin, S. E. & Sanford, J. P. (1969). The epidemiology of St Louis encephalitis: a review. Annual Review of Medicine 20, 329–50.CrossRefGoogle ScholarPubMed
Lumsden, W. H. R. & Buxton, A. P. (1951). A study of the epidemiology of yellow fever in West Nile district, Uganda. Transactions of the Royal Society of Tropical Medicine and Hygiene 45, 53–78.CrossRefGoogle ScholarPubMed
McGowan, J. E. Jr., Bryan, J. A. & Gregg, M. B. (1973). Surveillance of arboviral encephalitis in the United States, 1955–1971. American Journal of Epidemiology 97, 199–207.CrossRefGoogle ScholarPubMed
McIntosh, B. M., Jupp, P. G., Dos Santos, I. & Meenehan, G. M. (1976). Epidemics of West Nile and Sindbis viruses in South Africa with Culex (culex) univittatus Theobald as vector. South African Journal of Science 72, 295–300.Google Scholar
Maeda, O. J., Karaki, T., Kuroda, A., Karogi, Y., Sasaki, O. & Takenokuma, K. (1978). Epidemiological studies on Japanese encephalitis in Kyoto City area, Japan. II. Annual. patterns of virus dissemination on virus recoveries from unfed Culex tritaeniorhynchus summorosus. Japanese Journal of Medical Science and Biology 31, 39–51.CrossRefGoogle ScholarPubMed
Murray, M. D. (1970). The spread of ephemeral fever of cattle during the 1967–68 epizootic in Australia. Australian Veterinary Journal 46, 77–82.CrossRefGoogle ScholarPubMed
Muul, I., Johnson, B. K. & Harrison, B. A. (1975). Ecological studies of Culiseta melanura (Diptera: Culicidae) in relation to eastern and western equine encephalomyelitis viruses on the eastern shore of Maryland. Journal of Medical Entomology 11, 739–48.CrossRefGoogle ScholarPubMed
Nevill, E. M. (1971). Cattle and Culicoides biting midges as possible overwintering hosts of bluetongue virus. Onderstepoort Journal of Veterinary Research 38, 65–72.Google ScholarPubMed
Newton, L. G. & Wheatley, C. H. (1970). The occurrence and spread of ephemeral fever of cattle in Queensland. Australian Veterinary Journal 46, 561–8.CrossRefGoogle ScholarPubMed
Omori, T. (1961). Bluetongue-like disease in Japan. Bulletin de l'Office International des Épizooties 55, 1109–17.Google Scholar
Omori, T., Inaba, Y., Morimoto, T., Tanaka, Y., Ishitani, R., Kurogi, H., Munukata, K., Matsuda, K. & Matumoto, M. (1969). Ibaraki virus, an agent of epizootic disease of cattle resembling bluetongue. I. Epidemiologic, clinical and pathologic observations and experimental transmission to calves. Japanese Journal of Microbiology 13, 139–57.CrossRefGoogle ScholarPubMed
Oxford World Atlas (1973). London: Oxford University Press.Google Scholar
Rainey, R. C. (1951). Weather and the movements of locust swarms: a new hypothesis. Nature, London 168, 1057–60.CrossRefGoogle Scholar
Rainey, R. C. (1973). Airborne pests and the atmospheric environment. Weather, London 28, 224–39.CrossRefGoogle Scholar
Rainey, R. C. (1974). Biometeorology and insect flight: some aspects of energy exchange. Annual Review of Entomology 19, 407–39.CrossRefGoogle Scholar
Ratcliffe, F. M., Myers, K., Fennessy, B. V. & Calaby, J. H. (1952). Myxomatosis in Australia. A step towards biological control of the rabbit. Nature, London 170, 7–11.CrossRefGoogle Scholar
Reeves, W. C. (1974). Overwintering of arboviruses. Progress in Medical Virology 17, 193–220.Google ScholarPubMed
Rosen, L., Tesh, R. B., Lien, J. C. & Cross, J. H. (1978). Transovarial transmission of Japanese encephalitis by mosquitoes. Science 199, 909–11.CrossRefGoogle ScholarPubMed
St George, T. D., Standfast, H. A., Christie, D. G., Knott, S. G. & Morgan, I. R. (1977). The epizootiology of bovine ephemeral fever in Australia and Papua-New Guinea Australian Veterinary Journal 53, 17–28.CrossRefGoogle Scholar
Satti, M. H. & Haseeb, M. A. (1966). An outbreak of yellow fever in the southern Fung and Upper Nile Province, Republic of Sudan. Journal of Tropical Medicine and Hygiene 69, 34–44.Google Scholar
Saugstad, E. S., Dalarymple, J. M. & Eldridge, B. F. (1972). Ecology of arboviruses in a Maryland freshwater swamp. I. Population dynamics and habitat distribution of potential mosquito vectors. American Journal of Epidemiology 96, 114–22.CrossRefGoogle Scholar
Seddon, H. R. (1938). The spread of ephemeral fever (three-day sickness) in Australia in 1936–37. Australian Veterinary Journal 14, 90–101.CrossRefGoogle Scholar
Sellers, R. F. (1975). Bluetongue in Cyprus. Australian Veterinary Journal 51, 198–203.CrossRefGoogle ScholarPubMed
Sellers, R. F., Pedgley, D. E. & Tucker, M. R. (1977). Possible spread of African horse sickness on the wind. Journal of Hygiene 79, 279–98.CrossRefGoogle Scholar
Sellers, R. F., Pedgley, D. E. & Tucker, M. R. (1978). Possible windborne spread of bluetongue to Portugal, June–July 1956. Journal of Hygiene 81, 189–96.CrossRefGoogle ScholarPubMed
Sellers, R. F., Gibbs, E. P. J., Herniman, K. A. J., Pedgley, D. E. & Tucker, M. R. (1979). Possible origin of the bluetongue epidemic in Cyprus, August 1977. Journal of Hygiene 83, 547–55.CrossRefGoogle ScholarPubMed
Simpson, D. I. H., Bowen, E. T. W., Way, H. J., Platt, G. S., Hill, M. N., Kamath, S., Wah, L. T., Bendell, P. J. E. & Heathcote, O. H. U. (1974). Arbovirus infection in Sarawak, October 1968–February 1970: Japanese encephalitis virus isolations from mosquitoes. Annals of Tropical Medicine and Parasitology 68, 393–404.CrossRefGoogle ScholarPubMed
Simpson, D. I. H., Smith, C. E. G., Marshall, T. F., de, C., Platt, G. S., Way, H. J., Bowen, E. T. W., Bright, W. F., Day, J., McMahon, D. A., Hill, M. N., Bendell, P. J. E. & Heathcote, O. H. U. (1976). Arbovirus infections in Sarawak: the role of the domestic pig. Transactions of the Royal Society of Tropical Medicine and Hygiene 70, 66–72.CrossRefGoogle ScholarPubMed
Spence, L., Artsob, H., Grant, L. & Th'ng, C. (1977). St Louis encephalitis in southern Ontario: laboratory studies for arboviruses. Canadian Medical Association Journal 116, 35–7.Google ScholarPubMed
Takahashi, K., Matsuo, R., Kuma, M. & Noguchi, H. (1965). Studies on mosquito infection with Japanese encephalitis virus in 1964 in Nagasaki prefecture. Endemic Diseases Bulletin, Nagasaki University 7, 165–77.Google Scholar
Taylor, W. P. & McCausland, A. (1976). Studies with bluetongue virus in Nigeria. Tropical Animal Health and Production 8, 169–73.Google ScholarPubMed
Tesh, R. B., Chaniotois, B. N. & Johnson, K. M. (1972). Vesicular stomatitis virus (Indiana serotype); transovarial transmission by phlebotomine sandflies. Science 175, 1477–9.CrossRefGoogle Scholar
Theiler, A. (1921). African horse sickness (Pestis equorum). South Africa, Department of Agriculture Science Bulletin, no. 19.Google Scholar
Ura, M. (1976). Ecology of Japanese encephalitis virus in Okinawa, Japan. I. The investigation on pig and mosquito infection of the virus in Okinawa island from 1966 to 1976. Tropical Medicine 18, 151–63.Google Scholar
Van Peenen, P. F. D., Joseph, P. L., Atmosoedjono, S., Irsiana, R. & Saroso, J. S. (1975 a). Japanese encephalitis virus from pigs and mosquitoes in Jakarta, Indonesia. Transactions of the Royal Society of Tropical Medicine and Hygiene 69, 477–9.CrossRefGoogle Scholar
Van Peenen, P. F. D., Joseph, P. L., Atmosoedjono, S., Irsiana, R. & Saroso, J. S. (1975 b). Isolation of Japanese encephalitis virus from mosquitoes near Bogor, West Java, Indonesia. Journal of Medical Entomology 12, 573–4.CrossRefGoogle ScholarPubMed
Vilchis, J. (1972). Human disease: Mexico. In Proceedings of the Workshop Symposium on Venzuelan Encephalitis VirusPan American Health OrganisationWashington, pp. 215–217.Google Scholar
Wada, Y., Kawai, S., Oda, T., Miyagi, I., Svenaga, O., Nishigaki, J., Omori, N., Takahashi, K., Matsuo, T., Itoh, T. & Takatsuki, Y. (1969). Dispersal experiment of Culex tritaeniorhynchus in Nagasaki area (preliminary report) Tropical Medicine 11, 37–44.Google Scholar
Wada, Y., Oda, T., Mogi, M., Mori, A., Omori, N., Fukumi, H., Hayashi, K., Mifune, K., Shichijo, A. & Matsuo, S. (1975). Ecology of Japanese encephalitis in Japan. II. The population of vector mosquitoes and the epidemic of Japanese encephalitis. Tropical Medicine 17, 111–27.Google Scholar
Walker, A. R. (1977). Adult lifespan and reproductive status of Culicoides species (Diptera, Ceratopogonidae) in Kenya, with reference to virus transmission. Bulletin of Entomological Research 67, 205–15.CrossRefGoogle Scholar
Waters, J. R. (1976). An epidemic of Western encephalomyelitis in humans–Manitoba, 1975. Canadian Journal of Public Health 67, Suppl. 1, 28–32.Google ScholarPubMed
Watts, D. M., Pantuwatana, S., De Foliart, G. R., Yuill, T. M. & Thompson, W. H. (1973). Transovarial transmission of La Crosse virus (California encephalitis group) in the mosquito, Aedes triseriatus. Science 182, 1140–41.CrossRefGoogle Scholar
Wellings, F. M., Lewis, A. L. & Pierce, L. V. (1972). Agents encountered during arboviral ecological studies: Tampa Bay area, Florida, 1963 to 1970. American Journal of Tropical Medicine and Hygiene 21, 201–13.CrossRefGoogle ScholarPubMed
Yamada, K., Hashimoto, N. & Kanamitsu, M. (1972). Epidemiological study of Japanese encephalitis in Hokkaido. 4. Serological and climatological investigations of Japanese encephalitis virus infection in domestic animals. Virus 22, 38–47.Google ScholarPubMed