Hostname: page-component-cd9895bd7-jn8rn Total loading time: 0 Render date: 2024-12-22T16:27:31.595Z Has data issue: false hasContentIssue false
  • English
  • Français

Weather factors in the prediction of western equine encephalitis epidemics in Manitoba

Published online by Cambridge University Press:  15 May 2009

R. F. Sellers  and
A. R. Maarouf
R. F. Sellers
Affiliation:
Agriculture Canada, Health of Animals Laboratory Division, Halldon House, 2255 Carting Avenue, Ottawa, Ontario K1A 0Y9
A. R. Maarouf
Affiliation:
Environment Canada, Canadian Climate Centre, 4905 Dufferin Street, Downsview, Ontario M3H 5T4
Rights & Permissions [Opens in a new window]

Summary

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Cases of western equine encephalitis in horses in 1987 in western USA and Manitoba, Canada were examined by backward trajectory analysis of winds. Culex tarsalis mosquitoes infected with western equine encephalitis virus could have been carried on southerly winds from Texas and Oklahoma to northern LTSA and from there to Manitoba. The presence of the Polar front over North Dakota and Minnesota at the end of July would have led to the landing of Cx. tarsalis in Montana and Wisconsin and prevented further carriage into Manitoba. Temperatures in southern Texas during the winter months (average daily maximum temperatures 19.7 °C and higher) would have permitted continuous transmission of western equine encephalitis virus by Cx. tarsalis in this area.

Weather factors involved in outbreaks from 1975–88 were analysed to see if epidemics in Manitoba (23 or more cases in horses) could be predicted. The conditions for epidemics could be defined as follows: (a) the number of cases in horses in LTSA was 98 or more, (b) winds were southerly with speeds 45 kmh-1 or higher, and (c) counts of Cx. tarsalis females/light trap per day were 3·2 or higher. There were 3 or fewer cases in Manitoba, when the number of cases in USA was 27 or less, even when Cx. tarsalis counts were higher than 3·2. With Cx. tarsalis counts below 3 and/or unsuitable winds, or the Polar front further south, the number of cases in Manitoba was between 0 and 17, even when the number of cases in USA was from 38–172. Without information on the extent of infection further south, the weather variables would probably be more useful in excluding the possibility of an epidemic in Manitoba than in predicting one.

Type
Research Article
Information
Epidemiology & Infection , Volume 111 , Issue 2 , October 1993 , pp. 373 - 390
Copyright
Copyright © Cambridge University Press 1993

References

REFERENCES

1.Reisen, WK, Monath, TP. Western equine encephalomyelitis. In: Monath, TP, ed. The arboviruses: epidemiology and ecology, vol V. Boca Raton: CRC Press, 1989: 89–137.Google Scholar
2.Reisen, WK, Hardy, JL, Presser, SB, et al. Mosquito and arbovirus ecology in southeastern California, 1986–90. J Med Entomol 1992; 29: 512–24.CrossRefGoogle Scholar
3.Sellers, RF, Maarouf, AR. Impact of climate on western equine encephalitis in Manitoba, Minnesota and North Dakota, 1980–83. Epidemiol Infect 1988; 101: 511–35.CrossRefGoogle Scholar
4.Eads, RB. Biological notes on Culex tarsalis in the lower Rio Grande Valley of Texas. Mosq News 1965; 25: 61–3.Google Scholar
5.Centers for Disease Control. Wrestern equine encephalitis - United States and Canada. 1987. M M W R 1987; 36: 655–9.Google Scholar
6.Raddatz, RL. A biometeorological model of an encephalitis vector. Bound Layer Meteorol 1986; 34: 185–99.CrossRefGoogle Scholar
7.Sekla, L, ed. Western equine encephalitis in Manitoba. Winnipeg: Manitoba Health Services Commission, 1982.Google Scholar
8.Mitchell, CJ, Francy, DB, Monath, TP. Arthropod vectors. In: Monath, TP, ed. St. Louis Encephalitis. Washington: American Public Health Association, 1980: 313–79.Google ScholarPubMed
9.Meteorological Office. Tables of temperature, relative humidity and precipitation for the world. Part I. North America and Greenland (including Hawaii and Bermuda). London: HMSO, 1980.Google Scholar
10.Chew, RM, Gunstream, SE. Geographical and seasonal distribution of mosquito species in southeastern California. Mosq News 1970; 30: 551–62.Google Scholar
11.Reeves, WC. Bellamy, RE, Scrivani, RP. Relationships of mosquito vectors to winter survival of encephalitis viruses. I. Under natural conditions. Am J Hyg 1958; 67: 78–89.Google ScholarPubMed
12.Arntfield, PW, Gallaway, WJ, Brust, RA. Blood-feeding in overwintering Culex tarsalis (Diptera: Culicidae) from Manitoba. Can Entomol 1982; 114: 85–6.CrossRefGoogle Scholar
13.Henderson, LP, Brust, RA, Wong, FC. Biological transmission of western encephalomyelitis virus by Culex tarsalis Coquillett. Mosq News 1979; 39: 385–90.Google Scholar
14.Kramer, LD, Hardy, JL, Presser, SB. Effect of temperature of extrinsic incubation on the vector competence of Culex tarsalis for western equine encephalomyelitis virus. Am J Trop Med Hyg 1983; 32: 1130–39.CrossRefGoogle ScholarPubMed
15.Johnson, CG. Migration and dispersal of insects by flight. London: Methuen. 1969.Google Scholar
16.Pearson, JE. In: Proc US Anim Health Assoc 1988; 92: 219–23.Google Scholar
17.Pearson, JE. In: Proc US Anim. Health Assoc 1983; 87: 43.Google Scholar
18.Pearson, JE. In: Proc US Anim Health Assoc 1989; 93: 366–73.Google Scholar
19.Potter, ME, Currier, RWT, Pearson, JE, Harris, JC, Parker, RL. Western equine encephalomyelitis in horses in Northern Red River Valley, 1975. J Am Vet Med Assoc 1977; 170: 1396–9.Google ScholarPubMed
20.Lillie, LE, Wong, FC, Drysdale, RA. Equine epizootic of western encephalomyelitis in Manitoba - 1975. Can J Publ Hlth 1976; 67 Suppl 1: 21–7.Google ScholarPubMed
21.Neufeld, JL, Nayar, GPS. Western equine encephalitis in Manitoba - equine cases 1975–1981. In: Sekla, L, ed. Western equine encephalitis in Manitoba. Winnipeg: Manitoba Health Services Commission, 1982: 62–79.Google Scholar
22.Neufeld, J. WEE epizootic in Manitoba. 32nd Conference of Canadian Workers in Animal Pathology,1982:153–61.Google Scholar
23.Neufeld, J. Western equine encephalitis in Manitoba, 1975–1983. Canadian Animal Pathology Conference,1984: abstract 21.Google Scholar
24.Calisher, CH, Emerson, JK, Muth, DJ, Lazuick, JS, Monath, TP. Serodiagnosis of western equine encephalitis virus infections: relationships of antibody titer and test to observed onset of clinical illness. J Am Vet Med Assoc 1983; 183: 438–40.Google ScholarPubMed
25.Brust, RA, Ellis, RA. Mosquito surveys in Manitoba during 1975. Can J Publ Hlth 1976; 67: Suppl 1: 47–53.Google ScholarPubMed
26.Brust, RA. Population dynamics of Culex tarsalis Coquillett in Manitoba. In: Sekla, L, ed. Western equine encephalitis in Manitoba. Winnipeg: Manitoba Health Services Commission. 1982: 21–30.Google Scholar
27.Raddatz, RL. Forecasts of Culex tarsalis populations in Winnipeg, Manitoba. In: Sekla, L, ed. Western equine encephalitis in Manitoba. Winnipeg; Manitoba Health Services Commission. 1982: 36–49.Google Scholar
28.Ellis, RA. Annual Reports on Insect Surveillance and Control, 1985–1988. City of Winnipeg, Insect Control Branch.Google Scholar
29.Olson, MP, Oikawa, KK, Macafee, AWT. A trajectory model applied to the long-range transport of air pollutants. Atmospheric Environment Service, Long Range Transport of Air Pollutants 78–44 1978: 1–24.Google Scholar
30.Reisen, WK, Meyer, RP, Presser, SB, Hardy, JL. Effect of temperature on the transmission of western equine encephalomyelitis and St. Louis encephalitis viruses by Culex tarsalis (Diptera: Culicidae). J Med Entomol 1993; 30: 151–60.CrossRefGoogle ScholarPubMed
31.Rosenberg, LJ, Magor, JI. Flight duration of the brown planthopper, Nilaparvata lugens (Homoptera: Delphacidae). Ecol Entomol 1983; 8: 341–50.CrossRefGoogle Scholar
32.Farrow, RA, Daley, JC. Long-range movements as an adaptive strategy in the genus Heliothis (Lepidoptera: Noctuidae): a review of its occurrence and detection in four pest species. Aust J Zool 1987; 35: 1–24.CrossRefGoogle Scholar
33.Drake, VA, Farrow, RA. The influence of atmospheric structure and motions on insect migration. Ann Rev Entomol 1988; 33: 183–210.CrossRefGoogle Scholar
34.McManus, ML. Weather, behaviour and insect dispersal. Mem Ent Soc Can 1988; 146: 71–94.CrossRefGoogle Scholar
35.McLintock, J, Burton, AN, Rempel, JG. Interepidemic hosts of western encephalitis virus in Saskatchewan. Proc Xew Jersey Mosq Exterm Assoc 1967; 54: 97–104.Google Scholar
36.Mitchell, CJ. Occurrence, biology, and physiology of diapause in overwintering mosquitoes. In: Monath, TP, ed. The arboviruses: epidemiology and ecology, vol I. Boca Raton: CRC Press. 1988: 191–217.Google Scholar
37.Henderson, LP, Brust, RA. Studies on potential transovarial transmission of western equine encephalomyelitis virus by Culex tarsalis Coquillett. Manitoba Entomol 1977; 11: 69–73.Google Scholar
38.Reisen, WK, Hardy, JL, Reeves, WC, Presser, SB, Milby, MM, Meyer, RP. Persistence of mosquito-borne viruses in Kern County, California. 1983–1988. Am J Trop Med Hyg 1990: 43: 419–37.CrossRefGoogle ScholarPubMed
39.Scott, TW. Vertebrate host ecologv. In: Monath, TP, ed. The arboviruses: epidemiology and ecology, vol I. Boca Raton: CRC Press. 1988: 257–80.Google Scholar
40.Trapido, H, Galindo, P. The epidemiology of yellow fever in Middle America. Exp Parasitol 1956; 5: 285–323.CrossRefGoogle ScholarPubMed
41.Pan American Health Organization. Venezuelan Encephalitis. Scientific Publication No 243. Washington. 1972.Google Scholar
42.Nichiporick, W. The aerial migration of the six-spotted leafhopper and the spread of the virus disease aster yellows. Int J Biometeorol 1965; 9: 219–27.CrossRefGoogle Scholar
43.Sellers, RF. Weather, host and vector - their interplay in the spread of insect-borne animal virus diseases. J Hyg 1980; 85: 65–102.CrossRefGoogle ScholarPubMed
44.Thresh, JM. The long-range aerial dispersal of plant viruses by arthropod vectors. Phil Trans R Soc Lond B 1983; 302: 497–528.Google Scholar
45.Irwin, ME, Thresh, JM. Long-range dispersal of cereal aphids as virus vectors in North America. Phil Trans R Soc Lond B 1988; 321: 421–46.Google Scholar
46.Sellers, RF, Maarouf, AR. Trajectory analysis of winds and vesicular stomatitis in North America, 1982–5. Epidemiol Infect 1990; 104: 313–28.CrossRefGoogle ScholarPubMed
47.Sellers, RF, Maarouf, AR. Trajectory analysis of winds and eastern equine encephalitis in USA, 1980–5. Epidemiol Infect 1990; 104: 329–43.CrossRefGoogle ScholarPubMed
48.Eldridge, BF. Strategies for surveillance, prevention, and control of arbovirus diseases in Western North America. Am J Trop Med Hyg 1987; 37 Suppl: 77–86.CrossRefGoogle ScholarPubMed
49.Hess, AD, Hayes, RO. Seasonal dynamics of western encephalitis virus. Am J Med Sci 1967; 253: 333–48.CrossRefGoogle ScholarPubMed
50.Reeves, WC. Current observations on mosquito-borne viruses of concern to mosquito abatement districts in California. Proc Calif Mosq Vector Control Assoc 1970; 38: 6–9.Google ScholarPubMed