Increase in West Nile neuroinvasive disease after Hurricane Katrina.After Hurricane Katrina  Editing of this page by unregistered or newly registered users is currently disabled due to vandalism. , the number of reported cases of West Nile West Nile may refer to:
********** Hurricane Katrina devastated dev·as·tate tr.v. dev·as·tat·ed, dev·as·tat·ing, dev·as·tates 1. To lay waste; destroy. 2. To overwhelm; confound; stun: was devastated by the rude remark. portions of Louisiana and Mississippi on August 29, 2005. Previous reports of West Nile neuroinvasive disease (WNND) in this area after this hurricane did not examine any statewide increases in 2005 (1). However, this report did not show potential regional increases of WNND in areas that experienced substantial hurricane damage. Because West Nile virus West Nile virus, microorganism and the infection resulting from it, which typically produces no symptoms or a flulike condition. The virus is a flavivirus and is related to a number of viruses that cause encephalitis. (WNV WNV West Nile Virus WNV World Net Visions ) is now endemic in areas of the United States United States, officially United States of America, republic (2005 est. pop. 295,734,000), 3,539,227 sq mi (9,166,598 sq km), North America. The United States is the world's third largest country in population and the fourth largest country in area. that are at risk for hurricanes, understanding effects of such events on WNV epidemiology is important for directing appropriate public health responses. The objective of this study was to determine whether cases of WNND increased regionally after Hurricane Katrina. The Study We used WNV human case data for Louisiana and Mississippi from the Centers for Disease Control and Prevention Centers for Disease Control and Prevention (CDC), agency of the U.S. Public Health Service since 1973, with headquarters in Atlanta; it was established in 1946 as the Communicable Disease Center. (CDC See Control Data, century date change and Back Orifice. CDC - Control Data Corporation ) (2); cases of meningitis, encephalitis encephalitis (ĕnsĕf'əlī`təs), general term used to describe a diffuse inflammation of the brain and spinal cord, usually of viral origin, often transmitted by mosquitoes, in contrast to a bacterial infection of the meninges , or meningoencephalitis meningoencephalitis /me·nin·go·en·ceph·a·li·tis/ (me-ning?go-en-sef?ah-li´tis) inflammation of the brain and meninges. toxoplasmic meningoencephalitis reported to CDC were considered WNND cases. Cases are listed by date of onset of first symptoms and corresponding CDC week, and parish or county of residence at the estimated time of infection. Affected parishes or counties were defined as those in which >50% of the total area was within 50 miles of the hurricane track coordinates (3) (ArcView 8.0; Environmental Systems Research Institute, Redlands, CA, USA). Eight of 64 parishes in Louisiana <onlyinclude>The U.S. state of Louisiana is divided into 64 parishes in the same way that 48 of the other states of the United States are divided into counties (Alaska is divided into boroughs and census areas). and 21 of 82 counties in Mississippi List of 82 counties in the U.S. state of Mississippi: State Abbr. FIPS State Code State MS 28 Mississippi FIPS County Code County Name 001 Adams County 003 Alcorn County 005 Amite County 007 Attala County 009 Benton County 011 Bolivar County fit our definition of hurricane affected (Figure 1). Counties within the storm's track after its winds had diminished to <75 miles per hour were considered not affected. We compared the number of WNND cases during the 3-week period before the storm with the number of cases in the 3-week period immediately after Hurricane Katrina to determine whether the number of WNND cases changed immediately after the storm in Louisiana and Mississippi. Because the hurricane-affected region experienced extensive migration of its residents and no valid population estimates exist for this period, the number of WNND cases reported was used. Landfall land·fall n. 1. The act or an instance of sighting or reaching land after a voyage or flight. 2. The land sighted or reached after a voyage or flight. of Hurricane Katrina occurred at the beginning of CDC week 35, and news reports estimated that the final evacuation of persons from the New Orleans New Orleans (ôr`lēənz –lənz, ôrlēnz`), city (2006 pop. 187,525), coextensive with Orleans parish, SE La., between the Mississippi River and Lake Pontchartrain, 107 mi (172 km) by water from the river mouth; founded area occurred the following Sunday, September 4 (4), the beginning of CDC week 36. Because WNV infection has a 3-14-day incubation period incubation period n. 1. See latent period. 2. See incubative stage. Incubation period (5), persons with storm-related exposures could have contracted WNV and become symptomatic as early as CDC week 35 or as late as the end of week 37. We considered WNND cases in which the reported onset of symptom dated from CDC weeks 35-37 as potentially influenced by the hurricane. In Louisiana, no cases of WNND were reported in the 3 weeks before Hurricane Katrina (CDC weeks 32-34) in the 8-parish region affected by the storm. In the 3 weeks after the storm (CDC weeks 35-37), 11 WNND cases were reported in the affected region (Table 1). This increase in WNND cases in the hurricane-affected region was not observed during the same periods in 2002, 2003, 2004, or 2006. No increase was noted after the hurricane in unaffected parishes during the same periods. A similar pattern was observed in Mississippi. In the 3 weeks after landfall, the affected region showed an increase from 0 to 10 WNND cases; the unaffected region of Mississippi showed only a minor increase in cases during the same periods (8 cases before and 10 cases after the storm). [FIGURE 1 OMITTED] To assess potential long-term effects of Hurricane Katrina on WNND incidence, we compared incidence rates of WNND for both states during 2006 with rates during the 4 years preceding the storm (2002-2005). Because the hurricane-affected region experienced population displacement, we used special population estimates from the US Census Bureau Noun 1. Census Bureau - the bureau of the Commerce Department responsible for taking the census; provides demographic information and analyses about the population of the United States Bureau of the Census for rate estimations for 2006 (6). For unaffected parishes or counties that did not have an updated census estimate, we used the Census 2000 population estimate (7). Louisiana had population reductions of 398,853 persons (-28%) in hurricane-affected parishes and 17,521 persons (<-1%) in unaffected parishes. Mississippi had population reductions of 21,708 persons (-3%) in affected counties and 34,545 persons (-2%) in unaffected counties. Despite losses in population, the affected parishes of Louisiana had an increase in the number of WNND cases from an average annual number of 30 cases in 2002-2005 to 45 cases in 2006. In the affected counties of Mississippi, WNND cases increased from an annual number of 23 cases in 2002-2005 to 55 cases in 2006. Incidence rate ratios and 95% confidence intervals confidence interval, n a statistical device used to determine the range within which an acceptable datum would fall. Confidence intervals are usually expressed in percentages, typically 95% or 99%. were calculated for each state and region (affected and unaffected) (Table 2). Incidence rate ratios for 2006 were >2-fold higher in the hurricane-affected regions of both states than the mean historic incidence rates (2002-2005). Unaffected areas of both states showed decreased (Louisiana) and stable (Mississippi) WNND incidences compared with historical incidence. Figure 2 shows epidemic curves of 2005-2006 cases by week in affected and unaffected areas for both states. Conclusions Our evidence demonstrates that areas directly affected by Hurricane Katrina experienced increases in WNND cases after the storm compared with before the storm. Analyses of the immediate period after the storm indicate that the observed increase was unique both in time and to the affected region. WNND incidence in 2006 equaled or exceeded the incidence rates in both states during the 2002 epidemic. Because WNND complications are seen in [approximately equal to] 1% of WNV infections (5), a small increase in WNND cases represents a much larger increase in WNV human transmission. [FIGURE 2 OMITTED] Because our study is based on surveillance data, confounding confounding when the effects of two, or more, processes on results cannot be separated, the results are said to be confounded, a cause of bias in disease studies. confounding factor factors that may bias our analysis should be considered. Although Lehman et al. (1) indicated that case reporting lagged in Louisiana after Hurricane Katrina, no evidence was provided to suggest that year-end case totals were affected. To account for potential interstate reporting differences, we have conducted separate analyses for each state. Creation of 3-week periods on the basis of the day (August 29, 2005) and week (CDC week 35) that the storm made landfall may also introduce bias. Some cases with reported onset dates in the 2 weeks after the storm may have resulted from transmission events before August 29th. However, storm-related exposure to mosquitoes began before the storm's landfall, when in preparation for the approaching storm, residents boarded windows and cleared yards. Despite these potential confounding factors, we believe the magnitude of the increase in WNND cases occurring immediately after Hurricane Katrina and the increases in WNND incidence in 2006, within the hurricane-affected region, is substantial enough to warrant further examination. The immediate increase in cases may be attributed to increased human exposure to mosquitoes. Tens of thousands of persons in the hurricane-affected region were living in damaged housing or were waiting outside for days to be evacuated e·vac·u·ate v. e·vac·u·at·ed, e·vac·u·at·ing, e·vac·u·ates v.tr. 1. a. To empty or remove the contents of. b. To create a vacuum in. 2. . The sudden decrease in WNND cases in the hurricane-affected areas 3 weeks after landfall could be attributed to reduced human exposure caused by eventual evacuation and aerial application Aerial application, commonly called crop dusting, involves spraying crops with fertilizers, pesticides, and fungicides from an agricultural aircraft. The specific spreading of fertiliser is also known as aerial topdressing. of insecticides insecticides, chemical, biological, or other agents used to destroy insect pests; the term commonly refers to chemical agents only. Chemical Insecticides (8). The increase in WNND incidence in 2006 might also be due to increased human-mosquito exposure as a result of mosquito larval larval 1. pertaining to larvae. 2. larvate. larval migrans see cutaneous and visceral larva migrans. habitat creation (root ball voids from fallen trees, and flooded abandoned swimming pools), continued substandard substandard, adj below an acceptable level of performance. living conditions living conditions npl → condiciones fpl de vida living conditions npl → conditions fpl de vie living conditions living , and increased outdoor reconstruction activities. Hurricane Katrina was the first major tropical cyclone tropical cyclone Severe atmospheric disturbance in tropical oceans. Tropical cyclones have very low atmospheric pressures in the calm, clear centre (the eye) of a circular structure of rain, cloud, and very high winds. to make landfall in a large metropolitan area since the 1999 introduction of WNV into the United States. The scale of hurricane damage, especially to residences, may have contributed to increases in WNND. We recommend a region-specific, short--and long-term analysis of arboviral disease to accurately assess the public health effect of natural disasters. Prepositioning mosquito control assets and continuing to provide enhanced emergency assistance for surveillance and control could aid in inhibition of mosquito-transmitted diseases during the immediate period after a hurricane and throughout an extended recovery period. Use of trade names is for identification only and does not imply endorsement by the Public Health Service or by the U.S. Department of Health and Human Services Noun 1. Department of Health and Human Services - the United States federal department that administers all federal programs dealing with health and welfare; created in 1979 Health and Human Services, HHS . Acknowledgments We thank John C. Carlson, Fawaz Mzayek, and 2 anonymous reviewers for their critical and thoughtful review of our manuscript. References (1.) Lehman JA, Hinckley AF, Kniss KL, Nasci RS, Smith TL, Campbell GL, et al. Effect of Hurricane Katrina on arboviral disease transmission. Emerg Infect Dis. 2007;13:1273-5. (2.) Centers for Disease Control and Prevention. Neuroinvasive and non-neuroinvasive domestic arboviral diseases (includes diseases caused by California serogroup viruses; eastern and western equine encephalitis viruses The Western equine encephalitis virus is the causative agent of relatively uncommon viral disease Western equine encephalitis (WEE). An Alphavirus of the family Togaviridae, the WEE virus is an arbovirus (arthropod-borne virus) transmitted by mosquitoes of the genera ; and Powassan, St. Louis encephalitis St. Louis encephalitis see St. Louis encephalitis. , and West Nile viruses). 2004 [cited 2007 Oct 23]. Available from http://www.cdc.gov/ncidod/dvbid/westnile/surv&control.htm#casedefinition (3.) Knabb RD, Rhome JR, Brown DE Tropical cyclone report: Hurricane Katrina, August 23-30, 2005 [cited 2008 Feb 19]. Available from http://www.nhc.noaa.gov/pdf/TCR-AL122005 Katrina.pdf (4.) Final evacuation of New Orleans completed. Reuters [International Herald Tribune International Herald Tribune Daily newspaper published in Paris. It has long been the staple source of English-language news for American expatriates, tourists, and businesspeople in Europe. ]. 2005 Sep 4. (5.) Hayes EB, Komar N, Nasci RS, Montgomery SP, O'Leary DR, Campbell GL. Epidemiology and transmission dynamics of West Nile virus disease. Emerg Infect Dis. 2005; 11: 1167-73. (6.) US Census Bureau. Special population estimates for impacted counties in the Gulf Coast area. 2007 [cited 2008 Feb 19]. Available from http://www.census.gov/Press-Release/www/emergencies/impacted_ gulf estimates.html (7.) US Census Bureau. US census 2000 [cited 2008 Feb 19]. Available from http://www.census.gov/main/www/cen2000.html (8.) Breidenbach M, Haagsma K, Olson S Olson may refer to:
Kevin A. Caillouet,* Sarah R. Michaels,* Xu Xiong,* Ivo Foppa,* and Dawn M. Wesson* * Tulane University History Founding/early history The University dates from 1834 as the Medical College of Louisiana.<ref name="facts" /> With the addition of a law department, it became The University of Louisiana School of Public Health and Tropical Medicine tropical medicine, study, diagnosis, treatment, and prevention of certain diseases prevalent in the tropics. The warmth and humidity of the tropics and the often unsanitary conditions under which so many people in those areas live contribute to the development and , New Orleans, Louisiana, USA Address for correspondence: Kevin A. Caillouet, Department of Tropical Medicine, Tulane University School of Public Health and Tropical Medicine, 1430 Tulane Ave, SL-17, New Orleans, LA 70112, USA; email: kcaillou@tulane.edu Dr Caillouet is a postdoctoral post·doc·tor·al also post·doc·tor·ate adj. Of, relating to, or engaged in academic study beyond the level of a doctoral degree. Noun 1. research fellow at Tulane University School of Public Health and Tropical Medicine. His research interests include vector-borne disease vector-borne disease Infectious diseases Any infection, usually transmitted by insects–eg, ticks–eg, Lyme disease, Rocky Mountain spotted fever, ehrlichiosis, Colorado tick fever; mosquitos–eg, California-or La Crosse, St Louis, Eastern, Western ecology and aquatic mosquito ecology.
Table 1. West Nile neuroinvasive disease (WNND) before and after
Hurricane Katrina for the 3 years before the storm (2002-2004),
the year of the storm (2005), and the year after the storm (2006)
in Louisiana parishes and Mississippi counties *
Affected areas
CDC weeks CDC weeks
32-34 ([dagger]) 35-37 ([double dagger])
WNND WNND
State cases 95% CI cases 95% CI
Louisiana
2002 22 14.6-33.3 8 4.1-15.8
2003 2 0.6-7.2 3 1.09-8.8
2004 1 0.2-5.6 1 0.2-5.6
2005 0 0-3.0 ([section]) 11 6.2-19.7 ([section])
2006 11 6.2-19.7 8 4.1-15.8
Mississippi
2002 13 7.7-22.2 12 6.9-21.0
2003 3 1.1-8.8 3 1.1-8.8
2004 1 0.2-5.6 2 0.6-7.2
2005 0 0-3.0 ([section]) 10 5.5-18.4 ([section])
2006 12 6.9-21.0 9 4.8-17.1
Unaffected areas
CDC weeks CDC weeks
32-34 ([dagger]) 35-37 ([double dagger])
WNND WNND
State cases 95% CI cases 95% CI
Louisiana
2002 37 26.9-51.0 20 13.0-30.9
2003 18 11.4-28.5 16 9.9-26.0
2004 23 15.4-34.5 11 6.2-19.7
2005 28 19.4-40.5 12 6.9-21.0
2006 13 7.7-22.2 16 9.9-26.0
Mississippi
2002 38 27.7-52.2 21 13.8-32.1
2003 5 2.2-11.7 4 1.6-10.2
2004 12 6.9-21.0 4 1.6-10.2
2005 8 4.1-15.8 10 5.5-18.4
2006 14 8.4-23.5 9 4.8-17.1
* CDC, Centers for Disease Control and Prevention; CI, confidence
interval (Poisson).
([dagger]) 3 weeks before landfall of hurricane.
([double dagger]) 3 weeks after landfall of hurricane.
([section]) p < 0.05.
Table 2. Incidence rate ratios of West Nile neuroinvasive disease
(WNND) in 2002-2005 and 2006 in Louisiana parishes and Mississippi
counties *
West Nile neuroinvasive disease
incidence rate ([dagger])
2002 2003 2004
([double ([double ([double
State, area dagger]) dagger]) dagger])
Louisiana
Affected 5.6 1.3 0.2
Unaffected 4.1 2.7 2.7
Mississippi
Affected 6.1 2.1 0.8
Unaffected 5.5 1.7 1.2
West Nile neuroinvasive disease
incidence rate ([dagger])
2005
([double 2002-2005 2006
State, area dagger]) ([section]) ([paragraph])
Louisiana
Affected 1.4 2.1 4.4
Unaffected 3.2 3.2 1.5
Mississippi
Affected 1.5 2.6 6.5
Unaffected 1.3 2.4 1.7
Incidence rate ratio
State, area (95% CI)
Louisiana
Affected 2.09 (1.48-2.94)
Unaffected 0.47 (0.35-0.64)
Mississippi
Affected 2.45 (1.77-3.47)
Unaffected 0.71 (0.55-1.03)
* WNND incidence rates increased 2-fold in the hurricane-affected
regions of both states. The unaffected regions showed a decrease
in WNND incidence rates (Louisiana) and no change in incidence
(Mississippi). CI, confidence interval.
([dagger]) No. cases/100,000.
([double dagger]) Population estimate based on 2000 US Census (8).
([section]) Cumulative WNND incidence = (no. WNND cases 2002 + 2003
+ 2004 + 2005) / cumulative population (Census 2000 [8] 100,000).
([paragraph]) Population estimate based on 2006 US Census estimate (7).
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