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Temporal trends and climatic factors associated with bacterial enteric diseases in Vietnam, 1991-2001.

Kelly-Hope LA, Alonso WJ, Thiem VD, Canh do G, Anh DD, Lee H, Miller MA - Environ. Health Perspect. (2008)

Bottom Line: Cholera was mostly epidemic along the central coast between May and November (0.07-2.7), and then decreased dramatically nationwide from 1997 onward.Significant climate differences were found only between high- and low-disease periods.Climate plays a role in defining high- and low-disease periods, but it does not appear to be an important factor influencing outbreaks.

View Article: PubMed Central - PubMed

Affiliation: Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA. kellyhopel@mail.nih.gov

ABSTRACT

Objective: In Vietnam, shigellosis/dysentery, typhoid fever, and cholera are important enteric diseases. To better understand their epidemiology, we determined temporal trends, seasonal patterns, and climatic factors associated with high risk periods in eight regions across Vietnam.

Methods: We quantified monthly cases and incidence rates (IR) for each region from national surveillance data (1991-2001). High- and low-disease periods were defined from the highest and lowest IRs (1 SD above and below the mean) and from outbreaks from positive outliers (4 SDs higher in 1 month or 2 SDs higher in > or = 2 consecutive months). We used general linear models to compare precipitation, temperature, and humidity between high- and low-risk periods.

Results: Shigellosis/dysentery was widespread and increased 2.5 times during the study period, with the highest average IRs found between June and August (2.1/100,000-26.2/100,000). Typhoid fever was endemic in the Mekong River Delta and emerged in the Northwest in the mid-1990s, with peaks between April and August (0.38-8.6). Cholera was mostly epidemic along the central coast between May and November (0.07-2.7), and then decreased dramatically nationwide from 1997 onward. Significant climate differences were found only between high- and low-disease periods. We were able to define 4 shigellosis/dysentery, 14 typhoid fever, and 8 cholera outbreaks, with minimal geotemporal overlap and no significant climatic associations.

Conclusions: In Vietnam, bacterial enteric diseases have distinct temporal trends and seasonal patterns. Climate plays a role in defining high- and low-disease periods, but it does not appear to be an important factor influencing outbreaks.

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Related in: MedlinePlus

Monthly incidence rates per 100,000 population and outbreaks of shigellosis/dysentery, typhoid fever, and cholera in eight regions of Vietnam. (A) Incidence rates. (B) Outbreaks. Dotted vertical lines define years, and individual bands indicate values for months; geographic regions are sorted by latitude.Outbreaks are displayed as SD above the modeled Fourier function.
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f3-ehp0116-000007: Monthly incidence rates per 100,000 population and outbreaks of shigellosis/dysentery, typhoid fever, and cholera in eight regions of Vietnam. (A) Incidence rates. (B) Outbreaks. Dotted vertical lines define years, and individual bands indicate values for months; geographic regions are sorted by latitude.Outbreaks are displayed as SD above the modeled Fourier function.

Mentions: Figure 3A shows the monthly IRs of shigellosis/dysentery, typhoid fever, and cholera for each region during 1991–2001. This figure highlights the widespread incidence of shigellosis/dysentery and its increase in the Central Highlands and the South Central Coast, the endemicity of typhoid fever in the Mekong River Delta and its emergence in the Northwest region, and the significant decline of cholera nationwide.


Temporal trends and climatic factors associated with bacterial enteric diseases in Vietnam, 1991-2001.

Kelly-Hope LA, Alonso WJ, Thiem VD, Canh do G, Anh DD, Lee H, Miller MA - Environ. Health Perspect. (2008)

Monthly incidence rates per 100,000 population and outbreaks of shigellosis/dysentery, typhoid fever, and cholera in eight regions of Vietnam. (A) Incidence rates. (B) Outbreaks. Dotted vertical lines define years, and individual bands indicate values for months; geographic regions are sorted by latitude.Outbreaks are displayed as SD above the modeled Fourier function.
© Copyright Policy - public-domain
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2199291&req=5

f3-ehp0116-000007: Monthly incidence rates per 100,000 population and outbreaks of shigellosis/dysentery, typhoid fever, and cholera in eight regions of Vietnam. (A) Incidence rates. (B) Outbreaks. Dotted vertical lines define years, and individual bands indicate values for months; geographic regions are sorted by latitude.Outbreaks are displayed as SD above the modeled Fourier function.
Mentions: Figure 3A shows the monthly IRs of shigellosis/dysentery, typhoid fever, and cholera for each region during 1991–2001. This figure highlights the widespread incidence of shigellosis/dysentery and its increase in the Central Highlands and the South Central Coast, the endemicity of typhoid fever in the Mekong River Delta and its emergence in the Northwest region, and the significant decline of cholera nationwide.

Bottom Line: Cholera was mostly epidemic along the central coast between May and November (0.07-2.7), and then decreased dramatically nationwide from 1997 onward.Significant climate differences were found only between high- and low-disease periods.Climate plays a role in defining high- and low-disease periods, but it does not appear to be an important factor influencing outbreaks.

View Article: PubMed Central - PubMed

Affiliation: Division of International Epidemiology and Population Studies, Fogarty International Center, National Institutes of Health, Department of Health and Human Services, Bethesda, MD 20892, USA. kellyhopel@mail.nih.gov

ABSTRACT

Objective: In Vietnam, shigellosis/dysentery, typhoid fever, and cholera are important enteric diseases. To better understand their epidemiology, we determined temporal trends, seasonal patterns, and climatic factors associated with high risk periods in eight regions across Vietnam.

Methods: We quantified monthly cases and incidence rates (IR) for each region from national surveillance data (1991-2001). High- and low-disease periods were defined from the highest and lowest IRs (1 SD above and below the mean) and from outbreaks from positive outliers (4 SDs higher in 1 month or 2 SDs higher in > or = 2 consecutive months). We used general linear models to compare precipitation, temperature, and humidity between high- and low-risk periods.

Results: Shigellosis/dysentery was widespread and increased 2.5 times during the study period, with the highest average IRs found between June and August (2.1/100,000-26.2/100,000). Typhoid fever was endemic in the Mekong River Delta and emerged in the Northwest in the mid-1990s, with peaks between April and August (0.38-8.6). Cholera was mostly epidemic along the central coast between May and November (0.07-2.7), and then decreased dramatically nationwide from 1997 onward. Significant climate differences were found only between high- and low-disease periods. We were able to define 4 shigellosis/dysentery, 14 typhoid fever, and 8 cholera outbreaks, with minimal geotemporal overlap and no significant climatic associations.

Conclusions: In Vietnam, bacterial enteric diseases have distinct temporal trends and seasonal patterns. Climate plays a role in defining high- and low-disease periods, but it does not appear to be an important factor influencing outbreaks.

Show MeSH
Related in: MedlinePlus