By S C Rawlins PhD, Emeritus Scientist c/o Caribbean Epidemiology Centre, Trinidad

1. An Assessment of the Impact of Climate Features on Dengue Fever and its Vectors in Five Caribbean Countries (AIACC Project) By S C Rawlins PhD, Emeritus Scientist c/o Caribbean Epidemiology Centre, Trinidad

2. Introduction • In the last two decades there has been an unprecedented increase in the occurrence and severity of dengue fever (DF) in Caribbean countries. • Any tool useful to predicting outbreaks and implementing enhanced prevention strategies – adaptation – would be most welcome. Cert

4. Introduction contd.

5. Caribbean Countries

6. Introduction Contd. • Already, we have examined the impact of climate change features especially warming conditions on retrospective dengue fever data in the Caribbean region. • We have shown some association in the increased occurrence of DF and warming periods in some Caribbean Epidemiology Centre (CAREC) Member Countries (CMCs)

7. Caribbean countries

9. Prospective Studies, 2002-2004 • . In this present study we are examining prospectively the occurrence of DF and population features of the vector with varying climate features such as temperature and precipitation. • Here, we are examining the patterns of reported dengue fever cases in the Caribbean region – mainly CMCs with a population of just over 6 - 7 millions – to demonstrate any climate-related patterns of disease presentation over 2002 - 2004

10. Design and Methods • Data on reported monthly dengue fever (DF) cases, vector – Aedes aegypti – indices, and climatic indicators were collected prospectively for a 12 month period beginning early 2003 in 5 Caribbean countries • Jamaica, Trinidad and Tobago (T&T), Barbados, St Vincent and the Grenadines (SVG) and St Kitts/Nevis (SKN). • Data were analyzed by ANOVA for evidence of climate impact on DF cases and vector indices.

11. St Vincent Results • SVG data showed minor fluctuations of vector breteau (BIs) and house indices (HIs) with precipitation • Dryer periods coincided with low vector HIs of 9-22%. In wet periods, both indices were higher – HIs (17-72%) and BIs (31-55). • Temperature varied slightly (23-32˚C) throughout the year.

12. St Kitts/Nevis Results • SKN vector data showed a bimodal pattern with peaks of HIs and BIs in May-June and October-December, the latter associated with significant precipitation. • Mean monthly temperatures only varied between 26 -29˚C (Fig. 4).

13. Trinidad and Tobago • T&T data for 2002 and 2003 showed distinct dry and wet seasonal patterns • In 2002 dry periods (January-May), there were low BIs (21– 29), and mean monthly DF cases of 290.4. • Increases in BIs (32-44), (P=0.000) and mean monthly DF cases (695/month) coincided with the wetter period (June – December). • Temperature varied slightly 22-25˚C (min) to 31 -33˚C (max) for the period.

15. Conclusions 1 • Patterns from SKN, SVG and T&T data discerned a correlation of seasonal effect on BIs and in T&T on DF transmission • . Temperature variations did not seem to be significant, but may have affected the onset of precipitation and in turn, vector production, an increase in indices and DF cases

16. Conclusions 2 • The data confirm the usefulness of recognizing the wet season as a risk factor for DF transmission in the region • Utilising this knowledge for preparation of early warning systems for DF prevention will be vital