Climatological influence in the epidemiology of leptospirosis in humans in SVG – part 1

Dr Eric Alanzo Audain Tue, Aug 28, 2012

Introduction

Outbreaks of LEPTOSPIROSIS have occurred in both developed and developing countries. The United States of America, Chile, Argentina, Brazil, Germany and Panama, just to name a few, have had outbreaks of leptospirosis in their respective human population. Cuba, Trinidad and Tobago, Grenada, Dominica, Barbados and St Vincent and the Grenadines have seen an increase in the number of reported confirmed clinical cases of the disease, some of which were fatal.{{more}}

In St Vincent and the Grenadines, the impact of climate on the number of reported confirmed clinical cases of leptospirosis in humans is unknown, and as a result, an investigative study was conducted by Dr Eric Audain, Dr Adolfo Pedroso Sosa and Dr Dania Ferrara. The team collected and studied all the data regarding the number of reported confirmed clinical cases of the disease in human during the period 2001-2010 from the Milton Cato Memorial Hospital and the Epidemiological office. Climatological registration (temperature, precipitation and humidity) was also collected from the Meteorological Office at Arnos Vale for the same period. A series of statistical analyses was done so as to determine the level of correlation between the occurrence of the disease and the above mentioned climatic factors in SVG.

The results are of great importance in our efforts regarding the prevention and control of the disease. We have agreed to share our findings with you the people through this medium. The study of leptospirosis is of great importance, since this disease affects the health of both humans and animals and has a socio-economic and political impact. Modifications in the climatic patterns have significantly influence the incidence and prevalenced of this disease on a global scale. Research shows that the occurrences of this disease depend greatly on the presence of certain climatic conditions.

In summarizing our findings for the period 2001-2010: 83 per cent of the confirmed clinical cases of leptospirosis in humans in SVG occur during the rainy season and little over 80 per cent of the recorded rainfall was registered during that same season. There is a statistically significant correlation (p<0, 05) between the number of reported confirmed clinical cases of leptospirosis in humans and the recorded rainfall (precipitation) over the same period. The male population is most affected by the disease. Finally the highest reported number of confirmed clinical cases of LEPTOSPIROSIS in SVG was noted in our farming communities. Part 1: LEPTOSPIROSIS LEPTOSPIROSIS is a seasonal, environmental and occupational re-emerging zoonotic disease (spreads naturally from animals to human and from human to animals) and is caused by very intelligent and potentially fatal bacteria (L. interrogans). There are two known species of Leptospira (L. interrogans and L. biflexa); the first is pathogenic (causes disease) while the other lives free in the environment and is non-pathogenic. The disease caused by L. interrogans is known as LEPTOSPIROSIS. The L. interrogans consists of more than 200 serovares (serological variants), which in readity are individual bacterium that forms part of the same family. However, the immune response that the infected person or animal produces is specific to a particular serovar and for this reason the disease is very complicated and thus explaining the fact that no vaccine can give humans or animals protection from this deadly zoonotic disease. A vaccine will only be effective if the strain of the infected bacteria is known and the vaccine is manufactured specifically against that particular serovar (strain). The global presence of leptospirosis in humans is as a result of a number of climatological factors (precipitation, humidity and temperature) on the survival of the bacteria while in the external environment. This explains the reason for the high number of clinical confirmed cases of the disease in both tropical and sub-tropical countries. This series on leptospirosis to be continued next week in the Midweek SEARCHLIGHT.