Leptospirosis in suspected cases of dengue in Jamaica, 2002-2007.

Due to overlapping clinical features with other febrile illnesses, the diagnosis of leptospirosis is often overlooked, resulting in delay in treatment and increased mortality. In this study the prevalence of leptospirosis was determined in 590 patients with dengue-like illnesses using the Leptospira IgM dipstick and dengue enzyme-linked immunosorbent assays. Leptospira IgM antibodies were found in 27 (5.0%) patients. Dengue IgM negative (6.9% versus 2.5%, P < 0.05) and dengue IgG positive patients (8.0% versus 3.5%, P < 0.01) were more likely to be leptospira IgM positive. Fever, skin rash, central nervous system and respiratory involvement were the most common presenting features. The presence of arthralgia (P = 0.016), hepatitis (P = 0.000), jaundice (P = 0.003), splenomegaly (P = 0.041) and haematuria (P = 0.029) were associated with leptospirosis. In countries with an endemicity of leptospirosis and dengue it is important that patients with dengue-like illnesses, especially those with no serological evidence of current primary dengue infection, be investigated for leptospirosis.

Seroprevalence of dengue virus antibodies in healthy Jamaicans.

Dengue fever, a mosquito borne viral infection, is endemic to Jamaica. The seroprevalence of dengue IgG and IgM antibodies were determined in 277 healthy Jamaicans by enzyme linked immunosorbent assay (ELISA). The seroprevalence of dengue IgG antibodies was 100% (277/277) while dengue IgM antibodies were found in 3.6% (10/277). A statistically significant association was found between the presence of dengue IgM antibodies and gender (males 10/105, 9.5% vs females 0/172, 0.0%); chi(2) = 17.0, p=0.000.The high seroprevalence rate of dengue IgG antibodies and the presence of dengue IgM in the healthy population are in keeping with the endemicity of the virus in Jamaica. Therefore tests for dengue IgG antibodies are of limited usefulness in Jamaica and can be safely excluded from diagnostic testing as a cost saving measure. Serological diagnosis of current dengue infection should be centred around the dengue IgM tests although the limitations in the predictive values of such tests should also be considered. The results also suggest that the risk of emergence of the more severe forms of dengue, dengue haemorrhagic fever (DHF) and dengue shock syndrome (DSS) in the Jamaican population, due to the presence of enhancing antibodies, is high.

Patterns of dengue virus IgM and IgG antibodies in suspected cases of dengue in Jamaica, 2003-2006.

The patterns of dengue immunoglobulin (Ig) M and IgG antibodies in patients presenting with dengue-like illnesses during 2003-2006 were investigated using enzyme linked immunosorbent assays (ELISA). The seroprevalence of dengue antibodies, dengue IgM and dengue IgG antibodies were 59.4% (979/1647), 15.4% (254/1647) and 51.1% (841/1647), respectively. A statistically significantly increasing trend in the prevalence of dengue IgG antibodies with age was observed, ranging from 38.4% in patients aged less than 1 year to 90% in those 60 of years and over (p = 0.000; 95% confidence interval (CI) = 0.000-0.002). Conversely the seroprevalence of dengue IgM did not differ significantly with age and no seasonality in the number of cases was observed. The patterns of IgM and IgG antibodies found in the present study are consistent with those found in dengue endemic countries during inter-epidemic periods indicating that an increasing risk of a new dengue outbreak due to the accumulation of susceptible population. Preventive measures should be maintained to control the endemic spread and reduce the risk of outbreaks of dengue in Jamaica. The high seroprevalence rate of dengue IgG antibodies might have implications for the emergence of the more severe forms dengue infection in the Jamaican population.