Dengue virus serotypes in Jamaica, 2003-2007.

BACKGROUND: Dengue virus (DENV) infection is increasing in prevalence and severity globally. The severity of dengue is influenced by several factors including the immune response, viral and host genetic factors. METHOD: The DENV serotypes were determined in 770 serum samples from dengue immunoglobulin (Ig) M antibody positive (n = 469), dengue IgM negative (n = 185) and dengue antibody negative (n = 116) patients with suspected dengue who presented during (n = 150) or after (n = 620) the acute phase of illness during 2003-2007. Dengue antibodies were detected by enzyme-linked immunosorbent assays and DENV RNA by reverse transcriptase-polymerase chain reaction (RT-PCR) performed on serum and cell culture supernatants of C6/36 mosquito cells inoculated with acute phase serum (n = 150). RESULTS: Based on serological profiles, 41% of acute phase sera and 66% of post acute sera were from patients with current primary or secondary dengue, while 41% and 35% of acute and post-acute phase sera, respectively, were from patients with secondary dengue or past exposure only. Dengue virus RNA was found in 20/770 samples (2.6%). Only 1.5% (9/620) of sera collected after the acute phase of illness tested positive for DENV RNA compared with 2.6% (4/150) of sera collected during the acute phase and 7.3% of cell culture supernatants inoculated with acute phase serum (11/150, p = 0.001). All four serotypes including DENV-1 (3/20, 15%), DENV-2 (7/20, 35%), DENV-3 (3/20, 15%) and DENV-4 (7/20, 35%) were identified over the five-year period. These results also showed that DENV-1, 2 and 4 were present during 2007 and that DENV-2 and DENV- 4 were the likely causative viruses of the 2007-2008 dengue outbreak in Jamaica. The three strains of DENV-3 were isolated from infants less than three years of age with primary infection during 2006. CONCLUSION: This study highlights the increasing threat of dengue and severe dengue disease to the Jamaican population. Preventative measures including laboratory surveillance and vector control should be strictly maintained at the highest level.

Molecular epidemiology of dengue in Jamaica dengue virus genotypes in Jamaica, 2007.

The genotypes of dengue viruses (DENV) isolated from patients with dengue in Jamaica during 2007 were determined using DNA sequencing and phylogenetic analysis of the C-prM gene junction. The 17 DENV analysed included strains of DENVserotypes 1 (DENV-1, n = 3), DENV-2 (n = 7) and DENV-4 (n = 7). All strains ofDENV-1 were classified as genotype III, while 1 of 7 strains of DENV-2 belonged to the Asian American/Asian genotype, genotype I/III (Jamaica genotype), 2 were genotype V, the American genotype and 4 strains clustered with reference strains belonging to genotype IV. The 6 DENV-4 strains from Jamaica and the control strain clustered together in a separate clade from Caribbean/American reference strains, which belong to genotype II and Asian strains, classified as genotypes I and III. There has been little evolution in the DENV-1 strains circulating in Jamaica over the years and this might reduce the risk of outbreaks due to this serotype. In contrast, the high genetic diversity in strains of DENV-2 viruses in circulation, the presence of more recently introduced genotypes and a new clade of DENV-4 might contribute to the epidemic potential of these DENV serotypes. These preliminary data clearly indicate the need to maintain laboratory surveillance, and other control measures against hyperendemicity of dengue in Jamaica.

Dengue HLA associations in Jamaicans.

BACKGROUND: Polymorphisms in the human leukocyte antigen (HLA) genes might predispose certain individuals to dengue fever (DF) and the severe forms of the disease: dengue haemorrhagic fever/ dengue shock syndrome (DHF/DSS). SUBJECTS AND METHOD: A DNA-based HLA typing method was used to determine the HLA class I and II alleles in 50 patients with dengue, including 45 cases of DF 5 cases of DHF and 177 healthy individuals in Jamaica. RESULTS: HLA-A*24 and - DRbeta5*01/02 were significantly associated with dengue infection while possession of HLA-A*23, -CW*04, -DQbeta*02, -DQbeta*03 and DQbeta*06 were protective. No other significant associations were found after correction for the number of alleles tested at each HLA-locus. CONCLUSION: This is the first study to report a significant association with HLA-A*24 and DF although this allele is associated with DHF and DSS in Vietnamese patients. The other HLA associations observed in the Jamaican cohort also are different from those reported in other ethnic groups. Further studies which involve larger numbers of patients with DHF and explore functional aspects of HLA allelic associations with dengue in Jamaicans are necessary.

High genetic diversity in human immunodeficiency virus-type 1 in Jamaica.

The subtypes of the human immunodeficiency virus - type 1 (HIV-1) strains from 54 HIV-1 - infected persons including 44 strains which were typed previously by heteroduplex mobility assay (HMA) were determined by DNA sequencing and phylogenetic analysis. Of 54 HIV- infected persons, 92.5% were infected with HIV-1 subtype B and 7.5% with other HIV-1 subtypes including subtypes D (3.7%), A (1.9%) and J (1.9%). In the phylogenetic analysis, the subtype A virus found in the sample clustered with subtype A reference strains and a circulating recombinant form (CRF) reference strain which originates in Central Africa and is circulating in Cuba indicating a close relationship between these viruses. There was 86% concordance between HMA and DNA sequencing in assigning subtype B viruses. For the non-B subtype viruses, there was less concordance between the two methods (67%). The results confirm the predominance of HIV-1 subtype B strains and the high genetic diversity of HIV-1 strains in circulation in Jamaica. The efficacies and some limitations of the HMA as a method of HIV-1 subtyping also were noted. It is important that the HIV/AIDS epidemic in Jamaica be monitored meticulously for possible expansions in non-B subtypes and the emergence of inter-subtype recombinant forms. We recommend that the more expensive DNA sequencing and phylogenetic analysis, including HIV-1 genotyping for antiretroviral drug resistance testing, be used as an adjunct to the more cost-effective HMA to track the HIV/AIDS epidemic in Jamaica.

Human immunodeficiency virus type-1 (HIV-1) subtypes in Jamaica / Subtipos del virus tipo-1 de la inmunodeficiencia humano (VIH-1) en Jamaica

The subtypes of 141 isolates of human immunodeficiency virus type-1 (HIV-1) from Jamaica were determined by a combination of env and gag heteroduplex mobility analysis (HMA) genotyping. The majority of HIV-1 isolates were subtype B (131/141, 93.0); one (0.8) isolate each of subtypes C, D and E was found and 7 (4.9) were indeterminate. These results and the failure of the sets of primers used to amplify some of the HIV-1 isolates provide strong evidence of genetic diversity of the HIV/AIDS epidemic in Jamaica. Surveillance of the circulating HIV-1 genetic subtypes is a pre-requisite for developing regional vaccine strategies and understanding the transmission patterns of the virus. This is the first study of its kind in Jamaica and the findings complement data from other Caribbean countries. This work supports the view of colleagues from the French and Spanish-speaking Caribbean that an epidemiological network supported by regional laboratories will help track this epidemic accurately with positive outcomes for the public.

Los subtipos de 141 aislados del virus tipo 1 de la inmunodeficiencia humno (VIH-1) en Jamaica, fueron determinados combinando la genotipificación por análisis de heterodúplex (HMA) en los genes env y gag. La mayor parte de los aislados HIV-1 fueron del subtipo B (131/141, 93.0%), se halló uno (0.8%) aislado para cada uno de los subtipos C, D y E, en tanto que 7 (4.9%) fueron indeterminados. Estos resultados y el fallo de los conjuntos de primers usados para amplificar algunos de los aislados de VIH-1, ofrecen fuerte evidencia de la diversidad epidémica del VIH/SIDA en Jamaica. La vigilancia de los subtipos genéticos de VIH-1 en circulación, constituye un pre-requisito, tanto para desarrollar estrategias de vacunas a nivel regional, como para entender los patrones de transmisión del virus. Este es el primer estudio de este tipo en Jamaica, y nuestros hallazgos complementan los datos obtenidos en otros países del Caribe. Coincidimos con nuestros colegas del Caribe francófono e hispano-parlante en cuanto a que una red epidemiológica apoyada por los laboratorios regionales, nos ayudaría a continuar rastreando esta epidemia con exactitud, y con resultados positivos para el público.

Human immunodeficiency virus type-1 (HIV-1) subtypes in Jamaica.

The subtypes of 141 isolates of human immunodeficiency virus type-1 (HIV-1) from Jamaica were determined by a combination of env and gag heteroduplex mobility analysis (HMA) genotyping. The majority of HIV-1 isolates were subtype B (131/141, 93.0%); one (0.8%) isolate each of subtypes C, D and E was found and 7 (4.9%) were indeterminate. These results and the failure of the sets of primers used to amplify some of the HIV-1 isolates provide strong evidence of genetic diversity of the HIV/AIDS epidemic in Jamaica. Surveillance of the circulating HIV-1 genetic subtypes is a pre-requisite for developing regional vaccine strategies and understanding the transmission patterns of the virus. This is the first study of its kind in Jamaica and the findings complement data from other Caribbean countries. This work supports the view of colleagues from the French and Spanish-speaking Caribbean that an epidemiological network supported by regional laboratories will help track this epidemic accurately with positive outcomes for the public.

Antibiotic susceptibility of Clostridium difficile isolates from adult patients at two Jamaican hospitals. Clinical and epidemiological implications.

The susceptibility of 39 toxin producing Clostridium difficile isolates from stools of hospitalized patients was determined, by disc diffusion, to six antibiotics. All but one isolate (toxin A negative) produced toxin A and toxin B. A wide variation in susceptibility to clindamycin, tetracycline and chloramphenicol was noted. Erythromycin and cotrimoxazole showed a clear-cut discrimination in resistance and susceptibility, while all isolates were sensitive to vancomycin. Erythromycin sensitive isolates demonstrated a significant association with diarrhoea (60.9%, 14/23, p < 0.001). These strains were predominantly found at the University Hospital of the West Indies (UHWI, 94.1%, 16/17). Strains resistant to erythromycin and clindamycin together were commonly found at the National Chest Hospital (NCH, 68.2%, 15/22). All erythromycin sensitive strains found at the NCH were from patients transferred to that hospital. These findings suggest that there is a common strain of C difficile (erythromycin resistant) at the NCH different from that found at the UHWI; the resistant pattern seen with isolates from the NCH was typical of toxigenic serogroup C strain and could be typed by the the disc diffusion method. Patients at the NCH who were colonized with either of the two strains of C difficile were likely to get diarrhoea, once there was suppression of the normal microflora by antibiotics and colonic overgrowth with C difficile.

Antibiotic susceptibility of clostridium difficile isolates from adult patients at two Jamaican hospitals. Clinical and epidemiological implications

The susceptibility of 39 toxin producing Clostridium difficile isolates from stools of hospitalized patients was determined, by disc diffusion, to six antibiotics. All but one isolate (toxin A negative) produced toxin A and Toxin B. A wide variation in susceptibility to clindamycin, tetracycline and chloramphenicol was noted. Erythromycin and cotrimoxazole showed a clear-cut discrimination in resistance and susceptibility, while all isolates were sensitive to vancomycin. Erythromycin sensitive isolates demonstrates a significant association with diarrhoea (60.9 percent, 14/23, p<0.001). These strains were predominantly found at the University Hospital of the West Indies (UHWI, 94.1 percent, 16/17). Strains resistant to erythromycin and clindamycin together were commonly found at the National Chest Hospital (NCH, 68.2 percent, 15/22). All erythromycin sensitive strains found at the NCH were from patients transfered to that hospital. These findings suggest that there is a common strain of C difficile (erythrmycin resistant) at the NCH different from that found at the UHWI; the resistant pattern seen with isolates from the NCH was typical of toxigenic serogroup C strain and could be typed by the disc diffusion method. Patients at the NCH who were colonized with either of the two strains of C difficile were likely to get diarrhoea, once there suppression of the normal microflora by antibiotics and colonic over growth with C difficile. (AU)

Antibiotic susceptibility of Clostridium difficile isolates from adult patients at two Jamaican hospitals. Clinical and epidemiological implications

The susceptibility of 39 toxin producing Clostridium difficile isolates from stools of hospitalized patients was determined, by disc diffusion, to six antibiotics. All but one isolate (toxin A negative) produced toxin A and toxin B. A wide variation in susceptibility to clindamycin, tetracycline and chloramphenicol was noted. Erythromycin and cotrimoxazole showed a clear-cut discrimination in resistance and susceptibility, while all isolates were sensitive to vancomycin. Erythromycin sensitive isolates demonstrated a significant association with diarrhoea (60.9, 14/23, p < 0.001). These strains were predominantly found at the University Hospital of the West Indies (UHWI, 94.1, 16/17). Strains resistant to erythromycin and clindamycin together were commonly found at the National Chest Hospital (NCH, 68.2, 15/22). All erythromycin sensitive strains found at the NCH were from patients transferred to that hospital. These findings suggest that there is a common strain of C difficile (erythromycin resistant) at the NCH different from that found at the UHWI; the resistant pattern seen with isolates from the NCH was typical of toxigenic serogroup C strain and could be typed by the the disc diffusion method. Patients at the NCH who were colonized with either of the two strains of C difficile were likely to get diarrhoea, once there was suppression of the normal microflora by antibiotics and colonic overgrowth with C difficile.

Clostridium difficile infection in immunocompromised patients a three health-care facilities in Jamaica

A cross-sectional study was conducted (April 96 to July 97) to investigate the prevalence of Clostridium difficile infection in immunocompromised patients at 3 health care institutions. Standard bacteriological procedure, tissue culture and enzyme immunoassay were used to investigate faecal specimens from immunocompromised inpatients (N = 113) including 21 patients treated with immunosuppressive drugs, 39 patients had received radiotherapy and 53 patients who were not treated with immunosuppressive drugs. The overall prevalence of C. difficile infections was 14.2 percent (16/113). All the C. difficile isolates were identified as toxigenic strains. The prevalence of C. difficile infection in patients who had received immunosuppressive drugs (23.8 percent, 5/21) did not differ significantly from those who had not (20.7 percent, 11/53), but was significantly lower in patients who received radiotherapy (p<0.01). The occurrence of C. difficile was not significantly associated with antibiotics in patients who were on immunosuppressive drugs (2/13, 15.4 percent vs 3/8, 37.5 percent) or patients who were not (7/32, 21.8 percent vs 4/21, 19.0 percent). Eighty percent (4/5) of C. difficile isolates from patients on immunosuppressive drugs were from those whose regimens include cytotoxic drugs. Similarly, anti-tubercolosis drugs were the antibiotics most frequently associated with C. difficile infections (4/8, 50 percent). C. difficile infections are likely to occur in patients treated with cytotoxic drugs and certain antibiotics.(AU)

Antibiotic susceptibility of 39 Clostridium difficile isolates from adult patients at the University Hospital of the West Indies (UHWI) and the National Chest Hospital (NCH)

The antibiotic susceptibility to six antibiotics of 39 C. difficile isolates (38 toxigenic) from stool specimens (14 adult diarrhoeal and 25 adult nondiarrhoeal) was determined by disc diffusion. Susceptibility to clindamycin (CC), cotrimoxazole (SXT), erythromycin (E), vancomycin (VA), tetracycline (TE) and chloramphenicol (C) was correlated with diarrhoeal and nondiarrhoeal cases. With the exception of VA, a wide variation in susceptibility was noted with CC, E, SXT, TE, and C, with a strong correlation between E sensitive isolates in diarrhoeal cases (69.8 percent). Compartively and of equal significance were erythromycin resistant isolates, primarily form NCH (93.8 percent). All erthromycin resistant isolates were simultaneously resistant to clindamycin (no zone) with only one isolate associated with a diarrhoeal case from UHWI. A review of patients' dockets revealed that actual transferrals to hospitals were largely responsible for the differences in erythromycin susceptibility among isolates.(AU)

The role of chickens in the epidemiology of eastern equine encephalomyelitis virus in Jamaica

Since 1962, when Jamaica experienced its first and only outbreak of eastern equine encephalomyelitis (EEE), surveillance for the causitive virus has been in progress. Wild birds, rodents, mosquitoes, sandflies and sentinels (domestic chickens, guinea pigs, mice and hamsters) have been constantly examined for EEE virus and serological conversion. In essence, only negative results have been obtained. Since June 1976, domestic chickens have been investigated as a possible reservoir and several have been found to have haemagglutinating antibodies, with titres ranging from 1:10 to 1:160. These titres fell rapidly, eg, from 1:160 to 1:10 within 60 days. These results incriminate the domestic fowl as a major reservoir for the virus, and suggest that the life of immunoglobulins against EEE is short in birds. Thus, the large number of negative serological tests found in previous investigations might be misleading since positive sera might have been missed between intervals of capture and recapture of the birds. The results indicate that investigators could usefully modify their procedure by bleeding wild birds as early as one to two weeks after initial capture. The importance and duration of the dominant avian anti-EEE virus immunoglobins should be investigated (AU).