Trends in the patterns of IgM and IgG antibodies in febrile persons with suspected dengue in Barbados 2006-2013

OBJECTIVES: To describe the seroprevalence of dengue antibodies in febrile suspected persons and investigated for dengue in this country. DESIGN AND METHODS: This was a retrospective population based study of all febrile children and adults with probable dengue from 2006 to 2013. Persons with probable dengue were investigated for dengue IgM and IgG antibodies in the blood sample drawn between days 3 to 5 of their illness. RESULTS: Among the 8296 cases that were tested for IgM antibodies, 2605 (36.6%) cases tested positive. Of the 7227 suspected cases who were tested for IgG, 5473 (75.7%) were positive. During the study years, between 80% and 90% of persons older than 20 years had a positive IgG antibody. Among the persons younger than five years (excluding the first year), between 10% and 20% had a positive IgM titre and a negative IgG titre, between 5 and10% had a positive IgM and IgG titre, 5% had a positive IgG titre and a negative IgM titre and between 45% and 65% had a negative IgM and a negative IgG titre. Between 37% and 59% had a serological evidence of past dengue in absence of any current dengue. CONCLUSIONS: The pattern of IgG antibodies seen in this study was comparable to those seen in the countries known to be hyperendemic for dengue. Based on the pattern of antibodies, the age of infection was likely to shift down to younger age groups with the likelihood of more severe forms of dengue in the future.

Screening thoroughbreds for antibodies to the Equine infectious anemia virus.

One hundred and seventy two Thoroughbreds were screened for the presence of anitbodies to the capsid protein, p26 of the equine infectious anemia (EIA)virus using agarose gel immunodiffusion (AGOD) Coggins test. Horses ranged in age from 1 month to 21 years old and were either imported or locally bred. The majority were involved in racing and breeding and were housed either at the Santa Rosa Racing Complex at Arima or at privately owned farms. Complete blood counts (CBCs) were performed on all horses. Low haemoglobin concentrations were found in 18(10.5%), high white blood cell counts in 17 (9.9%) with neutrophilia in 13 (7.6%). Low red blood cell counts were seen in 11 of 154 horses (7.1%). At least 12 horses had evidence of clinical babesiosis, but only 7 were confirmed infected by examination of Giemsa stained blood smears. Racehorses from trinidad and Tobago occasionally move inter-island for racing and increasingly come in contact with foreign horses with the increasing importation of horses from countries known to harbour the virus. All 172 horses tested negative for antibodies to EIA virus. This implies that the strict adherence to import and quarantine regulations may have contributed to keeping the country free from EIA virus. This ongoing study is the first to provide sero-prevalence data and document the prevalence of EIA in the equine population in Trinidad and Tobago.

Screening thoroughbreds for antibodies to the Equine infectious anemia virus.

One hundred and seventy two Thoroughbreds were screened for the presence of anitbodies to the capsid protein, p26 of the equine infectious anemia (EIA)virus using agarose gel immunodiffusion (AGOD) Coggins test. Horses ranged in age from 1 month to 21 years old and were either imported or locally bred. The majority were involved in racing and breeding and were housed either at the Santa Rosa Racing Complex at Arima or at privately owned farms. Complete blood counts (CBCs) were performed on all horses. Low haemoglobin concentrations were found in 18(10.5%), high white blood cell counts in 17 (9.9%) with neutrophilia in 13 (7.6%). Low red blood cell counts were seen in 11 of 154 horses (7.1%). At least 12 horses had evidence of clinical babesiosis, but only 7 were confirmed infected by examination of Giemsa stained blood smears. Racehorses from trinidad and Tobago occasionally move inter-island for racing and increasingly come in contact with foreign horses with the increasing importation of horses from countries known to harbour the virus. All 172 horses tested negative for antibodies to EIA virus. This implies that the strict adherence to import and quarantine regulations may have contributed to keeping the country free from EIA virus. This ongoing study is the first to provide sero-prevalence data and document the prevalence of EIA in the equine population in Trinidad and Tobago.

The comparative value of various diagnostic tests for malaria - abstract

When 300 blood samples taken from patients attending a fever clinic in Georgetown Public Hospital were examined microscopically, 47.6 percentwere found positive for malaria. IgG antibodies stored in filter paper or liquid serum gave 68 percent and 81 percent positive rate, repsectively. Sixty-one per cent (61 percent) of the patients had positive levels of IgG antibodies. Elevation of the cut-off point of IgG antibody titres from 1:256 to 1:1,024 help to reduced false positives of the indirect flourescent antibody test. Clinical symptoms, visits to endemic areas, occupation and its life styles, as well as age could assist in making a diagnosis. The microscopic method will continue to be the gold standard (AU)

Immunologically determined prevalence rates of antibodies to toxocara canis in school children in Trinidad, West Indies - abstract

Preliminary observations of a high frequency of serum antibodies to Toxocara canis in patients attending Eye Clinic at the General Hospital, Port of Spain, Trinidad led to the hypothesis that children with pet dogs may have as high a frequency. Hence, the sera of 339 school children, randomly selected from the school register, were tested by ELISA for the presence of IgG and IgM antibodies to T. canis. The prevalence rate of T. canis antibodies in schoolchildren in Countries Victoria and St. Patrick (32.5 percent) were similar but higher than that in Country Caroni (12.7 percent). Overall, a prevalence rate for Trinidad was determined (77.6 percent) which was similar to that found in Dominica (78.9 percent), St. Kitts/Nevis (75.3 percent) and Grenada (78.5 percent). Apart from Toxocara, other helminths only, 12 had helminths and protozoan parasites and 26 had protozoan parasites only. Of 31/83 students without antibodies to T. canis, 7 had helminths only, 2 had helminths and protozoan parasites and 22 had protozoan parasites only (AU)

Age-dependency of infection status and serum antibody levels in human whipworm (Trichuris trichiura) infection

This study examines the age-dependency of the relationships between human infection with whipworm (Trichuris trichiura) and parasite-specific antibody level measured by ELISA against an extract of adult worms after preincubation of the sera with Ascaris lumbricoides adult worm extract. The convex age-profile of parasite infection intensity is shown to be mirrored by age-dependent change in age-class mean levels of IgG (all subclasses except IgG3), IgA, IgM and IgE. Mean antibody levels rise with increasing acquisition of infection in childhood. Immunoblot analysis of selected sera from different age-classes indicates that antigen recognition is similarly dependent on infection intensity. In individual children, antibody levels correlate positively with acquisition of infection, consistent with a simple model of antigen dosage specifying the magnitude of the humoral immune response. In adults, IgG4 correlates positively and IgA negatively with intensity of infection, suggesting involvement of these isotypes in functional roles of immune blockade or effector mechanisms, respectively.(AU)

Cutaneous infections in Trinidad

Skin infection is common in patients with any skin diseases where pruritus is a prominent feature. A retrospective analysis was performed on the results of skin swab cultures from patients with eczema and a variety of other conditions. This paper presents the findings of bacteriologic culture and sensitivity testing of 131 swabs from 122 patients over a period of 22 months and examines the results in terms of the reported relationship between scabies and acute poststreptococcal glomerulonephritis. Staphylococcus aureus was most often isolated, and this appears to indicate that antistaphylococcal antibiotics should be the first line of treatment in the absence of the results of cultures. (AU)

Absence of islet cell autoantibodies in Jamaican Blacks with diabetes mellitus

Forty-two patients, mainly of Black ancestry, attending the Diabetic Clinic, University Hospital of the West Indies, were studied for the frequency of autoantibodies against pancreatic islet cells (ICA), thyroid microsomes (TMA) and gastric parietal cells (PCA). There were 24 men and 18 women with an age range of 6-77 years and a mean age of 56.3 ñ 16.5 years. They had had diabetes for periods ranging from 1 to 40 years with a mean duration of 12.3 yearsñ 7.9 years. Sixty per cent had had insulin therapy for periods ranging from 0.25 to 25 years with a mean duration of 7.6 ñ 6.4 years. The mean body mass index was 24.0 ñ 2 with a range of 16.5 - 32.1. No patient had ICA. Of the insulin-treated patients, 17 percent were TMA positive. No patient had both TMA and PCA positivity. Amongst black populations, there is less evidence for autoimmune pathogenesis of insulin-requiring diabetes. The results suggest geographic as well as racial heterogeneity for black populations with diabetes, and emphasize the limitations of Caucasian Euro-American classifications of the disease, (AU)

A serological evaluation of an immunization programme in Salt Cay, Turks and Caicos Islands

A serological survey in Salt Cay, Turks and Caicos Islands, British West Indies, suggested that immunization against poliomyelitis carried out since 1971 had been unexpectedly ineffective. Immunity as judged by antitoxin levels was satisfactory for tetanus but poor for diptheria. The value of serological studies in the evaluation of immunization programmes is demonstrated. Effective evaluation of a vaccination programme must involve accurate vaccination records and continuous surveillance of disease incidence, cold chain adequacy, and vaccine delivery to susceptible groups (AU)

A malaria outbreak due to Plasmodium malariae on the island of Grenada

An outbreak of Plasmodium malariae malaria occurred in Grenada some 16 years after the end of the malaria eradication campaign, probably due to renewal of transmission from recrudescent cases. Serological studies were used in addition to blood film surveys in defining the outbreak, and their value in such surveillance situations is emphasised (AU)

Serological and clinical evidence of toxoplasmosis in the Upper Leeward Islands

Toxoplasma infections are common on the Upper Leeward Islands (Saba, St. Maarten and St. Eustatius, Neth. Antilles) as proved by clinical evidence and serological determinants in patients and in healthy people. In schoolchildren an overall positive percentage of 45.5 percent was found. On St. Eustatius the highest frequency of recent infections was in the youngest age groups, in contrast with findings in the Netherlands and in Germany (AU)

Application of the enzyme linked immunosorbent assay (ELISA) for the serodiagnosis of Schistosoma mansoni infections in St. Lucia

As part of our search for a serodiagnostic assay to replace the expensive and tedious stool examination in the diagnosis of Schistosoma mansoni infection, we have studied the sensitivity, specificity and quantative features of an enzyme linked immunoassay (ELISA) using crude S. mansoni egg antigen preparation. Results of studies carried out in both London and St. Lucia indicate that the assay can give useful serodiagnostic information ranging from 82 to 99.5 percent sensitivity, depending on the level of infection intensity and method of blood collection and 100 percent specificity in St. Lucian/St. Vincent populations. The St. Lucia study also showed that the assay could be operated in a qualitative form in an endemic area (AU)

Leptospirosis in patients from Grenada, West Indies

Evidence of leptospirosis in humans from Grenada, W.I., is reported here for the first time. Of 139 hospital patients with pyrexia of undetermined origin, 94 were jaundiced, and 16 (17 percent) of these were positive for hepatitis B antigen (HBsAg) and not examined further. 20 of the remaining 123 (16 percent) febrile patients were positive for leptospiral antibodies; 11 of them were current or recent cases. 25 of 182 (14 percent) afebrile out-patients showed evidence of previous exposure to leptospiral organisms. The most frequently encountered serogroups in the 45 seropositive in- and out- patients were Icterohaemorrhagiae (38 percent) Panama (24 percent) and Canicola (11 percent) (Summary)

Immune response during human schistosomiasis mansoni. II. Occurrence of eosinophil-dependent cytotoxic antibodies in relation to intensity and duration of infection

Plasma samples from St. Lucians were tested for the presence of antibodies which cooperate in vitro with normal human luekocytes in causing cytotoxic damage to schistosomula of Schistosoma mansoni. The in vitro antibody activity, which has been previosly shown to depend on eosinophil effector cells was detected in 56 percent of the individuals with known, current S. mansoni infections and in 14 percent of control subjects from the same endemic area. Quantitatively, eosinophil dependent cytoxic antibody (EDCA) activity, when expressed as the maximum amount of damage to schistosomula induced at high plasma concentration, correlated significantly with the intensity of S.mansoni infection as detemined by fecal egg count, the highest levels of activity occuring in patients with stool counts of 60 eggs/ml or greater. In addition, plasma ECDA activity was found to correlate with the in vitro blastogenic responsiveness of patients' lympjocytes to three different parasite antigen preparations. In contrast, titrations of ECDA activity failed to reveal a relationship between ECDA titer and the most recent egg count performned on each subjects. However, a significant correlation was observed when titers were compared to egg counts averaged over a 3-year period. Neither maximal ECDA activity nor titer was found to correlate with the duration of known schistosome infection (AU)

Simultaneous vaccination against cholera and yellow fever

A study of serum-samples from immunised individuals showed that administration of yellow-fever and cholera vaccine, simultaneously or one to three weeks apart, reduced the vibriocidal and yellow-fever-virus-neutralising antibody titres (AU)

Relationship of acute rheumatic fever to acute glomerulonephritis in Trinidad

The incidence of acute rheumatic fever decreased during a major epidemic of acute glomerulonephritis in Trinidad in 1965. Subsequently, several minor increases in the incidence of acute rheumatic fever have been coincident with more marked increases in the incidence of acute glomerulonephritis. The relation of streptococcal infections to acute glomerulonephritis has been studied in Trinidad for the past six years. Their relation to acute rheumatic fever also has been examined during the last year of these studies. The streptococcal strains isolated from patients with acute rheumatic fever generally have differed from those found in patients with acute glomerulonephritis. Moreover, while streptococcal skin infections have been associated with acute glomerulonephritis, no such association has been apparent with rheumatic fever. However, titers of antistreptolysin O were relatively low, while titers of antihyaluronidase were makedly increased in the patients with acute rheumatic fever, much as they have been in most patients with acute glomerulonephritis in Trinidad (AU)

Studies of Patois group arboviruses in Mexico, Guatemala, Honduras, and British Honduras

Patois, Zegla, and Shark River-like arboviruses in the Patois group were isolaed in Mexico, Guatemala, Honduras, and British Honduras during 1963 to 1968. Twenty-three Patois viruses came from mosquitoes, sentinel hamsters, and suckling mice, 21 Zegla viruses from sentinel hamsters and mice and from a wild cotton rat, and two Shark River-like viruses from sentinel hamsters. Hemagglutination-inhibition(HI) and neutralizing antibody tests with Patois virus were positive with human sera from each country, and HI antibody tests were positive with sera from pigs in Mexico, Guatemala, and British Honduras and from small wild mammals, wild birds, and cattle in Mexico.(AU)