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.

Detection of red blood cell antibodies using bacterial antiglobulins: a new assay [abstract]

OBJECTIVE: To develop an agglutination technique using Staphylococcal protein A (SpA) and Steptococcalprotein G (SpG) to detect human red blood cell antibodies. METHODS: Blood samples were obtained from the National Transfusion Service of Jamaica. SpA, SpG, and anti-IgG, -C3d were commercial preparations. SpA and ApG were incubated with sensitized human red blood cells (RBC) to assess their RBC agglutinating capacity. The Ouchterlony technique was used to determine binding between the bacterial antigens and the IgG in human serum. Polyethyleneglycol (PEG) was used as an agglutination enhancer. Agglutination techniques for a large number of samples were developed, using 96 percent well polystyrene microplates and a microscope for visualizing the agglutination techniques to detect human anti-RBC IgG was compared with the traditional Coombs' test. Sensitivity and specificity were determined. RESULTS: SpA and SpG did not appear to cause agglutination of the red cells sensitized in vivo and in vitro. However, no precipitation bands were formed between human serum and the supernatant obtained after reaction of the sensitized RBC with SpA and SpG (Ouchterlony technique). These results indicated that indeed there was binding of SpA and SpG with the sensitized cells since they were not available for binding with human serum. In additon, SpA and SpG agglutinated the sensitized red blood cells in the presence of the PEG. When compared to the Coombs' test, the following results were obtained with new techniques. For the direct method, sensitivity was 93.8 percent and 95.1 percent for SpA and SpG respectively (n= 81), and specificity was 91.4 percent and 93.5 percent for SpA and SpG, respectivley (n= 93). For the indirect method, sensitivity was 96.3 percent and 97.5 percent for SPA and SpG, respectively (n= 81) and its specificity was 100 percent for both proteins (n= 85). CONCLUSION: Agglutination techniques using SpA and SpG constitute alternative and feasible tests for the detection of human red blood cell antibodies. (AU)

Chlamydia trachomatis antibody and DNA determination in ectopic pregnancy in Trinidad

OBJECTIVE: To determine the prevalence of C. trachomatis in ectopic pregnancy by serum IgG and IgM antibody and by chlamydia DNA in endometrial, Fallopian tube and ovarian tissues. DESIGN AND METHODS: A cross-sectional study included 32 women presenting with tubal ectopic pregnancy and 94 fertile controls. Methods employed were ELISA for IgG and IgM and Polymerase Chain Reaction (PCR) and in situ hybridization (ISH) for DNA. RESULTS: Chlamydial IgG and IgM antibody detection was higher in the ectopic than the control groups (IgG, p<0.01; IgM, p<0.01). A similar finding was also noted for chlamydia DNA by PCR (p<0.05). DNA detection was also significantly higher at each site in the upper genital tract (endometrium p<0.01, Fallopian tube p<0.05, ovary p<0.05). CONCLUSION: By antibody detection, this study confirms the role played by genital tract C. trachoma infection and subsequently ectopic pregnancy, but more importantly, identifies chlamydial DNA in upper genital tract tissues. These results support allocation of resources towards screening programmes for C. trachomatis.(Au)

Evaluation of the MRL diagnostics dengue fever virus IgM capture ELISA and the PanBio Rapid Immunochromatographic Test for diagnosis of dengue fever in Jamaica

We evaluated two new commercial dengue diagnostic tests, the MRL Diagnostics Dengue Fever Virus IgM Capture ELISA and the PanBio Rapid Immunochromatographic Test, on serum samples collected during a dengue epidemic in Jamaica. The MRL ELISA method correctly identified 96 percent (78 of 80) of the samples as dengue positive, while the PanBio test identified 100 percent (80 of 80). Both tests were 100 percent (20 samples of 20) specific.(Au)

Diagnosis and treatment of Helicobacter pylori in Guyana - abstract

This study was designed to assess usefulness of an HP, igG serum blot immunoassay, "Flex-sure test" (F/S) in accurately guiding treatment of HP infection, to compare metronidazole 500mg bd, omeprazole 20 mg bd and clarithromycin 500 mg bd orally (MOC); and amoxicillin 500 mg bd, omeprazole 20 mg bd and clarithromycin 500 mg bd orally (AOC) for 10 days, ineradicating HP 115 of 322 patients with moderate to severe dyspeptic symptoms who were screen with the F/S test were positive and were randomly assigned to 2 treatment regimes. C14 breadth test (B/T) was performed to confirm infection at the start of the treatment, 4 weeks and 6 months after the treatment. 12/115 patient (10.4 percent) were withdrawn from the study after three confirmatory B/T were negative. 6/115 patients (5.2 percent) did not return for treatment. Ninety-seven (97) F/S and B/T positive patients were treated and followed up for 6 months. The most significant symptomatic relief occurred at the first month post-treatment. Bitterness, headache, nausea and diarrhea were the major symptoms experienced. The recurrent rate of HP at 6 months was 2/97 (2 percent). We conclude that F/S assay is a good and fairly accurate screen to commence primary therapy and that MOC and AOC are equally effective in eradicating HP after 10 days of oral theraphy with low recurrence at 6 months. (AU)

Short report: long-term serum antibody isotype responses to Strongyloides stercoralis filariform antigens in eight patients treated with ivermectin

The enzyme-linked immunosorbant assay was used to investigate long term changes in serum immunoglobulin G1 (IgG1), IgG4, IgE, and IgA against Strongyloides stercoralis phosphate-buffered saline-soluble filariform larval antigens in eight Jamaican patients treated with ivermectin. Patients were followed for periods of between 170 and 542 days. Based on repeated formalin-ether concentration and agar plate culture, all patients were found to be uninfected up to 18 months following chemotherapy. Generally, all antibody isotype levels decreased following treatment, although there was considerable heterogeneity among patients. In a single patient with hyperinfection, the decrease in IgG4 was marginal and may represent a treatment failure. Reduction in serum antibody isotype responses to S. stercoralis following treatment may be used to assess the effectiveness of ivermectin in treating endemic strongyloides (AU)

Anterior horn cell degeneration in polymyositis associated with human T lymphotropic virus Type-1 in patients from Barbados

Anterior horn cell degeneration has only ocassionally been noted in patients with tropical spastic paraparesis associated with human T lymphotropic virus type-1 (HTLV-1) infection. We report on three adult patients with HTLV-1-associated polymyositis who had clinical evidence of anterior horn cell degeneration. One patient had moderate proximal weakness and muscle wasting in all four limbs, while two had mild upper limb weakness with more profound proximal weakness and wasting in the lower limbs. In all three patients, elctromyographic findings were compatible with motor unit loss and muscle biopsies showed mononuclear inflammatory cell infiltration; muscle cell biopsies in two patients showed features of denervation. Immunoglobulin G (IgG) antibodies to HTLV-1 were detected by enzyme-linked immunosorbent assay (ELISA) and confirmed by Western immunoblot in serum and cerobrospinal fluid in all three patients. In two, cell cultures were established from peripheral blood lymphocytes and HTLV-1 antigen was identified by immunofluorescence and the ELISA antigen-capture technique using an anti-p19 HTLV-1 mouse monoclonal antibody. The three cases illustrate the variety of neuromuscular disease, other than spastic paraparesis, that may occur in HTLV-1 infection. In some cases of HTLV-1-associated polymyositis, anterior horn cell degeneration may make a significant contribution to the muscle atrophy observed. (AU)

Retroviruses and schizophrenia in Jamaica

Reports of an 18-fold higher incidence of schizophrenia among second-generation Afro-Caribbeans, and especially Jamaican migrants in the United Kingdom were soon called an epidemic of schizophrenia, with the inference that a novel virus, likely to be perinatally transmitted, was a possible etiological agent. This intriguing observation led us to explore a possible link with human T-cell lympotropic virus type one (HTLV-I), because it is a virus that is endemic in the Caribbean Island, is perinatally transmitted, known to be neuropathogenic, and the cause of a chronic myelopathy tropical spastic paraparesis/HTLV-I associated myelopathy. We therefore examined inpatients as the Bellevue Mental Hospital, Kingston, Jamaica and did standard serological tests for retroviruses HTLV-I and HTLV-II and HIV-I and HIV-II on 201 inpatients who fulfilled ICD-9 and DSM II-R criteria for schizophrenia. Our results produced important negative data, since the seropositivity rates for HTLV-I, the most likely pathogen, were no greater than the seropositivity range for HTLV-I carriers in this island population, indicating the HTLV-I and the other retroviruses tested do not play a primary etiological role in Jamaican schizophrenics(AU)

Human T cell lymphotropic virus (HTLV-1): cutaneous manifestations

Skin manifestations are a common feature of HTLV-1 associated disorders and of HTLV-1 infection itself. These include the lymphomatous skin infiltrates in adult T-cell lymphoma/leukaemia, most commonly manifesting as persistent, generalised papules, nodules and plaques with later ulceration, acquired ichthyosis and xeroderma in HAM/TSP, infective dermatitis of children, dermatomyositis, crusted (Norwegian) scabies, psoriasiform rashes which may precede one of the more serious disease associations, and possibly also seborrhoeic dermatitis. Disorders typically associated with immunosuppression such as disseminated herpes zoster, and ulcerative non-healing herpes simplex may also be seen occasionally both in ATK as well as in other wise asymptomatic HTLV-1 infection (AU)

Strongyloides stercoralis: characterization of immunodiagnostic larval antigens

Forty-one-, 31-, and 28-kDa proteins of strongyloides stercoralis filariform larvae have previously been demonstrated to be sensitively and specifically recognized by serum IgG in individuals with strongyloidiasis. Characteristics of these proteins, their immunodominant epitopes, and reactive antibodies are described here. The proteins are soluble is aqueous as well as detergent extracts. The immunodominant epitopes are present in S. stercoralis but not in S. cebus or S. ratti. Epitopes on the three proteins are not shared, as determined by cross-absorption of serum with each of the size components on nitrocellulose. In most sera from strongyloidiasis patients there was reactivity to each of the proteins by IgG1 and IgG4, but reactivity by IgG2 or IgG3 was detectable only in a minority. A rabbit antiserum raised to a 41-kDa size fraction of S. stercoralis larvae reacted against a doublet of 41-kDa which was distinct from the immunodiagnostic 41-kDa protein.(AU)

Prospective evaluation of enzyme-linked immunosorbent assay and immunoblot methods for the diagnosis of endemic Strongyloides stercoralis infection

Recently described enzyme-linked immunosorbent assay (ELISA) and immunoblot methods for the detection of serum IgG against Strongyloides stercoralis larval antigens were prospectively evaluated for the diagnosis of endemic strongyloidiasis. A modification of the ELISA involved preincubation of sera with Onchocerca gutturosa phosphate-buffered saline-soluble extract to remove cross-reactivity with other helminths. The sensitivity of the ELISA increased from 80 percent and 85 percent following preincubation. Similarly, there was an increase in specifity from 94 percent to 97 percent. The IgG recognition of 41-, 31-, and 28-kD filariform larval components showed sensitivities of 100 percent, 85 percent and 65 percent, respectively. Both the ELISA following incubation of sera with O. gutturosa extract and serum IgG reactivity to a 41-kD larval component using immunoblotting are sensitive and specific techniques for diagnosing endemic strongyloidiasis.(AU)

Serum IgG reactivity with 41-, 31- and 28-kDa larval proteins of Strongyloides stercoralis in individuals with strongyloidiasis

Proteins from a deoxycholate-soluble extract of Strongyloides stercoralis infective larvae were separated by SDS-PAGE, blotting onto nitrocellulose paper, and reacted with sera from individuals with confirmed S. stercoralis infections (n = 100), suspectedS. stercoralis infections in whom no larvae could be detected (n = 27), and other nematode infections (40 with Wuchereria bancrofti, 20 with Onchocerca volvulus, 20 with Necator americanus, and 20 with mixed Ascaris lumbricoides and Trichuris trichiura infections). Immunodominant proteins of approximately 41, 31, and 28 kDa were recongnized by IgG in 91 percent, 88 percent and 90 percent respectively, of sera from those with confirmed strongyloidiasis; in 100 percent, 100 percent, and 93 percent of sera from those with suspected strongyloidiasis; and in 9 percent, 12 percent and 14 percent of sera from those infected with other nematodes. IgG reactivity to each of these proteins was a more specific means of immunodiagnosis than the currently use indirect ELISA; the methods were equally sensitive.(AU)

Evaluation of methods for the laboratory diagnosis of malaria in Guyana

When 297 blood samples taken from patients attending a fever clinic in Georgetowm Public Hospital were examined microscopically, after thick and thin blood films had been stained with Giemsa, one hundred and forty-two (47.8 percent) were microscopically positive for malaria. After processing the patients' serum samples by the Indirect Fluourescent Antibody (IFA) technique, specific IgG and IgM antibodies were detected in 239 (81.3 percent) and 179 (60.1 percent), respectively, of the sera. Based on the microscopical findings, the IFAT gave positive and negative values of 54.4 percent and 81.8 percent (IgG), and 57.5 percent and 67.8 percent (IgM), suggesting that the IgM would be more useful than the IgG in the diagnosis of current malaria. An odds ratio analysis showed that the presence of symptoms, IgG or IgM antibodies, as well as visits to endemic regions, could be good indicators of current malaria. Age and occupation are not. The microscopical method will continue to be the gold standard - the best available criterion for the validation of our tests - for our diagnosis of acute malaria. (AU)

Human parvovirus infection in homozygous sickle cell disease

We studied the epidemiology of human parvovirus B19 infection in 308 children with homozygous sickle cell (SS) disease and 239 controls with a normal haemoglobin (AA) genotype followed from birth in a cohort study. Annual serum samples identified the time and frequency of B19 infection, which did not differ between SS and AA children, about 40 percent of each age group developing specific IgG by age 15. B19 infection followed an epidemic pattern similar to that observed for aplastic crises; accounted for all 91 aplastic crises that occurred; and was found in an additional 23 SS patients, of whom 10 showed mild haematological changes and 13 no changes. The magnitude or duration of IgG response did not differ between these groups. No patient had 2 attacks of aplasia and no patient nor control had 2 attacks of B19 infection. Following B19 infection, serial specific IgG concentrations remained high after 5 years in only 45 percent of SS patients, although the rarity of recurrent aplasia suggests lifelong immunity. B19 infection accounts for most if not all aplastic crises in SS disease, but at least 20 percent of infections do not result in aplasia. An effective vaccine against B19 might make an important contribution to the management of sickle cell disease (AU)

The age of infection with varicella-zoster virus in St. Lucia, West Indies

Sera from an age-stratified sample of 1810 people from the Caribbean island of St. Lucia were tested for antibodies against varicella-zoster virus. The results indicate that very few infections occur in childhood which agrees with clinical survey data from other tropical countries, but contrasts with the observed high case rate in children in temperate countries. The alternative hypothesis which may explain these results are discussed, and it is suggested that high ambient tempertaures interfere with the transmission of the virus. Irrespective of the cause the pattern of varicella incidence observed has important implications for any vaccination policy adopted in tropical countries (AU)

Durability of passive measles antibody in Jamaican children

Measles antibody titres were determined by haemagglutination inhibition and by neutralization in 221 sets of serum collected from delivering mothers, umbilical cords, and infants when about six months of age. Radio-immunoassay was also used to measure antibody in 120 sera. Total IgG concentration was determined in the infant sera. All mothers had measles antibody and the mean titre was high. At the time of birth, measles antibody had been further concentrated in the infant. Nevertheless, many children lost protective titres before six months of age. The rate of loss was correlated with the infant's total serum lgG so that high lgG levels at six months correlated with rapid loss of measles-specific antibody. It is suggested that in homes where sanitation is poor, antibody is made to many agents as an early age. To maintain physiological balance, homeostatic mechanisms then increase the rate of catabolism of all lgG, including that passively acquired. In keeping with its stage of sanitary development, vaccination in Jamaica can profitably be given earlier than in the United States, but it must be later than in many African countries. (AU)

Immunological profiles in patients with chronic glomerulonephritis - abstract

The objectives of the study were to determine the humoral and cellular immunological profiles of 14 patients with chronic glomerulonephritis (CGN) who were about to be dialyzed. Fourteen healthy subjects matched for age, sex and ethnic origin served as controls. Serum IgG levels showed no significant difference in the two groups. However, serum IgA levels were elevated (p<0.01) but serum IgM levels were suppressed (p<0.001). Immune complexes (IC) were prepared by the polyethylene glycol 6,000 precipitation method and their immunoglobulin content measured. The IgG and IgM levels in IC were markedly depressed (p<0.001, p<0.001 respectively. IgG subclass determinations showed that IgG1 and IgG3 were essentially the same in patients and controls. The IgG2 level, however, was markedly elevated (p<0.02) in patients. Cellular immune responses to the rheumatogenic M41 and to the nephritogenic M55 cell membrane antigens at 3 concentrations (100, 10, 1 ug/ml) as well as to phytohaemagglutinin (PHA) a non-specific mitogen, were measured. In patients, there was depressed cellular sensitivity to the M55 antigen at all 3 concentrations (p<0.01; p§.05; p<0.05, respectively). This suppression was greatly exaggerated when cellular sensitivity to the M55 antigen at the same 3 concentrations was measured (p<0.001, p<0.001, p<0.001 respectively. Patients and controls showed no difference in their response to PHA. These results suggest that both the cellular and humoral immunological factors play a role in the pathogenesis of chronic renal disease (AU)