South African Eye Study (SAES): ethnic differences in central corneal thickness and intraocular pressure.

PurposeGlaucoma is the leading cause of irreversible blindness worldwide. South Africa has a diverse population but there is a lack of published ethnic specific normative data. The purpose of the study is to determine the distribution of intraocular pressure (IOP) and central corneal thickness (CCT) values in a multi-ethnic South African population and to determine additional systemic and ocular factors that influence IOP and CCT.Patients and methodsThis cross-sectional study included a total of 402 participants with 706 eyes aged 18-94 years. Participants underwent a standardized interviewer-administered questionnaire for risk factor assessment followed by a full ophthalmic examination. The averages of six IOP readings were measured with an Icare PRO tonometer and CCT was measured with a Pentacam.ResultsThe mean CCT readings in the African, Mixed ethnicity, and Caucasian participants were 514.77±31.86, 531.77±35.17, and 549.97±30.51 µm (P<0.001). The mean IOP in the African, Mixed ethnicity, and Caucasian participants were 15.51±2.49, 15.09±2.12, and 15.13±2.53 mm Hg (P=0.07). Africans had significantly higher IOP than Mixed ethnicity (P=0.034) and Caucasians (P=0.011). Hypertensives had a higher IOP (P=0.03). Age and pseudophakia were associated with a lower IOP (P<0.001) and higher CCT (P<0.001). There was a strongly positive correlation between CCT and IOP (ß=0.021; P<0.001).ConclusionsIn the South African Eye Study (SAES), Africans had the thinnest corneas and highest IOP followed by Mixed ethnicity and Caucasians. Including systemic and ocular factors that influence IOP specific to each population and ethnic group, will lead to a more accurate clinical risk stratification in glaucoma management.

Lymphatic filariasis in the Caribbean region: the opportunity for its elimination and certification.

In order to support the case for a certification of elimination of lymphatic filariasis (LF) in some Caribbean countries, we compared the prevalence of circulating Wuchereria bancrofti antigen in communities in Guyana, Suriname, and Trinidad. For the study, we assayed school children in six communities in Guyana, five communities in Suriname, and three communities in Trinidad for the prevalence of circulating W. bancrofti antigen, using a new immunochromatographic test for LF. We also assayed adults in these three countries, with a special focus on Blanchisseuse, Trinidad, where mass treatment for LF elimination had been carried out in 1981. The prevalences of W. bancrofti circulating antigen found in the school children populations ranged from 1.7% to 33.2% in Guyana and were 0.22% overall in Suriname and 0.0% in Trinidad. Among adults in two Guyana communities the prevalences were 16.7% and 32.1%. The results were all negative from 211 adults in communities in the north, center, and south of Trinidad, as well as from 29 adults in Suriname. The data suggest that contrary to reports of LF endemicity from the World Health Organization, LF may no longer be present in Trinidad and may be of very low prevalence in Suriname. Trinidad and Tobago and other Caribbean nations proven negative could seek to be awarded a certificate of LF elimination. In Suriname the small localized pocket of infected persons who may serve as a reservoir of LF infection could be tested and appropriately treated to achieve LF elimination. Such LF-positive countries as Guyana should access new international resources being made available for LF elimination efforts. An adequate certification program would help identify which countries should seek the new LF elimination resources.

Seroprevalence of Toxocara infections in children in Trinidad: effects of infection on cognitive skills

OBJECTIVE: To determine the seroprevalence of Toxocara infections and their effects on cognitive skills in children. DESIGN AND METHODS: Serum specimens from 1009 students from 27 primary schools in Trinidad were tested by the ELISA method for the presence of antibodies to Toxocara using an excretory-secretory antigen. Students having a titre of > or = 1:800 as well as matched controls were administered with the school achievement test to measure cognitive skills. Relationships between seroloprevalence and host factors were explored using information obtained via a questionnaire. RESULTS: Overall seroprevalence was 62.3 percent while prevalence indicative of current or recent infection (> or = 1:800) was 27.2 percent. There was no significant relationship between age and the presence of infection. Males were significantly more commonly infected than females as were attendees of rural schools. Pet ownership and the absence of pipe-borne water in the house were significantly associated with positive serology (P<0.05). Measurement of cognitive skills by the school achievement test showed that children with positive serology had lower scores (P<0.001) than age- and sex-matched controls with negative serology. CONCLUSION: The high level of infection indicated by earlier though limited studies in Trinidad was confirmed. It is recommended that the public should be educated on the transmission of disease and all dogs and cats should be periodically dewormed and environmental sanitation measures should include children away from contaminated areas.(AU)

A longitudinal study of the persence of gastrointestinal tract parasitic infections in children of St. Kitts over the 15-year period, 1982-1997

When 188 (1962), 266 (1991) and 222 (1997) five and nine year old children in St. Kitts were assessed for the presence of parasitic infections, there were significant reductions in the prevalence of trichurias from 83 percent through 58 percent to 27 percent, of ascariasis from 24 percent through 8.6 percent to 0.9 percent and of giardiasis from 15 percent through 9.4 percent to 5 percent, respectively; over the 15 year period. Anthelminthic use, which appeared to be the most important responsible intervention tool, remained roughly at the same level at 59-51 percent. However, the types of anthelminthics used changed over the period. Piperazine citrate, which was used by 66 percent in 1982, had only 35 percent usage in 1991 and 11.3 percent in 1197. Albendazole, which was not used at all in 1982, was taken by 32 percent of the children in 1991 and 45.9 percent in 1997, and at the same time use of laevo-tetramisole increase by 20 percent in 1991 from 14 percent in 1982, to 42.9 percent in 1997. Details are given of a proposed island-wide parasitic infection with the assistance of identified private and public sector partners.(AU)

Features of toxoplasmosis in the Caribbean - abstract

In 1995 and 1996, 7.5 percent of 321 serum samples (IgM) and 48.0 percent of 352 serujm samples (IgG) assayed for antibiotics at CAREC, were positive for exposure to Toxoplasma. IgM antibodies were not detected in the first 6 months of life, but thereafter levels rose to peak (27.3 percent) in the >6 month - 10 year age group. IgG rose from 16.7 percent in the youngest to 62 percent in the adult age group. Symptoms most commonly associated with positive IgMs were lymphadenopathy (20.8 percent) > eye disease (11.8 percent) > congenital events (7.7 percent). IgG antibodies were associated with eye diseases (53.5 percent) > congenital manifestation (50.0 percent) > missed abortions(41.0 percent) >lymphadenopathy (36.0 percent) > perinatal events (27.8 percent) > central nervous systems symptoms (21.1 percent). IgM determinants were more commonly obtained in sera from Suriname (7.7 percent) > Barbados (7.4 percent) > St. Lucia (4.2 percent). For IgGs the order was Grenada (66.7 percent) > St Lucia (61.1 percent) > St. Vincent (50.0 percent) > Barbados (47.8 percent) >Suriname (46.2 percent). (AU)

Pulmonary pathogens in induced sputum in persons with Human Immunodeficiency Virus (HIV) in Trinidad

A study was undertaken to identify the common micro-organisms occuring in induced sputum specimens from HIV-infected/non-infected individuals with pulmonary manifestations in Trinidad. Only 13 percent of HIV seropositive patients with pneumonia were found to be positive for P. carinii. This low yield may have been due to low prevalence of the P. carinii in Trinidad or to prior antibiotic therapy. Active mycobacterial infection was demonstrated in only 13 percent HIV seropositive patients with pneumonia, though 43 percent HIV patients had a clinical diagnosis of tuberculosis. This may have been due to the low sensitivity of the acid-fast technique. The most common microbial pathogen is identified in HIV patients with pneumonia was Candida sp. Followed by gram negative bacteria. A listing is made of the various organisms occuring singly or mixed in HIV seropositive and HIV seronegative patients (AU)

Cryptosporidiosis in some Caribbean children and an evaluation of the efficacy of tests used for its laboratory diagnosis

Clinical data and samples of diarrhoeal stools were taken from 160 paediatric patients at the Port-of-Spain General Hospital (POSGH), Trinidad (120), and the University Hospital of the West Indies, Jamaica (40). Of the 33 patients found to be Cryptosporidium-positive, diarrhoea, fever, vomiting and abdominal pain were the main presenting features. The mean age of positive patients was 4.0 ñ 4.03 years and the average duration of symptoms was 5.3 ñ 6.9 days with a mean of 7.1 ñ 3.7 bowel motions per day. In the laboratory there was a 20.6 percent Cryptosporidium-positive rate by the ELISA technique, while the Ziehl Neilson (ZN) preparation only gave a 1.25 percent, and the wet preparation a 0 percent rate. The unit costs of the tests were as follows: ELISA (US $7.00), ZN (US$2.00), Wet preparation (US$ 1.00). The high level of specificity and sensitivity recommends the ELISA technique above the other methods (AU)

"New protozoal parasites" Causing diarrhoeal syndrome in humans

This article will serve as a medium to sensitize laboratory and medical personnel that these parasites do exist and that several diagnostic methods are presently available (at CAREC) for their detection(AU)

Microscopical and serological diagnosis of Wuchereria bancrofti.

Venous blood from 292 patients attending a Filaria Clinic in Georgetown, Guyana, was assayed by ELISA for IgG and IgM antibodies and by Indirect Haemagglutination Antibody Assay (IHA) against filaria parasites. They were also assayed by microscopic methods before and after concentration procedures for microfilaraemia. Of the 41 blood samples microscopically positive for Wuchereria bancrofti microfilariae, 87.8% (ELISA IgG), 65.9% (ELISA IgM) and 73.2% (IHA) occurred in samples with sub-diagnostic serological threshold titres of < 1:32 (IgG and IgM) and < 1:128 (IHA). But indicators of value based on the standards of the presence of chronic and acute symptoms, the IgG and IgM diagnostic data gave 79.9% sensitivity, 96.4% specificity, 97.1% positive predictable value and 44.3% negative predictive value. A membrane filtration system (92.7%) was slightly better than a centrifugation technique (90.2%), but more efficient than a thick smear preparation (75.6%) for the detection of microfilariae. The filtration system was vastly superior for yields of microfilariae. However, the Knott's concentration (sedimentation) was the most economical in terms of technician time and materials. Most microscopically confirmed filaria cases were in the 20-29-year age group (25%), followed by the broad 30-69-year age groups (10-12%). Males were significantly more commonly affected by the ratio 24.2:6.0. It is recommended that skills and materials for concentration of microfilariae from peripheral blood be maintained in all Caribbean countries. In known filaria endemic countries, it is recommended that the serological tool be used as an aid in diagnosis for patients with acute and chronic symptoms.

Microscopical and serological diagnosis of wuchereria bancrofti

Venous blood from 292 patients attending a Filaria Clinic in Georgetown, Guyana, was assayed by ELISA for IgG and IgM antibodies and by Indirect Haemagglutination Antibody Assay (IHA) against filaria parasites. They were also assayed by microscopic methods before and after concentration procedures for microfilaraemia. Of the 41 blood samples microscopically positive for Wuchereria bancrofti microfilfariae, 87.8 percent (ELISA IgG), 65.9 percent (ELISA IgM) and 73.2 percent (IHA) occurred in samples with subdiagnostic serological threshold titres of<1:32 (IgG and IgM) and <1:128(IHA). But indicators of value based on the standards of the presence of chronic and acute symptoms, the IgG and IgM diagnostic data gave 79.9 percent sensitivity, 96.4 percent specificity, 97.1 percent positive predictable value and 44.3 percent negative predictive value. A membrane filtration system (92.7 percent) was slightly better than a centrifugation technique (90.2 percent), but more efficient than a thick smear preparation (75.6 percent) for the detection of microfilariae. The filtration system was vastly supeior for yields of microfilariae. However, the Knott's concentration (sedimentation) was the most economical in terms of technical time and materials. Most microscopically confirmed filaria cases were in the 20 - 29-year age group (25 percent), followed by the broad 30--69-year age groups (10-12 percent). Males were significantly more commonly affected by the ratio 24.2:6.0. It is recommended that skills and materials for concentration of microfilariae from peripheral blood be maintained in all Caribbean countries. In known filaria endemic countries, it is recommended that the serological tool be used as an aid in diagnosis for patients with acute and chronic symptoms. (AU)

Microscopical and serological diagnosis of wuchereria bancrofti

Venous blood from 292 patients attending a Filaria Clinic in Georgetown, Guyana, was assayed by ELISA for IgG and IgM antibodies and by Indirect Haemagglutination Antibody Assay (IHA) against filaria parasites. They were also assayed by microscopic methods before and after concentration procedures for microfilaraemia. Of the 41 blood samples microscopically positive for Wuchereria bancrofti microfilfariae, 87.8//(ELISA IgG), 65.9//(ELISA IgM) and 73.2//(IHA) occurred in samples with subdiagnostic serological threshold titres of<1:32 (IgG and IgM) and <1:128(IHA). But indicators of value based on the standards of the presence of chronic and acute symptoms, the IgG and IgM diagnostic data gave 79.9//sensitivity, 96.4//specificity, 97.1//positive predictable value and 44.3//negative predictive value. A membrane filtration system (92.7//) was slightly better than a centrifugation technique (90.2//), but more efficient than a thick smear preparation (75.6//) for the detection of microfilariae. The filtration system was vastly superior for yields of microfilariae. However, the Knott's concentration (sedimentation) was the most economical in terms of technical time and materials. Most microscopically confirmed filaria cases were in the 20 - 29-year age group (25//), followed by the broad 30--69-year age groups (10-12//). Males were significantly more commonly affected by the ratio 24.2:6.0. It is recommended that skills and materials for concentration of microfilariae from peripheral blood be maintained in all Caribbean countries. In known filaria endemic countries, it is recommended that the serological tool be used as an aid in diagnosis for patients with acute and chronic symptoms

Seroprevalence of toxocara infections in schoolchildren in the Eastern Caribbean - abstract

Very little is known about the prevalence of Toxocara infections in the Eastern Caribbean. The development of the enzyme-linked immunosorbent assay (ELISA) has proved to be of great value in assisting clinicians in diagnosing toxocariasis and has been a useful tool in the study of the prevalence of toxocariasis. We have used ELISA to study the prevalence of toxocariasis in six countries of the Eastern Caribbean. The secretory-excretory antigen and reference sera for the assay were obtained from the University of Toronto. Test sera were collected from school children aged 5 years and 9 years from Antigua, Montserrat, Dominica, St. Vincent, St. Christopher-Nevis and Grenada. These sera were collected for polio antibody prevalence surveys and were stored in our serum bank. Sera with a titre of 100 or more were considered positive for Toxocara. Overall prevalence rates were: Antigua - 38.8 percent (n=322), Montserrat - 47.4 percent (n=228), Dominica - 59.9 percent (n=157), St. Vincent - 63.2 percent (n=285), St. Christopher-Nevis - 66.1 percent (n=168) and Grenada - 78.0 percent (n=387). Although antibody prevalence was high, no full-blown cases of visceral larva migrans have been reported in these countries. The public health significance of these findings is unclear (AU)

Evaluation of methods for the laboratory diagnosis of malaria in Guyana.

When 297 blood samples taken from patients attending a fever clinic in Georgetown Public Hospital were examined microscopically, after thick and thin blood films had been stained with Giemsa, one hundred and forty-two (47.8%) were microscopically positive for malaria. After processing the patient's serum, samples by the Indirect Fluorescent Antibody (IFA) technique, specific IgG and IgM antibodies were detected in 239 (81.3%) and 179 (60.1%), respectively, of the sera. Based on the microscopical findings, the IFAT gave positive predictive and negative values of 54.4% and 81.8% (IgG), and 57.5% and 67.8% (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 were not. The microscopical method will continue to be the gold standard-the best available criterion for the validation of our tests-for diagnosis of acute malaria.

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)

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 per cent ) 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 per cent ) and 179 (60.1 per cent ), respectively, of the sera. Based on the microscopical findings, the IFAT gave positive and negative values of 54.4 per cent and 81.8 per cent (IgG), and 57.5 per cent and 67.8 per cent (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.

A comparative study of available diagnostic tools for lymphatic filariasis - abstract

Venous blood from 300 patients attending a filaria clinic in Georgetown, Guyana, was taken and assayed by ELISA for IgG and IgM antibodies against filaria parasites, and by microscopic methods before and after concentration procedures for microfilaraemia. Negative serum titres (<1:32) of IgG and IgM coincided with 90 per cent and 65 per cent, respectively, of positive microscopy. A membrane filtration system (95 per cent) was slightly better than a centrifugation (92.5 per cent) technique, but significantly more efficient than a thick smear preparation (75 per cent) for the detection of microfilaraemia. The filtration system was vastly superior for yields of microfilaria. However, the Knott's concentration (sedimentation) was the most economical in terms of technician time and materials. Most microscopically confirmed filaria cases were in the 20 - 29 year-age group (25 per cent), followed by the broad 30 - 69 year-age group (10 - 12 per cent). Males were more commonly affected by the ratio of 2.6 : 1. Symptoms included swollen limbs, tenderness, fever, swollen glands, headache and joint pains but 17 (42.5 per cent) patients were asymptomatic (AU)

Significant changes in gastrointestinal tract parasitic infections in children of St. Kitts over the 9-year period 1982-1991.

When 239 (1982) and 361 (1991) five- and nine-year-old children in St. Kitts were assessed for the presence of parasitic infections, there were significant reductions in the prevalence of trichuriasis from 83% to 58%, of ascariasis from 24% to 8.6% and of giardiasis from 15% to 9.4%. Anthelminthic use, which appeared to be the most important responsible intervention tool, remained roughly at the same level at 59-51%. However, the types of anthelminthics used changed over the period. Piperazine citrate, which was used by 66% in 1982, only had 35% usage in 1991. Albendazole which was not used at all in 1982 was taken by 32% of the children in 1991 and at the same time use of laevo-tetramisole increased by 20% from 14%. Suggestions are made for an island-wide mass intervention programme to manage parasitic infections.

Significant changes in gastrointestinal tract parasitic infections in children of St. Kitts over the 9-year period 1982-1991

When 239 (1982) and 361 (1991) five-year and nine-year-old children in St. Kitts were assessed for the presence of parasitic infections, there were significant reductions in the prevalence of trichuriasis from 83 percent to 58 percent, of ascariasis from 24 percent to 8.6 percent and of giardiasis from 15 percent to 9 percent. Anthelminthic use, which appeared to be the most important responsible intervention tool, remained roughly at the same level at 59-51 percent. However, the types of anthelminthics used changed over the period. Pizerazine citrate, which was by 66 percent in 1982, only had 35 percent usuage in 1991. Albendazole which was not used at all in 1982 was taken by 32 percent of the children in 1991 and at the same time the use of laevo-tetramisole increased by 20 percent from 14 percent. Suggestions are made for an island-wide mass intervention programme to manage parasitic infections. (AU)