African dust clouds are associated with increased paediatric asthma accident and emergency admissions on the Caribbean island of Trinidad

Objective: To determine if there is any association between paediatric Accident & Emergency (A&E) asthma admissions and Saharan dust cloud cover Methods: A retrospective ecological study of paediatric asthma patients who attended the A&E department of the Eric Williams Medical Sciences Complex in relation to Saharan dust visibility andother climactic variables for the period May 23 2001 to May 13 2002. A quasi-likelihood approach was used to develop a statistical model for the relationship between acute paediatric asthma A&Evisits and Saharan dust cover.Results: 2655 A&E visits for acute asthma during the study period. There were significant associations between paediatric admissions and two climate variables; Saharan dust levels (p <0.05)and barometric pressure (p <0.01). In the absence of dust however, barometric pressure by itself hadno predictive power. Dust cover & barometric pressure were most strongly associated with increased admissions the day after dust cover Conclusions: Saharan dust cloud cover over Trinidad was associated with an increase inpaediatric asthma A&E visits on the following day. The dust effect was strongly influenced by prevailing barometric pressure; heavy dust cover and low pressure were most strongly associated with increased acute asthma visits.

African dust clouds are associated with increased paediatric asthma accident and emergency admissions on the Caribbean island of Trinidad.

A retrospective ecological study of paediatric asthma patients who attended the Accident and Emergency (A and E) department of the Paediatric Priority Care Facility at the Eric Williams Medical Sciences Complex in relation to Saharan dust visibility and other climatic variables for the period 23 May 2001 to 13 May 2002 was undertaken to determine if there is an association between paediatric A and E asthma visits and Saharan dust cloud cover. A Poisson regression model was used to determine the statistical relationship between acute paediatric asthma A and E visits and Saharan dust cover with and without other variables such as climatic parameters and month. During the study period, there were 2,655 A and E visits for acute asthma. There was an association between increased paediatric asthma admissions and increased Saharan dust cover. The best fitting model estimated that in one month, such as June, a deterioration of visibility due to increased Saharan dust cover from no dust (visibility =16 km) to very dusty (visibility =7 km) would increase a daily admission rate of 7.8 patients to 9.25 when climate variables such as barometric pressure and humidity were kept constant.

A retrospective study of the 1996 DEN-1 epidemic in Trinidad: demographic and clinical features

A retrospective analysis of the 1996 DEN-1 epidemic in Trinidad was undertaken to better understand the clinical and demographic expression of dengue infection in the island during one of the larger epidemics in the past 10 years and following the reintroduction of DEN-1 into the island in 1991 after a gap of 14 years. A total of 393 laboratory-confirmed cases were identified. Of these, notes for 157 patients were available for analysis. The epidemic was island-wide, though most cases occurred in the most densely populated county of St. George. There was a slight predominance of females (51.6 per cent) among the cases, and while all age groups were affected, older children and adults comprised the majority. South Asians among the population predominated. Overall, 27 clinical symptoms were reported. The most common were: fever (98.7 per cent), generalized pain (96.2 per cent) and anorexia (63.1 per cent). Rash, arthralgia, retro-orbital pain and haemorrhage (all mentioned in the WHO clinical description for dengue fever) were reported in <50 per cent of cases. Gastrointestinal symptoms were also very common and occurred in over two-thirds of cases at presentation. Bleeding manifestations were reported in 30 per cent of patients and commonly involved the gastrointestinal tract. Features of DHF were noted in only six (4 per cent)

Climatic variables are associated with seasonal acute asthma admissions to accident and emergency room facilities in Trinidad, West Indies.

OBJECTIVES: To determine if there is seasonal variation in acute asthmatic visits to accident and emergency (A&E) facilities in Trinidad and to identify the climatic variables associated with such visits. DESIGN AND METHODS: A retrospective census of patients with asthma, defined as those who required emergency bronchodilator nebulization, was taken at two A&E facilities in Trinidad from 1 January 1997 to 31 December 1999. The study included patients aged 64 years and under. Patient demographic data were obtained from the A&E records. Climate variables were taken from the island's sole Meteorological Office. Multiple regression was used to identify climate variables that were independent predictors of A&E asthma visits. RESULTS: There were a total of 45 842 asthma admissions to the two facilities during the study period. Visits exhibited a cyclic pattern over the 3 years that varied according to the island's dry (January-May) and wet (June-December) seasons. There were more visits during the wet season than the dry (40 [SD=2] vs. 32 [SD=2] visits/day; P<0.001). The results of multiple regression indicated that season (P<0.001), barometric pressure (P<0.001), temperature difference (P<0.001), minimum temperature2 (P<0.001) and wind speed2 (P=0.032) were predictors of paediatric visits. Independent predictors of adult visits were season (P<0.001), relative humidity (P<0.001), minimum temperature (P=0.01), temperature difference2 (P<0.001) and minimum temperature2 (P=0.004). Season and climatic variables explained 18% of the variance of the total A&E asthma admissions. CONCLUSION: There is seasonal variation in acute asthma visits to A&E facilities in Trinidad, which remains significant after controlling for climate variables. However, while climate has a role, there are other factors that may also be responsible for increased visits during the wet season. More research is needed to identify these factors.

A retrospective analysis of invasive Streptococcus pneumoniae infections in Trinidad.

A retrospective analysis of culture-positive cases of S pneumoniae from normally sterile body fluids is reported. Over 40% of patients were 5 years old or less while 28% of patients were 50 years old or more. Meningitis (44%) was the commonest clinical presentation followed closely by pneumonia (31%). The commonest predisposing disorder was human immunodeficiency virus infection though there were no identifiable risk factors in the majority of patients. Mortality from invasive pneumococcal disease was significantly higher in elderly patients compared with other age groups (p = 0.0003). In this study, all S pneumoniae isolates, for which there were antibiotic sensitivity data, were penicillin and/or amoxycillin sensitive.

Descriptive epidemiology of asthma in Trinidad, West Indies.

This cross-sectional study documents the demographic features of asthmatics seeking acute asthma care at four institutions on the island of Trinidad from January 1 to December 31, 1997. More than 15,000 (15,035) different patients made 27,353 visits during the study period. Pediatric and adolescent male patients outnumbered females, but this was reversed in patients aged 20-69 years. Frequency of visits per patient ranged from 1 to 242. Significant variation in monthly admissions was observed; admission rates were highest in the last quarter of the year but were lowest in July and August. The overall crude prevalence rate was estimated at 1.71 per 100 (range 1.16-2.34).

A preliminary study of neopterin as a potential marker for severe dengue virus infection

Dengue virus cause the non-fatal dengue fever and the life-threating dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS). Early clinical features of DF and DHF/DSS are indistinguishable and it is difficult to identify early DHF/DSS using clinical and laboratory parameters. A prospective observational study (KALAYANAROOJ et al, 1997) of Thai children with fever for less than 72h revealed that, at enrolment, plasma aspartate aminotransferase (AST)levels were significantly raised in children who developed DHF but were of relatively low positive predictive value (PPV=0.27 for AST>40U/mL). MONATH (1997), in his review of the paper by Kalayanaroo et al., noted the lack of 'clear clinical prognostic indicators for DHF' and called for strategies to improve diagnosis (AU)

Asthma in the English-speaking Caribbean

The prevalence of asthma in the Caribbean is high and seems to be increasing. Asthma research in this region has been biased towards the paediatric population and there is little published on adult disease. There is a high prevalence of other allergic diseases in the patients studied, with skin reactivity to at least one allergen in 50-81of subjects. Reactivity to house dust mite, especially Dermatophagoides pteronyssinus, occurred most commonly and sensitivity to this mite correlated with high levels of mite proteins in mattress and bedroom dust. Asthmatic admissions to hospitals are highest in the last quarter of the year but fall to their lowest levels in April. Admission rates are influenced by climatic variables such as relative humidity and wind speed. In some territories current management of asthma remains reliant on the use of oral bronchodilators with underutilization of inhaled beta-agonists and corticosteroid preparations.

Asthma in the English-speaking Caribbean.

The prevalence of asthma in the Caribbean is high and seems to be increasing. Asthma research in this region has been biased towards the paediatric population and there is little published on adult disease. There is a high prevalence of other allergic diseases in the patients studied, with skin reactivity to at least one allergen in 50-81% of subjects. Reactivity to house dust mite, especially Dermatophagoides pteronyssinus, occurred most commonly and sensitivity to this mite correlated with high levels of mite proteins in mattress and bedroom dust. Asthmatic admissions to hospitals are highest in the last quarter of the year but fall to their lowest levels in April. Admission rates are influenced by climatic variables such as relative humidity and wind speed. In some territories current management of asthma remains reliant on the use of oral bronchodilators with underutilization of inhaled beta-agonists and corticosteroid preparations.

A glycoprotein pneumococcal conjugate vaccine primes for antibody responses to a pneumococcal polysaccharide vaccine in Gambian children.

BACKGROUND: Streptococcus pneumoniae is a major cause of acute respiratory infections and acute bacterial meningitis in children. Pneumococcal polysaccharide vaccines are poorly immunogenic in this highly vulnerable group, but protein polysaccharide conjugate vaccines are likely to be more effective. OBJECTIVES: To determine whether immunization of infants with a pneumococcal conjugate vaccine induces immunologic memory. METHODS: Eighty-four Gambian children, who had been vaccinated previously with two or three doses of a pentavalent pneumococcal conjugate vaccine (CRM197) or with a Haemophilus influenzae type b (Hib) conjugate vaccine were immunized when approximately 2 years old with a 23-valent pneumococcal polysaccharide vaccine, and a blood sample was obtained 10 days later. Pneumococcal antibody titers in prevaccination and postvaccination sera were measured by enzyme-linked immunosorbent assay and by an opsonophagocytic assay. RESULTS: On revaccination with a pneumococcal polysaccharide vaccine, children who had previously received pneumococcal conjugate vaccine had higher antibody concentrations to each of the five polysaccharide components of the conjugate vaccine than did control children. For type 6B polysaccharide, which is poorly immunogenic in young children, postvaccination antibody concentrations were 0.37, 27.6 and 50.9 microg/ml in children who had received no previous pneumococcal immunization or two or three doses of conjugate vaccine, respectively. Type 14 antibodies produced after revaccination were of high avidity and had opsonic activity. CONCLUSION: Vaccination of young infants with two or three doses of a pneumococcal conjugate vaccine primes the immune system to respond strongly and rapidly on subsequent exposure to pneumococcal polysaccharide.

Defective antibody-mediated opsonisation of S. pneumoniae in high risk patients detected by flow cytometry.

Invasive pneumococcal infection continues to be a significant cause of morbidity and mortality especially in patients with antibody deficiencies and disorders affecting the reticulo-endothelial system. Current recommendations for prophylaxis in these patients include immunization with 23-valent pneumococcal polysaccharide capsular vaccines. Post-immunization responses are commonly assessed by measuring serum antibody levels. However, there is no defined protective antibody range and this approach fails to determine the functional capacity of the antibodies. A simple, reproducible flow cytometric method of assessing the antibody-mediated opsonic activity against S. pneumoniae is described. This assay detected defective opsonic function in post-immunized at-risk patients who developed invasive pneumococcal infection.

Mannose binding protein gene mutations associated with unusual and severe infections in adults.

A defect in opsonisation can cause a common immunodeficiency. A mutation in mannose binding protein (MBP) caused by point mutations in the MBP gene will lead to such a defect. This type of syndrome can cause recurrent infections in infants between 6 and 18 months of age but is not generally believed to predispose to adult infections. We looked at 4 patients with severe and unusual infections in whom MBP gene mutations were the only identified cause of immunodeficiency and one patient with combined MBP and IgA deficiency. We analysed the MBP genotypes of all the patients in whom we suspected an immunodeficiency because of their clinical history. Infections seen were recurrent skin abscesses, chronic cryptosporidial diarrhoea, meningococcal meningitis with recurrent herpes simplex, and fatal klebsiella lobar pneumonia. Both sexes were affected and ages ranged from 15 to 56 years. Two patients were homozygous for codon 54 mutations, one patient had codon 52 and codon 54 mutations and was phenotypically homozygous, and two patients were heterozygous for codon 54 mutations. Individuals homozygous for MBP mutations are unusual in the general population (approximate frequency 0.3%). The occurrence of three homozygotes for MBP mutations among these five infected patients suggests that MBP deficiency may confer a life-long risk of infection.

Relationship of in vitro phagocytosis of serotype 14 Streptococcus pneumoniae to specific class and IgG subclass antibody levels in healthy adults.

The role of specific IgG2 antibody in the protection against serious infection with Streptococcus pneumoniae is unclear. We therefore decided to investigate the relationship between serum antibody levels and opsonization and phagocytosis of this microorganism. We have measured serum IgM, IgA and IgG subclass antibody specific for pneumococcal capsular polysaccharide and in vitro phagocytosis of serotype 14 pneumococcus by polymorphs, in healthy adults before and after immunization with Pneumovax II. IgM and IgG2 were the predominant anti-pneumococcal antibodies seen, IgA and IgG1 being present at low titre. No significant relationship of phagocytosis with specific IgM and IgA antibodies was found. However, both specific IgG1 and IgG2 antibodies in post-immunization sera correlated significantly with phagocytosis of the pneumococcus in the presence of complement (r = 0.57, P = 0.029 and r = 0.59, P = 0.022 respectively). After heat-inactivation, the remaining opsonic activity of sera correlated only with levels of specific IgG2 antibody (r = 0.61, P = 0.0006). Whereas phagocytosis supported by specific IgG1 and IgG2 antibody to serotype 14 pneumococcus after immunization is mediated by complement activation, IgG2-specific antibody in high titre may also be able to function by complement-independent interaction with Fc gamma receptors on polymorphs.

Specific IgG subclass antibody levels and phagocytosis of serotype 14 pneumococcus following immunization.

Complement and specific antibody directed against capsular polysaccharide are necessary for efficient phagocytosis of pneumococci. In normal adults, specific antibody to pneumococci is predominantly of the IgG2 subclass. However, the role of IgG2 in bacterial clearance is debatable. We therefore decided to investigate the relationship between specific IgG subclass antibody levels and phagocytosis of serotype 14 pneumococcus, before and after immunization with a pneumococcal capsular polysaccharide vaccine. Specific IgG subclass antibody was measured by an ELISA technique and the effect of serum on phagocytosis of radiolabelled pneumococci by normal polymorphs was determined. We found that in the presence of complement, phagocytosis correlated significantly with both specific IgG1 and IgG2 antibody titres (r = 0.547, P = 0.002 and r = 0.464, P = 0.009, respectively). However, in decomplemented sera, the correlation with IgG1 antibody was lost, whereas that with IgG2 antibody was strengthened (r = 0.641, P = less than 0.001). The possibility that IgG2 binds to receptors on polymorphs should be considered.

Staphylococcal opsonization and anti-Staphylococcus aureus IgG subclass antibodies in patients with severe or recurrent S. aureus infections.

Opsonization of Staphylococcus aureus (Oxford strain) and specific IgG subclass antibodies against formalised staphylococci were measured in plasmas from 27 patients with significant S. aureus infections and 35 healthy adults and 15 children. There were no statistically significant differences in the IgG2 and IgG4 levels between two groups and IgG3 was not detected, but the median plasma IgG1 level was significantly higher in patients with staphylococcal infections (P less than 0.00003). The concentration of IgG2 anti-S. aureus antibodies was 25-47 times greater than that of IgG1. If plasmas were decomplemented, the raised IgG1 levels were associated with increased opsonophagocytosis by normal neutrophils (P less than 0.0002).