Biomedical subjects

C O Everard

Publications and source records attributed to C O Everard.

At least 37 records · Page 2Linked to original sources

PubMed1990

Leptospires in the whistling frog (Eleutherodactylus johnstonei) on Barbados.

Two groups of whistling frogs (Eleutherodactylus johnstonei) comprising 99 and 117 animals were examined for leptospiral infection. Group I animals were caught in 14 areas of Barbados, and Group II animals in seven areas of suburban Bridgetown. Leptospires were isolated from the kidneys or body fluid of six frogs in Group I and the kidneys of 3 frogs in Group II. Two of the Group I isolates died out; the others were identified as bajan (a new serovar in the Australis serogroup) (6) and bim (Autumnalis) (1). The macerated body tissues and fluid of Group I frogs were put into phosphate buffered saline and examined by the microscopic agglutination test using 22 antigens. The results were all negative. For the Group II frogs the methodology was altered; blood was collected onto filter paper discs and allowed to dry out before being agitated in PBS and examined by the MAT. 15/117 (12.8%) animals were positive at greater than or equal to 1:100 and 19 (16.2%) at greater than or equal to 1:50. The geometric mean titre was 179. Seventeen of the sera reacted predominantly to antigens in the Australis serogroup, and two to Pyrogenes on its own. The serological results reflected the identity of the isolates. Serovars of Australis are not known to cause illness on Barbados, but bim is the commonest cause of severe leptospirosis on the island.

Animals↗

PubMed1990

Leptospirosis in Barbados. A clinical study.

A 39-month clinical study of leptospirosis was undertaken at the Queen Elizabeth Hospital, Barbados. Eighty-eight patients had a confirmed diagnosis of the disease during the period. The major serogroups identified were autumnalis (including a new serovar bim), icterohaemorrhagiae, ballum and canicola. The majority of patients presented with jaundice (95%,) anorexia and headaches (85%), fever (76%) and conjunctival suffusion (54%). While abnormal creatinine levels were seen in 49% of patients on admission, only 16% were judged to have had renal failure. The urine to plasma urea ratio showed high sensitivity and specificity in the diagnosis of pre-renal azotemia. Cardiac arrhythmias and myocarditis occurred in 18% of patients and pericarditis in 6%. An elevated serum amylase was found in 65% of cases. The bilirubin level took 5.5 weeks to return to normal. Thrombocytopenia was shown not to be due to a disseminated intravascular coagulation, and a randomised trial of high dose penicillin did not reveal any benefit to jaundiced patients. The overall mortality during the study was 5.7%.

Adolescent↗

PubMed1989

Leptospiral infection in school-children from Trinidad and Barbados.

A serological survey for leptospiral agglutinins was undertaken between 1980 and 1983 in over 500 Barbadian and 500 Trinidadian school-children aged 7-14 years. The children were selected randomly from urban and rural schools, and examined three times at approximately annual intervals. A total of 12.5% of the Barbadian children and 9.5% of the Trinidadian children were seropositive at a titre of 50 using the microscopic agglutination test. On both islands, seroprevalence was higher in males than females, the difference being significant in rural schools. There was no evidence of a difference in prevalence between urban and rural schools, or between junior and secondary age-ranges. Analysis of the association of serology with socio-economic and behavioural factors showed a significant association in Trinidad with father's occupation, but most other variables on both islands showed only weak non-significant associations. Fourteen children in Trinidad and three in Barbados seroconverted. Seroconversion in Trinidad occurred at a rate of 1.6% per annum and was significantly associated with livestock contact and with absence of a tapped water supply. In Trinidad, Autumnalis was the most commonly recorded serogroup, but this accounted for less than a quarter of seropositives. In Barbados, Panama accounted for over half the seropositives and was about four times more common than the next most common serogroup, Autumnalis. In Barbados, 39 persons aged 19 or less were hospitalized with leptospirosis between November 1979 and December 1986. Average annual incidence rates were 2.2, 4.9 and 13.3 per 100,000 in the 5-9, 10-14 and 15-19 age-groups, respectively.

Adolescent↗

PubMed1989

An immunoprotective monoclonal antibody directed against Leptospira interrogans serovar copenhageni.

A monoclonal antibody (mAb) was prepared by hybridoma technology in BALB/c mice immunized to Leptospira interrogans serovar copenhageni. This mAb agglutinated serovars copenhageni and icterohaemorrhagiae to high titres and protected hamsters, dogs and monkeys against challenge with a virulent strain of serovar copenhageni. The mAb gave protection to hamsters at dilutions up to 1 in 1000; at a 1 in 10 dilution the protective effect lasted for at least two weeks. Biochemical analysis by SDS-PAGE and Western blotting indicated that this mAb reacted with an epitope of a carbohydrate nature.

Animals↗

PubMed1989

Leptospirosis in piggery workers on Trinidad.

Of 133 cases of human leptospirosis recorded in Trinidad between 1977 and the end of February 1982, at least eight (6%) were in people who worked on pig farms. Three of the eight died, and their presumptive infecting serogroups were Icterohaemorrhagiae (3), Canicola (2), Pyrogenes (2) and Grippotyphosa (1). Six of the eight cases were followed up. Altogether, sera from 201 pigs, 78 other livestock animals, 38 workers and 34 dogs were tested for leptospiral agglutinins. The seropositivity prevalence among pigs on farms with human illness (43% greater than or equal to 1:100) was similar to that in pigs from farms not associated with illness (46%), but the titres among the former group (geometric mean 209.5) were higher than among the latter (91.5), where only titres less than or equal to 1:400 were recorded. Similar infecting serogroups were recorded among pigs on the two groups of farms, with Icterohaemorrhagiae, Autumnalis, Canicola and Pyrogenes most frequently recorded overall. There was little evidence of the pig-adapted serogroups Pomona and Tarassovi. Twelve of 13 workers (93%) from a farm on which at least two other people had contracted leptospirosis had serological evidence of exposure, compared with seven of 24 (29%) on a neighbouring farm not associated with human illness. Dogs and rodents are thought to be the major sources of leptospirosis in pigs and piggery workers in Trinidad.

Adolescent↗

PubMed1989

Urinary diagnostic indices in the management of leptospirosis. Selection of patients for dialysis therapy.

Cases of leptospirosis admitted to the Queen Elizabeth Hospital (QEH), Barbados, were assessed for the presence of "pre-renal azotaemia" (NON-ARF) as opposed to "acute renal failure" (ARF). Distinction between the two diagnoses was made on the basis of clinical course. Peritoneal dialysis was inappropriately utilised in 26% of patients receiving such therapy. This study evaluates diagnostic tests for pre-renal azotaemia, and acute renal failure in leptospirosis, and indicates guidelines for the management of azotaemia in such patients. U/P urea and osmolar ratios show high sensitivity and specificity in diagnosing pre-renal azotaemia. While "early" dialysis is essential for patients with acute leptospiral renal failure, in those with plasma creatinines less than 600 mumol/litre on entry and indices indicating NON-ARF, decisions regarding dialysis can safely be delayed for 48-72 hours while the effect of rehydration is assessed.

Acute Kidney Injury↗

PubMed1988

Prevalence of leptospirosis in Belize.

In a search for leptospirosis in Belize, at least one current case was diagnosed among 11 febrile hospital patients examined in a 2-week period in mid-1984. Sera from 440 survey subjects in 6 schools, 4 urban communities and 9 rural communities were examined for leptospiral antibodies by the microscopic agglutination test. 20 of 174 (11.5%) school pupils, 19 of 88 (22%) urban community subjects and 66/178 (37%) rural community subjects were positive at titres greater than or equal to 1:50, and 7.5%, 17% and 26%, respectively, were positive at greater than or equal to 1:100. Among all groups of survey subjects, serological reactions to antigens in the Australis serogroup predominated. Up to 81% of 155 sera from cattle in various areas of Belize were positive at titres greater than or equal to 1:100. Serological reactions to serogroup Sejroe predominated (43%), followed by Pyrogenes (16%) and Australis (15%). 20 of 71 (28%) pig sera were positive at greater than or equal to 1:100, predominantly to serovars in the Australis serogroup (51%). Of 162 sheep or goat sera examined, 65 (40%) were positive at greater than or equal to 1:100, mainly to serogroup Autumnalis (25%), followed by Australis (15%).

Animals↗

PubMed1988

Penicillin therapy in icteric leptospirosis.

A prospective, controlled randomized study of penicillin therapy in icteric human leptospirosis was carried out between 1 October 1983 and 31 December 1986. Thirty-eight patients received intravenous crystalline penicillin for 5 days, while 41 assigned to a control group received intravenous fluids only. A comparison of the results of laboratory tests made on the day of admission revealed no significant differences between the 2 groups. There was no significant difference in time for defervescence, return of biochemical parameters to normal, incidence of iritis, or mortality in the 2 groups. Three patients (7.3%) in the control group and 1 patient (2.6%) in the treatment group died. The overall mortality rate was 5.9%. Leptospira were recovered from urine cultures in 6 control patients but from none of the treated patients' post-treatment cultures. We conclude that penicillin has little effect on clinical outcome in icteric leptospirosis.

Adult↗

PubMed1988

Leptospires in the marine toad (Bufo marinus) on Barbados.

Leptospires were isolated from the kidneys of four of 211 toads (Bufo marinus) caught on Barbados. Two of the isolates were identified as Leptospira interrogans serovar bim in the Autumnalis serogroup (the most common cause of leptospiral illness on Barbados), and two as possibly new serovars in the Australis serogroup. Sera from 198 of the toads were examined by the leptospire microscopic agglutination test. Forty-two (21%) were positive at titers of greater than or equal to 1:100, and 54 (27%) at greater than or equal to 1:50. The predominating serogroups were Australis (50%), Autumnalis (23%) and Panama (13%). The agglutination tests on the culture-positive toads showed that serologic studies alone may be of limited value in these animals. Bufo marinus can harbor pathogenic leptospires, and it may be a significant source of the Autumnalis serogroup infections in the Caribbean.

Agglutination Tests↗

PubMed1987

Leptospires in vervet monkeys (Cercopithecus aethiops Sabaeus) on Barbados.

Agglutinins to Leptospira were found at titers of greater than or equal to 1:100 in 150 of 501 (29.9%) vervet monkeys (Cercopithecus aethiops sabaeus) bled within 1 mo of capture in Barbados. Including a further 34 of 145 bled within 1 yr of capture, the seropositivity prevalence was 28.5%. A further 35 monkeys (5.4%) had traces of agglutinins or gave titers of 1:50. The proportion of seropositive adults (41.5%) was more than twice that of seropositive immature monkeys (17.6%). Among adults, 49.2% of males and 35.7% of females were seropositive, while among juveniles proportions of seropositive males and females were similar (17.8% and 17.4%, respectively). Seropositivity prevalences tended to increase in proportion to rainfall. In each of 165 of the 184 positive sera, a single serogroup predominated in the serological reactions. These serogroups were Ballum (61%), Icterohaemorrhagiae (16%), Autumnalis (15%), Pyrogenes, Panama, Pomona, Tarassovi and Canicola (8% altogether). In the other 19 positive sera no single serogroup predominated. Serial bleeding showed that vervet monkeys can retain naturally-acquired antibodies to Leptospira for at least 2.5 yr. The evidence suggests that vervet monkeys in Barbados are transmitting leptospiral infections among themselves independently of other groups of animals, and are not a major source of human leptospirosis.

Agglutinins↗

PubMed1987

The incidence of severe leptospirosis in Trinidad.

Between February 1977 and September 1982, sera from febrile patients from all areas of Trinidad were examined for leptospiral agglutinins; 158 of 1714 patients (9%) were confirmed as current cases of leptospirosis (annual average 26 or 2.6 per 100,000 population). Of the remaining 1556 patients only 711 provided paired sera; 167 of these (23%) showed evidence of previous leptospiral infection. Of the 845 single samples, 125 were positive. The true incidence of the disease is probably much higher than reported here. Males comprised 74% of the current cases; their highest rate of infection was in the 30-39 year age group, the incidence in late teenage approaching this rate. For females, incidence increased with age up to late middle-age. The presumptive infecting serogroups most commonly recorded among the 158 current cases were Icterohaemorrhagiae (37%), Canicola (16%) and Autumnalis (11%). 13 of the cases died (case fatality rate, 8.2%).

Adolescent↗

PubMed1986

Thrombocytopenia in leptospirosis: the absence of evidence for disseminated intravascular coagulation.

In a prospective study of human leptospirosis, thrombocytopenia was demonstrated in 54% of 24 cases. The only additional laboratory evidence suggestive of disseminated intravascular coagulation lay in a mild elevation of fibrinogen degradation products, but this occurred with equal frequency in nonthrombocytopenic patients. There is therefore no causal relationship between disseminated intravascular coagulation and the thrombocytopenia of human leptospirosis.

Adult↗

PubMed1985

Serological studies on leptospirosis in livestock and chickens from Grenada and Trinidad.

Sera from 1,206 livestock animals and chickens on Grenada and Trinidad were tested for leptospiral antibodies by the microscopic agglutination test. 376 of the sera were positive (25% of those tested on Grenada and 44% on Trinidad). The positive sera were obtained from 25% of 324 cattle, 35% of 130 pigs, 35% of 146 sheep, 25% of 44 goats and 11% of 175 chickens on Grenada; and 92% of 26 cattle, 53% of 122 pigs, 76% of 87 horses and donkeys and 11% of 144 chickens on Trinidad. Eight sera from ducks and geese on Trinidad were tested and found to be negative. The serogroups most commonly found to react with the sera of the Grenadian animals were Autumnalis, Icterohaemorrhagiae, Hebdomadis and the related serogroups Sejroe and Mini, and Pyrogenes; in the Trinidadian animals they were Icterohaemorrhagiae, Autumnalis, Hebdomadis and its related serogroups, and Panama. Strains of serogroup Pomona do not appear to have become established as livestock pathogens on the islands.

Agglutination Tests↗

PubMed1985

A serosurvey for leptospirosis in Trinidad among urban and rural dwellers and persons occupationally at risk.

A survey for leptospiral antibodies was made of 1,375 persons in northern Trinidad between mid-1977 and mid-1978. The subjects were employees in seven occupational categories thought to entail a high risk of exposure to leptospires, and members of the general population of three rural and two urban communities. They were questioned inter alia about their leisure and occupational activities, household water supply and effluent, and contact with animals. Leptospiral infection was found to be widespread in the general population but not primarily associated with employment. Among the occupational groups the highest prevalence of antibodies was found in sugar-cane workers (45% infected), while among the communities prevalence was highest in the rural village of Cacandee (37%) and lowest in Woodbrook (Port-of-Spain) (5%). Keeping cattle, hunting and walking barefoot in the countryside were significantly associated with leptospiral serology. Over-all, serogroups Icterohaemorrhagiae and Autumnalis each accounted for about 25% of the seropositives in the general population. Among the occupational groups Autumnalis was the most commonly found (36%). It accounted for 42% of the seropositive sugar-cane workers and 57% of the seropositive rice farmers.

Adult↗

PubMed1984

The prevalence of severe leptospirosis among humans on Barbados.

Leptospirosis was confirmed by the Leptospira Laboratory in 138 hospital patients on Barbados between early November 1979 and the end of 1982 (annual average 43.6 cases). These were the great majority of severe cases occurring on the island during that time. The crude incidence rate ranged between 15 and 23 per 100,000 population per year (average 17.6). 26 of the patients died (15 males, 11 females), giving an over-all case fatality rate of 18.8%, and an average of 8.2 deaths per year. 68% of all cases were in males. The highest percentages of cases were in males aged 20 to 24 and females aged 55 to 59, but the incidence of the disease in both sexes increased with age up to 60 years. Previous figures recorded on the island by the Ministry of Health for 1975-79 were considerably lower, with a mean of 23.6 cases per year and a crude annual incidence of 9.5 per 100,000. 15 of the patients died (13 males, 2 females), giving an over-all case fatality rate of 12.7% and an average of 3 deaths per year. 74% of all cases were in males. The highest percentages of cases were in the 20 to 29 and 50 to 59 year age groups for males and females, respectively, i.e., similar to those in the present series. In both sexes the incidence of leptospirosis increased with age up to 60 years.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

PubMed1984

Bim, a new serovar of Leptospira interrogans isolated from a dog in Barbados.

A new serovar of Leptospira interrogans was isolated from a dog in Barbados. The proposed name of the new serovar is bim, and the designated type strain is 1051. The serogroup of the new serovar is the Autumnalis serogroup. The new serovar was subsequently isolated from six patients with leptospirosis in Barbados.

Animals↗

PubMed1983

Leptospires in wildlife from Trinidad and Grenada.

Serum samples from 894 wild animals (representing 31 species) from Trinidad and Grenada were examined by the microscopic agglutination test for leptospiral antibodies; 198 were positive. These included 39 bats, 88 mongooses, six opossums, 10 peridomestic rodents, 15 forest rodents, 10 lizards, and 30 toads. Thirteen pathogenic serogroups were involved. Thirty-nine Leptospira isolates were reported from mongooses, opossums, rodents and toads.

Agglutinins↗

PubMed1982

A survey of leptospirosis in febrile patients mainly from hospitals and clinics in Trinidad.

Acute and convalescent sera were obtained from 202 febrile patients, most of whom were admitted to or attended hospitals or clinics in northern Trinidad during the 12 months from mid-February 1977 to mid-February 1978. Laboratory tests confirmed that 10 of the patients were suffering from current leptospirosis while another 54 had serological evidence of previous leptospiral infections. Antibodies to strains of the Icterohaemorrhagiae serogroup were most commonly found, followed by those to the Hebdomadis and Autumnalis serogroups. Isolates were obtained from the blood of two and the urine of three of the 10 current cases. Four of these strains were identified as belonging to copenhageni serovar of the Icterohaemorrhagiae serogroup and one to serovar brasiliensis of the Bataviae serogroup. Seven of the patients suffering from leptospirosis were males, all rural dwellers, and all except one under 20 years of age. Two of the three female patients were over 60 years old and were urban dwellers. It was not possible to identify the sources of infection with certainty, although dogs may have been responsible for three of the Icterohaemorrhagiae and one of the Canicola infections. Of the 192 patients who were not currently infected, serological evidence of previous infection was obtained in 31 (40%) males and 23 (21%) females and was most common among farmers and rural workers.

Adolescent↗