Age-relationships of Toxocara canis seropositivity and geohelminth infection prevalence in two communities in St. Lucia, West Indies

Sera were examined from an age-stratified sample of two Caribbean communities using the Toxocara-Elisa with larval Es antigen. Seropositivity was markedly age dependent, attaining maximal values (40 and 60 percent) in 5-15 year olds and declining in adults. The rate of acquisition of infection with Toxocara canis and the age-prevalence profile are similar to those of Ascaris lumbricoides and Trichuris trichiura. It is suggest that toxocariasis is likely to be prevalent in tropical areas with endemic geohelminthiasis.(AU)

A community-based study of gastrointestinal helminth and protozoan infection in Western Jamaica

A study of gastrointestinal parasitic infection was conducted in four communities in the Parish of Westmoreland, Jamaica. All blood smears (n=1,025) were negative and 63.7 percent of stool specimens (n=696) contained ova/cysts of one or more of 7 helminth and 9 protozoan species. Trichuris and Giardia were the most prevalent species. Prevalence was markedly age-dependent, with infection occurring most commonly in children. It is concluded that gastrointestinal parasitic infections persist at intensity and prevalence levels likely to have a significant impact on community health (AU)

Predisposition to Trichuris trichiura infection in humans

The study examines the distribution of Trichuris trichiura infection in a village community in St. Lucia, West Indies. The infection intensity of the same age-stratified population was assessed (by drug expelled worm burden and faecal egg count) at the intiation of the study, and after 17 months of reinfection following treatment. The frequency distribution of worm numbers per person was similar at both periods of sampling. There was a significant correlation between the initial infection intensity of an individual, and the intensity acquired by the same individual following the 17 month period of reinfection. This relationship was observed in a broad range of host age classes. The study provides firm evidence that individuals are predisposed to heavy (or light) T. trichiura infection. (Summary)

Age-related prevalence and intensity of Trichuris trichiura infection in a St. Lucian community

Age-related changes in the average worm burden and the prevalence of Trichuris trichiura infection, in a village community in St. Lucia, were examined by field studies based on worm expulsion techniques. Horizontal age-intensity profiles were convex in form with peak parasite loads occurring in the 2 to 15-year-old children. Prevalence is shown to be a poor indicator of changes in average worm load with age. Faecal egg counts (epg and epd) provide a qualitative measure of worm burdens since fecundity is shown to be approximately independent of worm load. The parasites were highly aggregated within the study community, with most people harbouring low burdens while a few individuals harboured very heavy burdens. Of the total parasite populations in the study sample, 84 percent were harboured by the 2 to 15-year-old children. Of those individuals harbouring 100 worms or more, 87 percent were in the 2 to 10-year-old age range. Crude estimates of population parameters (basic reproductive rate, 4-5; rate of reinfection, 90 year-1) suggest that the rate of reinfection is higher than for other helminth parasites of man. The control of morbidity and parasite transmission is discussed in the context of targeting drug treatment at the child segment of the study population.(AU)

Epidemiology and population dynamics of Ascaris lumbricoides and trichuris trichiura infection in the same community

The gastrointestinal helminth infection status of an age-stratified sample from a single Caribbean community was assessed using anthelmintic expulsion techniques. The same sample was re-assessed in a similar manner after a 17 month period of re-infection. The age-prevalence profile of Ascaris lumbricoides was convex while that of Trichuris trichiura was asymptotic. The age-intensity profiles of both species were convex. These differing patterns are attributed to differences in the absolute worm burdens of the 2 species. The frequency distributions of infection intensity were similar for both species, and largely independent of host age. The basic reproductive rate of A. lumbricoides (R. = 1-1.8) was similar to that recorded elsewhere and much lower than that of T. trichiura (R. = 4-6), implying that the latter is intrinsically more resistant to control. Individual hosts were predisposed to high (or low) intensity infection with either species, although predisposition to both species simultaneously was not conclusively demonstrated. Futher studies are required to determine the cause of these observations.(AU)

Attitudes to after-hour calls in Barbadian family practice - abstract

A 6-month prospective study was carried out at the General Practice Unit in Wildey and at two privately run group practices. An after-hour call was defined as any request for care outside regular office hours. Information recorded by the doctor included estimation of the necessity of the call and his or her reaction to it. Wherever possible, patients were contacted at a later date by an interveiwer who recorded the type of management, the patient's perception of his or her main reason for calling and the satisfaction with the service received. A total of 557 calls were made, representing 3.0 percent of the total workload (office visits and AH visits). Of the 339 patients interviewed the majority gave discomfort and anxiety as their main reason for calling. Two hundred and twenty-nine of all patients (41.1 percent) were managed on the telephone. One hundred and thirty-six of these were among the group of patients interviewed. Only 6(4.4 percent) were dissatisfied with the service received. Three hundred and seventy of all calls (65.4 percent) were judged by the doctor as being necessary. Only 68 (12.0 percent) were judged to be totally unnecessary. The majority of calls (61.4 percent) engendered interest and satisfaction with only 99 (18.2 percent) evoking anger and frustration. Surprisingly, only 4.0 percent of 52 patients interviewed, who belonged to the latter group, were dissatisfied with the service received. This study has shown that a great deal of satisfaction can be derived from doing after-hour work. Areas of educational importance have also been identified, such as the need for teaching the skills of "telephone medicine", dealing with anger and frustration and the "very unnecessary" call (AU)

Horizontal-age prevalence and intensity of trichuris trichiura infection in a rural population in St. Lucia - abstract

The clinical severity of trichuriasis and the rate of production of Trichurius infective stages are dependent upon the size of the worm burden. This study examines the horizontal-age distribution of prevalence and intensity of Trichurius infection in a St. Lucian village, with the twofold aim of identifying the age group which makes the major potential contribution to the transmission of infection and is at its greatest risk of disease. Duplicate faecal specimens from a minimum of 16 individuals in 8 age groups (<0.5->30 years) were examined twice, using the Kato thick-smear technique. A minimum of 16 individuals, infected with Trichuris, from 6 of the age groups (1->30 years) had their worm burdens determined by expulsion with mebendazole (Vermox, Janssen Pharmaceutica). Ovogenic infections occurred in 6 percent of children under 12 months; the youngest case was 5 months. Prevalence increased dramatically after the first year of life, exceeding 90 percent by 3 years of age, and remaining high and constant into adulthood. Intensity rose over a similar time preiod to prevalence but approximately one year later in life. Maximum intensity was attained in the age group 2-10 years old, and thereafter declined with increasing age. These results indicate that the population is exposed and susceptible to trichurius infection before 12 months of age. The decline in worm burden after 10 years of age may reflect age-dependency in the force of infection or the development of an immune response. Children aged 2-10 years have the largest worm burdens and are therefore: (1) the major contributors to the transmission of infection and hence the major focus for targeted chemotherapy; and (2) most likely to develop the clinical manifestations of trichuriasis (AU)

Rate of expulsion of Trichuris trichiura with multiple and single dose regimens of albendazole

The efficacy of multiple and single dose regimens of albendazole on Trichuris trichiura infection was evaluated by counting the number of worms expelled/day from two pair-matched groups of children, for nine days following therapy. The temporal patterns of worm expulsion were similar whether the children received a single 400 mg dose or two consecutive doses: no worms were passed before the second day, or after the sixth day, after intervention, and the maximum worm expulsion rate was attained on the fourth day. A second treatment six days after the first expelled no more worms. The results obtained here resemble those obtained previously with a three-day (600 mg) regimen of mebendazole in a study of heavily infected children. We conclude: that irrespective of dose, benzimidazole carbamates require the gut transit time plus 48 hours to immobilize T. trichiura; and that single dose of albendazole is effective against light infections of T. trichiura but requires further evaluation with high intensity infections.(AU)

Population dynamics and chemotherapeutic control of Trichuris trichiura infection of children in Jamaica and St. Lucia

Population dynamical parameters of Trichuris trichiura infections in children were estimated from longitudinal intensity and prevalence data from a population (n=23) in a children's home in Jamaica. The theoretical predictions of a deterministic model incorporating these parameters were approximated to observe horizontal-age prevalence data from a naturally infected population (n=203) of children in a St. Lucian village, and a rough estimate of the basic reproductive rate (Ro=8-10) of T. trichiura obtained. The findings suggest that T. trichiura populations are intrinsically more difficult to control by traditional mass-treatment chemotherapy (eradication requires >91 percent of the population to be treated every 6 months for >5 years) than are populations of Ascaris, but may be more susceptible to selective chemotherapy programmes which aim to treat only the most heavily infected individuals (AU)

Population distribution of Trichuris trichiura in a community of Jamaican children

The trichuris trichiura worm burdens of 23 children in a Place-of-Safety in Kingston, Jamaica were assessed by stool collection for more than five days after treatment with mebendazole. This procedure was repeated after a seven-month period of natural reinfection. For both collections the maximum rate of worm expulsion was achieved on the fourth day after starting treatment. The worm populations were overdispersed and well described by the negative binomial probability model (k=0.29) in each case. For any one individual, the number of worms passed on the first expulsion was unrelated, absolutely or relatively, to the number passed on the second. These data suggest that: knowledge of the time dependency of helminth expulsion is essential for the accurate determination of worm burdens by this method; populations of Trichuris are more highly aggregated than those of Ascaris and thus may be more susceptible to control by selective rather than random chemotherapy; and the inherent predisposition of hosts to infection may be of minor importance in determining the distribution of worms in the population-heavily infected hosts appear no more or less likely to acquire large worm burdens on subsequent exposures. (AU)

Use of reason for encounter classification (RFE-C) in general practice - abstract

This study was part of an international field trial of the RFE-Classification developed by a working party of the Classification Committee of the World Health Organisation (WHO). It aims to discover the patient's reason for seeking an encounter with primary health care providers. Doctors working at the General Practice Unit (GPU) and nurses who encountered and managed patients on their own recorded the reason for each patient seeking health care over a 3-month period. Special RFE - Data Collection Forms designed by the Department of Epidemiology and Statistics of WHO were used. Data included age, sex, place of encounter, status of encounter (whether or not episode was previously presented by patient to any provider), RFE code and RFE text. Field trial manual and shortened versions were used at each encounter to code the reason as agreed to by provider and patient. The Classification consist of 16 chapters (each representing a body system by an alphabetical designation), each divided into 7 similar components. In the 3-month period, 434 males and 1,014 females made encounters with health-care providers. The greatest demands on health services were made by females (420 or 29 percent) in the 15-44 year age group who attended mainly for problems related to menstruation, contraception and pregnancy. The reasons for demands on the health services were: 1. cough (153) - 8.8 percent, 2. uncomplicated hypertension (87) - 5 percent, 3. diabetes mellitus (86) - 5 percent, 4. general and unspecified follow-up encounters (83) - 5 percent, 5. skin rash (61) - 3.5 percent, 6. immunizations (58 percent) - 3.3 percent, 7. headaches (36) - 2 percent, 8. pregnancy (36) - 2 percent. The most frequent reason for encounter was related to general and unspecified diseases (380 or 21.9 percent) followed by respiratory 290 (16.6 percent), female genital 162 (9.3 percent), skin 155 (8.9 percent), musculo-skeletal 153 (8.8 percent) and circulatory 141 (8.1 percent). This classification is patient-oriented rather than disease- or provider-centered, hence 2. it avoids interpretation by doctors and inevitable variation in diagnosis of a particular disease 3. it enables all reasons for patients seeking health care to be categorized even if a diagnosis cannot be made, and 4. in the absence of a doctor, other health care providers can classify why patients seek health care (AU)

Epidemiological aspects of toxocariasis in St. Lucia - abstract

Toxocariasis is known to occur in children and dogs throughout the Caribbean region but has never been quantified. The objects of the present study are to determine seroprevalence in a paediatric population and to assess transimission variables at the same locus. The study was conducted in the village of Anse-la-Raye, St. Lucia. Sera were collected from randomly selected children (1 - 8 years old ) absorbed with Ascaris SE-antigen to minimise cross-reactivity, and tested using CDC ELISA (titres> 1:32 taken as positive). Soil and canine faecal samples were collected throughout the village. Toxocara eggs were isolated from soil using the DAda-Linduist double-centrifugation method and from faecals using the Ritchie formal-ether concentration. A questionnaire survey of dog ownership and mangement was conducted at 88 representative households identified by a concurrent demographic survey. 86 percent (n=71) of the children had positive Toxocara antibody titres, compared with 5 percent seroprevalence for children in urban temperate environments. Patent T. canis infection was identified in 33 percent (n = 21 ) of village dogs although the sample protocol under-represented the most frequently infected youngest age group. Toxocara eggs were present in 19.5 percent ( n = 41 ) of soil samples overall, adn 62.5 percent of soil samples from the school yard. 77 percent of households had more than two dogs, and 76 percent of this proportion allowed their animals to wander freely, while only 28 percent had at any time administered canine anthelminthics. These results suggest that a very large population of children in the study village are infected at an early age and are at risk of both visceral and ocular larva migrans. Infection exposure is attributable to intense environmental contamination with T. canis eggs from a relatively unconstrained, and untreated, dog population. These findings suggest, on epidemiological and serological grounds, that toxocariasis is of potential public health significance to Caribbean children (AU)

The diagnosis and treatment of human strongyloidiasis: a prospective study - abstract

A prospective hospital-based study evaluating the accuracy of diagnostic instruments in human strongyloidiasis is reported together with a reassessment of standard anti-helminthic therapy by strict criteria for cure. Eleven patients, 7 men and 4 women, whose ages ranged from 16 to 70 (median 53) years were studied before treatment. Four (1 man, 3 women) were assessed before 2 consecutive courses of treatment. The following tests were done: (1) formol-ether stool concentration, (2) Harada-Mori stool culture for 24 and 48 hours, direct microscopy of (3) duodenal aspirate and (4) duodenal mucosal biopsy, (5) duodenal mucosal biopsy histology, (6) examination for parsitic adults in stools collected over 48 hours after beginning treatment with thiabendazole (25 mg/kg twice daily) for 10 days. The results are given in the Table. Tests (1) - (5) were repeated 2 months after treatment, but Harada-Mori culture was continued for 7 days. Post-treatment assessment was completed in 9 of 11 patients (1 died, 1 default) and in 3 who were treated and assessed twice. Of 12 treatments, 9 failed (75 percent), although the number of parasites appeared reduced in all but 2 (17 percent). Results that was shown in the table as follows: TECHINQUE (n) are - Harada-Mori, Formol-ether, Duodenal aspirate, Mucosal Biopsy:(a) Microscopy, (b) Histology; SENSITIVITY ( percent) - PRE-TREATMENT (15):- 93, 87, 73, 53, 33 respectively; POST-TREATMENT (12):- 100, 67, 44, 33, 11 respectively. The Harada-Mori stool culture technique appears to be the single, most sensitive, diagnostic test. Although it may need to be supplemented with other tests to achive maximun diagnostic accuracym it is recommended that where strongyloidiasis is suspected, it becomes a standard diagnostic method. Formol-ether concentration is less sensitive in low-intensity infection. Previous studies from Jamaica have reported similarly low cure rate in contrast to those achieved in developed countries. Failure of treatment may indicate interaction between nutritional status and immuno-competence (AU)