A cross-sectional prevalence study of the protozoan and helminth infections in school children 6-12 years of age in Grenada

Data on the public health importance of intestinal parasites in Grenada have not been available for over 60 years and this study aimed to redress this information gap. Between May and June 1999, a cross-sectional point prevalence study of intestinal protozoans and helminths was carried out in school children aged 6-12 years of age in three schools in St George's Parish, Grenada. After receiving informed consent, a single stool sample was obtained which was immediately aliquoted and samples stored in either the refrigerator or freezer. The refrigerator sample was processed by a salt flotation concentration technique. The frozen sample was analysed by ELISA assay for antigens of intestinal protozoa. A total of 315 samples was collected. For protozoans, prevalence rates of 36, 12 and 3 percent were obtained for Giardia lamblia, Entamoeba histolytica and Cryptosporidium parvum, respectively. For helminths, prevalence rates were 0.4, 1.3, 5.3 and 1.4 percent for hookworm, Enterobius vermicularis, Trichuris trichuria and Ascaris lumbricoides, respectively. Protozoans are prevalent in Grenadians school children but helminths are not as common. These differences in prevalence rates may reflect the easy availability of broad spectrum antihelmintics whilst drugs for protozoan infections are obtained by prescription only. The dramatic difference in the prevalence of intestinal helminths from earlier in the 20th century may also reflect a considerable improvement in the socio-economic status of the population. (Au)

Does poor health nutrition affect school achievement in rural Jamaican children?

In recent years, increasing attention has been given to the effects of health and nutrition on schoolchildren's ability to learn. This study was conducted to determine whether nutritional status, anaemia and geohelminth infections were related to school achievement after controlling for a wide range of social variables. Eight hundred children were randomly selected from all those enrolled in grade 5 in 16 rural primary schools in Jamaica. School achievement was assessed by the Wide Range Achievement Test (WRAT). Children's weights and heights were converted to Z-scores using the NCHS references. Haemoglobin was measured using a haemoglobin photometer (Hemocue), and the presence and intensity (eggs per gram stool) of Trichuris trichura and Ascaris lumbricoides assessed by the Kato Thick Smear method. Socio-economic variables were assessed by questionnaire and observation, and school attendance obtained was from the class registers. The mean height-for-age of the children was -0.4 ñ 1.0 SD with 25.3 percent having heights <-ISD of the NCHS references. Fourteen point seven per cent (14.7 percent) of the children were anaemic (Hb < 1lg/dl), 38.3 percent were infected with Trichuris trichura and 19.4 percent with Ascaris lumbricoides. Height-for-age (p<0.001) was positively correlated with scores on the WRAT, and anaemia (p<0.05), Trichons and Ascaris infections (p<0.001) were associated with lower scores. In a multiple regression analysis, after controlling for attendance, sex, socio-economic status, possession of school books and uniform quality, the achievement of children with Trichuris infections was significantly worse than that of uninfected children in spelling, reading and the total WRAT score (p < 0.01). Height-for-age (p < 0.001) and anaemia (p < 0.05) contributed significantly to the variance in arithmetic. Despite the mild levels of undernutrition and the low intensity of the geohelminth infections, they were still associated with achievement. This suggests that efforts to increase school achievement levels in developing countries should include strategies to improve the health and nutritional status of children (AU)

The development and validation of an age-structured model for the evaluation of disease control strategies for intestinal helminths

Epidemiological modelling can be a useful tool for the evaluation of parasite control strategies. An age-structured epidemiological model of intestinal helminth dynamics is developed. This model includes the explicit representation of changing worm distributions between hosts as a result of treatment, and estimates the morbidity due to heavy infections. The model is used to evaluate the effectiveness of different programmes of age-targeted community chemotherapy in reducing the amount of morbidity due to helminth infection. The magnitude of age-related heterogeneities is found to be very important in determining the results of age-targeted programmes. The model was verified using field data from control programmes for Ascaris lumbricoides and Trichuris trichiura, and was found to provide accurate predictions of prevalence and mean intensities of infection during and following different control regimes (AU)

Geohelminth infections in school-aged children in Jamaica

There is concern that geohelminthiasis may adversely affect the growth and development of children. The relevance of this in the Caribbean in unclear since in many territories the prevalence of geohelminths is unknown. We report the results of three surveys conducted in Jamaican primary schools located in areas at high risk for geohelminthiasis. The first was conducted in 12 Kingston schools and comprised children in grades 2 to 5 (age 7 to 10 years). The second and third surveys were conducted in rural areas with children in grades 2 to 5 and grades 4 and 5, respectively. Overall, 9244 children provided stool sample for analysis. The prevalence of Trichuris trichiura ranged from 42 percent to 47 percent among the surveys while that for Ascaris lumbricoides ranged from 15 percent to 37 percent. Children in grades 2 and 3 had lower T. trichiura prevalences than those in grades 4 and 5 in the first and second surveys (p<0.05 and p<0.005, respectively). In the second survey only, children in grades 2 and 3 had a lower prevalence of A. lumbricoides than those in grades 4 and 5(p<0.005). Most infections were light with approximately 1 percent of the sample having heavy egg densities (AU)

Helminthiasis in Montserrat after the parasite control programme and hurricane Hugo - abstract

The Parasite Control Programme of Montserrat, West Indies, was a child-targeted chemotherapeutic control programme which ran from August 1986 to July 1989. The Programme involved the delivery of a broad spectrum antihelminthic to children (2-15 years old) once every school term. Two months after the end of the Programme, Hurricane Hugo devastated Montserrat on September 17, 1989. The Health Department (Montserrat) felt that the reductions in prevalence and intensity of Trichuris trichiura and Ascaris lumbricoides gained as a result of the Programme would be compromised by the disruption to sanitation and water supply caused by Hugo. In December 1989, a cycle of treatment was therefore administered to the child target group using the same infrastructure and procedure as that used in the Control Programme. The treatment compliance was 97.0 percent of the student population (n=2,125). Six months later, an age-stratified survey was done to assess the level of infection in the population and the age-standardised prevalence of T. trichiura for the overall population. Changes in the age-standardised intensity of both helminths before and after Hugo were recorded for the overall population: for T. trichiura the intensity went from 0.8 to 1.5 epg-faeces, while for A. lumbricoides the intensity rose from 1.2 to 1.7 epg.faeces. The observed rise in the infection levels of the overall population not statistically significant. The changes seen in the prevalence and intensity of both parasites taken from the surveys before and after Hugo were all found to be non-significant. There appeared to have been a non-significant increase in parasitic infection levels 9 months after Hugo to levels seen in the latter part of the Control Programme (AU)

The age-targeted chemotherapeutic control of helminthic infections in Montserrat - abstract

This study describes the age-targeted chemotherapeutic control of Trichuris trichiura and Ascaris lumbricoides in the total population (n = 11,479) of Montserrat, West Indies. The intervention programme involved the treatment with a single dose albendazole of all children aged 2-15 years (approximately 2,500) in seven sequential cycles at 4 monthly intervals. Infection status was monitored by an initial coprological survey of an age-stratified sample (11.5 per cent) of the population, and by surveys of smaller samples (4-5 per cent) after two (7 months), 4 (15 months), 6 (23 months), and 7 (29 months) cycles of treatment. The programme delivered treatment to > 90 per cent of the target population at each cycle. The overall prevalence of T.trichiura fell from 12.1 per cent at the initial survey to 1.4 per cent 29 months later. Similarly, the prevalence and intensity of infection was observed to fall in both the target group and the adults (>15 years) even though the treatment of the latter was not actively sought. The study demonstrates that child targeted chemotherapy is effective and can be practically implemented within an existing health and educational infrastructure (AU)

Nutritional status of preschoolers in a new settlement in Haiti - abstract

The three-year-old housing scheme at Petit Place Cazeau (PPC) was part of an urbanization programme set up by the government of Haiti. Satisfactory sanitary and housing conditions were provided for the 328 resident low-income working class families. The anthropometry of all the 6 to 36-month-olds were taken. Their medical history, socio-economic background and the prevalence of helminthiasis were investigated. According to the Gomez classification, 41.5 per cent of the children were normal, 38.1 per cent had grade 1 malnutrition, 15.5 per cent had grade 2 and 3.4 per cent had grade 3. The factors significantly associated with poor nutritional status were the following: previous hospital admission (p < 0.01), being female (p < 0.01), crowding (p < 0.05) and low family income (p < 0.05). The children's risk of having low weight for age and low weight for height (wasting), increased with age. Children whose fathers worked in the military tended to thrive well. A very low helminths prevalence was revealed. The prevalence of malnutrition among these preschoolers, although high, was lower than that observed in Haitian urban slums and on the national level. This survey identified children needing immediate treatment. It also provided the nearby clinics with baseline data and information about those at risk of malnutrition for the formulation of relevant and targeted intervention (AU)

Parasitic infections in young Jamaicans in different ecological Zones in the Island - abstract

A gastrointestinal tract parasitological study was done on 2,947 young Jamaicans drawn from all ecological zones and from all parochial divisions of the island where pica was practised by 6.9 percent. Generally, the prevalence was Trichuris 12.3 percent, Ascaris 9.5 percent, Hookworm 2.2 percent, Strongyloides 0.3 percent, Giardia 6.3 percent and E. coli 7.7 percent. Several other spp. of protozoans were recorded. Prevalence of Ascaris, Trichuris and Necator was significantly greater in upland than in lowland areas, both urban and rural, while the situation was reversed for Giardia infections. Greatest variations in prevalence were age-related. Ascaris and Trichuris reached peak prevalences of 15.3 percent and 20.5 percent, respectively, in 5-9 year olds, while Hookworm peaked later at 15-19 years of age. Suggestions are made for a national, even a regional, antihelminthic programme for the mass treatment of pre- and primary school age children. This would aim at the eventual eradication of helminthiasis in the region (AU)

A survey of intestinal helminths of well-cared-for dogs in Jamaica, and their potential public health significance

This study investigates the level of helminthic infestation in better-cared-for dogs in a middle-class community in suburban Kingston. A canine zoographic study was conducted, and fresh faecal deposits were collected and analysed for helminth life-cycle stages. The survey indicated that 73 percent (n=93) of households in the study area owned one dog or more (mean=1.4). Resident's attitudes towards canine management suggested that the dog population was, in general, restricted to the residential estate, and most owners claimed to have dewormed their dogs at least as young animals. Of 141 faecal specimens, 58 percent contained eggs or larvae of one or more of eight helminths: Uncinaria stenocephala (26 percent), Ancylostoma sp. (23 percent), Trichuris vulpis (9 percent), Toxocara canis (8 percent), Spirocerca lupi (6 percent), Strongyloides sp. (6 percent), Apophallus sp. (4 percent) and taeniids (1 percent). There was a high level of multiple infection in the host animals, with approximately one fifth of the infected samples containing three or more helminth types. Infection intensity was apparently low, but some dogs harboured heavy worm loads. (AU)

Parasitism and nutritional status of poor suburban Jamaican toddlers

A survey was conducted on 145 toddlers, 6-36 months of age, in a suburb in Kingston, Jamaica. The aim of the study was to measure the prevalence of and association between parasitism and nutritional status. Forty-two per cent were malnourished (<80 percent of standard weight for age), most commonly (76 percent) in the 12-17 month age group. Thirty-four per cent had one or more parasites, particularly Trichuris trichuria (21 percent) or Ascaris lumbricoides (19 percent). The peak prevalence of parasitism was among the 30-36 month old children (63 percent). Nutritional status did not differ between children with and without parasites. Most of them had light intensities of infection. Therefore, in this sample, there was no association between parasitism and nutritional status (AU)

Quantitative assessment of geophagous behaviour as a potential source of exposure to geohelminth infection

The common form of pica, geophagy, has direct adverse nutritional effects and also exposes children to soil-borne infection. Existing methods for assessing geophagy are either inappropriate for field use (radiology) or unreliable (reporting). A new method is described, based on the measurement of soil-derived silica in stools. More than 90 percent of silica is excreted within one gut transit period of ingestion. The amount excreted is proportional to the amount ingested. Faecal level of dietary silica (<2 percent dry wt stool) can be distinguished from levels due to geophagy (up to 25 percent dry wt stool). Studies in 2 children's homes in Jamaica showed that 33 percent and 66 percent of children were geophagous, ingesting up to 10g soil day-1. The geophagy of <20 percent of the children accounted for >60 percent of the total soil ingested. This overdispersion of exposure to soil-borne infection may contribute to the observed aggregation of geohelminth infection.(AU)

An island-wide survey for helminth parasites in Montserrat, West Indies - abstract

In August 1986, a three-year Parasite Control Programme, based on the targeting of treatment to children, was started in Montserrat. The first phase of this programme was an island-wide population survey to assess the current prevalence and intensity of helminth infection. From August to December 1986, faecal specimens were collected through all four district clinics of each of the three health regions, using an age-stratified protocol. Samples were processed by the KATO Thick Smear method. Twelve per cent (1,320 samples) of the island's population was sampled by the survey; of this, 12.1 percent were positive for Trichuris trichiura, 2.0 percent for Ascaris lumbricoides, and less than 1.0 percent for hookworm, Schistosoma mansoni and Enterobius vermicularis. Children are therefore most at risk of morbidity and are the major source of infection. The treatment of children on a national scale should give maximum results for the minimum of doses dispensed, i.e. chemotherapy should be cost-effective. This programme is supported by the Ministry of Health, Montserrat and Smith, Kline and French Ltd. (AU)

The human public health significance of well-cared for dogs in Jamaica - abstract

It is axiomatic that straying and neglected domestic fissipeds represent a health risk to the human population in tropical zones through transmission of parasitic infection. The object of this study was to investigate the level of helminthic infection in better-cared-for dogs in a middle-class suburban community in Jamaica and to analyse the data in the context of human health risk. The study area was located adjacent to the Mona Campus of the UWI. A canine demographic survey was conducted, and fresh faecal deposits collected and analysed, using the modified Ritchie formol-ether technique. Replication of faecal samples was minimised as far as possible. Seventy-three per cent (n=93) of the households owned one or more dogs (av. = 1.2; range = 1-4); there were 82 dogs resident in the study area. The attitude of residents towards canine management suggests that the dog population was, in general, restricted to the residential estate, and most owners claimed to have dewormed their dogs at least as young animals. The following represents the prevalence and intensity of canine helminthic infection as determined by coproscopic analyses of 141 specimens; the prevalence was 26 percent and mean intensity (epg/1pg) 19 for the parasite, uncinaria stenocephala; prevalence was 23 percent and mean intensity (epg/1pg) 16 for the parasite, ancylostoma spp.; prevalence was 9 percent and mean intensity (epg/1pg) 4 for the parasite, trichuris vulpis; prevalence was 8 percent and mean intensity (epg/1pg) 9 for the parasite, toxocara canis; prevalence was 6 percent and mean intensity (epg/1pg) 10 for the parasite, strongyloides stercoralis; prevalence was 6 percent and mean intensity 15 for the parasite, spirocerca lupi; prevalence was 4 percent and mean intensity 13 for the parasite, apophallus sp.; prevalence was 1 percent and mean intensity 1 for the parasite, taeniid eggs. Apart from Apophallus sp. and, possibly, the Taeniid organisms,all these parasites infect humans. The comparatively high prevalence and intensity, and the multiple infections in dogs which are otherwise well-cared for, indicates the need for comprehensive canine and environmental monitoring in order to control pollution by eggs and larvae of helminth parasites with the indiscriminate defaecation by dogs in peri-domestic areas (AU)

The role of environmental and host behavioural factors in determining exposure to infection with Ascaris lumbricoides and Trichuris trichiura

This study examines the contribution of environmental and host behavioural factors to the rate of reinfection with geohelminths in children. Preceeding the field study, two practical procedures for estimating these factors were developed and standardised: first, a method, based on existing procedures, for extracting parasite eggs from soil samples; and second, an original method, based on the assessment of soil-derived silica from faeces, for quantifying the rate of soil ingestion (geophagia) by the study children In the field study, exposure of Ascaris lumbricoides and Trichuris trichiura was examined longitudinally at two Places-of-Safety (childrens' homes) in urban Kingston, Jamaica. At the start of the study, existing helminth infections were chemotherapeutically removed from the study populations who then naturally reacquired infection during a three month exposure period. At the end of this period the infection intensity was determined. Exposure to infection was quantified by estimating the rate of ingestion of geohelminth eggs throughout the study period. This was achieved by determining the density of eggs in the soil and the rate of soil ingestion. The eggs of both geohelminths were recovered from the soil at both localities. The mean egg densities ranged from 0.05 to 4.0 epg-soil. The eggs were overdispersed at the other. The estimated rate of egg ingestion (of each species) was overdispersed among the two populations. At the home with young children of relatively uniform age, there was a significant correlation between the rate of egg ingestion and the reacquired infection intensity: subjects who have a high rate of egg ingestion have high worm burdens. This correlation was not significant for the population of older children who were heterogeneous in age. It is suggested that the older subjects may have shown more restrained geophagic behaviour. Additionally, those who were more homogeneous in age, and perhaps susceptible to infection, tended to show a more direct relationship between the rates of egg ingestion and parasite establishment. The study demonstrated that the number of parasites established in the host was of the same order of magnitude as the number of eggs ingested from soil. This implies that for the study populations, soil ingestion is a major source of geohelminth infection (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)

Faecal preservation with azide for diagnosis of helminthic infection by direct examination - abstract

Direct examination of a cleared sample of faeces is a simpl, reliable and quantitative method for the diagnosis of helminthic ingection. As such, it is preferred to the cumbersome and less precise formalin preservation and concentration techniques. These latter method have had to be used in experiments or surveys where ther is a delay in analysis because established direct techniques required fresh, undiluted faeces. This study tested sodium azide as a preservative of faeces for later direct quantitative egg counts. Gresh faeces from chilren known to have Trichocephalus trichuris infection were each pressed through a 100-mesh sieve to remove fibre. Quadruplicate 50 mg aliquots of fresh stool were prepared and examined by the Kato thick-smear technique (Martin and Beaver, Amer J. Trop. Med. & Hyg., 17:382-391, 1968) and the eggs counted. 1.5 to 2g of faeces was stirred thoroughly using a match-stick with 6 mg of powdered sodium azide in a 4 ml autoanalyser cup. The container was capped and stored at ambient temperature (circa 25§C). Egg counts were repeated at intervals. There was no evidence of fermentation of the stool. The mean egg counts of fresh stool and after preservation for 1, 2 and 4 week were 126 ñ 45, 128 ñ 44, 124 ñ 46 and 137 ñ 49. The standard deviation of the differences between the fresh samples and the preserved samples were 11, 10 and 16 respectively. None of these differences were significant. Stools from children containing T. trichuris, Necator americanus, and fertile and infertile Ascaris eggs were photographed whilst fresh and after azide preservation for up to 6 months. The morphology of the eggs appeared unchaged during this time. The azide preservation technique has made available direct quantitative analysis of stools in situations where stool must be preserved. It has been successfully used in a survey of the Turks and Caicos Islands where samples were transported to Jamaica for analysis (AU)