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Biomedical subjects

R C Ratard

Publications and source records attributed to R C Ratard.

At least 19 recordsLinked to original sources
PubMed2002

Spatial and intensity-dependent variations in associations between multiple species helminth infections.

Estimated associations between infections with different helminth species can be used to predict the proportion of a population infected with multiple species infections. This is an important measure of disease burden, as those with multiple infections are often at an increased risk of morbidity. In this paper, we investigate variation amongst the estimated associations between Ascaris lumbricoides, Trichuris trichiura and hookworm, over a number of different spatial levels among schoolchildren in Cameroon. Associations between species were largely homogeneous within districts, provinces and ecological zones, although variation between these regions was identified, implying that a single measure of association may not be appropriate in different epidemiological settings. Further data collected amongst school children in Kenya and Uganda were analysed, to assess the dependence of the associations on the intensity of infection. It was found that the strength of the association between A. lumbricoides and T. trichiura increased with intensity, such that those with more intense infections with one species are increasingly likely to harbour concurrent intense infections with the other species. The implications of these results are discussed in relation to the estimation of the disease burden due to multiple helminth species.

Adolescent↗
PubMed1994

Water contact and schistosomiasis infection in Kumba, south-western Cameroon.

Kumba, a town with a population of mixed background and socio-economic status, is a new and intense focus of schistosomiasis. Although fountains provide clean water, the population still uses the river and streams which cross the town for most of its bathing, laundry and swimming. A multivariate analysis indicated that a local subject's age, ethnic group, knowledge about schistosomiasis and the intensity of his or her contact with the river and/or streams were all significantly associated with schistosome infection. Surprisingly, a high level of knowledge about schistosomiasis was positively associated with the infection.

Adolescent↗
PubMed1994

Injuries to international petroleum drilling workers, 1988 to 1990.

Nonfatal work-related injury (NFI) rates are 49% higher among oil and gas field workers than among workers in all US industries combined, and these injuries are more severe (the rate of lost workdays in the oil and gas field services industry is 2.8 times that of all US industries combined). We analyzed the 1988 to 1990 incident reports submitted by drilling companies to the International Association of Drilling Contractors, an industry-wide international trade association representing 95% of the world's oil and gas drilling companies. We determined geographic and occupation-specific incidence rates by full-time equivalents, calculated per job category and year. Of the 5,251 reports, 5,218 (99.4%) were of NFI and 33 (0.6%) of fatal work-related injuries (FI). The overall NFI rate was 1.2/100 full-time equivalents and the overall FI rate was 7.5/100,000 full-time equivalents. Reported NFI in US territory was 4 times more common than in non-US territory. Reported FI in US and non-US waters were 4 and 5 times more common than on land, respectively. Three job categories--floormen, roustabouts, and derrickmen--accounted for 74% of the NFI and 64% of FI, with a rate ratio, compared with rates for all other occupations, of 10.5, 8.5, and 7.0 for NFI and 5.0, 9.4, and 4.0 for FI. Among all occupations, the body part most frequently injured was the upper extremity (1,631/5,218 [31%]). The four key NFI types and circumstances identified included the upper extremities "caught in" (857/5,218 [16%]),the back "strained" (592/5,218[11%]), the lower extremities "struck by" (538/5,218 [10%]), and the lower extremities injured while "slipping" (402/5,218 [8%]). Results of these analyses revealed several high-risk occupations in this industry and identified high-risk activities that can be targeted for further study.

Accidents, Occupational↗
PubMed1993

How to interpret fish consumption advisories.

The goal of this paper is to explain the guidelines used in Louisiana to issue advisories against consumption of chemically contaminated seafood or fish and explain some of the uncertainties encountered. In the absence of federal regulations the State had to develop its own approach. The concentrations resulting from Louisiana policies are generally low in comparison with the FDA tolerances and, thereby, well within reasonable limits justified by the need to protect populations with high fish consumption.

Animals↗
PubMed1993

Impact of Schistosoma haematobium infection and of praziquantel treatment on anaemia of primary school children in Bertoua, Cameroon.

There is some debate as to the extent to which Schistosoma haematobium haematuria may be the cause of anaemia. Our goal was to evaluate the impact of a single 40 mg kg-1 dose of praziquantel on anaemia. Since praziquantel does not reduce the hookworm intensity of infection (a major cause of anaemia in children in the area) changes in the prevalence of anaemia in the study population should be due only to the elimination of S. haematobium. Seven hundred and seventy-one primary schoolboys from Bertoua (East Cameroon) were divided into four groups: high infection, moderate infection treated with praziquantel or placebo, and non-infected. Haemoglobin concentrations of the children were determined at the onset of the study and 6 months after the praziquantel intervention. Mean haemoglobin concentrations were not significantly different for no infection or for mild or heavy infection by S. haematobium. A factorial analysis of variance using S. haematobium intensity of infection, malaria and intestinal parasite infections and age as independent variables and haemoglobin concentration as the dependent variable show that only age and malaria infection show a significant relationship with haemoglobin concentration. Despite treatment with praziquantel, all the children in the treatment groups had lower mean haemoglobins 6 months after intervention. A factorial analysis of variance using age, malaria infection and the treatment category as independent variables and the difference in haemoglobin concentration as the dependent variable shows that only malaria infection showed a significant relationship with haemoglobin concentration.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Distribution of hookworm infection in Cameroon.

Prevalence of hookworm infection was measured in Cameroon during a national survey carried out for a schistosomiasis research project. The survey provided a representative sample of the 10-19 year age group for each one of the 49 administrative divisions. Prevalences were low in the Extreme North province with a sahelian climate. Prevalences were high in the provinces with an equatorial climate except for the Centre province which is more developed. Regions with tropical Cameroonian climate, which receive a very heavy rainfall, showed the highest prevalences. Urbanized areas had lower infection rates than rural areas. It should not be assumed that hookworm prevalence is uniformly high throughout a tropical country. Since hookworm distribution shows wide variations, large control programmes should start with a thorough evaluation of the situation.

Adolescent↗
PubMed1992

[Measure and analysis of urinary bilharziasis incidence levels in the village of Douloumi (Cameroon)].

A study on urinary schistosomiasis was carried out in the village of Douloumi to evaluate the changes in transmission over a one year period. It showed a stable prevalence rate between 1987 and 1988. However close scrutiny of the different population groups showed this apparent stability was the result of several trends: 1) a high incidence among the resident cohort with increase of prevalence among the younger age groups; 2) a high prevalence among individuals emigrating and 3) a low prevalence among immigrants. Incidence is considered as a better tool to evaluate the recent transmission of schistosomiasis, however incidence evaluation depends on the sensitivity of the case ascertainment method. In this study, a comparison of prevalences among a resident cohort was a good substitute to incidence.

Adolescent↗
PubMed1992

The impact of Schistosoma haematobium infection and of praziquantel treatment on the growth of primary school children in Bertoua, Cameroon.

Our objective was to determine in a Cameroonian school population the effect of mild to moderate S. haematobium infection intensity on growth and development of children before and 6 months after praziquantel treatment. Previous studies have yielded contradictory results. Children from Bertoua schools were divided into four study groups: heavily infected (> 500 eggs 10 ml-1), moderately infected (1-499 eggs 10 ml-1) treated with praziquantel, a similar group treated with placebo, and an uninfected control group. Anthropometric measures--height for age per cent median (HAPM), and weight for age per cent median (WAPM)--were significantly higher among the uninfected children. Stepwise regression analysis showed that S. haematobium and Ascaris infections were the strongest predictors of the HAPM with hookworm and malaria infections playing a lesser role. Post treatment comparison of the praziquantel treatment group and the placebo group showed no significant differences for the anthropometric indicators except for mid-arm circumference. Longer observations of growth after treatment as well as monitoring of the rate of reinfection would be necessary to understand better the effect of S. haematobium on growth.

Adolescent↗
PubMed1991

A new focus of Schistosoma haematobium/S. intercalatum hybrid in Cameroon.

Terminal-spined schistosome eggs were found in both stool and urine specimens of a high proportion of infected individuals in Kinding Njabi, a village located in a savannah/forest ecotone of Center Province, Cameroon. Infections with terminal-spined schistosomes are not common in that region and first appeared in Kinding Njabi in the mid-1980s. The village population, determined by house-to-house census in 1986, was 345. Of 302 stool samples examined by a thick smear technique, 58 (19%) were positive, and of 320 urine samples examined by sedimentation, 40 (12%) were positive. Twenty-six (37%) of a total of 71 infected persons passed eggs in both stool and urine. Egg size distribution and morphology were similar to previous reports for Schistosoma haematobium/S. intercalatum hybrids. Bulinus forskalii was the only snail found during extensive surveys in and around Kinding Njabi; infected snails were recovered from several temporary habitats. This focus is of particular interest because it represents the first report of transmission of hybrid schistosomes outside of the hybrid zone. Interviews with villagers and local health officials suggest that schistosomiasis was introduced by immigrants from Loum, a town approximately 100 km southwest of Kinding Njabi, where S. haematobium, S. intercalatum, and their hybrid are known to exist. Results from snail host specificity studies using the Kinding Njabi parasite showed that stool-derived miracidia were compatible only with B. forskalii, the exclusive host for S. intercalatum in Cameroon. Urine-derived miracidia were compatible only with B. truncatus, a S. haematobium host in Cameroon.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

Schistosoma mansoni eggs in urine.

S. mansoni eggs show a preferential localization in stools with localization in urine being unusual. The factors that influence the appearance of S. mansoni in urine have not been studied extensively. The data presented here were collected during a schistosomiasis survey conducted in the northern provinces of Cameroon and a longitudinal community survey in Douloumi. As expected, the majority of individuals infected with S. mansoni had eggs in their stools. However, this is not always the case. Under special epidemiologic conditions, very high S. haematobium prevalence and much lower S. mansoni prevalence, urinary localization may become dominant. Individuals with high intensities of infection by S. mansoni do not have a higher probability for having S. mansoni in urine (there is no 'spill over').

Adolescent↗
PubMed1990

Human schistosomiasis in Cameroon. I. Distribution of schistosomiasis.

The status of schistosomiasis in Cameroon was examined in a nationwide survey of 5th grade schoolchildren. Five hundred twelve schools were surveyed; 19,524 urine and 22,166 stool samples were examined. The 3 northern provinces, which comprised 29% of the population, had 87% of all urinary and 82% of all intestinal cases. These provinces have a low seasonal rainfall. The presence of temporary bodies of water and of molluscan intermediate hosts adapted to this environment permits intense transmission of schistosomiasis haematobium and mansoni. In the rest of the country, the distribution of Schistosoma haematobium and S. mansoni was highly focal. S. intercalatum endemic areas were restricted to the equatorial forest and were small with low prevalences and intensities.

Adolescent↗
PubMed1990

Human schistosomiasis in Cameroon. II. Distribution of the snail hosts.

A nationwide survey for snail hosts of human schistosomes was carried out in Cameroon between 1985 and 1988. In total, 668 sites at 432 locations were sampled. In the arid, northern half of the country (tropical climatic zone), where both intestinal and urinary schistosomiasis are hyperendemic, Biomphalaria pfeifferi was the only Schistosoma mansoni host and Bulinus globusus and B. senegalensis the most common S. haematobium hosts. In that region, these snails occurred almost exclusively in temporary bodies of water. Taking into account results from a companion study on the distribution of schistosomiasis in humans, our results clearly show that temporary water bodies in the tropical zone are the principal foci of transmission. These findings disagree with commonly held views about schistosome transmission in Cameroon. B. truncatus, a S. haematobium host, was also present in the tropical zone but was found principally in perennial habitats. Although some perennial habitats were important transmission sites, they represent only a small portion of the overall problem. B. truncatus is the principal S. haematobium host in the wetter southern half of the country where schistosomiasis haematobium is highly focal. Biom. camerunensis was far more common than Biom. pfeifferi in the South but did not occur where S. mansoni prevalence rates were high; thus it appears to be a poor host. B. forskalii, the sole host of S. intercalatum in Cameroon, occurs widely throughout the country; however, the schistosome is restricted to a small region in the South.

Animals↗
PubMed1990

Distribution and preservation of Schistosoma mansoni eggs in stools.

Thirty-eight stool samples were preserved with sodium azide, 5 mg g-1 of stool. Results show that after 12 weeks, all the samples with S. mansoni eggs remained positive with good egg morphology. Egg counts show an average decrease of about 20%. Given the logistic advantages provided by using a small quantity of dry preservative this method is acceptable for mass prevalence surveys where sensitivity is not critical. The distribution of eggs in the stool was studied in 10 samples. Results showed no significant differences between centre and surface of the stools.

Analysis of Variance↗
PubMed1984

Evaluation and cleanup of a lead monoxide spill in Greenwood, Louisiana.

On April 25, 1983, 1,780 lbs of lead monoxide were dumped from a truck on a 1.5 mile stretch of highway. Cooperation between local and state police, health agencies and the Poison Control Center in Shreveport resulted in the evacuation of 120 residents, rapid cleanup by flushing and sweeping of the highway with subsequent scooping of surface soil from both sides of the highway, and setting up of an area lead screening clinic. Initial tests on about 114 residents and cleanup workers included blood lead and FEP analysis from capillary blood (fingerstick). Five of these were elevated, however, retesting with venous blood gave normal blood lead values. Complaints of exposed individuals centered on gastrointestinal upsets (nausea, vomiting, cramping) and upper respiratory irritation. The differences between clinical manifestations of acute and chronic lead poisoning will be emphasized.

Environmental Pollution↗