High risk behaviours and schistosomiasis infection in Kumba, South-West Province, 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 activities. A multivariate analysis indicated that a local subject's age, ethnic group, knowledge about schistomiasis and the intensity of his or her contact with the river and/or stream were all significantly associated with schistosome infection. Surprisingly, a high level of knowledge about schistosomiasis was positively associated with the infection. The potential risk of schistosome infection from water contact shows that; the younger age groups are at relatively high risk and male are at more risk than females. In terms of knowledge about schistosomiasis those aged 15-19 years had the highest means score and those aged >44 years the lowest, with males having a significantly higher knowledge than females. Age, as expected and as observed in most schistosomiasis surveys, was a major determinant of schistosomiasis infection. At similar level of exposure children are more susceptible to schistosomiasis probably because they lack the immunity built up in the adults as a result of previous infections. Most surface-water contact by the children, the group most affected by schistosomiasis, occurs during playing and swimming. It is unlikely that health education will have a significant impact on this recreational high-risk behaviour.

Surveillance for West Nile virus cases in Louisiana 2001-2004.

West Nile virus (WNV) was first detected in Louisiana during August of 2001. An outbreak of 204 human cases of neuro-invasive disease (NID) and 25 deaths occurred in 2002. In the 2 years following, lower numbers of human cases were identified (101 NID cases in 2003 and 84 in 2004) but intense localized foci were observed. The incidence of NID has been particularly high in the elderly (65 years and older). The distribution of West Nile cases has consisted of sporadic cases with a few very intense foci. Annually, human cases have occurred from June through December, with a peak number of new cases in August. As compared with other WNV serosurveys conducted in the United States, it appears that the WNV seroprevalence in Louisiana is not elevated.

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)

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.

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.

Population-based nutritional risk survey of pensioners in Yerevan, Armenia.

Armenia, a republic of the former Soviet Union, currently suffers from hyperinflation of its currency, a five-year country-wide blockade, and a war with Azerbaijan. Pensioners 60 years of age or older may be at high risk for significant nutritional deficits. We drew a stratified systematic sample (with a random starting point) of 456 pensioner names from all eight administrative regions in Yerevan, the capital of Armenia. We administered a questionnaire that gathered data including self-reported weight and height, demographic characteristics, living conditions, medical and dietary history, income, and aid received from various sources. The survey yielded 381 of 456 (84%) completed interviews. Ninety-one percent reported their diet had gotten worse during the past six months, including less variety (83%) and quantity (85%) of food. Seventy-six percent reported they did not have enough money to buy food, and 91% had cut the size of their meals or skipped meals. Forty-five percent reported a weight loss of > or = 5 kg in the previous year. After we adjusted for potential confounders, weight loss of > or = 5 kg was associated with illness affecting eating (adjusted odds ratio [OR] = 2.2, 95% confidence intervals [CI] = 1.4, 3.4), not having received aid (adjusted OR = 2.2, 95% CI = 1.1, 4.1), and cutting the size of or skipping meals (OR = 2.7, 95% CI = 1.1, 6.7).(ABSTRACT TRUNCATED AT 250 WORDS)

Estimation of the number of cases of schistosomiasis in a country: the example of Cameroon.

An estimate of the number of schistosomiasis infections in Cameroon was based on a statistically representative national prevalence survey carried out in the entire country. The number of cases of infection by Schistosoma haematobium was estimated to be 393,900, and 419,600 for S. mansoni, a total of 813,500. Taking into account the dual infections the total number of cases was 719,100 (95% confidence interval: 392 900-1 027,800). A current World Health Organization estimate extrapolating from the results of limited epidemiological surveys showed 2,239 591 cases for Cameroon, an estimate 3.1 times higher than the more accurate estimate based on the national survey. Schistosomiasis being a focal disease, prevalences observed in limited foci are not representative of regional prevalences. Prevalence survey data in the literature are biased toward reporting only positive results. Therefore extrapolations made on limited surveys may lead to an overestimation of the number of cases of schistosomiasis.

Ascariasis and trichuriasis in Cameroon.

A national survey of Ascaris lumbricoides and Trichuris trichuria was carried out in Cameroon on more than 22,000 children from a random sample of 512 schools. Prevalence rates of both A. lumbricoides and T. trichuria infection were very low in the tropical zone (below 5%). They increased markedly in the equatorial zone, Guinea-type climate, to 60-85% for A. lumbricoides and 85-95% for T. trichuria. In the equatorial zone with Cameroon-type climate, prevalences were slightly lower: 50-70% for A. lumbricoides and 70-90% for T. trichuria infections. Environmental conditions are the main factors explaining these differences. Other factors (altitude, population density and urbanization) were not important. The entire population of villages selected from distinct climatic zones of Cameroon were also examined. The age group distribution of A. lumbricoides and T. trichuria infections indicated acquisition early in life, reaching a peak in early childhood, followed by a stable prevalence rate.

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.

[Measure and analysis of urinary bilharziasis incidence levels in the village of Douloumi (Cameroon)]. / Mesure et analyse des taux d'incidence de la bilharziose urinaire au village de Douloumi (Cameroun).

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.

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.