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[Study On The Status Of Helminthic Infections In Koreans]

This study was undertaken to evaluate the present status of intestinal helminthic infections in Koreans, from April 1967 through May 1969. The nationwidely collected stool specimens and scotch-tape anal swabs from primary schoolchildren, middle school students, draftees to army recruitment camp, soldiers and inhabitants of various parts of Korea were examined. The methods employed were Kato's cellophane thick smear technique and formalin-ether sedimentation technique in 40,581 for the prevalence rate of various intestinal helminths, scotch-tape anal swab technique in 8,585 for the prevalence rate of Enterobius vermicularis and by Stoll's dilution egg counting technique in 1,174 for the evaluation of the worm burden of some helminths. The results are as follows. I. Result of stool examination: 1. The positive rate of intesinal helminthes of any kind was 90.5% among 40,581. In rural people, it was 92.3% in average in contrast to 85.0% in Seoul inhabitants. 2. The infection rate of A. lumbricoides in 40,581 was 58.2%. It was higher in rural people 62.9% than in Seoul inhabitants and highest in 5-9 year-old group by age. 3. The infection of Trichocephalus trichiurus showed the highest prevalence rate in Koreans and it was 74.5%. No remarkable difference was observed between Seoul inhabitants(72.2%) and rural people(75.2%). The tendency of higher prevalence rate with the older age group was observed. 4. The infection rates of hookworm and Trichostrongylus orientalis in 40,581 examinations by cellophane thick smear were 5.1% and 5.8% respectively. But in 4,949 examinations for which refined cellophane thick smear technique and formalin-ether sedimentation technique were employed, the infection rates were turned out 17.6% in hookworm and 15.9% in T. orientalis. Although rural people showed higher infection rate of hookworm(18.8%) than Seoul inhabitants(13.8%), the reverse was true in T. orientalis infection rate(14.5% : 20.3%). Both kinds of infections were tend to be higher with the increase of age. 5. The infection rates of Clonorchis sinensis and Metagonimus yokogawai were 4.7% and 0.4% respectively. In both kinds of infections male showed higher infection rates than female and the tendencies of higher infection rate in the older age group were observed. The provinces which showed the higher infection rate of C. sinensis were South and North Kyongsang Do and North Cholla Do, all of which are provinces of southern part of Korea. Some endemic foci of M. yokogawai were noticed in South Kyongsang Do and South Cholla Do. 6. The infection rate of Taenia spp. by applying only the stool examination was 0.7% throughout the survey. No sex difference in infection rate of Taenia spp. was noticed, but in older age group it was increased. Cheju Do, the island of extreme southern part of Korea seemed the most endemic area and South and North Cholla Do were next in ranking of Taenia infection rate. The ova of Hymenolepis nana were observed in 0.2% and all of them were under the age of 20 except only one caes. The infection rate seemed higher in female (0.3%: 0.1%). No geographical difference was noticed except 1.1% of schoolchilderen and students of Cheju Do. II. Result of Scotch-tape anal swab technique for E. vermicularis infection. The infection rate of E. vermicularis in 8,585 urban and rural schoolchildren and rural inhabitants was 46.6%. Female (57.9%) had definitely higher infection rate than male (41.4%). The infection rate was significantly higher in rural people than Seoul schoolchildren. The exteme example was 79.7% in schoolchildren of South Cholla Do. III. Result of worm burden examination by Stoll's dilution egg-counting technique: 1. Among 1,174 examinations, countable(E.P.G.> 100) cases of A. lumbricoides were 745(63.5%) and the mean E.P.G. was 9,723. The mean E.P.G. in Seoul inhabitants was 5,835 in contrast to 10,820 in rural people. The age group of 5-9 showed the heaviest mean E.P.G., 11,337. 70.6% of 745 cases were less than 10,000 in E.P.G. which means light infection. 2. Countable cases by Stoll's technique for T. tr trichiurus ova were 63.5% and mean E.P.G. was 649. No difference between Seoul and rural inhabitants was observed. Grade I and II in which E.P.G. is less than 5,000 involve 99.3% of positive cases. 3. 91 cases (7.9%) in 1,174 were positive for hookworm ova by Stoll's technique and mean E.P.G. was 501. All cases were in Grade I and II which were less than 5,000 in E.P.G. Trichostrongylus orientalis was positive only in 25 cases (2.1%) by Stoll's technique and mean E.P.G. was 340. No cases were found to have more than 5,000 in T. orientalis E.P.G. 4. The mean E.P.G. of Clonorchis sinensis among the referred cases of clonorchiasis to Department of Parasitology, Seoul National University, was 9,416. On the other hand mean E.P.G. of C. sinensis was 21,376 among cases in the hyperendemic area of Kimhae, South Kyongsang Do, and 3,073 in cases from other various localities. Among referred clonorchiasis cases to our Department, 21.6% were turned out to have the E.P.G. more than 10,000. The cases who have the E.P.G. more than 10,000 in hyperendemic area, Kimhae were 40.7% and in other various localities were 9.1%

Journal Article↗

Incidence of parasites found on vegetables collected from markets and vegetable gardens in Taegu area.

A parasitic survey on vegetables collected from markets and vegetable gardens in Taegu area was conducted for the discovery of human parasitic eggs and larvae. Three species of vegetable, lettuce (Lactuca sativa), young radish(Raphanus sapivus) and Chinese cabbage (Brassica pekinensis) were selected. All vegetable leaves were washed with a hard brush, and then species of parasites and the approximate mean number of parasitic eggs per 200 grams of vegetable leaves were investigated. When vegetables collected from markets were examined, 5 species of parasite eggs (ascarid, trichurid, Trichostrongylus, Clonorchis and hookworms) and 2 larvae (filariform and rhabditoid ) were found. Furthermore, a number of eggs and larvae of undetermined species were also observed. Of the parasites studied, ascarid egg was found to be highest (49.0%), followed Trichostrongylus egg(18.0%) as well as filariform larva of hookworms (19.7%), and the least often observed was rhabditoid larva of hookworms(0.7%). The recovery rate of parasites among lettuce, young radish and Chinese cabbage collected from markets ranged from 23.2 to 91.9 percent and was similar to that from vegetable gardens, where Chinese cabbage showed the highest (91.1%) and lettuce being next(49.0%) in positivity of ascarid eggs. In the case of filariform larva, the rate of Chinese cabbage was twice as high as that of lettuce and young radish. There was a significant reduction in the rate of filariform larva, suggesting that a single washing of vegetables at the vegetable washing stand would reduce the number of parasites attached to vegetable leaves, when young radish washed at the stand was compared with that unwashed. In the monthly rate of parasites recovered from young radish, there was significant fluctuations between the eggs and filariform larva of hookworms. The mean number of ascarid egg per 200 grams of vegetable was 7.5 in young radishes, 3.1 in lettuces, and 0.5 in Chinese cabbages, in decreasing order. It is noteworthy that young radish contained more than 10 times more than Chinese cabbage. These results would seem to indicate that one of the important routes of infection is due to consumption of pickled young radishes in summer than pickled Chinese cabbages in winter.

Journal Article↗

[Demonstration Of Helminth Eggs And Larvae From Vegetable Cultivating Soil]

In order to clarify the contamination of vegetable gardens with human intestinal helminths, the soil samples were examined for the presence of eggs and larvae during the period from September 1973 to August l974. When soil samples collected from the vegetable gardens in Taegu were examined, four species of helminth eggs (ascarid, whipworm, hookworm and liver fluke) and a number of unknown eggs were found. Ascarid was found to be highest in the rate of detection(82.5%), followed by whipworm. The rates of hookworm, liver fuke and Trichostrongylus species were unexpectedly low. There was no difference between detection rate of vegetable gardens and that of vinyl green houses. However, the average number of helminth eggs detected from the soil of vinyl green houses was higher than the number of vegetable gardens. In the monthly incidence of ascarid eggs, the highest rate was found in September, and the least often was observed in August. While, the peak in the average number of the egg was encountered in August. There was no distinct trend in the monthly incidence of whipworm. However, it is likely that the detection number of whipworm per 100 gm of soil examined was relatively abundant in a period from May to August, and very little from October to April of next year. When the soil of vegetable gardens was divided into superficial, intermediate and deep layers and examined for presence of ascarid egg. The average number of the eggs found of the superficial layer was more abundant than those of the intermediate and deep layers, but the rate for the former was similar with the latter. In the demonstration of larval nematodes from the soil of vegetable gardens and vinyl houses, there found the filariform and rhabditoid larvae of hookworm and the larvae of Trichostrongylus species and unknown one. The majority of the larvae detected was belonged to unknown species, followed by hookworm larvae. The least was found in the rate of Trichostrongylus species. Generally, the filariform larva of hookwom could be detected during the hot season from May to August, but no larva was found in the winter. This suggests that the soil of vegetable gardens and vinyl green houses in Taegu is contaminated with human intestinal helminths.

Journal Article↗

Epidemiology of human ancylostomiasis among rural villagers in Nanlin County (Zhongzhou Village), Anhui Province, China: II. Seroepidemiological studies of the age relationships of serum antibody levels and infection status.

Anti-hookworm antibody serologic responses were measured in residents of an Anhui provincial Chinese village where Ancylostoma duodenale is the predominant hookworm. Antibody responses were measured against either soluble infective third-stage larval (L3) or adult antigens. Immunoglobulins of the IgG class, especially IgG4 correlated with both the prevalence and intensity of A. duodenale hookworm infections. In contrast, there was an inverse correlation with IgM, but no correlation with IgA or IgE. Circulating IgG4 antibody responses might serve as a surrogate marker for active A. duodenale hookworm infection.

Ancylostomiasis↗

Relationship of intestinal parasites to the environment and to behavioral factors in children in the Bolikhamxay Province of Lao PDR.

From March to July 1998 the infection rates of 732 children aged below 15 years were assessed. The investigation was conducted in selected villages of the Bolikhamxai Province in Lao PDR. Socio-economic conditions and behavioral pattern were studied. The three soil-transmitted helminths, Ascaris lumbricoides, Trichuris trichiura and hookworm were found with prevalence rates of 67.14, 17.49 and 12.83%, respectively. Infection rates with other intestinal parasites were negligible. Of the children investigated, 56.7% harbored one and 20.45% more than one parasite. Except for hookworms, no statistically significant differences were found between genders. The probability of being infected with A. lumbricoides is associated with living in mountainous areas. For hookworms, infection is associated with staying in the plains. A river in the vicinity of the village is linked with the probability of being infested with Trichuris trichiura. Not to belong to a family with the ability to own expensive items increases the probability by almost two times of getting infested with A. lumbricoides. Unhygienic behavioral factors were important in increasing the probability of suffering from A. lumbricoides and T trichiura infection. Behavioral factors did not seem to be related to hookworm infections. It was concluded that after mass treatment, besides promoting the construction of toilets, it is also important to improve personal hygiene so that a lasting impact on the infection rate of the most prevalent parasites in Lao PDR could be achieved. Measures to control parasitic infections do not have to be postponed until a marked improvement of the economic situation has occurred.

Adolescent↗

Efficacy of mebendazole and levamisole alone or in combination against intestinal nematode infections after repeated targeted mebendazole treatment in Zanzibar.

OBJECTIVE: To evaluate the efficacy of and resistance to mebendazole (500 mg) and levamisole (40 or 80 mg), alone or in combination, for the treatment of Ascaris lumbricoides, Trichuris trichiura and hookworm infections on Pemba Island - an area exposed to periodic school-based mebendazole treatment since 1994. METHODS: A randomized, placebo-controlled trial was carried out in 914 children enrolled from the first and fifth grades of primary schools. Stool samples collected at baseline and 21 days after treatment were examined by the Kato-Katz technique to assess the prevalence and intensity of helminth infection. FINDINGS: Efficacies of mebendazole and levamisole as single treatments against intestinal nematode infections were comparable with those in previous trials, but mebendazole treatment of hookworm infections gave significantly lower cure (7.6%) and egg reduction (52.1%) rates than reported in a study undertaken before the beginning of periodic chemotherapy (cure rate, 22.4%; egg reduction rate, 82.4%). Combined treatment with mebendazole and levamisole had a significantly higher efficacy against hookworm infections (cure rate, 26.1%; egg reduction rate, 88.7%) than either drug given alone. No difference in mebendazole efficacy was found in children who had been treated repeatedly compared with those who had not been treated previously. CONCLUSION: The overall efficacy of mebendazole against hookworm infections after periodic chemotherapy is reduced. The efficacy of benzimidazoles in chemotherapy-based control programmes should be monitored closely. Combined treatment with mebendazole and levamisole may be useful as a tool to delay the development of benzimidazole resistance.

Antinematodal Agents↗

School-based helminthiases control: I. A baseline study of soil-transmitted helminthiases in Nakhon Si Thammarat Province, Thailand.

A baseline study of soil-transmitted helminthiases was carried out in Nakhon Si Thammarat Province, southern Thailand. The study sites were Wat Krou Chou Primary School and nearby villages in Sichon district, and Wat Thang Phoon Primary School and nearby villages in Chalerm Phrakiat District. Surveys of the schoolchildren's stools were conducted by the Kato-Katz technique. The results showed that 23.7% of schoolchildren in Wat Krou Chou and 24.7% of those in Wat Thang Phoon were infected with soil-transmitted helminths, with a 24.1% overall infection rate. The major infection was hookworm (22.2% and 19.6%) and the minor one was trichuriasis, (2.9% and 8.7% respectively). The intensity of infection was similar in both schools, 85.7% and 90.2% respectively for light intensity hookworm. Schoolchildren with hookworm infection were not anemic. The hemoglobin value of children with hookworm infection was not significantly different from that of uninfected children. Data regarding the health behavior of children's parents in both schools were reported.

Female↗

Schistosoma japonicum and occult blood loss in endemic villages in Leyte, the Philippines.

Schistosoma japonicum has been related to anemia, but the mechanisms mediating this relationship remain unresolved. The primary objective of this study was to assess the role of occult blood loss in mediating S. japonicum-associated anemia after adjusting for age, sex, socioeconomic status (SES), and other helminth infections. The secondary objective was to identify intensity categories of risk for occult blood loss for Trichuris and hookworm after adjustment for the presence of other helminth infections. The role of occult blood loss in mediating S. japonicum-associated anemia was studied cross-sectionally in 729 individuals 8-30 years old in Leyte, The Philippines. Three stool specimens were examined in duplicate for helminth eggs. Hemoglobin, fecal occult blood loss, and anemia were measured and related to the presence and intensity of helminths. Multivariate models were made to adjust for confounding by other helminths and SES. In multivariate models, hemoglobin significantly decreased with increasing infection intensity of S. japonicum, hookworm, and T. trichuria (P < 0.0031, P < 0.0001, and P < 0.0001, respectively). Individuals with higher intensities S. japonicum and T. trichuria were significantly more likely to be fecal occult positive (odds ratio [OR] = 3.54; P = 0.008 and OR = 2.68; P = 0.013, respectively), although this was not true for individuals with hookworm. Additionally, individuals with higher intensities of S. japonicum, hookworm, and T. trichuria were all more likely to be anemic (OR = 3.7, P = 0.0002; OR = 5.3, P = 0.0003; and OR = 1.6, P = 0.021, respectively). It is likely that occult blood loss plays a role only at heavier intensity S. japonicum infections and some other mechanism, such as anemia of inflammation, may be contributing to anemia.

Adolescent↗

Relationship between intensity of soil-transmitted helminth infections and anemia during pregnancy.

A direct relationship exists between the intensity of hookworm infection and blood loss. Other parasites may also contribute to blood loss. Our objective was to assess the relationship between the intensity of soil-transmitted helminth infections and anemia in pregnant women in a highly endemic area of Peru. Recruitment occurred between April and November 2003. Overall, 47.31% of 1,042 women had anemia (hemoglobin < 11 g/dL), 47.22% were infected with hookworm and 82.25% with Trichuris. Prevalences of infections were not associated with anemia. However, those infected with moderate and heavy intensities of hookworm infection (OR = 1.84; 95% CI: 1.06, 3.17) and those with moderate and heavy intensities of both hookworm and Trichuris infections (OR = 2.13; 95% CI: 1.10, 4.13) were more likely to suffer from anemia than women having no or light intensities. These results support routine anthelminthic treatment within prenatal care programs in highly endemic areas.

Adolescent↗

Prevalence of multiple intestinal helminths among children in a rural community.

Impairment of physical and mental development has been identified as deleterious effects of helminthic infection. As a result, there have been concerted efforts to control this group of diseases especially among children who are most vulnerable. However, knowing the prevalence of multiple infections will strengthen or otherwise justify the use of broad spectrum antihelminthics in the prophylaxis and treatment of intestinal helminthes among children. This study was carried out in a farming community with no tarred access road, electricity or pipe-borne water. The diagnosis of intestinal helminthes was by Kato-Katz thick smear examination technique. One hundred and seventy stool samples from 88 male and 82 female children were examined. The mean age of the children was 8 +/- 1.6years. One hundred and sixteen of 170 (68.2%) of the study volunteers had one intestinal helminthic infection or the other. Co-infection by more than one helminth was not uncommon and this occurred in 49.1% of the infected population while 35.4%, 11.2% and 2.6% had double, triple and quadruple infections respectively. Ascaris lumbricoides and hookworm were the most common combinations observed in the study 52.6%, followed by the combination of A. lumbricoides and T. trichiura 17.5%. The triad of A. lumbricoides, hookworm and T. trichiura accounted for 12.3% among the multiply infected population. However, quadruple infection with A. lumbricoides, hookworm, T. trichliura and E. vernlicularis had 2.6% prevalence rate among the study population. Ascaris lumbricoides is the most prevalent among all the children, with a prevalence of 81.6%, 63.3% and 52.4% among children aged 12 -17years, 6-11 years and 0-5 years respectively. In conclusion, the presence of multiple infections especially of Ascaris lumbricoides and hookworm in almost 26% of the study population and multiple infections in 49.1% of the infected population justified the use of broadspectrum antihelminthics in the management of helminthiasis among school children of the rural community. Thus treatment and mass chemotherapy directed at school children will be a step in the right direction.

Adolescent↗

Strongyloides fuelleborni kellyi and other intestinal helminths in children from Papua New Guinea: associations with nutritional status and socioeconomic factors.

This survey examined the prevalence and intensity of Strongyloides fuelleborni kellyi and other intestinal helminths in children 5 years of age or under living near Kanabea, Papua New Guinea. Of 179 samples, 27% of the children tested positive for Strongyloides, with 81% of these children being a year or less in age. Overall, 68% of the children had one or more infections including Ascaris lumbricoides and hookworm (Necator americanus) as well as Strongyloides. Egg counts in the stools ranged from 100 to 98,300 eggs/ml for Strongyloides, 100 to 59,200 eggs/ml for Ascaris and 100 to 3400 eggs/ml for hookworm. There were significant associations between Strongyloides intensity and weight for age and weight for height such that children with higher intensities had, on average, lower z-scores. Relationships between the prevalence of helminth infections and socioeconomic factors were also observed. Logistic regression models showed that children living farther away from Kanabea (more than 2 hours' walking distance), in smaller households (5 or less people) and with uneducated mothers best predict children with Strongyloides. Two of these variables also predicted the presence of hookworm: maternal education and household size. However, in contrast to Strongyloides, a larger household size (6 or more people) was significantly associated with the presence of hookworm. House type was associated with the prevalence of Ascaris, with children living in houses with tin roofs being less likely to have Ascaris than those living in traditional houses. In addition, maternal education was associated with Ascaris intensity in those children with infection, such that the mean intensities were greater in children of uneducated mothers.

Animals↗

Longitudinal study on the health status of children in a rural Tanzanian community: parasitoses and nutrition following control measures against intestinal parasites.

Three repeated cross-sectional surveys were undertaken among children (1 month to 15 years) of a rural community in southeastern Tanzania. The study was part of a longitudinal project on the interactions among nutrition, parasitic infections and immunity within a primary health care programme emphasizing village health workers. All children underwent interviews and parasitological, anthropometric, anamnestic and clinical examinations. Out of 550-590 children examined each year, a cohort of 170 children could be followed for three consecutive years. Malaria was holo- to hyperendemic in the community, P. falciparum accounting for greater than 90% of the infections. The parasite and spleen rates were 88% and 67%, respectively, and the average enlarged spleen index was 2.0 among children from 2-9 years in 1982. Transmission of malaria was high and stable as indicated by a parasite rate of 80% among infants between 1 month and 1 year during the whole period of study. G. lamblia, hookworm (N. americanus), Strongyloides spp. and Schistosoma haematobium were highly prevalent and annual incidence rates were high, while Entamoeba histolytica, Ascaris and Trichuris were of minor importance. Prevalence and incidence of parasitic infections did not differ by sex. Multiparasitism was very frequent and less than 11% of all children were parasite-free in each year. Not a single child remained parasite-free for three consecutive years. An anthropometric assessment showed a high degree of stunting (35-71%) and a substantial proportion of wasting (3-20%). The growth potential was normal in girls and boys during the whole period of study. There were indications that malaria was the main contributory factor to growth retardation among young children. Hookworm infection did not significantly affect the packed-cell volume of the children, probably owing to the low intensity of infection. Due to the multiparasitism and the lack of parasite-free individuals, single-parasite and single-nutrient effects were difficult to unravel. A latrine campaign followed by a single mass treatment against hookworm (single oral dose of albendazole, 400 mg) and/or G. lamblia (single oral dose of ornidazole, 40 mg/kg) only temporarily affected the prevalence and incidence of G. lamblia, and only resulted in a decrease in the intensity of hookworm infections up to six months after the interventions. As the effects of the latrine campaign and a single mass treatment on the parasite load were only transient, no sustained impact on nutritional variables was observed.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗

Survey for soil-transmitted helminths in Asahan Regency, North Sumatra, Indonesia.

The survey on soil-transmitted helminthiasis was carried out in the three villages of Asahan Regency, North Sumatra, Indonesia, between October 1981 and December 1982. The prevalence rates of geohelminthiasis proved to be extremely high (average 97%) in the three villages and more than 70% harboured three or more helminths, especially Ascaris lumbricoides, Trichuris trichiura and hookworm. Necator americanus and Ancylostoma duodenale were detected in 61.1% and 52.2% of 835 fecal specimens, respectively. The effects of two anthelmintics, Combantrin and Trivexan, were essentially the same against A. lumbricoides and hookworm, although Trivexan was better than Combantrin against T. trichiura. The kinetic changes of parasitic infection in community after mass treatment were examined. Ten months after the first drug treatment, the incidence of Ascariasis or trichuriasis reverted nearly to pre-treatment level, while hookworm infection rate remained significantly low. Four months after the second mass treatment, the reinfection rate of A. lumbricoides was most prevalent followed by trichuriasis and hookworm infection. The reinfection rate (63.6%) of A. lumbricoides in children was about six times higher than that (10.4%) in adults at four month after the mass treatment. This study indicates that mass treatment with Trivexan at two month intervals for children and four month intervals for adults is necessary for the effective helminth control scheme in highly endemic areas of North Sumatra.

Adolescent↗

Intestinal helminths in an adult hospital population in the Eastern Highlands of Papua New Guinea: relationship with anaemia, eosinophilia and asthma.

The principal helminths present in adult medical patients at Goroka Base Hospital were hookworm, probably Necator americanus, (in 83%), Ascaris lumbricoides (in 14%) and Trichuris trichiura (in 16%). Enterobius vermicularis was also present (in 1.6%), and Hymenolepis nana in a single patient. Females were infected more frequently with Ascaris than males and they had higher egg counts of both Ascaris and Trichuris than males, and the difference was statistically significant. Haemoglobin values were significantly negatively correlated with hookworm egg counts in both males and females. Eosinophil counts were not correlated with either Ascaris or hookworm egg counts in either males or females, but relatively more males with eosinophilia had high hookworm egg counts when compared with normal males. Patients with asthma had significantly lower egg counts than other patients.

Adult↗

Prevalence of intestinal helminthic infections in Kao District, north Halmahera, Indonesia.

A parasitological survey was conducted on the inhabitants of six villages of Kao District, Halmahera Island, North Maluku, Indonesia, in July 1993. A total of 422 fecal samples were examined by using Kato-Katz thick smear, modified Harada-Mori culture and formalin ether concentration techniques. Seven nematode species, ie Ascaris lumbricoides, Trichuris trichiura, Necator americanus, Ancylostoma duodenale, Strongyloides stercoralis, Enterobius vermicularis and unidentified rhabditoids of free-living nature, were detected. Trematode and cestode infection was not proven. Necator americanus was the predominant species of hookworm. Soil-transmitted nematode infections were highly prevalent. Among the young inhabitants aged less than 15, positive rates of Ascaris, Trichuris and hookworm infections were 32.7, 52.7 and 68.6%, respectively. Among the people aged 15 or more, the positive rate for hookworm (85.9%) was much higher than that for Ascaris and Trichuris (13.5 and 40.5%, respectively). Egg count revealed that more than 90% of inhabitants with Trichuris or hookworm had light infections. The latrines in the surveyed area seemed to have only limited effects on the improvement of the parasitological status because the prevalence of Trichuris infections was much higher in a village where most houses were provided with latrines. These conflicting conditions were considered to have been caused by many factors including the inadequate structure of the latrines.

Adolescent↗

[Studies on the efficacy of albendazole candy for treatment of intestinal nematode infections].

A single dose of albendazole (candy) 100 mg and 100 mg qd for two days was given respectively to 135 and 321 children who were infected with Enterobius vermicularis. All cases were cured 3wk later according to perianal tape examination. The same drug of 150 mg qd and 200 mg qd for two days was administered respectively to residents with single or multi-infections of Ascaris, hookworm and Trichuris; the egg negative conversion rates of the two dosages were revealed to be 99.4% (466/469) and 99.8% (487/488) for Ascaris infection, 96.8% (91/94) and 94.3% (99/105) for hookworm infection, and 53.4% (228/427) and 76.3% (370/486) for Trichuris infection. The maximal numbers of worm expelled were 100 on d2-3, 88 on d3-5 and 588 on d2-4 for Enterobius, Ascaris and hookworm, respectively; whereas the discharged Trichuris were scarce, merely 4.3 in average. The results exhibited promising efficacy of the drug on Enterobius, Ascaris and hookworm infections, but not so on trichuriasis.

Albendazole↗

Field evaluation of an improved Kato-Katz thick smear technique for quantitative determination of helminth eggs in faeces.

A new method for the quantification of helminth eggs in faeces was developed, in which 7.5% nigrosin in 10% formaldehyde mixed with 5% eosin yellow in 10% formaldehyde was substituted for the malachite green solution used in the standard Kato-Katz method. This modification revealed the eggs of parasites like Schistosoma mansoni, Ascaris lumbricoides, Trichuris trichiura and hookworms distinctly. The slides made with this new technique could be accurately read within one hour. Faecal smears from 100 pupils in Kigungu, Entebbe, Uganda, were studied with both methods. The egg counts of S. mansoni, A. lumbricoides and T. trichiura by both methods were equal. The modified method, however, showed significantly higher hookworm egg counts (p < 0.001). Hookworm eggs were equal one hour after preparation of the slides as 16 hours after preparation. The intensity of infection detected was higher with the modified method for both S. mansoni and hookworms.

Ancylostomatoidea↗

Schistosoma and geohelminth infections in Mali, west Africa.

We report on the prevalence of schistosomiasis and geohelminth infections in Mali, Central West Africa, based on data from the National Schistosomiasis Control Programme of Mali (1982-1991) and from our recent surveys (1992-1993). Combined national figures and regional data are presented from both surveys. Schistosomiasis showed an overall prevalence of 30.1%, with lowest prevalence in Sikasso Region and highest prevalence in Segou Region. Ascaris lumbricoïdes (0.12%) and Trichuris trichiura (0.42%) were comparatively rare, but hookworm infections were more widespread (8.0%). No hookworm infections were detected in the arid northern Region and the highest prevalence (18.7%) was encountered in the humid south of the country. There was a significant positive relationship between the prevalence of hookworm infection and total annual rainfall per region. Overall the prevalence of concurrent infections with schistosomes and hookworms was significantly less than expected, although there were regional differences which were discussed in the light of local variations in climatic and other factors likely to affect transmission.

Adolescent↗