Human Intestinal Helminth Research Articles

Rapid appraisal of human intestinal helminth infections among schoolchildren in Osh oblast, Kyrgyzstan

A population-representative lot quality assurance sampling (LQAS) survey was conducted in 2009 to determine the prevalence of intestinal helminth infections among schoolchildren across Osh oblast, Kyrgyzstan. The diagnostic approach consisted of duplicate Kato-Katz thick smears from a single stool sample and an adhesive tape test. A questionnaire was administered to identify risk factors for infections. A total of 1262 schoolchildren aged 6–15 years were recruited; 41% of them harboured at least one of the eight identified helminth species. The two most prevalent helminths were Ascaris lumbricoides (23.1%) and Enterobius vermicularis (19.3%). Lower prevalences were found for Hymenolepis nana (4.4%), Fasciola hepatica (1.9%) and Dicrocoelium dendriticum (1.8%). Washing raw vegetables was a protective factor with regard to A. lumbricoides infection (odds ratio (OR) = 0.69, p = 0.022); tap water was borderline protective (OR = 0.56, p = 0.057). Children of the richest families were at a lower risk of E. vermicularis infection than the poorest ones (OR = 0.41, p = 0.011). Sharing the bed with more than one person was a risk factor for E. vermicularis infection (OR = 2.0, p = 0.002). The results call for targeted interventions against intestinal helminths in Osh oblast. In a first stage, annual deworming of schoolchildren and other high-risk groups with albendazole or mebendazole should be implemented, and reliable diagnosis and additional anthelminthic drugs should be made available. Subsequently, transmission control including locally-adapted health education, improved water supply and adequate sanitation should become the central features.

Th2 cytokines are associated with reduced worm burdens in a human intestinal helminth infection.

Although T helper 2 (Th2) cytokines are known to be critical in the generation of protective immunity against intestinal helminths in mouse models, it is unclear whether they are important in natural immunity against gut helminthiases in humans. Therefore, we investigated cytokine production in ex vivo whole-blood cultures in response to Ascaris lumbricoides antigen and mitogen in a cross-section of a community where the parasite is hyperendemic. The intensity of A. lumbricoides infection was significantly reduced after age 11 years. Levels of cytokines associated with Th2 lymphocytes (interleukin [IL]-4, IL-9, IL-10, and IL-13) demonstrated an inverse relationship with intensity of A. lumbricoides infection only in individuals aged >11 years. Furthermore, the IL-9, IL-10, and IL-13 produced in response to parasite antigen were of primary importance in this relationship. These findings promote a role for Th2-mediated responses in the age-dependent reduction of intestinal helminth infections in humans.

Peripheral cytokine responses to Trichuris muris reflect those occurring locally at the site of infection.

The study of human cellular immune responses to parasite infection under field conditions is very complex. Often, the only practical site from which to sample the cellular responses is the peripheral blood. Sampling peripheral blood lymphocytes (PBL) relies on the assumption that these peripheral responses accurately reflect the immune responses acting locally at the site of infection. This is a particularly important point for the human intestinal helminth Trichuris trichiura, which solely inhabits the cecum and large intestine and so will stimulate a localized immune response. Using the well-defined model of T. trichiura, T. muris in the mouse, we have demonstrated that the dominant cytokine responses of the mesenteric lymph nodes (MLN) can be detected by sampling PBL. Resistant mice which mount a type 2 cytokine response in their MLN had PBL producing interleukin-4 (IL-4), IL-5, and IL-9, with negligible levels of gamma interferon (IFN-gamma). Conversely, susceptible mice which mount a type 1 cytokine response in their MLN had PBL producing IFN-gamma and negligible levels of type 2 cytokines. We have also shown that the PBL are capable of mounting a functional immune response against T. muris. PBL from immune mice were capable of transferring immunity to T. muris-infected severe combined immunodeficient (C.B-17 scid/scid) mice. Sampling PBL responses is therefore a viable option for monitoring human intestinal immune responses during T. trichiura infection in the field.

A survey of the microbial quality of wastewaters in Ismailia, Egypt and the implications for wastewater reuse

The occurrence of parasite ova, cysts and faecal coliforms in urban wastewater and their removal was determined after sewage treatment in gravel bed hydroponic (GBH) constructed wetlands receiving conventionally treated wastewater at Abu Attwa, Ismailia. Samples of raw wastewater and GBH influent and effluents were examined for eggs of intestinal helminths over two months in 1995. All raw wastewater samples were found to be positive for Ascaris lumbricoides but eggs of Hymenolepis spp, Trichuris spp, Ancylostoma duodenale and Toxocara spp were also detected in raw and conventionally treated wastewaters. In Ismailia, the concentration of eggs of human intestinal helminths in raw wastewater ranged from 6–42/L. In the influent to the GBH beds, the concentration of helminth eggs was reduced and ranged from 0–11/L; eggs of Ascaris were found in 28% of the samples. No helminth eggs were recovered from GBH treated effluents. Cysts of protozoa and faecal coliform bacteria were also removed by GBH beds to some degree. Raw wastewater contained cysts of the protozoa, Entamoeba coli, E. histolytica and Giardia spp. Although the density and diversity of species was reduced after treatment in the GBH beds, some amoebic cysts were found in the effluents. Faecal coliform removal averaged 2–3 logs during sewage treatment in GBH beds but effluents did not satisfy WHO guidelines for unrestricted irrigation. This survey indicates that GBH beds have the capacity to remove pathogens from wastewaters. Improvement in wastewater quality after GBH treatment satisfied WHO microbiological quality guidelines for restricted irrigation. With a retention time of 6h, GBH constructed wetlands have practical applications for wastewater treatment for safe reuse in Egypt.

A survey of the microbial quality of wastewaters in Ismailia, Egypt and the implications for wastewater reuse

The occurrence of parasite ova, cysts and faecal coliforms in urban wastewater and their removal was determined after sewage treatment in gravel bed hydroponic (GBH) constructed wetlands receiving conventionally treated wastewater at Abu Attwa, Ismailia. Samples of raw wastewater and GBH influent and effluents were examined for eggs of intestinal helminths over two months in 1995. All raw wastewater samples were found to be positive for Ascaris lumbricoides but eggs of Hymenolepis spp, Trichuris spp, Ancylostoma duodenale and Toxocara spp were also detected in raw and conventionally treated wastewaters. In Ismailia, the concentration of eggs of human intestinal helminths in raw wastewater ranged from 6–42/L. In the influent to the GBH beds, the concentration of helminth eggs was reduced and ranged from 0–11/L; eggs of Ascaris were found in 28% of the samples. No helminth eggs were recovered from GBH treated effluents. Cysts of protozoa and faecal coliform bacteria were also removed by GBH beds to some degree. Raw wastewater contained cysts of the protozoa, Entamoeba coli, E. histolytica and Giardia spp. Although the density and diversity of species was reduced after treatment in the GBH beds, some amoebic cysts were found in the effluents. Faecal coliform removal averaged 2–3 logs during sewage treatment in GBH beds but effluents did not satisfy WHO guidelines for unrestricted irrigation. This survey indicates that GBH beds have the capacity to remove pathogens from wastewaters. Improvement in wastewater quality after GBH treatment satisfied WHO microbiological quality guidelines for restricted irrigation. With a retention time of 6h, GBH constructed wetlands have practical applications for wastewater treatment for safe reuse in Egypt.

Preliminary survey on intestinal helminths in asahan area of North Sumatra, Indonesia.

Surveys on human intestinal helminths were conducted in Asahan Regency of North Sumatra, Indonesia, during a period between May 1979 and July 1980. The overall positive rates of eggs in fecal specimens were 77.5 per cent for Ascaris lumbricoides, 88.2 per cent for Trichuris trichiura and 60.5 per cent for hookworms. Necator americanus and Ancylostoma duodenale were detected in 75.7 and 29.1 per cent of 247 hookworm positive fecal specimens, respectively. Positive rates of eggs were correlated negatively in A. lumbricoides and positively in hookworms with ratios of rice field area to the gross area in each village. Candidates breeding pigs harbored higher rates of hookworm eggs than those without pig, while the former harbored lower rates of eggs of A. lumbricoides and T. trichiura than the latter. Positive rate of A. lumbricoides eggs was lower in rice farmers than that in fishermen while that of hookworm eggs was higher in the former than that in the latter. Contribution of sources of drinking water to positive rates of the three predominant helminth eggs was not clear.

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.

A Comparison Of The Efficiency Of The Three Egg Count Techniques

Usually egg count technique has been employed to know the intensity of infestation of human intestinal helminths and to elucidate the effects of anthelmintics. Comparing the three egg count methods-Stoll's egg dilution method, Beaver's direct smear method and FHK counting board method-the authors reached the following results: 1) As the result of application of the three methods to 75 Ascaris egg positives and 95 Trichocephalus egg positives, in the case of Ascaris eggs, the egg detection rate was 99 per cent by Stoll's method, 97 per cent by Beaver's method and was lowest by FHK method at 79 %. Meanwhile, in Trichocephalus eggs, Stoll's method revealed 92 %, Beaver's method 95 %, and FHK method 95 %, there being no noticeable differences. 2) With regard to EPG, in counting Ascaris eggs, Stoll's method showed a value closest to the actual number of eggs, and the value revealed by FHK method was smaller than the actual number. 3) As the result of comparing the coefficiencies of variation of the three egg counting methods, both in Ascaris eggs and Trichocephalus eggs, the FHK method showed the smallest, followed by Stoll's method and Beaver's method.

Significance of Human Intestinal Helminths in Eastern Kentucky

Significance of Human Intestinal Helminths in Eastern Kentucky

Human intestinal helminths obtained from autopsies in Djakarta, Indonesia.

Summary The incidence of intestinal worms was determined in 664 autopsies consisting of 586 Indonesian, 69 Chinese and 9 European, all residents of Djakarta. Hookworm was found in 89.4% among Indonesians, with an average worm load of 62.7; in 59% among Chinese with an average worm load of 39 and three times in Europeans with an average worm load of 17. The average worm load in men was higher than in women, although the incidence was about the same for both sexes. Necator americanus was most often found; Ancyclostoma duodenale, although frequently found, showed a low worm load; Ancyclostoma ceylanicum was found seven times and Ancyclostoma caninum once. Trichuris trichiura was found in a frequency of 86.9% in Indonesians, with an average worm load of 13.3; 70% in Chinese with an average worm load of seven. Ascaris lumbricoides was less frequent than T. trichiura. The incidence was 63.6% in Indonesians and 42% in Chinese, while the average worm load was six and four, respectively. Oxyuris vermicularis was also found in a high frequency: 39.4% in Indonesians, 36% in Chinese and 4 cases in Europeans. Strongyloides stercoralis and Trichostrongylus species were also found; however, no trematodes and cestodes were recovered from this series of autopsies.

Earth Worms as Test Objects for Determining the Value of Drugs to Be Used in Human Intestinal Helminth Infestations

Earth Worms as Test Objects for Determining the Value of Drugs to Be Used in Human Intestinal Helminth Infestations