Intestinal parasitic infections among rural farming communities in eastern Sierra Leone

A study carried out in four rural, mainly farming villages in the Gorama Chiefdom, Kono District, Eastern Sierra Leone revealed that intestinal helminth infections are prevalent in this area of Sierra Leone. Out of the 1164 persons of all ages who were examined, 853 (73.5%) proved positive for at least one intestinal helminth infection. Ascaris lumbricoides was the most common helminth encountered (37.5%), followed by hookworms, 12.9%; Trichuris trichiura, 12.6%; Schistosoma mansoni, 5.6%; Strongyloides stercoralis, 3.8%; tapeworms 1.0%, and multiple infections were common. Adults used poorly built pit latrines, while children defecated indiscriminately and unsupervised around houses and in the nearby bush. In addition, in most of the villages, domestic water was obtained from polluted streams and rivers. Only one village had protected pipe borne water supply. The high prevalence of intestinal helminth infections in this area results from constant infection and reinfection caused by poor sewage disposal, poor environmental health, and the low socioeconomic status prevailing in these communities.     

Anaemia and intestinal parasitic infections among school age children in Behera Governorate, Egypt. Behera Survey Team

Anaemia is considered a serious public health problem in Egypt, although updated population-based data are lacking. Similarly, data on prevalence and intensity of infection with intestinal parasites, which are considered one possible cause of anaemia, are available only from small, unrepresentative sample surveys. The present research was implemented on an entire Governorate representative sample. The aim of the study was to assess the prevalence of anaemia and intestinal parasites in the area and to evaluate the role of each parasite in the epidemiology of anaemia among school age children. At the end of the survey, results of faecal analyses from direct smear and the Kato-Katz examination techniques were available from 1844 and 1783 children respectively, as well as haemoglobin levels measured by spectrophotometer from 1238 children aged 6-12 years. The prevalence of anaemia in the area was high (90 per cent), but very few serve forms were detected (< 2 per cent). Prevalence of intestinal parasites was high only for protozoa (Giardia intestinalis 24.7 per cent Entamoeba histolytica 17.5 per cent) and Schistosoma mansoni (20.7 per cent). From analysis of the results, Fasciola infection appeared to be highly endemic, even among children (3 per cent), and emerged as the factor most strongly correlated with low levels of haemoglobin (p < 0.0001). The effect of Fasciola on haemoglobin levels was related to the intensity of infection with this parasite. The role of S. mansoni as a risk factor for anaemia was supported by the present study. Among the protozoa, G. intestinalis was significantly correlated with low haemoglobin levels (p < 0.05). The present results substantiated similar findings from smaller studies. In future research, the relationship between Fasciola infection and anaemia needs to be studied with a well-controlled longitudinal design.     

Unusual cutaneous infectious and parasitic diseases

The cutaneous manifestations of thirteen unusual infections and parasitic diseases are described. Their geographic distribution, morphologic features of the causative organism, histopathologic changes, criteria for diagnosis, and treatment are included.     

Origin of the epidermis in parasitic platyhelminths

The epidermis of members of the major parasitic taxon Neodermata is distinctive among flatworms, being a syncytial, insunk, non-ciliated epidermis that develops through a wholesale replacement of larval epidermis at metamorphosis when the larva attacks a host. How it arose in evolution from what must have been a turbellarian-like ancestor is not immediately evident. While many turbellarian flatworms have also adopted a symbiotic way of life, the literature on ultrastructure of epidermis in these symbionts shows quite a variety of morphologies, many not so different from that of their free-living relatives. Various turbellarians do have syncytial or insunk epidermises or reduction of epidermal ciliation as is characteristic of the Neodermata, but co-occurrence in a single turbellarian of all features common to neodermatans has not been reported. Urastoma cyprinae, for example, which is ectosymbiotic on bivalves, has a ciliated cellular epidermis that is little different from what is known of epidermises of its free-living relatives. The endoparasitic Anoplodium hymanae, from the coelom of sea cucumbers, also bears a ciliated cellular epidermis, as is typical of many other rhabdocoels, but it shows marked phagocytic activity as well as incorporation of endosymbiotic bacteria. The closest similarity to neodermatan epidermis is that of the turbellarian Genostoma kozloffi, an ectosymbiont of the crustacean Nebalia: covering the bulk of the body is a non-ciliated syncytium with multiple branching connections to insunk nucleated portions, much as in epidermis of adult neodermatans and, on its ventral surface, is a field of ciliated cellular insunk epidermis resembling the epidermis of some larval neodermatans. Developmental clues to the origin of the neodermatan epidermis can be seen in turbellarian embryos. Before hatching, embryos of proseriate and triclad embryos go through 3 generations of epidermis, each replacing the next; 2 generations of epidermis are reported in the literature on rhabdocoel embryos. This process of replacement parallels the epidermal replacement that larval neodermatans undergo at metamorphosis. Ultrastructural study of developing acoel, polyclad and macrostomid embryos shows that they, too, have epidermal replacement and growth through immigration of deeper-lying cells, comparable to the processes seen in higher flatworms. Succession of distinct generations of epidermis in such animals as the proseriates, triclads and rhabdocoels is probably an adaptation to development of ectolecithal eggs, providing the means for the embryo to use yolk that resides in vitellocytes, outside its blastomeres. We propose that the Neodermata has taken advantage of this developmental mechanism, producing successive generations of epidermal cells even in its larval stages, to counter the defenses of hosts.     

Pathogenic and protective responses in parasitic infections

OBJECTIVE: To determine the degree to which a dual-lumen peripheral catheter prevented precipitation of solutions known to be incompatible due to pH during simultaneous infusion in an in vitro model. METHODS: An in vitro model was devised to simulate peripheral venous blood flow from an antecubital source to systemic circulation. Ondansetron was simultaneously infused with fluorouracil, aminophylline, sodium bicarbonate, and ampicillin sodium in concentrations reflective of clinical conditions into the Twin Cath 20/22 (the dual-lumen catheter used in this experiment). Study solutions were primed with the prepared drug solution and administered for 15 minutes. Phase I used Normosol-R as the diluent to gather preliminary data; phase II used human plasma. All samples were obtained immediately before the start of the infusion and at 5, 10, and 15 minutes during the infusion, and 5 minutes after the infusion. Samples were visually inspected at each time point for precipitation and analyzed in duplicate by the appropriate stability-indicating HPLC method (except for sodium bicarbonate). Compatibility was defined as no visual evidence of precipitation and no more than 15% mean change in final versus initial concentration. RESULTS: Phase I experiments showed immediate precipitation in Normosol-R within the venous flow. However, in phase II, because of the buffering capacity that plasma proteins add to plasma, no precipitation occurred. All the drug combinations used in this study have been reported to be incompatible at the concentrations tested; however, we detected no incompatibilities. CONCLUSIONS: The results of this study indicate that using a dual-lumen peripheral catheter, such as the Twin Cath, may allow solutions incompatible due to pH to be administered simultaneously.     

Diagnosis and management of parasitic hypereosinophilia]

ETIOLOGY: Helminth infestation of the digestive tract or organ tissues is a common and curable cause of high eosinophil counts. Parasite infestation should be the number one suspect in patients with hypereosinophilia. DIAGNOSIS: Clinical signs and epidemiology are suggestive. If the patient has travelled to the tropics, one should consider both exotic and cosmopolite parasites. LABORATORY TESTS: The causal agent can sometimes be identified by direct examination of tissue samples, depending on the localization. In practice however identification may be a difficult task when the level of infestation is low or the helminth is in a larval stage. The epidemiological situation, clinical features and results of serology tests must all be considered for diagnosis. ANTIHELMINTH TREATMENT (TEST): Clinical improvement after treatment can be a criteria for positive diagnosis. Normal eosinophil counts followed later by normal serology confirms the diagnosis.     

Pneumocystis carinii and parasitic infections in transplantation

Pneumocystis carinii remains an important pathogen in organ transplantation. New therapeutic options have been developed for the prevention and treatment of P. carinii pneumonia. Parasitic infections are recognized more frequently in potential organ donors or recipients as travel and technology for transplantation extend into endemic regions. Parasites important to transplantation are largely those that can replicate in humans and that cause infection, the intensity of which is regulated by immune mechanisms in the normal host. The spectrum of parasitic infections is likely to increase with improved diagnostic methods, expansion of intestinal transplantation, and xenotransplantation.     

Developmental switching in the parasitic nematode Strongyloides ratti

Strongyloides ratti is a nematode parasite of rats. It is able to undergo two types of development outside the host: heterogonic (free-living adults and sexual reproduction) and homogonic (direct larval development). Homogonic development has a number of similarities with the development of the dauer stage of free-living nematodes, including Caenorhabditis elegans. Using isofemale lines of the parasite, factors that control this developmental choice have been investigated. Isofemale lines can be selected for both heterogonic and homogonic development, but are still able to respond to environmental conditions. By using temperature shift experiments it has been possible to determine when larvae become developmentally committed. All larvae are developmentally committed after 24 h at 19 degrees C.     

Host movement and the genetic structure of populations of parasitic nematodes

Mitochondrial DNA (mtDNA) sequence data were used to compare the population genetic structures of five species of parasitic nematodes from three different hosts: Ostertagia ostertagi and Haemonchus placei from cattle, H. contortus and Teladorsagia circumcincta from sheep, and Mazamastrongylus odocoilei from white-tailed deer. The parasites of sheep and cattle showed a pattern consistent with high gene flow among populations. The parasite of deer showed a pattern of substantial population subdivision and isolation by distance. It appears that host movement is an important determinant of population genetic structure in these nematodes. High gene flow in the parasites of livestock also indicates great opportunity for the spread of rare alleles that confer resistance to anthelmintic drugs. All species, including the parasite of deer, had unusually high within-population diversities (averages of 0.019-0.027 substitutions per site between pairs of individuals from the same population). Large effective population sizes (Ne), perhaps in combination with rapid mtDNA evolution, appear to be the most likely explanation for these high within-population diversities.     

Surgical treatment of parasitic cysts

An interesting case with both antegrade and retrograde intussusception in an infant is reported. There was no apparent predisposing cause.     

Genetic resistance to parasitic infection

Intraventricular administration of carbachol can induce phase shifts in wheel-running activity in rodents, which depend on circadian phase and are mediated via muscarinic cholinergic receptors in Syrian hamsters. We studied the circadian variation in binding of [3H]-N-methylscopolamine ([3H]NMS), a hydrophilic muscarinic receptor antagonist, in micropunches obtained from the anterior hypothalamus and occipital cortex of Syrian hamsters housed in a 14:10 light:dark cycle. Binding sites were characterized on cells contained within 1 mm punches (obtained from slices 300 microm thick), using a method to selectively detect cell surface (functional) receptors. Atropine sulphate was used to determine nonspecific binding. Cortex showed a significant daily rhythm in [3H]NMS binding with a peak occurring late in the light phase and a trough at lights on, while the hypothalamus showed no detectable rhythm. Following suprachiasmatic nucleus (SCN) ablation or maintenance in constant darkness, the rhythm in the cortex was abolished. These findings suggest that photic information conveyed via the SCN is responsible for the receptor binding rhythm in the cortex. Autoradiographic studies ([3H]NMS; 2 nM, 3 weeks exposure) clearly revealed both M1 and M2 subtypes of muscarinic receptors in the region of the SCN and the visual cortex.     

Cytochrome P450 in parasitic protozoa and helminths

Cytochrome P450 has been demonstrated in flagellate and sporozoan Protozoa. In Plasmodium there is a correlation between chloroquine resistance and cytochrome P450 mono-oxygenase activity, but there is no evidence that the malarial parasite metabolises chloroquine by an oxidative mechanism. There is no evidence for cytochrome P450 in adult helminths (nematodes and platyhelminths) based on P450 content and mono-oxygenase activity with classical substrates, although low activities may be present in free-living larval stages.     

A guide to common parasitic diseases

The authors propose a highly effective method for isolation of lactoferrin from female colostrum. Lactoferrin is measured by the sandwich enzyme immunoassay. Its concentrations in the serum, urine, amniotic and cerebrospinal fluid in health are measured. The advantages of the method for lactoferrin purification and the practical significance of this protein are discussed.     

煤气鼓风机系统轴瓦再生的实践及应用

由于煤气介质的特殊性，特别是运行转炉煤气的鼓风机轴瓦的短时间失效，使轴瓦消耗很大。针对这一实际，结合设备检修情况，尝试将旧瓦重新浇注成新瓦，在煤气鼓风机上运行效果良好．经济价值凸现。     

Reproduction of nuclei in Pelomyxa palustris

Light and electron micrographs were made of nuclei in Pelomyxa palustris, a unicellular, multinucleated giant amoeboid organism. We analyzed 1019 pelomyxae and classified their nuclei according to their location in the nuclear cycle. The majority of organisms (56.3%) had interphase nuclei, some of which contained spores of mostly 1-3 microns in diameter. The nuclei had disintegrated in 1.3% of organisms that appeared to have no nuclei. The remainder (42.4%) had nuclei in the form of spores (1 to 10 microns spheroids) that were in various stages of development and growth. Mitotic figures were seen in some of them, with several chromosome pairs per nucleus. Interchromosomal fibers were seen at anaphase, and newly formed "young" interphase nuclei were observed.