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PubMed2005

Parasitological rebound effect and emergence of pyrimethamine resistance in Plasmodium falciparum after single-dose sulfadoxine-pyrimethamine.

Intermittent preventive treatment for malaria in infants (IPTi) is a promising malaria control strategy. However, mass preventive treatment for malaria inherently bears the risk of increasing drug resistance. Here, the effect of single-dose sulfadoxine-pyrimethamine (S-P) versus placebo on Plasmodium falciparum infection rates was assessed in 63 selected infants who were aparasitemic at enrollment. An increase in the proportion of infants with isolates exhibiting drug resistance-associated mutations was detected 3 weeks after drug application in the treatment group. S-P, in the setting of IPTi, appears to cause a parasitological rebound effect in which there is selection of drug-resistant parasites for a short period after drug clearance.

Animals↗
PubMed2007

Influence of consecutive-day blood sampling on polymerase chain reaction-adjusted parasitological cure rates in an antimalarial-drug trial conducted in Tanzania.

We assessed the influence that consecutive-day blood sampling, compared with single-day blood sampling, had on polymerase chain reaction (PCR)-adjusted parasitological cure after stepwise genotyping of merozoite surface proteins 2 (msp2) and 1 (msp1) in 106 children in Tanzania who had uncomplicated falciparum malaria treated with either sulfadoxine-pyrimethamine or artemether-lumefantrine; 78 of these children developed recurrent parasitemia during the 42-day follow-up period. Initial msp2 genotyping identified 27 and 33 recrudescences by use of single- and consecutive-day sampling, respectively; in subsequent msp1 genotyping, 17 and 21 of these episodes, respectively, were still classified as recrudescences; these results indicate a similar sensitivity of the standard single-day PCR protocol--that is, 82% (27/33) and 81% (17/21), in both genotyping steps. Interpretation of PCR-adjusted results will significantly depend on methodology.

Animals↗
PubMed1995

Clinical, parasitologic, and immunologic observations of patients with hydrocele and elephantiasis in an area with endemic lymphatic filariasis.

Hydrocele and elephantiasis, major clinical manifestations of bancroftian filariasis, are thought to share a common pathogenesis. The characteristics of 121 patients with hydrocele or elephantiasis in Leogane, Haiti, were compared: 39% of 57 men with hydrocele and 3% of 64 persons with lymphedema of the leg were microfilaria-positive (P < .001). Circulating filarial antigen, presumably from the adult worm, was detected in 15 (43%) microfilaria-negative men with hydrocele and 9 (15%) microfilaria-negative persons with leg edema (P = .004). Microfilaria-positive men had lower levels of filaria-specific IgG1 and hydroceles of significantly smaller volume and shorter duration than did microfilaria-negative men; hydrocele volume was inversely associated with microfilarial density (P = .001). In contrast, filarial antigen but not microfilariae was associated with filaria-specific IgG4 and decreased lymphocyte proliferation. Antigen status was not associated with severity of leg edema. In this filariasis-endemic area, men with hydrocele are more immunologically and parasitologically heterogeneous than are persons with elephantiasis.

Adolescent↗
PubMed2004

Effects of specific treatment on parasitological and histopathological parameters in mice infected with different Trypanosoma cruzi clonal genotypes.

The goal of this study was to verify the effect of specific treatment on parasitological and histopathological parameters in mice experimentally infected with different Trypanosoma cruzi clonal genotypes. Twenty cloned stocks were selected, representative of the whole phylogenetic diversity of the protozoan and belonging to the clonal genotypes 19 and 20 (T. cruzi I) and 39 and 32 (T. cruzi II). The stocks were inoculated in 40 BALB/c mice divided into four groups: (i) treated with benznidazole, (ii) treated with itraconazole and (iii and iv) untreated control groups (NT) for each drug, respectively. Seven parameters related to parasitaemia curves and histopathological lesions were analysed. Four during the acute phase (AP) and three during both the AP and chronic phase (CP) of infection. Statistical comparison between benznidazole-treated and NT groups for the biological parameters showed significant differences for all genotypes. Benznidazole treatment led to lower patent period, maximum of parasitaemia, day of maximum parasitaemia and area under the parasitaemia curve for all genotypes analysed. Percentage of positive haemoculture during AP and CP was lower for genotypes 19 and 32. Tissue parasitism (TP) and inflammatory process (IP) during AP were lower for genotypes 19 and 32, respectively. In general, itraconazole treatment induced a smaller reduction in these same parameters between treated and NT animals in relation to benznidazole treatment. Our results indicate that phylogenetic divergence among T. cruzi clonal genotypes must be taken in account in chemotherapy and studies dealing with all aspects of the parasite and the disease.

Animals↗
PubMed1979

Keep warm stools cold: on the status of parasitology.

Although the prevalence of parasites has decreased in some areas, no parasite has been eliminated, and the current literature indicates that parasitic diseases continue as a major cause of morbidity. In addition to endemic forms, imported parasitic diseases are being seen more frequently because of increased world travel and immigration. The high infection rates of intestinal helminths and protozoa being found in this country suggest the public is at risk of acquiring a parasitic disease. This report reviews the status of medical parasitology relative to laboratory methods and parasites prevalent in the United States.

Adolescent↗
PubMed1996

Clinical and parasitological responses after up to 6.5 years of ivermectin treatment for onchocerciasis.

There are plans to use mass treatment with ivermectin to clear all Africa of the worst ocular and cutaneous effects of onchocerciasis. However, there remains uncertainty about the most suitable treatment regimen and the likely effects of ivermectin on onchocercal skin disease. We have followed 948 subjects for over 6 years in a double-blind, randomized, controlled study of ivermectin for onchocerciasis in a hyperendemic focus in Sierra Leone. Using an intention-to-treat analysis we found a microfilarial prevalence of 16% 6 months after up to 4 annual doses of ivermectin, and 13% prevalence in the group receiving up to 10 doses of ivermectin at 6-monthly intervals. Microfilarial loads were well suppressed in both groups, but repopulation data suggest that adult female worms are still alive and fecund, strongly underlining the need to continue treatment. A clear effect of ivermectin was demonstrated on itching, with about one-third of cases being alleviated. Significant reductions in the prevalence of serious hyperkeratosis, and possibly dyspigmentation (leopard skin), were noted, but not for any other onchocercal skin lesion. Six-monthly and annual treatment regimens with ivermectin were equally effective in terms of dermatological and parasitological impact.

Adolescent↗
PubMed2000

Ten years of research activities on tropical parasitology of dromedaries, cattle, and small ruminants in Mauritania.

In the past, the essential part of the activity of the parasitology laboratory of the Centre National d'Elevage et de Recherches Vétérinaires (CNERV) was represented by diagnostic work that enabled the construction of an inventory of local parasitic fauna and a good collection of specimens. However, the small and irregular number of samples each year, led us to switch our activities in 1990 toward work that could better justify the existence of CNERV. We started work on applied research topics, such as tick-borne diseases, helminthology (nemathelminths and plathelminths), and trypanosomosis. These results were valorized through scientific publication and communication at international meetings. The most valuable information was conveyed to herders.

Animals↗
PubMed1995

Disseminated Encephalitozoon (Septata) intestinalis infection in a patient with AIDS: novel diagnostic approaches and autopsy-confirmed parasitological cure following treatment with albendazole.

Encephalitozoon intestinalis is a recently described microsporidian which causes intestinal and disseminated infections in severely immunocompromised patients with AIDS. Preliminary data suggest that albendazole can be an effective therapy for patients with E. intestinalis infection. However, relapses have been reported following treatment in some cases. These results were based upon examination of cytologic, biopsy, or stool samples with an inherent sampling bias. This report documents the first postmortem evaluation of a patient with E. intestinalis infection treated with albendazole. Antemortem microsporidial diagnosis was performed on nasal mucosal smear and duodenal biopsy specimens by electron microscopy and a newly developed indirect fluorescent-antibody method based upon in vitro cultivation of the organism. This case represents the initial report of using nasal cytologic specimens for ultrastructural and antibody-based species-level diagnosis of microsporidiosis. Following successful treatment of this infection with albendazole, the patient died of other causes. A thorough autopsy examination failed to reveal the presence of E. intestinalis in any tissue, providing confirmatory evidence for a complete parasitological cure with albendazole.

Acquired Immunodeficiency Syndrome↗
PubMed2006

Incidence and time course of Leishmania infantum infections examined by parasitological, serologic, and nested-PCR techniques in a cohort of naive dogs exposed to three consecutive transmission seasons.

Most experience in the comparison of diagnostic tools for canine leishmaniasis comes from cross-sectional surveys of dogs of different ages and breeds and in cases with unknown onset and duration of leishmaniasis. A longitudinal study was performed on 43 beagle dogs exposed to three transmission seasons (2002 to 2004) of Mediterranean leishmaniasis and examined periodically over 32 months through bone marrow microscopy and nested PCR (n-PCR), lymph node culture, serology (immunofluorescent-antibody test), and evaluation of clinical parameters. Starting from January 2003, the highest rate of positives was detected by n-PCR at all assessments (from 23.3% to 97.3%). Sensitivities of serologic and parasitological techniques were lower but increased with time, from 15.8% to 75.0 to 77.8%. Some dogs that tested positive by n-PCR but negative by other tests ("subpatent infection") remained so until the end of the study or converted to negative in subsequent assessments, whereas all dogs with positive serology and/or microscopy/culture ("asymptomatic patent infection") exhibited progressive leishmaniasis; 68% of them developed clinical disease ("symptomatic patent infection") during the study, at 7 (range, 3 to 14) months after being positive to all tests. Postexposure infection incidences were high and were significantly different between 2002 and 2003 exposures (39.5% and 91.7%, respectively). The time course of infection was highly variable in each dog, with three patterns being identified: (i) rapid establishment of a patent condition (0 to 2 months from detection of infection); (ii) a prolonged subpatent condition (4 to 22 months) before progression; and (iii) a transient subpatent condition followed by 10 to 21 months of apparent Leishmania-negative status before progression.

Animals↗
PubMed1999

Parasitological survey on wild carnivora in north-western Tohoku, Japan.

In the winter of 1997-1998, we collected parasitological data from 60 wild carnivora in the north-western part of Tohoku region, Japan. These included 7 foxes (Vulpes vulpes japonica), 20 raccoon dogs (Nyctereutes procyonoides viverrinus), 29 martens (Martes melampus melampus), 3 weasels (two Mustela sibirica itatsi and one M. nivalis namiyei), and one Japanese badger (Meles meles anakuma). Roundworms (Toxocara canis in foxes and Toxocara tanuki in raccoon dogs), hookworms (Ancylostoma kusimaense and Arthrostoma miyazakiense) and Molineus sp. in the small intestine were the most prevalent in foxes and raccoon dogs. In martens, Aonchotheca putorii in the stomach, Concinnum ten in the pancreatic duct, Molineus sp. and Euryhelmis costaricensis in the small intestine were the most prevalent. Collected parasites include some new helminth species for this region or Japan; the strobilar stage of Taenia polyacantha from foxes, Pygidliopsis summa from a raccoon dog, Eucoleus aerophilus, A. putorii, and Soholiphyme baturini from martens.

Animals↗
PubMedDate not supplied

Parasitological and serological studies on amoebiasis and other intestinal parasitic infections in the rural sector around Recife, northeast Brazil.

Parasitological examinations were carried out during July to December, 1989, on 485 inhabitants of four villages in São Lourenço da Mata, 25 km northwest of Recife, Pernambuco, Brazil. Approximately 99.6% of the inhabitants were infected with at least one species of intestinal parasites. A high prevalence of Schistosoma mansoni (82.1%), hookworm (80.2%) Trichuris trichiura (69.9%), Ascaris lumbricoides (61.9%) and Entamoeba coli (36.7%) infections were demonstrated. Test tube cultivation revealed that the most common species of hookworm in this region was Necator americanus (88.4%), and also that the prevalence of Strongyloides stercoralis was 5.8%. Three hundred and thirty-four sera were serologically examined for amoebiasis by the gel diffusion precipitation test (GDP) and enzyme-linked immunosorbent assay (ELISA). No positive reaction was observed in all sera as examined by GDP, while 24 sera were positive by ELISA.

Adolescent↗
PubMedDate not supplied

Hemocultures for the parasitological diagnosis of human chronic Chagas' disease.

With the purpose of standardization of an hemoculture technique presenting a higher positive rate in the parasitological diagnosis of chronic Chagas' disease in patients with reactive serology (IFT, HA, CFT) the following schedule was used. Thirty ml of venous blood was collected with heparin and the plasma was separated by centrifugation (2.000 rpm/30'). The packed cells were washed with LIT medium or PBS which was then removed by centrifugation (2.000 rpm/15'). This material was sampled in 6 screw-tubes 18 x 200 with 6 ml of LIT medium and incubated at 28 degrees C. These incubated cultures at 28 degrees C were examined after 15, 30, 45 and 60 days. When the hemoculture was not immediately processed after blood collection, the plasma was removed and the sediment enriched with LIT medium and preserved at 4 degrees C. The Xenodiagnosis was performed according to Schenone's method used here as a reference technique. Among the various groups of patients examined by both techniques the best results obtained were: 55.08% of positivity for hemocultures against 27.5% for xenodiagnosis (X2 = 4.54, p = 0.05), with a tube positivity of 26.6%. Recommendation for screening trials of drug assays is the repetition of method on a same patient 2 or more times in different occasions, as used in xenodiagnosis.

Chagas Disease↗
PubMedDate not supplied

The hamster (Mesocricetus auratus) as experimental model in Chagas' disease: parasitological and histopathological studies in acute and chronic phases of Trypanosoma cruzi infection.

This research characterizes the acute and chronic phases of Chagas' disease in hamster through parasitological and histopathological studies. The acute phase was achieved with 44 young hamsters injected intraperitoneally with 100,000 blood trypomastigotes of Benedito and Y strains of T. cruzi. The chronic phase was induced in 46 hamsters injected intraperitoneally with 35,000 trypomastigotes of Vicentia, Benedito and Y strains. Animals were sacrificed at regular intervals of 24 hours of acute phase and from the 3rd to the 10th month of infection of chronic phase. In the acute phase, parasites were easily recovered from all animals and there was an inflammatory reaction characterized by mononuclear and polymorphous leukocyte infiltration of variable degree in the majority of tissues and organs, specially in the connective loose and fatty tissues, smooth muscle myocardium and skeletal muscle. In the chronic phase the lesions occurred in the same tissues and organs, but the inflammatory response was less severe and characterized by mononuclear infiltration mainly with focal or zonal fibrosis in the myocardium. In 50% of infected animals parasites were found in myocardium and recovered from pericardic, peritoneal and ascitic fluids in some animals. Signs of heart failure, sudden death and enlargement of bowel were observed regularly. We concluded that the hamster is an useful model for Chagas' disease studies.

Acute Disease↗
PubMed2003

Serological and parasitological study and report of the first case of human babesiosis in Colombia.

A study on the presence of Babesia in humans was performed in Puerto Berr o (Latitude 6.50deg. Longitude: -74.38deg. River: Magdalena. Area: 74.410km , Colombia-South America). Indirect immunofluorescence, thin and thick blood smears were used to study 194 individuals. Patients were grouped according to their risk-factors for Babesia infection: (group 1) individuals with fever, chills, sweating and other malaria-type symptoms; (group 2) symptomatic and asymptomatic individuals from local cattle ranches, which were enrolled in an active form, and (group 3) workers from the local slaughterhouse. Seven individuals were serologically positive for Babesia: Three individuals presented IgM antibodies against B. bovis, while one had IgG against this species; one individual had IgM against B. bigemina, another had IgG and a third both IgM and IgG against this species. Only one individual was parasitologically positive for Babesiaand serologically positive for Babesia bovis (IgM 1:64)

Adolescent↗
PubMed2003

[Parasitological and morphological characteristics of Brazilian strains of Schistosoma mansoni in Mus musculus].

Aiming to determine parasitological and morphological differences between Brazilian strains (CMO, CM and BE) of Schistosoma mansoni the following parameters were studied: prepatent period, kinetics of egg releasing in feces, intestinal oogram, infectivity and the morphology of adult worms. No statistical difference (p>0.05) was found regarding the mean prepatent period (44 and 46 days) and infectivity (26% and 29%). All strains showed a higher concentration of trapped eggs in the small intestine than large intestine (p<0.05). All characteristics of the reproductive system and suckers of male worms presented significant differences (p<0.05). CMO strain was smaller in all measurements. Females showed significant differences (p<0.05) in the larger diameter of the eggs, in the area and perimeter of the spine egg and in the oral sucker area. We conclude that differences in strains can be expressed even when the strains have been cycled for several generations under laboratory conditions.

Analysis of Variance↗
PubMed2005

[A comparative study of the parasitological techniques: Kato-Katz and coprotest].

Parasitological diagnosis should be appropriately conducted with high sensitivity and specificity so that intestinal parasite can be detected as the specific treatment depends on this result. A comparative study was developed to evaluate the concordance between the Kato-Katz and coprotest methods in the detection of helminthes in 332 individuals in Pedro de Toledo. A significant difference was found in the case of the Trichuris trichiura - 16.2% with the Kato-Katz method and 7.5% with the coprotest method. Therefore, the positive and negative samples of the coprotest method were compared with the number of eggs per gram of feces (epg) obtained by the Kato-Katz method. When the coprotest method was negative, 65 epg of Trichuris trichiura were found by the Kato-Katz method and when the coprotest was positive the epg according to the Kato-Katz were far higher, 199 epg, which demonstrated that the coprotest was inferior to the Kato-Katz method regarding low intensity infections.

Ancylostomatoidea↗
PubMedDate not supplied

Canine visceral leishmaniasis in Rio de Janeiro, Brazil. Clinical, parasitological, therapeutical and epidemiological findings (1977-1983).

Forty dogs from the periphery of the city of Rio de Janeiro were studied. All dogs where diagnosed as positive for leishmaniasis either parasitologically and/or serologically. Among them, 19 came from areas where only Visceral Leishmaniasis (VL) occurs (Realengo, Bangu, Senador Camará). Clinical signs of the disease were seen in 36.8% of the cases, including emaciation - 100%, lymphadenopathy and depilation - 85.7%. The other 21 dogs came from an area (Campo Grande) where both diseases (VL, and American Cutaneous Leishmaniasis - ACL) occur. Clinical signs of the disease, mainly cutaneous or mucocutaneous ulcers were seen in 76.2% of the cases. Leishmania parasites were found in 39 cases: 22% in viscera, 42.5% in viscera and normal skin and 35% in cutaneous or mucocutaneous ulcers. All the Leishmania stocks isolated from dogs which came from Realengo, Bangu, Senador Camará (VL area), and from Campo Grande (VL + ACL area) were characterized as L. donovani (except in one case) according to their schizodeme, zymodeme and serodeme. The only stock characterized as L. b. braziliensis, was isolated from the lymph node of a dog from Campo Grande with visceral disease and without skin lesions. Antimony therapy attempted in eight Leishmania donovani positive dogs was unsuccessful.

Animals↗
PubMedDate not supplied

Evaluation of the rabbit as a model for Chagas' disease. I. Parasitological studies.

In order to investigate the value of the rabbit as an experimental model for Chagas' disease, 72 animals have been inoculated by intraperitoneal and conjunctival route with bloodstream forms, vector-derived metacyclic trypomastigotes and tissue culture trypomastigotes of Trypanosoma cruzi strains Y, CL and Ernane. In 95.6% of the animals trypomastigotes had been detected at the early stages of infection by fresh blood examination. The course of parasitemia at the acute phase was strongly influenced by the parasite strain and route of inoculation. At the chronic phase parasites had been recovered by xenodiagnosis and/or hemoculture in 40% of the examined animals. The xenodiagnosis studies have shown selective interactions between the T. cruzi strains and the four species of vectors used, inducing significant variability in the results. The data herein present are consistent with the parasitological requirements established for a suitable model for chronic Chagas' disease.

Animals↗