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PubMed2005

Giardia intestinalis and other zoonotic parasites: prevalence in adult dogs from the southern part of Mexico City.

The protozoan Giardia intestinalis is a mammalian-infecting parasite. It produces diarrhoea and malabsorption in its hosts. There is growing evidence that dogs could be reservoirs and play an important role in transmission. In Mexico, there are few data on the frequency of G. intestinalis. Therefore, we studied the small intestine of stray dogs, euthanazed at the "Culhuacan" Control Canine Centre, towards the end of 1997 and during the summer of 1998. We microscopically analysed intestinal contents and mucus samples taken every 3cm. During the cold season (winter), parasites were not found in 38/100 dogs, in contrast to 8/100 through the warm season. We found that 42/100 in winter and 51/100 in summer harboured G. intestinalis. To our knowledge, these G. intestinalis frequencies are the highest found in adult dogs worldwide. The results showed a rise in Ancylostoma spp. from 23/100 to 67/100 during the cold and warm seasons. Toxocara canis frequencies varied between 12/100 and 18/100, respectively. The data suggest that the probability of infection is higher during the hottest months compared to the coldest months of the year. Both puppies and adult dogs are highly infected. Dogs are reservoirs for zoonotic parasites; for this reason, it is imperative for humans to avoid fecal contamination in streets, public gardens and parks.

Ancylostoma↗
PubMed1989

Infectivity, growth, development and pathology of Echinostoma caproni (Trematoda) in the golden hamster.

Laboratory hamsters (Mesocricetus auratus) were experimentally infected with 75 +/- 15 metacercarial cysts of Echinostoma caproni. Worms were recovered from days 7 to 89 post-infection with eight to 90 (average 37) parasites in the small intestine. Worm wet weights averaged 0.85 mg at 10 days, 1.8 mg at 17 days, 3.4 mg at 45 days, and 7.7 mg at 89 days; average dry weights for the identical days were, 0.15, 0.30, 0.70 and 2.2 mg, respectively. The average body area of worms fixed in hot (80 degrees C) alcohol-formalin-acetic acid was 0.21 mm2 on day 3, 4.9 mm2 on day 10, and 17.7 mm2 on day 42. Clinical signs in some hamsters included progressive unthriftiness and watery diarrhea. Gross examination revealed enlarged lymphatic nodules along the length of the small intestine. The histopathological responses of hamsters to the parasite showed erosion of the intestinal villi with lymphocytic infiltration being the primary response; hemorrhagic areas were also observed in the villi.

Animals↗
PubMed1987

The pathogenesis of benzimidazole-resistant and benzimidazole-susceptible strains of Trichostrongylus colubriformis in the Mongolian gerbil (Meriones unguiculatus).

Mongolian gerbils were infected with either a benzimidazole-susceptible or a benzimidazole-resistant strain of Trichostrongylus colubriformis larvae. The comparative pathogenesis of both strains of T. colubriformis was investigated for 50 days post-infection. The gerbils infected with the drug-susceptible strain of the parasite showed lower survival rates, reduced body weights, higher parasite egg output and higher worm burdens than animals infected with the drug-resistant strain of parasite. There was also evidence of an enhanced hypoalbuminaemia and a more marked gastrointestinal plasma leak in the gerbils infected with the drug-susceptible strain of parasite. Scanning electron microscope examination of the small intestine showed signs of villus atrophy in both groups of infected gerbils.

Animals↗
PubMed1984

Local and systemic effects on inflammation during Eimeria nieschulzi infection.

Rats infected with Eimeria nieschulzi, a coccidium that inhabits intestinal epithelium, have a lower basal inflammatory state in their intestinal mucosa eight days postinoculation as reflected by a drop in mucosal peroxidase activity and a decrease in the number of granulocytes in the lamina propria. The reduction of systemic inflammation in infected rats was assessed from a reduction in the formation of granulation tissue around a sterile cotton string implanted under the abdominal skin of the hosts. This reduced inflammatory response, both locally and systemically, occurs during the development of gamonts by the parasite and the release of oocysts from the host. These results plus the presence of normal or slightly elevated numbers of granulocytes in peripheral blood lead to the conclusion that the parasite does not affect hematopoiesis but interferes with some phase in the directed migration of leukocytes to specific sites.

Animals↗
PubMed1998

Gastrointestinal helminths of loggerhead turtles (Caretta caretta) from the western Mediterranean: constraints on community structure.

Richness and composition of gastrointestinal helminth communities of 54 loggerhead turtles, Caretta caretta, from the western Mediterranean were interpreted from patterns of helminth exchange at 2 host taxonomic scales: exchange between marine turtles and other marine hosts and exchange within turtles. We predicted exchange of the former to be unimportant ecologically and evolutionarily because of the host phylogenetic distance. The absence of records of successful exchange at this host taxonomic scale confirmed that host physiological barriers seem to prevent contemporary parasite transfer between marine turtles and other sympatric hosts. Marine turtles also seem to exhibit an evolutionary association with their parasites largely independent from that of other marine hosts. Therefore, the composition of gastrointestinal helminth communities of marine turtles is predictably restricted to digeneans, nematodes, and aspidogastreans specific to these reptiles. At the scale of host species, helminth exchange among marine turtle species was expected to be significant. This was suggested by reports indicating a high proportion of parasites common to all sea turtle species. Mediterranean C. caretta harbored only 4 digenean species typical of marine turtles, and immature individuals of 1 digenean species accidentally acquired. Further, no relevant parasite exchange with other marine turtles was expected to occur because C. caretta is the only sea turtle species abundant in the western Mediterranean. Therefore, a predictable composition coupled with low species richness in infracommunities might be accounted for partly by constraints on parasite acquisition at both host scales. Host factors limiting parasite recruitment (mainly ectothermy and a wandering behavior) may also contribute to depauperate and isolationist infracommunities.

Animals↗
PubMed2003

Monoclonal IgA antibody-mediated expulsion of Trichinella from the intestine of mice.

To assess the potential role of IgA antibody in expulsion of the nematode of the genus Trichinella from the intestine, a panel of IgA monoclonal antibodies (mAbs) were produced from the mesenteric lymph node cells from BALB/c mice orally vaccinated with irradiated muscle larvae of Trichinella britovi. One IgA mAb, HUSM-Tb1, formed immunoprecipitates on the surface of live muscle larvae, and by immunohistochemistry reacted with their stichocytes and cuticular surface, but not with those tissues of the adult stage or newborn larvae. Intraperitoneal injection of BALB/c mice with this mAb 5 h before challenge conferred a high level of protection (more than 95%) against T. britovi infection, when 2.0 mg of specific IgA/20 g body weight was given to a mouse. The same treatment produced a similar effect in SCID mice lacking functional T- and B-cells, indicating no requirement of synergistc T-cell factors for the effect. Passive transfer of the mAb at the time of challenge or later showed less or no effect upon worm expulsion. It is concluded that the mucosal IgA response, when adequately induced, can impede the establishment of infective Trichinella parasites in the mouse intestine.

Animals↗
PubMed1977

Stenosis of the colon.

Seven cases of colonic stenosis due to an infectious, parasitic or ischemic origin are reported. Particular emphasis is laid on the need for an early differential diagnosis from Hirschsprung's disease.

Chloramphenicol↗
PubMed1987

Common internal parasites found in the stomach, large intestine, and cranial mesenteric artery of thoroughbreds in Kentucky at necropsy (1985 to 1986).

A total of 278 Thoroughbreds (less than 1 to 31 years old) were examined at necropsy (July 9, 1985, to Feb 2, 1986) in Kentucky for various internal parasites. Examination was not made of all the horses for each of the parasites. Specific parasites recovered from the stomach of foals (n = 30) and yearlings and older horses (n = 96) and percentage (in parentheses) of each age category infected, respectively, were as follows: Gasterophilus intestinalis 2nd instar (53% and 32%) and 3rd instar (37% and 24%); G nasalis 2nd instar (7% and 8%) and 3rd instar (7% and 10%); Habronema spp immature (7% and 13%); H muscae (3% and 8%); Draschia megastoma (3% and 5%) and lesions (0% and 2%); and Trichostrongylus axei (0% and 3%). Parasites in the large intestine included Anoplocephala perfoliata, which was found in the cecum of 30% of the foals (n = 87) and in 60% of the yearlings and older horses (n = 186). Probstmayria vivipara and immature Oxyuris equi were not found in the colon and rectum of any of the horses (n = 53 foals and n = 101 yearlings and older); mature O equi were not sought. Examination of the cranial mesenteric artery for Strongylus vulgaris revealed immature and/or mature specimens in 9% of foals (n = 87) and 14% of yearlings (n = 44); lesions of S vulgaris were present in 25% of foals (n = 87) and 34% of yearlings (n = 44).

Animals↗
PubMed2000

Strongyloides stercoralis: ultrastructural study of newly hatched larvae within human duodenal mucosa.

AIM: To investigate the ultrastructural features of the newly hatched larvae of Strongyloides stercoralis in human duodenal mucosa. METHODS: Duodenal biopsies from an AIDS patient were studied by transmission electron microscopy to investigate morphology, location, and host-worm relations of newly hatched larvae. RESULTS: Newly hatched larvae were found in the Lieberkuhn crypts within the tunnels formed by migration of parthenogenic females. Delimiting enterocytes were compressed. Release of larvae into the gut lumen was also documented. It was shown that both a thin and a thick membrane surrounded the eggs and larvae, as a tegument derived respectively from parasite and host. Segmentary spike-like waves, caused by contractures of worm body musculature, were observed on the surface of newly hatched larvae, and their intestinal lumen was closed and empty, with no budding microvilli. Immaturity of the cuticle and some degree immaturity of amphidial neurones were found, but there was no evidence of either immaturity or signs of damage to other structures. CONCLUSIONS: Newly hatched larvae of S stercoralis appear to be a non-feeding immature stage capable of active movement through the epithelium, causing mechanical damage. The tegument resulting from the thin and the thick membrane may protect the parasite and reduce any disadvantage caused by immaturity.

AIDS-Related Opportunistic Infections↗
PubMed1996

Prevalence and etiology of intestinal parasites in Lebanon.

As there are no studies done on the prevalence of intestinal parasites in Lebanon since 1967, this study was undertaken to reveal the current patterns of intestinal parasitic infestations in Lebanese patients from two geographic regions: Beirut and Tripoli. Analysis was based on 33,253 stool specimens examined at the American University of Beirut Medical Center (AUH) and 11,611 specimens examined at the Islamic Hospital (IH) in Tripoli over five and three years, respectively. The prevalence of intestinal parasites at AUH and IH were 8.47% and 45.35%, respectively (overall 18%). The prevalence in males vs females was almost the same; being 8.23% vs 8.74%, and 44.67% vs 45.88%, at AUH and IH, respectively. Multiple infections were noted in 8.8% and 3.5% of stool specimens at AUH and IH, respectively. Although 18 different types of parasites were encountered, the most common pathogenic parasites found at AUH vs IH were: Giardia lamblia (20.7% vs 10.5% of parasites found), Entamoeba histolytica (19.41% vs 1.25%), Taenia spp. (6.03% vs 4.08%) and Ascaris lumbricoides (2.09% vs 46.97%). The overall yearly or monthly prevalence of parasites recovered from both hospitals did not show clear seasonal patterns. Compared to developed countries, Lebanon still suffers from a high prevalence and a wide spectrum of intestinal parasites.

Animals↗
PubMed1992

Presence of non-Fab IgE binding molecules in the intestinal nematode parasite of mice Heligmosomoides polygyrus.

Unsuccessful attempts to identify serum parasite-specific immunoglobulin E (IgE) responses in mice following infections with the intestinal nematode parasite Heligmosomoides polygyrus prompted us to explore the possibility that IgE bound within the parasite antigen could account for the false-positive results observed. A live-worm ELISA was developed. Following incubation, irrelevant IgE monoclonal antibody to DNP, IgE present in normal mouse serum, as well as IgE in immune serum were independently identified within live adult worms in this H. polygyrus-modified ELISA. It was concluded that in addition to parasite-specific IgE binding to H. polygyrus, the parasite may attract both parasite-specific and non-parasite-specific IgE via non-Fab IgE-binding molecules.

Animals↗
PubMed2005

Intestinal coccidiosis in bluegill, Lepomis macrochirus.

Developmental stages of a coccidial parasite were observed in young-of-year bluegill (Lepomis macrochirus) from an impoundment lake in Norfolk County, Virginia. The fish were anorexic and lethargic. Necropsy examination revealed emaciated bluegill with little or no abdominal fat and no food in the stomach or intestines. Coccidia were present in the posterior intestine in moderately large numbers. Few sporulated oocysts were present, and identification to genus was not possible. Epithelial cell destruction, sloughing of the intestinal mucosa, and hemorrhage were associated with the developing coccidial parasites. Coccidia were not observed within other organ systems. No pathogenic bacteria were isolated from the fish tissues. Our findings indicate that intestinal coccidiosis may pose a significant health problem in young bluegill.

Animals↗
PubMed2000

Mucosal immunity against parasitic gastrointestinal nematodes.

The last two decades witnessed significant advances in the efforts of immunoparasitologists to elucidate the nature and role of the host mucosal defence mechanisms against intestinal nematode parasites. Aided by recent advances in basic immunology and biotechnology with the concomitant development of well defined laboratory models of infection, immunoparasitologists have more precisely analyzed and defined the different immune effector mechanisms during the infection; resulting in great improvement in our current knowledge and understanding of protective immunity against gastrointestinal (GI) nematode parasites. Much of this current understanding comes from experimental studies in laboratory rodents, which have been used as models of livestock and human GI nematode infections. These rodent studies, which have concentrated on Heligmosomoides polygyrus, Nippostrongylus brasiliensis, Strongyloides ratti/S. venezuelensis, Trichinella spiralis and Trichuris muris infections in mice and rats, have helped in defining the types of T cell responses that regulate effector mechanisms and the effector mechanisms responsible for worm expulsion. In addition, these studies bear indications that traditionally accepted mechanisms of resistance such as eosinophilia and IgE responses may not play as important roles in protection as were previously conceived. In this review, we shall, from these rodent studies, attempt an overview of the mucosal and other effector responses against intestinal nematode parasites beginning with the indices of immune protection as a model of the protective immune responses that may occur in animals and man.

Animals↗
PubMed1999

Pathological alterations caused by Anoplocephala perfoliata infection in the ileocaecal junction of equids.

The pathological alterations caused by Anoplocephala perfoliata in the ileocaecal junction of 28 equids slaughtered in an abattoir in Madrid (Central Spain) are described. The lesions were scored in grades based on the intensity of the damage and were related to the tapeworm number observed. The first grade (grade I) of alterations consisted of a slight enteritis associated with focal erosions observed in 43% of parasitized animals with low parasitic burden (1-26 tapeworms). The second grade (grade II) was a focal pseudomembranous enteritis, present in the ileocaecal junctions of 36% infected animals with moderate to high burden (23-188 tapeworms), and the third grade (grade III) was a regional necrotizing enteritis, present in the animals (21%) with the highest burden (72-248 tapeworms). The possible role of the lesions caused by this parasite in the aetiology of colic is discussed.

Animals↗
PubMed2003

Screening for intestinal parasites in recently arrived children from East Africa.

BACKGROUND: Intestinal parasitic carriage is common in East African populations with a wide spectrum of clinical severity. There are scant data on the rates of carriage in East African immigrants to Australia. This study describes the prevalence of and risk factors for intestinal parasite carriage among children recently arrived from East African countries. METHODS: Children aged 0-17 years, who attended an outpatient clinic, were born in East Africa and had immigrated since 1998 were eligible to participate. A single preserved stool specimen was collected for faecal microscopy, and blood tests were conducted for Strongyloides and Schistosoma serology, full blood examination and serum ferritin. RESULTS: One hundred and thirty-five children (median age 8.1 years, range 1.0-17.5) participated, of whom 133 (99%) provided a stool specimen. Parasites were detected in 50% of samples, and 18% of children carried a possibly pathogenic species. No child was symptomatic at diagnosis. Positive or equivocal serology occurred in 11% of children for Strongyloides and 2% for Schistosoma. Anaemia and iron deficiency were detected in 16% of all children. Those carrying an intestinal parasite were older (mean age 9.8 vs 7.4 years, P= 0.002) and less likely to be anaemic (odds ratio 0.37, 95% confidence interval 0.14-0.96) than those who were not carriers. CONCLUSIONS: Carriage of intestinal parasites is common among children from East Africa. Those carrying pathogenic organisms require treatment and follow up to ensure eradication. The results of this survey support the need for routine assessment of newly arrived immigrants from East Africa for intestinal parasites, anaemia and iron deficiency.

Adolescent↗