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Ancylostoma duodenale [keywords]
- Impact of Helminth Diagnostic Test Performance on Estimation of Risk Factors and Outcomes in HIV-Positive Adults. [Journal Article]
- PLoS One 2013; 8(12):e81915.
Traditional methods using microscopy for the detection of helminth infections have limited sensitivity. Polymerase chain reaction (PCR) assays enhance detection of helminths, particularly low burden infections. However, differences in test performance may modify the ability to detect associations between helminth infection, risk factors, and sequelae. We compared these associations using microscopy and PCR.This cross-sectional study was nested within a randomized clinical trial conducted at 3 sites in Kenya. We performed microscopy and real-time multiplex PCR for the stool detection and quantification of Ascaris lumbricoides, Necator americanus, Ancylostoma duodenale, Strongyloides stercoralis, and Schistosoma species. We utilized regression to evaluate associations between potential risk factors or outcomes and infection as detected by either method.Of 153 HIV-positive adults surveyed, 55(36.0%) and 20(13.1%) were positive for one or more helminth species by PCR and microscopy, respectively (p<0.001). PCR-detected infections were associated with farming (Prevalence Ratio 1.57, 95% CI: 1.02, 2.40), communal water source (PR 3.80, 95% CI: 1.01, 14.27), and no primary education (PR 1.54, 95% CI: 1.14, 2.33), whereas microscopy-detected infections were not associated with any risk factors under investigation. Microscopy-detected infections were associated with significantly lower hematocrit and hemoglobin (means of -3.56% and -0.77 g/dl) and a 48% higher risk of anemia (PR 1.48, 95% CI: 1.17, 1.88) compared to uninfected. Such associations were absent for PCR-detected infections unless infection intensity was considered, Infections diagnosed with either method were associated with increased risk of eosinophilia (PCR PR 2.42, 95% CI: 1.02, 5.76; microscopy PR 2.92, 95% CI: 1.29, 6.60).Newer diagnostic methods, including PCR, improve the detection of helminth infections. This heightened sensitivity may improve the identification of risk factors for infection while reducing ability to discriminate infections associated with adverse clinical outcomes. Quantitative assays can be used to differentiate infection loads and discriminate infections associated with sequelae.
- In vitro Screening of Compounds against Laboratory and Field Isolates of Human Hookworm Reveals Quantitative Differences in Anthelminthic Susceptibility. [JOURNAL ARTICLE]
- Am J Trop Med Hyg 2013 Dec 2.
A panel of 80 compounds was screened for anthelminthic activity against a laboratory strain of Ancylostoma ceylanicum and field isolates of hookworm obtained from school children in the Kintampo North District of the Brong Ahafo Region of Ghana. Although the laboratory strain of A. ceylanicum was more susceptible to the compounds tested than the field isolates of hookworm, a twofold increase in compound concentration resulted in comparable egg hatch percent inhibition for select compounds. These data provide evidence that the efficacy of anthelminthic compounds may be species-dependent and that field and laboratory strains of hookworm differ in their sensitivities to the anthelminthics tested. These data also suggest that both compound concentration and hookworm species must be considered when screening to identify novel anthelminthic compounds.
- Baboons as potential reservoirs of zoonotic gastrointestinal parasite infections at Yankari National Park, Nigeria. [Journal Article]
- Afr Health Sci 2013 Jun; 13(2):252-4.
Zoonoses pose a risk to public health.To carry out the investigation of the prevalence of gastrointestinal parasites of baboons, Papio anubis, frequenting the Wikki base Camp in Yankari National Park, Nigeria.Formol-ether concentration technique was used to isolate parasite eggs and cysts from faecal samples.Parasites recovered were Ascaris lumbricoides, Ancylostoma duodenale, Strongyloides stercoralis, Fasciola sp, Schistosoma mansoni, Hymenolepis nana, and Trichostrongylus sp, and cysts of protozoan parasites Entomoeba histolytica, E. coli, and Iodamoeba butschii.Most of the parasites identified are known to have high pathologic involvement in humans, implicating the baboons as potential source and reservoirs for human zoonotic parasitic infections although further molecular work would be necessary to ascertain if these gastrointestinal parasites are the same strains that infect humans.
- Molecular Identification of Ancylostoma caninum Isolated from Cats in Southern China Based on Complete ITS Sequence. [Journal Article]
- Biomed Res Int 2013.:868050.
Ancylostoma caninum is a blood-feeding parasitic intestinal nematode which infects dogs, cats, and other mammals throughout the world. A highly sensitive and species-specific PCR-RFLP technique was utilised to detect the prevalence of A. caninum in cats in Guangzhou, southern China. Of the 102 fecal samples examined, the prevalence of A. caninum in cats was 95.1% and 83.3% using PCR-RFLP and microscopy, respectively. Among them, the prevalence of single hookworm infection with A. caninum was 54.90%, while mixed infections with both A. caninum and A. ceylanicum were 40.20%. Comparative analysis of three complete ITS sequences obtained from cat-derived A. caninum showed the same length (738 bp) as that of dog-derived A. caninum. However, the sequence variation range was 98.6%-100%, where only one cat isolate (M63) showed 100% sequence similarity in comparison with two dog-derived A. caninum isolates (AM850106, EU159416) in the same studied area. The phylogenetic tree revealed A. caninum derived from both cats and dogs in single cluster. Results suggest that cats could be the main host of A. caninum in China, which may cause cross-infection between dogs and cats in the same area.
- Intestinal parasitic infection in Bhil tribe of Rajasthan, India. [Journal Article]
- J Parasit Dis 2012 Oct; 36(2):143-8.
A total of 224 Bhil tribal individuals (115 males and 109 females) of different age groups inhabiting tribal rural areas of Udaipur district of Rajasthan, India were investigated for the prevalence of intestinal parasitic (protozoan and helminths) infections. Fresh stool samples of these tribal subjects were examined microscopically by direct wet smear with saline and 1 % Lugol's iodine and formaline ether concentration. Of these 116 (51.78 %) were found to be infected with diverse species of intestinal parasites. Male individuals showed relatively higher (56.52 %) prevalence of infection as compared to their counterparts (46.78 %). Out of 116 infected tribal subjects, 53 (23.66 %), 33 (14.73 %) and 30 (13.39 %) were infected with protozoan, helminths and mixed (protozoan + helminths) parasitic infections, respectively. Maximum number of parasitic infections occurred in the age group of 6-10 years (69.23 %) in both sexes. Among the intestinal parasites, Entamoeba histolytica was the commonest (14.73 %) followed by Entamoeba coli (8.92 %), Taenia solium (5.35 %), Ascaris lumbricoides (4.46 %), Hymenolepis nana (2.23 %), Ancylostoma duodenale (0.89 %), Strongyloides stercoralis (0.89 %), Trichuris trichiura (0.44 %) and Hymenolepis diminuta (0.44 %). Data pertaining to distribution of parasite species in different age groups, and variation in prevalence of their infection in relation to age and sex were also analysed statistically and found to be significant. Possible causes for variation in prevalence of protozoan and helminthic infection are discussed.
- Update on the mapping of prevalence and intensity of infection for soil-transmitted helminth infections in Latin America and the Caribbean: a call for action. [Journal Article, Research Support, Non-U.S. Gov't]
- PLoS Negl Trop Dis 2013 Sep; 7(9):e2419.
It is estimated that in Latin America and the Caribbean (LAC) at least 13.9 million preschool age and 35.4 million school age children are at risk of infections by soil-transmitted helminths (STH): Ascaris lumbricoides, Trichuris trichiura and hookworms (Necator americanus and Ancylostoma duodenale). Although infections caused by this group of parasites are associated with chronic deleterious effects on nutrition and growth, iron and vitamin A status and cognitive development in children, few countries in the LAC Region have implemented nationwide surveys on prevalence and intensity of infection. The aim of this study was to identify gaps on the mapping of prevalence and intensity of STH infections based on data published between 2000 and 2010 in LAC, and to call for including mapping as part of action plans against these infections. A total of 335 published data points for STH prevalence were found for 18 countries (11.9% data points for preschool age children, 56.7% for school age children and 31.3% for children from 1 to 14 years of age). We found that 62.7% of data points showed prevalence levels above 20%. Data on the intensity of infection were found for seven countries. The analysis also highlights that there is still an important lack of data on prevalence and intensity of infection to determine the burden of disease based on epidemiological surveys, particularly among preschool age children. This situation is a challenge for LAC given that adequate planning of interventions such as deworming requires information on prevalence to determine the frequency of needed anthelmintic drug administration and to conduct monitoring and evaluation of progress in drug coverage.
- Occurrence, prevalence and intensity of internal parasite infections of African lions (Panthera leo) in enclosures at a recreation park in Zimbabwe. [Journal Article]
- J Zoo Wildl Med 2013 Sep; 44(3):686-93.
A coprological survey was conducted to determine the types, prevalence, and intensity of infection of internal parasites in a population of captive African lions (Panthera leo) at a recreational game park in Zimbabwe. Individual fecal samples were collected on three occasions over a 4-month period from each of 30 lions (55%) out of 55 animals held. The samples were examined using flotation and sedimentation techniques to assess the presence and count of parasite eggs, oocysts, and cysts per gram of feces as well as larvae identification. The overall prevalence of helminth infections was 100% (30/30), and 80% (24/30) of fecal samples also were positive for protozoan parasite forms. Eggs of Ancylostoma spp. were found in the feces of 23 (76.7%) lions, Physaloptera sp. in 14 (46.7%) lions, Toxascaris leonina in 13 (43.3%) lions, Toxocara cati in 12 (40%) lions, and Gnathostoma spinigerum and Toxocara canis in 2 (6.7%) lions. Furthermore, eggs of Cylicospirura subequalis, Gnathostoma spp., Lagochilascaris major, Acanthocephalan and Linguatula spp. as well as larvae of Aelurostrongylus sp. were identified in the feces of one lion. Oocysts of five apicomplexan parasites and cysts of one mastigophoran protozoan parasite were recorded, namely, Cystoisospora leonina in 11 (36.7%) lions' feces, Cystoisospora spp. in 9 (30.0%) lions, Cystoisospora felis in 5 (16.7%) lions; Toxoplasma-like spp. in 5 (16.7 %) lions, and Giardia spp. in 8 (26.7%) lions. The majority of lions (28/30) showed mixed infections with different internal parasites, whereas only two animals had single parasite infections. The intensity of infection was relatively low. Some parasite forms observed and identified, such as Eimeria spp. oocysts, were spurious and probably originated from the prey species for the lions. Among the parasites identified were some of zoonotic importance that have health implications for at-risk personnel and visitors who get into contact with the animals.
- Ancylostoma ceylanicum metalloprotease 6 DNA vaccination induces partial protection against hookworm challenge infection. [Journal Article, Research Support, Non-U.S. Gov't]
- Acta Parasitol 2013 Sep; 58(3):376-83.
Hookworms are blood feeding intestinal nematodes that infect more than 500 million people and cause iron deficiency anemia. Infected children suffer from physical and cognitive growth retardation. Because of potential anthelminthic drug resistance, the need for vaccine development is urgent. Numerous antigens have been tested in animal models as vaccines against hookworm infection, but there is no effective human vaccine. We cloned a cDNA encoding Ancylostoma ceylanicum metalloprotease 6 (Acemep-6). Ace-MEP-6 is a protein with a predicted molecular mass of 101.87 kDa and based on computational analysis it is very likely to be engaged in food processing via hemoglobin digestion. Groups of hamsters were immunized with an Ace-mep-6 cDNA vaccine, either once or three times. Animals that were administered one dose developed high resistance (80%, p < 0.01) against challenge infection, whereas triple immunization resulted in no worm burden reduction. These results suggest that DNA vaccines can be powerful tools in ancylostomiasis control, although the mechanisms through which protection is conferred remain unclear.
- Ancylostoma ceylanicum, a re-emerging but neglected parasitic zoonosis. [Journal Article]
- Int J Parasitol 2013 Nov; 43(12-13):1009-15.
Although Ancylostoma ceylanicum is known to be an endemic and widely distributed hookworm of dogs and cats in Asia, its contribution to human morbidity as a potentially zoonotic hookworm remains largely unexplored. Since its discovery by Lane (1913) as a 'new parasite' of humans a century ago, the hookworm has been regarded as a 'rare' and 'abnormal' parasite and largely overlooked in surveys of human parasites. Recent molecular-based surveys in Asia, however, have demonstrated that A. ceylanicum is the second most common hookworm species infecting humans, comprising between 6% and 23% of total patent hookworm infections. In experimentally induced infections, A. ceylanicum mimics the clinical picture produced by the anthroponotic hookworms of 'ground itch' and moderate to severe abdominal pain in the acute phase. Natural infections with A. ceylanicum in humans have been reported in almost all geographical areas in which the hookworm is known to be endemic in dogs and cats, however for the majority of reports, no clinical data are available. Much like the anthroponotic hookworm species, patent A. ceylanicum adults can isolate within the jejunum to produce chronic infections that on occasion, may occur in high enough burdens to produce anaemia. In addition, the hookworm can act much like Ancylostoma caninum and be found lower in the gastrointestinal tract leading to abdominal distension and pain, diarrhoea and occult blood in the faeces accompanied by peripheral eosinophilia. Whether A. ceylanicum is capable of producing both classical hookworm disease and evoking morbidity through an uncontrolled allergic response in some individuals remains unascertained. Future investigations combining the use of molecular diagnostic tools with clinical and pathological data will shed further light on its role as a human pathogen. The control of this zoonosis necessitates an integrated and inter-sectorial "One Health" approach be adopted in communities where large numbers of dogs share a close relationship with humans.
- Secretion of protective antigens by tissue-stage nematode larvae revealed by proteomic analysis and vaccination-induced sterile immunity. [Journal Article, Research Support, Non-U.S. Gov't]
- PLoS Pathog 2013 Aug; 9(8):e1003492.
Gastrointestinal nematode parasites infect over 1 billion humans, with little evidence for generation of sterilising immunity. These helminths are highly adapted to their mammalian host, following a developmental program through successive niches, while effectively down-modulating host immune responsiveness. Larvae of Heligmosomoides polygyrus, for example, encyst in the intestinal submucosa, before emerging as adult worms into the duodenal lumen. Adults release immunomodulatory excretory-secretory (ES) products, but mice immunised with adult H. polygyrus ES become fully immune to challenge infection. ES products of the intestinal wall 4th stage (L4) larvae are similarly important in host-parasite interactions, as they readily generate sterile immunity against infection, while released material from the egg stage is ineffective. Proteomic analyses of L4 ES identifies protective antigen targets as well as potential tissue-phase immunomodulatory molecules, using as comparators the adult ES proteome and a profile of H. polygyrus egg-released material. While 135 proteins are shared between L4 and adult ES, 72 are L4 ES-specific; L4-specific proteins correspond to those whose transcription is restricted to larval stages, while shared proteins are generally transcribed by all life cycle forms. Two protein families are more heavily represented in the L4 secretome, the Sushi domain, associated with complement regulation, and the ShK/SXC domain related to a toxin interfering with T cell signalling. Both adult and L4 ES contain extensive but distinct arrays of Venom allergen/Ancylostoma secreted protein-Like (VAL) members, with acetylcholinesterases (ACEs) and apyrase APY-3 particularly abundant in L4 ES. Serum antibodies from mice vaccinated with L4 and adult ES react strongly to the VAL-1 protein and to ACE-1, indicating that these two antigens represent major vaccine targets for this intestinal nematode. We have thus defined an extensive and novel repertoire of H. polygyrus proteins closely implicated in immune modulation and protective immunity.