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P M Schantz

Publications and source records attributed to P M Schantz.

At least 19 recordsLinked to original sources
PubMed2006

A molecular phylogeny of the genus Echinococcus inferred from complete mitochondrial genomes.

Taxonomic revision by molecular phylogeny is needed to categorize members of the genus Echinococcus (Cestoda: Taeniidae). We have reconstructed the phylogenetic relationships of E. oligarthrus, E. vogeli, E. multilocularis, E. shiquicus, E. equinus, E. ortleppi, E. granulosus sensu stricto and 3 genotypes of E. granulosus sensu lato (G6, G7 and G8) from their complete mitochondrial genomes. Maximum likelihood and partitioned Bayesian analyses using concatenated data sets of nucleotide and amino acid sequences depicted phylogenetic trees with the same topology. The 3 E. granulosus genotypes corresponding to the camel, pig, and cervid strains were monophyletic, and their high level of genetic similarity supported taxonomic species unification of these genotypes into E. canadensis. Sister species relationships were confirmed between E. ortleppi and E. canadensis, and between E. multilocularis and E. shiquicus, regardless of the analytical approach employed. The basal positions of the phylogenetic tree were occupied by the neotropical endemic species, E. oligarthrus and E. vogeli, whose definitive hosts are derived from carnivores that immigrated from North America after the formation of the Panamanian land bridge. Host-parasite co-evolution comparisons suggest that the ancestral homeland of Echinococcus was North America or Asia, depending on whether the ancestral definitive hosts were canids or felids.

Animals↗
PubMed2006

Echinococcosis: historical landmarks and progress in research and control.

Although hydatid cysts were recognised and described in ancient times, in both livestock and humans, it was not until the 17th Century that their biological nature began to be understood. The past 50 years have seen a veritable revolution in knowledge and technology applicable to the biology of the cestodes and the diseases they cause. The parasites that form hydatid cysts belong to the genus Echinococcus, which is now recognized as a complex of closely related cestode parasites adapted to a variety of host-assemblages linked by predator-prey relationships. Synanthropic transmission in dogs and domestic livestock greatly increases the possibilities of zoonotic transmission, and the highest prevalences of Echinococcus infection in humans therefore occur in populations engaged in livestock rearing in which domestic dogs have access to the viscera of the livestock that serve as intermediate hosts. The application of modern scientific technology over the last few decades has not only revealed the diversity of host-parasite relationships within the genus Echinococcus but also led to greatly improved technology for the diagnosis and treatment of the echinococcoses in humans and lower animals. Although control programmes have led to marked reductions in transmission in certain geographical and socio-political settings, transmission and the resultant diseases continue unabated throughout most of the parasites' world-wide distribution.

Animals↗
PubMed2003

Cystic echinococcosis in Jordan: socioeconomic evaluation and risk factors.

The costs of illness and surgical intervention for human cystic echinococcosis (CE) cases in Jordan was economically evaluated by 77 surgeons and 77 CE patients. The cost of diagnosis for each CE case was 111.30 US Dollars and 146.20 US Dollars as estimated by surgeons and patients, respectively. The cost of surgical extraction of hydatid cysts for each case was 590.20 US Dollars and 638.50 US Dollars as estimated by both groups, respectively. Knowledge, attitudes and practices (KAP) of 77 CE patients as well as several Jordanian groups with different occupations including 144 shepherds, 119 settled livestock owners, 25 slaughter house workers, 400 university students and 80 inhabitants of a CE focus in southern Jordan were analyzed through a set of questionnaires. All of these groups had poor knowledge of CE, especially the source and causes of infection. All practices and attitudes of each group favored continuous transmission of the parasite and indicate the need for the implementation of a proper control program in the country.

Adolescent↗
PubMed2003

Echinococcosis on the Tibetan Plateau: prevalence and risk factors for cystic and alveolar echinococcosis in Tibetan populations in Qinghai Province, China.

Infections by larval stages of tapeworms of the genus Echinococcus (echinococcosis or hydatid disease) are zoonotic infections of major public health importance throughout much of the world. Humans become infected through accidental ingestion of eggs passed in faeces of canid definitive hosts. Tibetan populations of China have some of the highest documented levels of infections by both Echinococcus granulosus and E. multilocularis, the causes of cystic and alveolar echinococcosis, respectively. In this study we measured the prevalence of cystic (CE) and alveolar (AE) echinococcosis disease in Tibetan communities in Qinghai, Province, China, and identified putative risk factors for both infections in these communities. 3703 volunteers in three predominately Tibetan counties of Qinghai were surveyed between June 1997 and June 1998. Parasitic lesions were diagnosed by imaging of characteristic space-occupying lesions in abdominal organs (ultrasound) or the lungs (radiographs). Specific serodiagnostic assays (Dot-ELISA and Em2-ELISA) were performed on sera of positively imaged subjects to further distinguish the disease agent. All participants completed a questionnaire documenting age, sex, education level, occupation, lifestyle (nomadic or settled), slaughter practices, drinking water source, hygienic practice and association with dogs. Data were analyzed using SAS version 8. 6.6% of the volunteers had image-confirmed infection with E. granulosus (CE) and 0.8% had E. multilocularis (AE) infection. The significant univariate factors for echinococcal infection (both CE and AE) included livestock ownership, Tibetan ethnicity, female gender, low income, herding occupation, limited education, water source, age greater than 25 years old, poor hygienic practices, offal disposal practices and dog care. Multivariate analysis revealed that livestock ownership was a significant risk factor for both forms of the disease, as well as age greater than 25 years, female gender, herding occupation, and being nomadic (vs semi-nomadic or settled). No additional significant risk factors were identified among the 344 nomadic participants. Being female and being older than 25 years of age were significant factors among the 1906 semi-nomadic participants. Among the 1445 settled participants, allowing dogs to sleep indoors was statistically significant. Issues such as inadequate assessment of animal ownership, selection bias, disease misclassification, and loss of information may have led to reduction in strength of some risk factor associations and need to be addressed in future epidemiologic analysis of echinococcosis in this population.

Adolescent↗
PubMed2001

Proposed diagnostic criteria for neurocysticercosis.

Neurocysticercosis is the most common helminthic infection of the CNS but its diagnosis remains difficult. Clinical manifestations are nonspecific, most neuroimaging findings are not pathognomonic, and some serologic tests have low sensitivity and specificity. The authors provide diagnostic criteria for neurocysticercosis based on objective clinical, imaging, immunologic, and epidemiologic data. These include four categories of criteria stratified on the basis of their diagnostic strength, including the following: 1) absolute--histologic demonstration of the parasite from biopsy of a brain or spinal cord lesion, cystic lesions showing the scolex on CT or MRI, and direct visualization of subretinal parasites by funduscopic examination; 2) major--lesions highly suggestive of neurocysticercosis on neuroimaging studies, positive serum enzyme-linked immunoelectrotransfer blot for the detection of anticysticercal antibodies, resolution of intracranial cystic lesions after therapy with albendazole or praziquantel, and spontaneous resolution of small single enhancing lesions; 3) minor--lesions compatible with neurocysticercosis on neuroimaging studies, clinical manifestations suggestive of neurocysticercosis, positive CSF enzyme-linked immunosorbent assay for detection of anticysticercal antibodies or cysticercal antigens, and cysticercosis outside the CNS; and 4) epidemiologic--evidence of a household contact with Taenia solium infection, individuals coming from or living in an area where cysticercosis is endemic, and history of frequent travel to disease-endemic areas. Interpretation of these criteria permits two degrees of diagnostic certainty: 1) definitive diagnosis, in patients who have one absolute criterion or in those who have two major plus one minor and one epidemiologic criterion; and 2) probable diagnosis, in patients who have one major plus two minor criteria, in those who have one major plus one minor and one epidemiologic criterion, and in those who have three minor plus one epidemiologic criterion.

Humans↗
PubMed2001

Environmental exposure to Toxocara as a possible risk factor for asthma: a clinic-based case-control study.

The zoonotic ascarid Toxocara has been suggested as a possible etiologic agent of asthma. We conducted a clinic-based case-control study to examine whether the zoonotic infection acquired by ingesting Toxocara eggs is associated with asthma in children. Blood samples were collected from children aged 2-15 years, 95 of whom had asthma and 229 of whom did not have asthma. Risk factors for asthma and Toxocara infection were assessed by a questionnaire given to each child's parent or legal guardian. Blood samples were tested for the presence of Toxocara antibodies, using an enzyme-linked immunosorbent assay. No significant association was found between Toxocara infection and asthma. Significant associations were found between asthma and risk factors and between Toxocara infection and risk factors. High prevalence of Toxocara infection was noted among Hispanic children of Puerto Rican descent.

Adolescent↗
PubMed2001

Impact of health education on knowledge and prevention behavior for congenital toxoplasmosis: the experience in Poznań, Poland.

In 1991-1997 educational activities were undertaken in the Poznań region of Poland to promote health education for the prevention of toxoplasmosis. The effect of education was measured in 2710 pregnant women by a questionnaire survey. Knowledge of toxoplasmosis and its prevention was almost doubled within 4 years. Similarly, the proportion of women having antenatal serological tests for toxoplasmosis significantly increased. In the examined population the knowledge of how Toxoplasma gondii is transmitted/acquired was better than the knowledge of individual risk factors for congenital toxoplasmosis. Correct hygienic behaviors in pregnancy were often practised by women who lacked good knowledge of toxoplasmosis. The experience from this study suggests the possible effectiveness of including prevention of toxoplasmosis into the whole package of preventing infectious diseases in pregnancy and into healthy lifestyle promotion. Health educational activities need to be realized by modern promotional technologies in addition to making available traditional written educational texts. There is a considerable role of medical services in promotion of a hygienic behavior in pregnant women preventing congenital toxoplasmosis in their offspring. Health education should be especially tailored to the population of pregnant women below the age of 21.

Adult↗
PubMed2000

Diagnosis of canine echinococcosis: comparison of coproantigen detection with necropsy in stray dogs and red foxes from northern Jordan.

The sandwich enzyme linked immunosorbent assay (ELISA) was used as a diagnostic test for Echinococcus granulosus infection by detecting coproantigens in 94 stray dogs Canis familiaris and eight red foxes (Vulpes vulpes) from northern Jordan. The results were analyzed in relation to actual helminth infection as revealed by necropsy. The infection rate of dogs with E. granulosus was 13.8% with a worm load ranging between 3-> 10,000 per infected dog. In contrast, eight of 13 E. granulosus infected dogs were coproantigen positive (overall sensitivity 61.5%). The sensitivity increased to 87.5% and 100% in dogs harboring > 20 and > 100 worms/dog, respectively. The specificity of coproantigen-ELISA was 91%. The greatest cross-reactivity was found in dogs infected with Dipylidium caninum. The positive and negative predictive values for the coproantigen-ELISA test were 50% and 94.2%, respectively. Thus, a coproantigen negative dog is most probably truly negative for E. granulosus. In contrast, a coproantigen positive dog may not be truly positive for E. granulosus, except if it has a high worm burden of > 100 worms/animal.

Animals↗
PubMed2000

Failure to identify alveolar echinococcosis in trappers from South Dakota in spite of high prevalence of Echinococcus multilocularis in wild canids.

Echinococcus multilocularis causes a rare but potentially lethal zoonotic disease in humans. This tapeworm has been known to be endemic in foxes (Vulpes vulpes) and coyotes (Canis latrans) within the northern United States since the 1960s. One purpose of this study was to provide recent data on the prevalence of E. multilocularis in foxes and coyotes from eastern South Dakota. In a survey conducted from 1987 to 1991 and involving 137 foxes and 9 coyotes from this area, 74.5% of the foxes and 4 of the coyotes were infected. To assess the possible prevalence of alveolar echinococcosis in a group at presumptive high risk, we also conducted a serological survey of members of the South Dakota Trappers Association in 1990 and 1991. Serum samples from 115 trappers were evaluated for the presence of E. multilocularis antibodies using enzyme-linked immunosorbent assay tests involving a purified antigen called Em2, a crude E. multilocularis antigen, and a recombinant E. multilocularis antigen called II/3-10. None of the trappers showed antibody evidence for the presence of E. multilocularis. Roughly half of the surveyed individuals had trapped more than 50 foxes during their life, and almost one-fourth had trapped more than 1,000 foxes.

Adolescent↗
PubMed1999

Epilepsy and neurocysticercosis in an Andean community.

BACKGROUND: Taenia solium neurocysticercosis (NCC) has been documented as one of the major causes of epilepsy in developing countries. However, methodological limitations have hindered the evaluation of the epidemiological relationship between cysticercosis and epilepsy at the community level. METHODS: We used the WHO protocol for epidemiological evaluation of neurological disorders to conduct a door-to-door survey among 2723 residents of San Pablo del Lago, an Ecuadorean rural community in which T. solium taeniasis/cysticercosis was known to be endemic. The WHO protocol was complemented by neuroimaging and immunological tests to confirm the diagnosis of this infection. RESULTS: In all 31 people suffering from active epilepsy were detected (prevalence 11.4 per 1000, 95% CI:7.7-15.4); 26 agreed to undergo a computer tomography (CT) examination, and 28 agreed to have blood drawn for serodiagnosis. Fourteen of the 26 (53.8%) had CT changes compatible with NCC and six of the 28 (21.4%) tested positive in the enzyme-linked immunoelectro-transfer blot (EITB) assay. In a seizure-free random sample of this population, 17 of 118 (144 per 1000) subjects examined by CT and 10 out of 96 (104 per 1000) examined by EITB had evidence of this infection. The differences between the epilepsy group and the random sample of the population were statistically significant (OR = 6.93, 95% CI: 2.7-17.5, P < 0.001) for CT diagnosis, but not for EITB results (OR = 2.75, 95% CI: 0.8-7.1, P > 0.12, NS). CONCLUSIONS: These findings confirm that T. solium NCC is a significant cause of epilepsy at the community level in Andean villages of Ecuador. It is important to initiate effective public health interventions to eliminate this infection, which may be responsible for at least half of the cases of reported epilepsy in Ecuador.

Adolescent↗
PubMed1999

Differential serodiagnosis for cystic and alveolar echinococcosis using fractions of Echinococcus granulosus cyst fluid (antigen B) and E. multilocularis protoscolex (EM18).

Echinococcus granulosus cyst fluid and E. multilocularis protoscolex extract were fractionated by a single step of preparative isoelectric focusing, resulting in an antigen B-rich fraction (8-kD) and an Em18-rich fraction, respectively. The usefulness of both fractions for differential serodiagnosis of cystic (CE) and alveolar (AE) echinococcosis was evaluated by a large-scale immunoblot analysis on a battery of 354 serum samples. These included 66 from AE patients originating from four different endemic areas, 173 from CE patients originating from seven different endemic areas, 71 from patients with other parasitic diseases, 15 from patients with hepatomas, and 29 from healthy individuals. In an immunoblot with the antigen B-rich fraction, 92% (158 of 173) of the CE sera as well as 79% (52 of 66) of the AE sera reacted with the 8-kD subunit. No cross-reactivity occurred with any sera from patients with cysticercosis, other parasitic diseases, or with hepatomas, or from healthy controls. In an immunoblot with the Em18-rich fraction, all but two sera from AE patients (64 of 66, 97%) recognized Em18, and only nine of 34 CE sera from China reacted with it. All other (139) CE sera from six other countries were negative as were all (115) other non-echinococcosis sera. These findings indicate that antigen B (8-kD) is not species-specific for E. granulosus but is genus-specific for Echinococcus, and that the Em18 antigen is a reliable serologic marker for species-specific differentiation of AE from CE.

Animals↗
PubMed1999

Trichinellosis in the United States, 1991-1996: declining but not gone.

Since the U.S. Public Health Service began recording statistics on trichinellosis in 1947, the number of cases reported by state health departments has decreased steadily. In the late 1940s, health departments reported an average of 400 cases and 10-15 deaths each year. From 1991 to 1996, the period covered in this report, three deaths in 230 cases were reported to the Centers for Disease Control and Prevention (an average of 38 cases per year), including 14 multiple case outbreaks from 31 states and Washington, DC. Information on the suspected food item was available for 134 (58%) of the 230 reported cases. Pork was implicated in 80 (60%) cases, bear meat in 31 (23%), walrus meat in 13 (10%), and cougar meat in 10 (7%). Sausage was the most frequently implicated pork product (i.e., 57 of the 64 cases for which the form of the pork product was identified). The proportion of trichinellosis cases attributable to consumption of commercial pork continued to decrease; this decrease was probably due to a combination of factors, including the continued reduction in the prevalence of Trichinella spiralis in domestic swine, the increased use of home freezers, and the practice of thoroughly cooking pork. As a proportion of all cases reported, those associated with wild game meat products has increased; however, the absolute numbers of such cases have remained similar at approximately 9-12 per year. The continued multiple case outbreaks and the identification of nonpork sources of infection indicate the need for further education and control measures.

Adolescent↗
PubMed1999

[Epidemiology of cerebral cysticercosis in an Andean community in Ecuador].

Taenia solium neurocysticercosis (NCC) has been documented to be an underlying cause of epilepsy, intractable headaches, hydrocephalus, dementia and other serious neurological conditions in many countries of Central and South America. However, methodological limitations had prevented the assessment of the true prevalence of this condition at the community level. We conducted a house-to-house neuroepidemiological survey of 6,118 residents of an Andean community. This information was used to target neuroimaging (CT-scan) and immunodiagnosis (enzyme-linked immunoelectrotransfer blot assay, EITB) tests in individuals suspected of harbouring Taenia solium NCC. In the rural population, NCC was confirmed in 8 out of 47 examined by CT-scan (17%) and in 6 of 42 examined by EITB (14%). In the urban population, NCC was confirmed in 35 of 147 examined by CT-scan (23.8%) and in 28 of 124 examined by EITB (22.6%). In a sample of relatives of patients with documented cerebral cysticercosis, 20 out of 81 examined by CT-scan (25%) and 12 of 79 (15%) examined by EITB had NCC. Finally, CT scans were performed for 83 school children from urban areas, and 9 (11%) were diagnosed as harbouring NCC. In a community-based study, cysticercosis appears to be much more frequent than initially thought, when CT examination is used as the "gold standard" for diagnosis.

Adolescent↗
PubMed1999

A population-based, case-control study of Taenia solium taeniasis and cysticercosis.

A two-phase study was conducted in a rural community in Honduras, to evaluate the association between neurocysticercosis (NCC) diagnosed by computed tomography (CT), epilepsy, seropositivity for antibodies to the cysticerci of Taenia solium [determined by enzyme-linked-immunoelectrotransfer-blot (EITB) assays], intestinal infection with this parasite, and various epidemiological factors. Of the 480 individuals studied in the first phase, 17% were seropositive and 2.5% supplied faecal samples which contained T. solium eggs. In the second phase, 148 individuals (74 of the seropositive subjects from the first phase and 74 matched controls from the seronegatives) underwent CT and neurological examinations. The CT results appeared normal in 110 (74%) of the 148, showed anatomical abnormality in seven (5%), and active or calcified lesions compatible with NCC in 31 (23% of the seropositives and 19% of the seronegatives). Only five of the latter had neurological symptoms (two being epileptics) and only five lived in households in which intestinal taeniasis had been detected. Subject age was significantly associated with NCC-compatible lesions but all the other factors investigated, including seropositivity, showed no significant association with the CT findings. The overall sensitivity of the EITB assays was found to be 55%. Taken together, the present results indicate that, even though it is a valuable tool in determining transmission levels in sero-epidemiological studies, the EITB assay should not be used to predict the existence of NCC or to estimate the prevalence of NCC. The results do provide further evidence that taeniasis and cysticercosis are widely prevalent in Honduras, and indicate that much larger studies of hyper-endemic communities may be necessary if the factors associated with the transmission of T. solium are to be elucidated.

Adolescent↗