SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Taenia solium

171

Taenia solium is a cestode parasite that causes cysticercosis in both humans and pigs. A serological survey was undertaken to assess the seroprevalence and risk factors associated with porcine cysticercosis in the rural district of Morropon, Peru. Pigs aged between 2 and 60 months were assessed by the Enzyme-linked Immunoelectrotransfer blot (EITB) assay to determine their serological status against porcine cysticercosis in a cross-sectional study. A total of 1,153 pigs were sampled. Porcine seroprevalence was 45.19% (42.31-48.06). The information about the animals and households was analyzed and risk factors associated with seroprevalence were determined by a multivariate logistic regression analysis. In the porcine population, the risk of being seropositive increased by 7% with every month of age (OR 1.07, 95% CI 1.05-1.09), and by 148% for pigs living in East Morropon (OR 2.48, 95% CI 1.82-3.37). Whereas, the presence of latrines in a household decreased the risk of being seropositive by 49% (OR 0.51; 95% CI 0.39-0.67). Sex and rearing system did not represent either risk or protective factors associated with the seroprevalence of porcine cysticercosis. The findings of this study could be used for further development of control programs that might focus on similar population groups within rural communities of developing countries where cysticercosis is endemic.

Concepts: Regression analysis, Logistic regression, Epidemiology, Population, Econometrics, Cestoda, Taenia solium, Cysticercosis

28

OBJECTIVES: To describe the occurrence of cysticercosis in patients living in rural areas of Northern Vietnam presenting clinical signs of neurocysticercosis. METHODS: Serological antigen detection, reflecting current infection with viable larval stages of Taenia solium, was used to estimate the prevalence of active cysticercosis in this patient population. RESULTS: The seroprevalence in epileptic patient population was <10%. However, antigen detection cannot detect dead cysticerci, which may also cause clinical signs. Therefore, the seroprevalence figures shown here may underestimate the role of neurocysticercosis as a causal agent of epilepsy and headaches in this population. CONCLUSIONS: Human and porcine cysticercosis remain public and veterinary public health problems in Northern Vietnam and probably in other parts of the country.

Concepts: Epidemiology, Disease, Population, Rural, Rural area, Rural culture, Taenia solium, Cysticercosis

28

Neurocysticercosis( NCC), an infection of the brain with the larval stage of the Taenia solium tapeworm is responsible for an estimated one third of adult onset epilepsy in endemic regions of the world. Currently, anthelmintic drugs used for treatment of NCC are only partially effective and there is, therefore, a pressing need for new therapeutic agents. Discovery of new anthelmintics with activity against T. solium has been limited by the lack of suitable sensitive assays that allow high throughput screening. Using an in vitro culture system with T. crassiceps metacestodes we demonstrate that changes in secretion of parasite-associated alkaline phosphatase (AP) and phophoglucose isomerase (PGI) can be used to detect and quantify anthelmintic effects of praziquantel (PZQ), a drug with activity against T. solium. We applied two enzyme release assays to screen for anti-T. crassiceps activity in non-conventional anti-parasitic drugs and demonstrate that nitazoxanide and artesunate induced release of both AP and PGI in a differing time and dose related patterns. Furthermore, imatinib, a tyrosine kinase inhibitor previously reported to have cidal activity against Schistosoma mansoni, also induced release of both AP and PGI in a dose dependent manner, similar in pattern to that observed with the other anthelmintics. We also evaluated release of adenine triphosphate (ATP) into cyst supernatants as an indicator of drug effects, but did not see any differences between treated and untreated cysts. These data provide the basis for rapid and quantitative screening assays for testing for anthelmintic activity in candidate anti-cestode agents.

Concepts: Signal transduction, Adenosine triphosphate, Praziquantel, Protein kinase, Anthelmintic, Taenia solium, Emodepside, Piperazine

28

Albendazole is an anthelmintic drug widely used in the treatment of neurocysticercosis (NCC), an infection of the brain with Taenia solium cysts. However, drug levels of its active metabolite, albendazole sulfoxide (ABZSO), are erratic, likely resulting in decreased efficacy and suboptimal cure rates in NCC. Racemic albendazole sulfoxide is composed of (ABZSO (+)-®- and (-)-(S)- enantiomers that have been shown to differ in pharmacokinetics and activity against other helminths. The antiparasitic activities of racemic ABZSO and its (+)-®- and (-)-(S)- enantiomers were evaluated in vitro against T. solium cysts. Parasites were collected from naturally infected pigs, cultured and exposed to the racemic mixture or to each enantiomer (range 10 to 500 ng/ml) or to praziquantel as a reference drug. The activity of each compound on cysts was assayed by measuring ability to evaginate and inhibition of alkaline phosphatase (AP) and parasite antigen release. (+)-®-ABZSO was significantly more active than (-)-(S)-ABZSO in suppressing the release of AP and antigen into the supernatant in a dose- and time- dependent manner, indicating that most of the activity of ABZSO resides in the (+)-®-enantiomer. Use of this enantiomer alone may lead increased efficacy and/or less toxicity compared to albendazole.

Concepts: Pharmacology, Intestinal parasite, Stereochemistry, Enantiomer, Anthelmintics, Racemic mixture, Taenia solium, Albendazole

28

Most species of the genus Taenia are of considerable medical and veterinary significance. In this study, complete nuclear 18S rRNA gene sequences were obtained from seven members of genus Taenia [Taenia multiceps, Taenia saginata, Taenia asiatica, Taenia solium, Taenia pisiformis, Taenia hydatigena, and Taenia taeniaeformis] and a phylogeny inferred using these sequences. Most of the variable sites fall within the variable regions, V1-V5. We show that sequences from the nuclear 18S ribosomal RNA gene have considerable promise as sources of phylogenetic information within the genus Taenia. Furthermore, given that almost all the variable sites lie within defined variable portions of that gene, it will be appropriate and economical to sequence only those regions for additional species of Taenia.

Concepts: DNA, Biology, RNA, Species, Ribosomal RNA, 18S ribosomal RNA, Taenia saginata, Taenia solium

27

Porcine cysticercosis (PC) caused by the larval stage of a zoonotic tapeworm Taenia solium, is known to pose serious economic losses and public health risk among smallholder pig production communities. The present study was conducted to determine prevalence and associated risk factors for PC in smallholder pig production systems in Mbeya region, the major pig rearing region of Tanzania. A cross-sectional survey employing a random sample of 300 pig keepers from 30 villages of Mbozi and Mbeya Rural districts, Mbeya region were used to evaluate pig production systems and practices. Concurrently, 600 male and female pigs of different age categories were randomly selected and examined for PC using lingual examination method and antigen enzyme-linked immunosorbent assay (Ag-ELISA). The overall pig level PC prevalence in Mbozi district was 11.7% (95% CI=8.5-15.8%) and 32% (95% CI: 27-37.5%) based on lingual examination and Ag-ELISA, respectively. In Mbeya Rural district, the prevalences were 6% (95% CI: 3.8-9.3%) and 30.7% (95% CI: 25.8-36.1%) by lingual examination and Ag-ELISA, respectively. In Mbozi district 46% of the households were found infected (one or more infected pigs) and the corresponding figure was 45% for Mbeya Rural district. The agreement between lingual examination and Ag-ELISA was poor (κ<0.40). There were no significant differences in the prevalence of PC in different sex categories of pigs. Significant risk factors associated with PC prevalence were free roaming of pigs (OR=2.1; 95% CI=1.3-3.6; p=0.006), past experience of porcine cysticercosis in the household (OR=2.6; 95% CI=1.5-4.8; p=0.002), increased age of pig (OR=1.9; 95% CI=1.2-3.0), slatted raised floor in pig pen (OR=8.4; 95% CI=1.0-70.0), in-house origin of the pig (OR=1.6; 95% CI=1.1-2.5) and sourcing of water from rivers (OR=3.1; 95% CI=1.6-6.3; p<0.001) and ponds (OR=5.0; 95% CI=1.2-21.7; p=0.031). This study has clearly revealed a high sero-prevalence of PC in the study area, which imposes a major economical and public health burden to the smallholder pig farmers. The study also points to a number of important risk factors in smallholder pig management that may be addressed (e.g. confinement, quality of pens and water sources) in future interventions and educational campaigns for control of T. solium.

Concepts: Epidemiology, Pig, Taenia solium, Cysticercosis, Mbeya Rural, Rungwe, Mbeya Region, Mbeya Urban

27

OBJECTIVE: To estimate and compare the performances of coprology, copro-Ag ELISA and real-time polymerase chain reaction assay (copro-PCR) for detection of Taenia solium tapeworm carriers. METHODS: The three diagnostic tests were applied on 817 stool samples collected in two Zambian communities where taeniasis is endemic. A Bayesian approach was used to allow estimation of the test characteristics. Two (0.2%; 95% Confidence Interval (CI): 0-0.8), 67 (8.2%; 95% CI: 6.4-10.3) and 10 (1.2%; 95% CI: 0.5-2.2) samples were positive using coprology, copro-Ag ELISA and copro-PCR, respectively. RESULTS: Specificities of 99.9%, 92.0% and 99.0% were determined for coprology, copro-Ag ELISA and copro-PCR, respectively. Sensitivities of 52.5%, 84.5% and 82.7% were determined for coprology, copro-Ag ELISA and copro-PCR, respectively. CONCLUSIONS: We urge for additional studies exploring possible cross-reactions of the copro-Ag ELISA and for the use of more sensitive tests, such as copro-PCR, for the detection of tapeworm carriers, which is a key factor in controlling the parasite in endemic areas.

Concepts: Statistics, Polymerase chain reaction, Molecular biology, Real-time polymerase chain reaction, DNA polymerase, Statistical inference, Thermus aquaticus, Taenia solium

27

To investigate the cause of an outbreak of bovine cysticercosis (Taenia saginata) infection on a cattle property in north-western New South Wales (NSW).

Concepts: New Zealand, New South Wales, Victoria, Taenia saginata, Taenia solium, National Rugby League, Parramatta Eels, Wests Tigers

11

The frequency of Taenia solium, a zoonotic helminth, is increasing in many countries of sub-Saharan Africa, where the prevalence of the human immunodeficiency virus (HIV) is also high. However, little is known about how these two infections interact. The aim of this study was to compare the proportion of HIV positive (+) and negative (-) individuals who are infected with Taenia solium (TSOL) and who present with clinical and neurological manifestations of cysticercosis (CC).

Concepts: HIV, AIDS, Immune system, Infectious disease, Africa, Infection, Cytomegalovirus, Taenia solium

6

Background Taeniasis and cysticercosis are major causes of seizures and epilepsy. Infection by the causative parasite Taenia solium requires transmission between humans and pigs. The disease is considered to be eradicable, but data on attempts at regional elimination are lacking. We conducted a three-phase control program in Tumbes, Peru, to determine whether regional elimination would be feasible. Methods We systematically tested and compared elimination strategies to show the feasibility of interrupting the transmission of T. solium infection in a region of highly endemic disease in Peru. In phase 1, we assessed the effectiveness and feasibility of six intervention strategies that involved screening of humans and pigs, antiparasitic treatment, prevention education, and pig replacement in 42 villages. In phase 2, we compared mass treatment with mass screening (each either with or without vaccination of pigs) in 17 villages. In phase 3, we implemented the final strategy of mass treatment of humans along with the mass treatment and vaccination of pigs in the entire rural region of Tumbes (107 villages comprising 81,170 people and 55,638 pigs). The effect of the intervention was measured after phases 2 and 3 with the use of detailed necropsy to detect pigs with live, nondegenerated cysts capable of causing new infection. The necropsy sampling was weighted in that we preferentially included more samples from seropositive pigs than from seronegative pigs. Results Only two of the strategies implemented in phase 1 resulted in limited control over the transmission of T. solium infection, which highlighted the need to intensify the subsequent strategies. After the strategies in phase 2 were implemented, no cyst that was capable of further transmission of T. solium infection was found among 658 sampled pigs. One year later, without further intervention, 7 of 310 sampled pigs had live, nondegenerated cysts, but no infected pig was found in 11 of 17 villages, including all the villages in which mass antiparasitic treatment plus vaccination was implemented. After the final strategy was implemented in phase 3, a total of 3 of 342 pigs had live, nondegenerated cysts, but no infected pig was found in 105 of 107 villages. Conclusions We showed that the transmission of T. solium infection was interrupted on a regional scale in a highly endemic region in Peru. (Funded by the Bill and Melinda Gates Foundation and others.).

Concepts: Epidemiology, Infectious disease, Taenia solium, Cysticercosis, Taenia, Bill & Melinda Gates Foundation, Bill Gates, Melinda Gates