Human Taeniasis and Cysticercosis and Related Factors in Phu Tho Province, Northern Vietnam

Several factors presumed to facilitate the transmission of Taenia spp. were reported in Vietnam. We conducted a cross-sectional study taking questionnaires from 1,185 participants, and collecting 1,151 sera and 1,036 stool samples in northern Vietnam. Sera were examined for circulating antigens of Taenia solium cysticerci using ELISA, stools for Taenia eggs by Kato-Katz smear, and copro-antigens by ELISA. Ag-ELISA revealed 4.6% antigen positivity, indicating infection with viable cysticerci. Taenia eggs were detected in 1.5% of participants. Copro-antigens were found in 2.8% of participants. Eating raw meat and/or vegetables was significantly associated with the presence of copro-antigen (OR=8.6, 95% CI: 1.16-63.9, P=0.01). Considering the high taeniasis prevalence and the associated threat, public health attention should be given to treat the tapeworm carriers in the projected areas.

Human Taeniasis and Cysticercosis and Related Factors in Phu Tho Province, Northern Vietnam

Several factors presumed to facilitate the transmission of Taenia spp. were reported in Vietnam. We conducted a cross-sectional study taking questionnaires from 1,185 participants, and collecting 1,151 sera and 1,036 stool samples in northern Vietnam. Sera were examined for circulating antigens of Taenia solium cysticerci using ELISA, stools for Taenia eggs by Kato-Katz smear, and copro-antigens by ELISA. Ag-ELISA revealed 4.6% antigen positivity, indicating infection with viable cysticerci. Taenia eggs were detected in 1.5% of participants. Copro-antigens were found in 2.8% of participants. Eating raw meat and/or vegetables was significantly associated with the presence of copro-antigen (OR=8.6, 95% CI: 1.16-63.9, P=0.01). Considering the high taeniasis prevalence and the associated threat, public health attention should be given to treat the tapeworm carriers in the projected areas.

Evaluating the Recombinant T24H Enzyme-Linked Immunoelectrotransfer Blot Assay for the Diagnosis of Neurocysticercosis in a Panel of Samples from a Large Community-Based Randomized Control Trial in 60 Villages in Burkina Faso.

Current guidelines for the diagnosis of neurocysticercosis (NCC) recommend the use of the lentil lectin-bound glycoprotein enzyme-linked immunoelectrotransfer blot assay (LLGP-EITB) as the reference standard for serological testing. In response to the drawbacks involved with the use of the LLGP-EITB, a recombinant T24H antigen (rT24H) EITB assay was developed, with promising results. However, the test has yet to be evaluated among individuals from sub-Saharan Africa (SSA). The aim of the present study was to investigate the performance of the rT24H EITB assay for the detection of NCC cases in a panel of serum samples (N = 366, of which 173 patients presented with epileptic seizures and/or severe chronic headaches, and 193 matched manifestation-free participants) collected as part of a large community-based trial in Burkina Faso. A perfect agreement between the rT24H EITB and the native gp24 (and its homodimer, gp42) LLGP-EITB was found (kappa value of 1.0). Furthermore, among patients with the neurological manifestations of interest who underwent a computed tomography scan, the rT24H EITB and native antigen LLGP-EITB had a comparable ability to correctly identify NCC cases with multiple viable (rT24H: sensitivity: 80.0%), single viable (66.7%), and calcified/degenerating cysts only (25.0%), albeit for multiple viable and calcified cysts, the rT24H estimated sensitivity seemed lower, but more uncertain, than previously reported. The rT24H EITB specificity was high (98.2%) and in line with previous studies. This study confirms the value of the recombinant rT24H EITB as an alternative to the native antigen LLGP-EITB for the diagnosis of NCC in a SSA community setting.

High prevalence of bovine cysticercosis found during evaluation of different post-mortem detection techniques in Belgian slaughterhouses.

Bovine cysticercosis (BCC), caused by the helminth Taenia saginata, is currently diagnosed solely by official meat inspection (MI) based on macroscopic detection of viable cysticerci or typical lesions of degenerated larvae. MI has a known low sensitivity (<16%), leading to a large proportion of infected cattle carcasses entering the human food chain and posing a risk to public health. Prevalence in Belgium based on MI results is estimated at around 0.22%. Due to the low sensitivity of MI, alternative techniques to detect BCC should be considered. This study evaluates MI, MI with additional incisions in the heart, specific antibody detection against excretory/secretory (E/S) in the Ab-ELISA and circulating antigens in the B158/B60 Ag-ELISA on 715 (101 MI-positive and 614 MI-negative) samples collected from carcasses at slaughterhouses in Belgium. Full dissection of the predilection sites was considered the reference test. During the study, mostly carcasses with (very) light infections were detected containing predominantly degenerated or calcified cysticerci and only few viable cysticerci. Dissection of the predilection sites detected 144 (23%) additional infections in the 614 MI-negative carcasses. When sequentially performing first the dissection of the predilection sites, followed by the Ag-ELISA and the Ab-ELISA, an additional 36% of MI-negative carcasses were found positive for BCC, resulting in a prevalence very much higher than the above mentioned 0.22%. The B158/B60 Ag-ELISA showed a sensitivity of 40% for the detection of carcasses containing viable cysticerci and a specificity of 100%, and detected 70 positive carcasses of which only 14 had been identified as positive during MI. If Ag-ELISA were implemented as a detection technique for BCC in the slaughterhouses, many infected carcasses would still not be detected due to the sensitivity of 40%. But as sensitivity increases with increasing number of cysticerci in the carcass, the infected carcasses passing inspection will be the ones containing only a few viable cysticerci and thus posing a smaller food safety problem. Ag-ELISA is preferred over the ES Ab-ELISA in this study, which had a sensitivity of 13.3% and a specificity of 91.7% in a population with overall low infection burdens.

Taenia hydatigena in pigs in Burkina Faso: A cross-sectional abattoir study.

Taenia hydatigena is a non-zoonotic cestode that has canines as definitive hosts and ruminants and pigs as intermediate hosts. In pigs, its presence causes cross-reactivity in serological testing for Taenia solium cysticercosis. Therefore, knowledge on the occurrence of T. hydatigena is paramount for validly estimating the seroprevalence of T. solium cysticercosis in pigs. In a cross-sectional abattoir study, we estimated the prevalence of T. hydatigena in pigs slaughtered in Koudougou, Burkina Faso. Carcasses of 452 pigs were examined by investigators for perceived and suspected T. hydatigena cysticercus lesions in the abdominal cavity or on the surface of abdominal organs. Routine meat inspection was performed by local inspectors to identify T. solium cysticerci. All lesions were subjected to PCR-RFLP analysis in order to differentiate Taenia spp. Additionally, individual blood samples were examined for the presence of circulating cysticercus antigens using the B158/B60 Ag-ELISA. Perceived T. hydatigena cysticerci were found in 13 pigs, whereas meat inspectors found seven carcasses infected with T. solium cysticerci. All were confirmed by molecular analysis. Of pigs with other suspected lesions, mostly located in the liver, 27 and six were found to harbour T. hydatigena and T. solium cysticerci, respectively. Overall, 8.8% of pigs (40/452) were found infected with T. hydatigena and 2.9% (13/452) with T. solium. Of these positive pigs, one was found infected with both Taenia spp. (0.2%, 1/452). Blood samples of 48.5% of pigs (219/452) were positive in the Ag-ELISA. Pigs with confirmed cysts of T. hydatigena and T. solium had a positive Ag-ELISA result in 57.5% (23/40) and 61.5% (8/13) of cases, respectively. The observed T. hydatigena prevalence in this study is relatively high in comparison to other studies in Africa. Estimates of the occurrence of active porcine T. solium infection using the B158/B60 Ag-ELISA should therefore be adjusted for the presence of T. hydatigena. The low level of T. solium infection detected upon meat inspection in this study is likely an underestimation of the true prevalence since routine meat inspection shows poor sensitivity and pigs perceived to be infected based on tongue palpation are rarely sent to official abattoirs.

Assessment of the repeatability and border-plate effects of the B158/B60 enzyme-linked-immunosorbent assay for the detection of circulating antigens (Ag-ELISA) of Taenia saginata.

The monoclonal antibody-based circulating antigen detecting ELISA (B158/B60 Ag-ELISA) has been used elaborately in several studies for the diagnosis of human, bovine and porcine cysticercosis. Interpretation of test results requires a good knowledge of the test characteristics, including the repeatability and the effect of the borders of the ELISA plates. Repeatability was tested for 4 antigen-negative and 5 antigen-positive reference bovine serum samples by calculating the Percentage Coefficient of Variation (%CV) within and between plates, within and between runs, overall, for two batches of monoclonal antibodies and by 2 laboratory technicians. All CV values obtained were below 20% (except one: 24.45%), which indicates a good repeatability and a negligible technician error. The value of 24.45% for indicating the variability between batches of monoclonal antibodies for one positive sample is still acceptable for repeatability measures. Border effects were determined by calculating the %CV values between the inner and outer wells of one plate for 2 positive serum samples. Variability is a little more present in the outer wells but this effect is very small and no significant border effect was found.

Urine antigen detection for the diagnosis of human neurocysticercosis.

Neurocysticercosis (NCC) is a major cause of seizures and epilepsy. Diagnosis is based on brain imaging, supported by immunodiagnosis in serum or cerebrospinal fluid (CSF). Lumbar puncture is invasive and painful. Blood sampling is slightly painful and poorly accepted. Urine antigen detection has been used for other parasites and tried in NCC with suboptimal performance. We used a monoclonal antibody-based ELISA to detect Taenia solium antigens in urine from 87 Peruvian neurocysticercosis patients (viable cysts, N = 34; subarachnoid cysticercosis, N = 10; degenerating parasites, N = 7; calcified lesions, N = 36) and 32 volunteers from a non-endemic area of Peru. Overall sensitivity of urine antigen detection for viable parasites was 92%, which decreased to 62.5% in patients with a single cyst. Most patients (30/36, 83%) with only calcified cysticercosis were urine antigen negative. Antigen levels in paired serum/urine samples (evaluated in 19 patients) were strongly correlated. Non-invasive urine testing for T. solium antigens provides a useful alternative for NCC diagnosis.