Immunochromatographic Card Test Research Articles

Integrated Mapping of Neglected Tropical Diseases: Epidemiological Findings and Control Implications for Northern Bahr-el-Ghazal State, Southern Sudan

BackgroundThere are few detailed data on the geographic distribution of most neglected tropical diseases (NTDs) in post-conflict Southern Sudan. To guide intervention by the recently established national programme for integrated NTD control, we conducted an integrated prevalence survey for schistosomiasis, soil-transmitted helminth (STH) infection, lymphatic filariasis (LF), and loiasis in Northern Bahr-el-Ghazal State. Our aim was to establish which communities require mass drug administration (MDA) with preventive chemotherapy (PCT), rather than to provide precise estimates of infection prevalence.Methods and FindingsThe integrated survey design used anecdotal reports of LF and proximity to water bodies (for schistosomiasis) to guide selection of survey sites. In total, 86 communities were surveyed for schistosomiasis and STH; 43 of these were also surveyed for LF and loiasis. From these, 4834 urine samples were tested for blood in urine using Hemastix reagent strips, 4438 stool samples were analyzed using the Kato-Katz technique, and 5254 blood samples were tested for circulating Wuchereria bancrofti antigen using immunochromatographic card tests (ICT). 4461 individuals were interviewed regarding a history of ‘eye worm’ (a proxy measure for loiasis) and 31 village chiefs were interviewed regarding the presence of clinical manifestations of LF in their community. At the village level, prevalence of Schistosoma haematobium and S. mansoni ranged from 0 to 65.6% and from 0 to 9.3%, respectively. The main STH species was hookworm, ranging from 0 to 70% by village. Infection with LF and loiasis was extremely rare, with only four individuals testing positive or reporting symptoms, respectively. Questionnaire data on clinical signs of LF did not provide a reliable indication of endemicity. MDA intervention thresholds recommended by the World Health Organization were only exceeded for urinary schistosomiasis and hookworm in a few, yet distinct, communities.ConclusionThis was the first attempt to use an integrated survey design for this group of infections and to generate detailed results to guide their control over a large area of Southern Sudan. The approach proved practical, but could be further simplified to reduce field work and costs. The results show that only a few areas need to be targeted with MDA of PCT, thus confirming the importance of detailed mapping for cost-effective control.

Rapid epidemiological and socio-cultural appraisal of lymphatic filariasis amongst the Igede ethnic group in Benue State, Nigeria

This study was conducted to determine the prevalence of lymphatic filariasis (LF) and investigate LF-related Knowledge, Attitude and Perception (KAP) amongst the Igede ethnic group of Benue State, Nigeria. The rapid immunochromatographic card test (ICT) for detecting Wuchereria bancrofti circulating antigen and prevalence of hydrocoele and lymphoedema were used as epidemiological tools while questionnaires were used to investigate KAP. 43.2 % of screened participants tested positive for W. bancrofti circulating antigen by the ICT card test, there was no significant difference in infection rate between male and female participants (X2 = 9.17, df = 1, p 0.05). 7.9 % of the study population had clinical manifestations (hydrocoele and lymphoedema) of the disease. Participants who had hydrocoele and lymphoedema were more knowledgeable than unaffected ones (X2 = 4.01, df = 1, p, 0.05). the knowledge of the cause, mode of transmission and prevention of LF were highly influenced by socio-cultural and traditional norms. This study provides reliable estimates of the prevalence of the disease and identified several areas of misconception and lack of knowledge on the etiology of LF. The implications of these findings were discussed and participatory community health education was suggested to encourage participation and sustainability of intervention activities. Keywords: lymphatic filariasis, ICT diagnosis, community perception, Igede ethnic group. Nigerian Journal of Parasitology Vol. 28 (2) 2007: pp. 118-124

Sensitivity of the Immunochromatographic Card Test Relative to Detection of Adult Wuchereria bancrofti Worms by Ultrasound

The diagnosis of active infection in bancroftian filariasis continues to pose an important and continuously evolving challenge to filariasis-endemic countries and to health personnel. Sensitivity of the immunochromatographic card test (ICT) relative to detection of adult Wuchereria bancrofti worms by ultrasound was evaluated in a retrospective study conducted in the Center for Teaching, Research and Tertiary Referral Hospital for bancroftian filariasis (Federal University of Pernambuco) in Recife, Brazil. The results showed that among 408 persons tested, the overall sensitivity of the ICT was 84.5% and varied from 52% to 100% when patients were grouped by different criteria (age, sex, presence or absence of living adult worms by ultrasound, microfilaremia status/density). The present study provides evidence that a negative antigen result should be interpreted cautiously and may help to explain the different sensitivities of the antigen test found by different investigators in settings with different transmission intensities.

The geographical distribution of lymphatic filariasis infection in Malawi

Mapping distribution of lymphatic filariasis (LF) is a prerequisite for planning national elimination programmes. Results from a nation wide mapping survey for lymphatic filariasis (LF) in Malawi are presented. Thirty-five villages were sampled from 23 districts excluding three districts (Karonga, Chikwawa and Nsanje) that had already been mapped and Likoma, an Island, where access was not possible in the time frame of the survey. Antigenaemia prevalence [based on immunochromatographic card tests (ICT)] ranged from 0% to 35.9%. Villages from the western side of the country and distant from the lake tended to be of lower prevalence. The exception was a village in Mchinji district on the Malawi-Zambia border where a prevalence of 18.2% was found. In contrast villages from lake shore districts [Salima, Mangochi, Balaka and Ntcheu (Bwanje valley)] and Phalombe had prevalences of over 20%.A national map is developed which incorporates data from surveys in Karonga, Chikwawa and Nsanje districts, carried out in 2000. There is a marked decline in prevalence with increasing altitude. Further analysis revealed a strong negative correlation (R2 = 0.7 p < 0.001) between altitude and prevalence. These results suggest that the lake shore, Phalombe plain and the lower Shire valley will be priority areas for the Malawi LF elimination programme. Implications of these findings as regards implementing a national LF elimination programme in Malawi are discussed.

Field Applicability of a Rapid‐Format Anti–Ov‐16 Antibody Test for the Assessment of Onchocerciasis Control Measures in Regions of Endemicity

A previously developed, specific, rapid-format immunochromatographic card test that detects immunoglobulin G4 to the recombinant Onchocerca volvulus antigen Ov-16 was modified to detect antibodies in whole blood. Ov-16 card test results were assessed in 1511 subjects > or =2 years of age in 7 West African villages with varying histories of onchocerciasis control measures. In villages in which control measures had been implemented, anti-Ov-16 antibody prevalence rates ranged from 5.2% to 65.1%. Antibody prevalence rates were close to zero among subjects born after effective control measures had been implemented. In 2 villages without a history of control measures where onchocerciasis was endemic, microfilariae (MF) prevalence rates were 82.8% and 65.1%, and antibody prevalence rates were 73.1% and 62.1%. In these 2 villages, the sensitivity of the Ov-16 card test was 81.1% and 76.5%, the specificity was 100%, and the positive predictive value was 91.8% and 80.5%. MF and antibody prevalence rates were correlated (Spearman's r=0.815; P<.038). The Ov-16 card test is field applicable, exhibits high sensitivity and specificity for O. volvulus infection, and has great potential as a tool for surveillance and for evaluating the success of onchocerciasis control measures.

Rapid assessment of the geographical distribution of lymphatic filariasis in Uganda, by screening of schoolchildren for circulating filarial antigens

To permit improvements in the targeting of control activities, the geographical distribution of lymphatic filariasis in Uganda was assessed by using a rapid immunochromatographic card test to check school-aged children for Wuchereria bancrofti-specific circulating filarial antigens (CFA). Survey sites were selected to represent the various ecological and topographical diversities in the country. Overall, 17,533 children from 76 sites were examined. CFA-positive cases were detected at 31 of the sites, with prevalences ranging from 0.4% to 30.7%. There appeared to be strikingly more lymphatic filariasis in the north of the country than in the south. The main focus was north of the Victoria Nile, where 27 (66%) of 41 sites had CFA-positive cases, often at high prevalences. Only four (11.4%) of the 35 sites south of the Victoria Nile had CFA-positive cases, and all four were along the western rift valley and had relatively low CFA prevalences. Geostatistical interpolation was used to create a map showing the geographical distribution of CFA prevalences in Uganda (by ordinary kriging), and to assess the population exposed to W. bancrofti transmission. Estimates based on population data from 2002 indicated that approximately 8.7 million people (35.3% of the national population) lived in areas where > 1% of the school-aged children were CFA-positive. CFA prevalences generally decreased with increasing altitude, and no CFA-positive cases were found at sites that were > 1300 m above sea level. Although it gives an under-estimate of the overall community prevalence (a fact that should be taken into account when interpreting the present results and comparing them with the results of other surveys), the screening of schoolchildren for CFA was found to be a simple and useful approach for mapping the geographical distribution of lymphatic filariasis.

Evidence for the interruption of transmission of lymphatic filariasis among schoolchildren in Trinidad and Tobago

This study was carried out to provide some evidence for the interruption of transmission of lymphatic filariasis (LF) among schoolchildren in Trinidad and Tobago. A cross-sectional survey for LF antigenaemia was performed among 63 (13.2%) of the 479 primary schools located in eight administrative (and geographical) regions of Trinidad and Tobago. From these communities, 2597 schoolchildren aged 6–12 years were sequentially selected for a survey of bancroftian antigenaemia. From each child, 100 μl (finger-prick) whole blood sample was applied to a Binax immunochromatographic card test (ICT), and read for the presence of antigenaemia. The ICT results showed a negative finding for LF antigenaemia and suggest that LF transmission has been interrupted in the survey areas.

RAPID ASSESSMENT FOR LYMPHATIC FILARIASIS IN CENTRAL NIGERIA: A COMPARISON OF THE IMMUNOCHROMATOGRAPHIC CARD TEST AND HYDROCELE RATES IN AN AREA OF HIGH ENDEMICITY

The rapid immunochromatographic card test (ICT) for Wuchereria bancrofti circulating filarial antigen is being used to map areas endemic for lymphatic filariasis. However, the ICT is expensive; thus, surveys based on this test must be relatively limited. Our study was conducted to determine if village-based hydrocele surveys could be used to supplement the ICT surveys in the mapping activities. We compared in 144 Nigerian villages the two assessment methods, ICT and examination for clinical hydrocele, in random samples of 30 adults selected using a procedure that obtained 15 younger males (reported age = 16-39 years old) and 15 older males (> or = 40 years), based on the assumption that hydrocele rates may be more prevalent in older age groups. The men were asked if they had scrotal swelling, then examined and tested by the ICT. We found a weakly positive correlation between village prevalence determined by the ICT and hydrocele (r = 0.041, P < 0.001). Only villages with hydrocele rates of 20% or greater were also consistently classified as having endemic filariasis by the ICT. There was no correlation between an individual's ICT positivity and clinical presence of hydrocele, and questioning about scrotal swelling was not predictive for presence of hydrocele. More research is needed to determine if community level hydrocele prevalence surveys can offer an economical and broadly applicable supplement to the ICT for determining the endemicity of filariasis.

Evaluation of the ICT whole-blood antigen card test to detect infection due to Wuchereria bancrofti in Sri Lanka

The sensitivity, specificity and cost effectiveness of an immunochromatographic card test (ICT, AMRAD) for the diagnosis of bancroftian filariasis were estimated against 2 standard parasitological techniques: thick blood film (TBF) and Nuclepore ® membrane filtration (NMF). Individuals were selected from endemic localities in the Western Province ( n = 213) and from the non-endemic Central Province ( n = 29) of Sri Lanka. Blood was collected between 21:00 and midnight. Sixty microlitre of non-heparinized blood, and 1 mL and 100 μL of heparinized blood were used in TBF, NMF and ICT, respectively. NMF was positive in 31 · 5% ( 67 213 ) of the endemic group, with a mean microfilaria (mf) count of 343/mL (range 8–1782, SD 422). All 67 were positive by ICT (sensitivity 100%), but only 63 by TBF (sensitivity 94%). Among the endemic population there were 12 who were mf negative but antigen positive by ICT. There were, however, no false positives among the non-endemic controls, indicating the possibility that the ICT may in fact be more sensitive and 100% specific. Thus, ICT filariasis test appears to be more effective (both sensitive and specific) than TBF or NMF in diagnosing infection in lymphatic filariasis. The direct unit recurrent costs of the 2 survey tools, TBF and ICT, were US$ 0.30 (Rs. 27/=) and US$ 2.75 (Rs. 248/=), respectively. The high cost of the ICT may be offset by other factors that are difficult to cost.

An assessment of the accuracy of clinical diagnosis, local microscopy and a rapid immunochromatographic card test in comparison with expert microscopy in the diagnosis of malaria in rural Kenya

An assessment of the accuracy of clinical diagnosis, local microscopy and a rapid immunochromatographic card test in comparison with expert microscopy in the diagnosis of malaria in rural Kenya

Accuracy of a rapid immunochromatographic card test for Plasmodium falciparum in a malaria control programme in South Africa

Accuracy of a rapid immunochromatographic card test for Plasmodium falciparum in a malaria control programme in South Africa