Evaluation of the SD FK70 Malaria Ag Plasmodium vivax rapid diagnostic test in a non-endemic setting

© 2009 Gillet et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Test characteristics of the SD FK80 Plasmodium falciparum/Plasmodium vivax malaria rapid diagnostic test in a non-endemic setting

<p>Abstract</p> <p>Background</p> <p>The SD FK80 P.f/P.v Malaria Antigen Rapid Test (Standard Diagnostics, Korea) (FK80) is a three-band malaria rapid diagnostic test detecting <it>Plasmodium falciparum </it>histidine-rich protein-2 (HRP-2) and <it>Plasmodium vivax</it>-specific lactate dehydrogenase (Pv-pLDH). The present study assessed its performance in a non-endemic setting.</p> <p>Methods</p> <p>Stored blood samples (n = 416) from international travellers suspected of malaria were used, with microscopy corrected by PCR as the reference method. Samples infected by <it>Plasmodium falciparum </it>(n = 178), <it>Plasmodium vivax </it>(n = 99), <it>Plasmodium ovale </it>(n = 75) and <it>Plasmodium malariae </it>(n = 24) were included, as well as 40 malaria negative samples.</p> <p>Results</p> <p>Overall sensitivities for the diagnosis of <it>P. falciparum </it>and <it>P. vivax </it>were 91.6% (95% confidence interval (CI): 86.2% - 95.0%) and 75.8% (65.9% - 83.6%). For <it>P. falciparum</it>, sensitivity at parasite densities ≥ 100/μl was 94.6% (88.8% - 97.6%); for <it>P. vivax</it>, sensitivity at parasite densities ≥ 500/μl was 86.8% (75.4% - 93.4%). Four <it>P. falciparum </it>samples showed a Pv-pLDH line, three of them had parasite densities exceeding 50.000/μl. Two <it>P. vivax </it>samples, one <it>P. ovale </it>and one <it>P. malariae </it>sample showed a HRP-2 line. For the HRP-2 and Pv-pLDH lines, respectively 81.4% (136/167) and 55.8% (43/77) of the true positive results were read as medium or strong line intensities. The FK80 showed good reproducibility and reliability for test results and line intensities (kappa values for both exceeding 0.80).</p> <p>Conclusion</p> <p>The FK80 test performed satisfactorily in diagnosing <it>P. falciparum </it>and <it>P. vivax </it>infections in a non-endemic setting.</p

Test characteristics of two rapid antigen detection tests (SD FK50 and SD FK60) for the diagnosis of malaria in returned travellers

<p>Abstract</p> <p>Background</p> <p>Two malaria rapid diagnostic tests were evaluated in a travel clinic setting: the SD FK50 Malaria Ag <it>Plasmodium falciparum </it>test (a two-band test) and the SD FK60 Malaria Ag <it>P. falciparum</it>/Pan test (a three-band test).</p> <p>Methods</p> <p>A panel of stored whole blood samples (n = 452 and n = 614 for FK50 and FK60, respectively) from returned travellers was used. The reference method was microscopy with PCR in case of discordant results.</p> <p>Results</p> <p>For both tests, overall sensitivity for the detection of <it>P. falciparum </it>was 93.5%, reaching 97.6% and 100% at parasite densities above 100 and 1,000/μl respectively. Overall sensitivities for <it>Plasmodium vivax, Plasmodium ovale </it>and <it>Plasmodium malariae </it>for the FK60 test were 87.5%, 76.3% and 45.2%, but they reached 92.6% and 90.5% for <it>P. vivax </it>and <it>P. ovale </it>at parasite densities above 500/μl. Specificities were above 95% for all species and both tests when corrected by PCR, with visible histidine-rich protein-2 lines for <it>P. malariae </it>(n = 3) and <it>P. vivax </it>and <it>P. ovale </it>(1 sample each). Line intensities were reproducible and correlated to parasite densities. The FK60 tests provided clues to estimate parasite densities for <it>P. falciparum </it>below or above 1,000/μl.</p> <p>Conclusion</p> <p>Both the FK50 and FK60 performed well for the diagnosis of <it>P. falciparum </it>in the present setting, and the FK60 for the diagnosis of <it>P. vivax </it>and <it>P. ovale </it>at parasite densities > 500/μl. The potential use of the FK60 as a semi-quantitative estimation of parasite density needs to be further explored.</p

A clinician’s perspective on yellow fever vaccine-associated neurotropic disease

Yellow fever (YF) causes high fever, liver dysfunction, renal failure, hypercoagulopathy and platelet dysfunction and can lead to shock and death with a case-fatality ratio of 20-50%. YF vaccination results in long-lasting protective immunity. Serious adverse events (SAEs), such as YF vaccine-associated neurotropic disease (YEL-AND) are rare. We present a case of a 56-year-old Caucasian man with fever, headache, cognitive problems at the emergency department. He received a primary YF vaccination 4 weeks prior to symptom onset. Cerebrospinal fluid tested positive (POS) for YF virus by reverse transcriptase polymerase chain reaction and confirmed diagnosis of YEL-AND. The patient recovered with symptomatic treatment. We reviewed published clinical reports on YEL-AND indexed for MEDLINE. We identified and analyzed 53 case reports. Forty-five patients were male and eight were female. Twenty-nine cases met criteria for definite YEL-AND and twenty-four for suspected YEL-AND according to YF Vaccine Safety Working Group. We applied the Brighton Collaboration diagnostic criteria to assess the diagnostic accuracy of the clinical diagnoses and found meningoencephalitis in 38 reported YEL-AND cases, Guillain Barre Syndrome (GBS) in seven, Acute Disseminated Encephalomyelitis (ADEM) in six and myelitis in five. Thirty-five patients recovered or improved; however, not all cases had a complete follow-up. The prognosis of YEL-AND presenting with GBS, ADEM or myelitis was poor. Fourteen patients received therapy (corticosteroids, intravenous immunoglobulins and/or plasmapheresis). In conclusion, YF vaccine-associated neurotropic disease is a very rare but SAE after YF vaccination. We described a case of YEL-AND and propose a standardized clinical workup of this condition based on a review of the literature. Centralized registration of complications of YF vaccination is encouraged

Falciparum Malaria in Patient 9 Years after Leaving Malaria-Endemic Area

Case ReportsLetterSCOPUS: le.jinfo:eu-repo/semantics/publishe

Chikungunya Fever in Travelers Returning to Europe from the Indian Ocean Region, 2006

Chikungunya fever should be added to the list of differential diagnoses for ill travelers returning from this region

First international external quality assessment scheme of nucleic acid amplification tests for the detection of Schistosoma and soil-transmitted helminths, including Strongyloides : a pilot study

Background Nucleic acid amplification tests (NAATs) are increasingly being used as diagnostic tools for soil-transmitted helminths (STHs;Ascaris lumbricoides,Trichuris trichiura,Necator americanus,Ancylostoma duodenaleandA.ceylanicum),Strongyloides stercoralisandSchistosomain human stool. Currently, there is a large diversity of NAATs being applied, but an external quality assessment scheme (EQAS) for these diagnostics is lacking. An EQAS involves a blinded process where test results reported by a laboratory are compared to those reported by reference or expert laboratories, allowing for an objective assessment of the diagnostic performance of a laboratory. In the current study, we piloted an international EQAS for these helminths (i) to investigate the feasibility of designing and delivering an EQAS; (ii) to assess the diagnostic performance of laboratories; and (iii) to gain insights into the different NAAT protocols used. Methods and principal findings A panel of twelve stool samples and eight DNA samples was validated by six expert laboratories for the presence of six helminths (Ascaris,Trichuris,N.americanus,Ancylostoma,StrongyloidesandSchistosoma). Subsequently this panel was sent to 15 globally dispersed laboratories. We found a high degree of diversity among the different DNA extraction and NAAT protocols. Although most laboratories performed well, we could clearly identify the laboratories that were poorly performing. Conclusions/Significance We showed the technical feasibility of an international EQAS for the NAAT of STHs,StrongyloidesandSchistosoma. In addition, we documented that there are clear benefits for participating laboratories, as they can confirm and/or improve the diagnostic performance of their NAATs. Further research should aim to identify factors that explain poor performance of NAATs. Author summary Tests that detect parasite DNA in human stool are increasingly being used for the diagnosis of infections with intestinal worms, including schistosomiasis. To ensure the quality in diagnostic testing of these parasitic worms, it is important that laboratories evaluate the diagnostic performance of their DNA-based tests. This can best be achieved by participating in an external quality assessment scheme (EQAS). An EQAS involves a blinded process where test results reported by a laboratory are compared to those reported by reference or expert laboratories, allowing for an objective assessment of the diagnostic performance of a laboratory. Currently, such an EQAS for parasitic worms is lacking. We therefore piloted an international EQAS for the diagnosis of parasitic worms involving 15 laboratories in Africa, Asia, Australia, Europe, and North America. Although most laboratories performed well, we could clearly identify those laboratories that may need to improve their test protocol. We found that laboratories were using many different test protocols, and further research should aim to verify whether this has an impact on the performance of the diagnostic outcomes

Giemsa-stained thick blood films as a source of DNA for Plasmodium species-specific real-time PCR

<p>Abstract</p> <p>Background</p> <p>This study describes the use of thick blood films (TBF) as specimens for DNA amplification with the <it>Plasmodium </it>species-specific real-time PCR that was recently validated on whole blood samples.</p> <p>Methods</p> <p>The panel of 135 Giemsa-stained clinical TBFs represented single infections of the four <it>Plasmodium </it>species with varying parasite densities or only gametocytes, mixed infections, and negative samples and was stored for up to 12 years. Half of the Giemsa-stained TBF was scraped off by a sterile scalpel and collected into phosphate buffered saline. DNA was extracted with the Qiagen DNA mini kit with minor modifications. DNA was amplified with the 18S rRNA real-time PCR targeting the four <it>Plasmodium </it>species with four species-specific primers and probes in combination with one genus-specific reverse primer. Results of the PCR on TBF were compared to those of the PCR on whole blood and to microscopy.</p> <p>Results</p> <p>Correct identification for single species infections was obtained for all TBF samples with <it>Plasmodium falciparum </it>(n = 50), <it>Plasmodium vivax </it>(n = 25), <it>Plasmodium ovale </it>(n = 25) and in all but one samples with <it>Plasmodium malariae </it>(n = 10). Compared to whole blood samples, higher Ct-values were observed by PCR on TBF with a mean difference of 5.93. Four out of five mixed infections were correctly identified with PCR on TBF. None of the negative samples (n = 20) gave a PCR signal. PCR on TBF showed a detection limit of 0.2 asexual parasites/μl compared to 0.02/μl for whole blood. Intra-run variation was higher for PCR on TBF (%CV 1.90) compared to PCR on whole blood (%CV 0.54). Compared to microscopy, PCR on TBF generated three more species identifications in samples containing a single species and detected the same four mixed-infections.</p> <p>Conclusions</p> <p>Giemsa-stained TBFs are a reliable source of DNA for <it>Plasmodium </it>real-time PCR analysis, allowing applications in reference and research settings in case whole blood samples are not available.</p

Sentinel surveillance of imported dengue via travellers to Europe 2012 to 2014: TropNet data from the DengueTools Research Initiative.

We describe the epidemiological pattern and genetic characteristics of 242 acute dengue infections imported to Europe by returning travellers from 2012 to 2014. The overall geographical pattern of imported dengue (South-east Asia &gt; Americas &gt; western Pacific region &gt; Africa) remained stable compared with 1999 to 2010. We isolated the majority of dengue virus genotypes and epidemic lineages causing outbreaks and epidemics in Asia, America and Africa during the study period. Travellers acted as sentinels for four unusual dengue outbreaks (Madeira, 2012-13; Luanda, 2013; Dar es Salaam, 2014; Tokyo, 2014). We were able to characterise dengue viruses imported from regions where currently no virological surveillance data are available. Up to 36% of travellers infected with dengue while travelling returned during the acute phase of the infection (up to 7 days after symptom onset) or became symptomatic after returning to Europe, and 58% of the patients with acute dengue infection were viraemic when seeking medical care. Epidemiological and virological data from dengue-infected international travellers can add an important layer to global surveillance efforts. A considerable number of dengue-infected travellers are viraemic after arrival back home, which poses a risk for dengue introduction and autochthonous transmission in European regions where suitable mosquito vectors are prevalent