Canine visceral leishmaniasis: performance of a rapid diagnostic test (Kalazar Detect) in dogs with and without signs of the disease

Current visceral leishmaniasis (VL) control programs in Brazil include the infected dog elimination but, despite this strategy, the incidence of human VL is still increasing. One of the reasons is the long delay between sample collection, analysis, control implementation and the low sensitivity of diagnostic tests. Due to the high prevalence of asymptomatic dogs, the diagnosis of these animals is important considering their vector infection capacity. Hence, a rapid and accurate diagnosis of canine visceral leishmaniasis is essential for an efficient surveillance program. In this study we evaluated the performance of rK39 antigen in an immunochromatographic format to detect symptomatic and asymptomatic Leishmania chagasi infection in dogs and compared the results with those using a crude antigen ELISA. The sensitivity of rK39 dipstick and ELISA were 83% vs. 95%, respectively, while the specificity was both 100%. Our results also demonstrated that the dipstick test was able to detect infected dogs presenting different clinical forms.     

Qualitative and Semi-Quantitative Comparison of an Rk39 Strip Test and Direct Agglutination Test for Detection of Anti-Leishmania Donovani Antibodies in the Sudan

Background: Until now, the comparison of the rK39 strip test (RKT) and direct ag-glutination test (DAT) for detection of visceral leishmaniasis (VL) is exclusively based on either positive or negative qualification of the reaction outcome. Objective: In this study, we compared the diagnostic performance of RKT and DAT for VL both qualitatively and semi-quantitatively. Methods: For comparison based on semi-quantitative grounds, the execution of RKT and DAT was according to the standard procedures. For comparison on semi-qualitative grounds with DAT, the RKT was ap-plied to aliquots from positive samples that were two-fold serially diluted in saline to determine, as for the DAT, the end-point reaction in RKT. Results: While qualita-tively both RKT and DAT demonstrated comparable reliability for VL detection (sen-sitivity = 96% and specificity = 98.7% or 99.3%), no significant correlation (r = 0.13) could be established between intensities of their positive reactions in 25 cases studied. A negative correlation was further determined in those 25 VL cases between the posi-tive intensities of the RKT and antibody levels measured semi-quantitatively with the same procedure (r = -0.36) or the DAT (r = -0.30). Irrespective of the low, moderate or high antibody levels measured with RKT (<1:8 and 1:16-1:32 >1:256) or DAT (< 1:25,600 and 1:51,200- 1:409,600 > 1:3,276,800) in patients with confirmed or uncon-firmed VL infection, exclusively strong positive intensities were obtained with RKT. Conclusion: For further optimizing diagnosis and simultaneously assessing magni-tude of immune response to L. donovani infection in Sudanese patients, the combined application of RKT and DAT is recommended.     

Accessibility of diagnostic and treatment centres for visceral leishmaniasis in Gedaref State, northern Sudan

OBJECTIVE: To evaluate the accessibility of visceral leishmaniasis (VL) treatment. METHOD: Community-based study using in-depth qualitative interviews and focus group discussions with key informants, as well as quantitative questionnaires with 448 randomly selected heads of households in nine representative villages in three geographical sub-regions. RESULTS: Despite the high incidence of the disease, most people in Gedaref State know little about VL, and help at a treatment centre is usually sought only after traditional remedies and basic allopathic drugs have failed. Factors barring access to treatment are: lack of money for treatment and transport, impassability of roads, work priorities, severe cultural restrictions of women's decision-making power and distance to the next health center. CONCLUSIONS: To provide more VL patients with access to treatment in this highly endemic area, diagnostic and treatment services should be decentralized. Health education would be a useful tool to rationalise people's health-seeking behaviour.     

Diagnosis of visceral leishmaniasis by the polymerase chain reaction using blood, bone marrow and lymph node samples from patients from the Sudan

We have evaluated the sensitivity of the polymerase chain reaction (PCR) as a diagnostic tool for Leishmania donovani using blood, bone marrow and lymph node samples from Sudanese patients with a confirmed infection. Forty patients were diagnosed by microscopic examination of bone marrow or lymph node samples. The PCR was able to detect parasite DNA in 37 out of 40 blood samples. In bone marrow and lymph node samples, the PCR was able to detect parasite DNA in all 7 and 6 samples, respectively. We suggest that the PCR should be considered as a valuable and sensitive tool for the diagnosis of L. donovani infection. However, if PCR diagnosis is to supplement or even replace microscopic diagnosis in developing countries, a large number of patients with no apparent signs of infection and patients with other diseases have to be tested in order to evaluate its true potential.     

Evaluation of a mass distribution programme for fine-mesh impregnated bednets against visceral leishmaniasis in eastern Sudan

During an epidemic of visceral leishmaniasis (VL) in eastern Sudan, Médecins Sans Frontières distributed 357,000 insecticide-treated bednets (ITN) to 155 affected villages between May 1999 and March 2001. To estimate the protective effect of the ITN, we evaluated coverage and use of ITN, and analysed VL incidence by village from March 1996 to June 2002. We provided ITN to 94% of the individuals >5 years old. Two years later, 44% (95% CI 39-48%) of nets were reasonably intact. Because ITN were mainly used as protection against nuisance mosquitoes, bednet use during the VL transmission season ranged from <10% during the hot dry months to 55% during the beginning of the rainy season. ITN were put up from 9 to 11 p.m., leaving children unprotected during a significant period of sandfly-biting hours after sunset. Regression analysis of incidence data from 114 villages demonstrated a significant reduction of VL by village and month following ITN provision. The greatest effect was 17-20 months post-intervention, with VL cases reduced by 59% (95% CI: 25-78%). An estimated 1060 VL cases were prevented between June 1999 and January 2001, a mean protective effect of 27%. Although results need to be interpreted with caution, this analysis indicates a potentially strong reduction in VL incidence following a community distribution of ITN. The effectiveness of ITN depends on behavioural factors, which differ between communities.     

Comparison of an rK39 dipstick rapid test with direct agglutination test and splenic aspiration for the diagnosis of kala-azar in Sudan

We compared an rK39 dipstick rapid test (Amrad ICT, Australia) with a direct agglutination test (DAT) and splenic aspirate for the diagnosis of kala-azar in 77 patients. The study was carried out under field conditions in an endemic area of north-east Sudan. The sensitivity of the rK39 test compared with splenic aspiration was 92% (46/50), the specificity 59% (16/27), and the positive predictive value 81% (46/57). Compared with the diagnostic protocol used by Médecins sans Frontières, the sensitivity of the rK39 test was 93% (50/54), the specificity 70% (16/23), and the positive predictive value 88% (50/57). Compared with splenic aspirates, the sensitivity of a DAT with a titre > or =1:400 was 100% (50/50), but its specificity only 55% (15/27) and the positive predictive value was 80% (50/62). Using a DAT titre > or =1:6400, the sensitivity was 84% (42/50), the specificity 85% (23/27) and the positive predictive value 91% (42/46). All four patients with DAT titre > or =1:6400 but negative splenic aspirate were also rK39 positive; we consider these are probably 'true' cases of kala-azar, i.e. false negative aspirates, rather than false DAT and rK39 seropositives. There were no false negative DATs (DAT titre < or =1:400 and aspirate positive), but there were four false negative rK39 tests (rK39 negative and aspirate positive). The rK39 dipstick is a good screening test for kala-azar; but further development is required before it can replace the DAT as a diagnostic test in endemic areas of the Sudan.     

Evaluation of the direct agglutination test based on freeze-dried Leishmania donovani promastigotes for the serodiagnosis of visceral leishmaniasis in Sudanese patients

The direct agglutination test (DAT) based on freeze-dried (FD) Leishmania donovani antigen was evaluated for the serodiagnosis of kala-azar in a rural setting in eastern Sudan. The performance of the FD-DAT was compared with standard liquid antigen (LQ) by testing serum samples and blood samples collected on filter paper of microscopically and PCR-confirmed VL patients, apparently healthy endemic controls and patients with other relevant infectious diseases for the region. In the present study, the FD-DAT had a sensitivity of 96.8% and a specificity of 96.2%. The LQ-DAT had a sensitivity of 91.0% and a specificity of 96.6%. A high degree of agreement (97.3%; r-value 0.94) was observed between the FD-DAT and the LQ-DAT, as well as between the FD-DAT performed on serum samples and corresponding blood samples collected on filter paper (agreement 97.8%; r-value 0.79). The FD-DAT is very suitable as diagnostic test for kala-azar in remote rural conditions as it is sensitive, specific and stable. The antigen is affordable, reproducible and available, which contributes to the sustainability of the DAT as a diagnostic test for VL.     

Multi-centre evaluation of repeatability and reproducibility of the direct agglutination test for visceral leishmaniasis

OBJECTIVE: To evaluate the repeatability and reproducibility of the serological direct agglutination test (DAT) for visceral leishmaniasis (VL) with aqueous antigen in a multi-centre study in VL-endemic areas in Sudan, Kenya and Nepal. METHODS: Repeatability within each centre and reproducibility between the centres' results and an external reference laboratory (Belgium) was assessed on 1596 triplicate plain blood samples collected on filter paper. RESULTS: High kappa values (range 0.86-0.97) indicated excellent DAT repeatability within the centres. The means of the titre differences between the reference laboratory and the centres in Sudan, Kenya and Nepal (2.3, 2.4 and 1.1, respectively, all significantly different from 0) showed weak reproducibility across centres. 95% of the titre differences between the reference laboratory and the respective centres were accounted for by large intervals: 0.6-9 fold titre variation for Sudan, 0.7-8 fold for Kenya and 0.26-4 fold for Nepal. CONCLUSION: High repeatability of DAT confirms its potential, but reproducibility problems remain an obstacle to its routine use in the field. Reproducibility was hindered by alteration of the antigen through temperature and shaking, especially in Kenya and Sudan, and by nonstandardization of the test reading. DAT handling procedures and antigen quality must be carefully standardized and monitored when introducing this test into routine practice.     

Comparative evaluation of parasitology and serological tests in the diagnosis of visceral leishmaniasis in India: a phase III diagnostic accuracy study

In this phase III trial for diagnostics for visceral leishmaniasis (VL) in India, we compared parasitological diagnosis with several serological tests: direct agglutination test (freeze dried; DAT-FD), rK-39 strip test, rK-26 strip test and a latex agglutination test for antigen detection in urine (KAtex) in 452 subjects from the endemic regions of Bihar, India. The subjects were segregated into four categories: 230 confirmed patients, 52 probable cases, 70 non-cases and 100 healthy endemic controls. The first two groups were used for estimating sensitivity, the latter two for specificity. Sensitivity of DAT-FD was 98.9%, rK-39: 98.9%, KAtex: 67.0% and rK-26: 21.3%. Sensitivity of DAT-FD on blood taken on filter paper (DAT-FDF) was 99.3%, which was comparable with that using serum. Specificity of serological tests was comparable and high (DAT-FD and DAT-FDF: 94%, rK-39 strip test: 97%, KAtex: 99% and rK-26 strip test: 100%). The classical 'gold standard' parasitological demonstration in splenic smear performed poorly as it missed 18.4% of cases that benefited from VL treatment. Reproducibility of the serological tests between field and central laboratories was excellent (kappa = 1.0, 0.99, 0.96 and 0.94 respectively for microscopy, DAT-FD, rK-39 strip test and rK-26 strip test). A high degree of agreement was observed between DAT-FD and rK-39 strip test (kappa = 0.986). Although DAT-FD and rK-39 strip test were highly sensitive with excellent specificity, the ease of use of the latter makes it most suitable for the diagnosis of VL in the field conditions.     

快速检测内脏利什曼病特异抗体胶体金免疫层析试条方法的建立与效果评价

目的 建立快速、简便地检测内脏利什曼病特异抗体的胶体金免疫层析试条方法,并评价效果. 方法 采用柠檬酸三钠还原法制备胶体金,用以标记链球菌G蛋白（streptococcal protein G,SPG）,并将其吸附于交联释放垫上;将杜氏利什曼原虫前鞭毛体粗抗原作为包被抗原,包被于硝酸纤维素膜适当位置,制成检测特异抗体的免疫层析试条.用该试条检测病原学确诊的内脏利什曼病（129例）、疟疾（20例）、细粒棘球蚴病（10例）、日本血吸虫病（10例）、并殖吸虫病（5例）、华支睾吸虫病（5例）等患者血清,以及健康者（40例）血清,评价其敏感性和特异性.同时用酶联免疫吸附试验（enzyme-linked immunosorbent assay,ELISA）进行平行检测. 结果 试条法检测129份黑热病患者血清,124份为阳性,敏感性为96.1％;与疟疾患者血清存在10.0％ （2/20）的交叉反应;与日本血吸虫病患者血清存在10.0％ （1/10）的交叉反应;与健康者血清存在2.5％ （1/40）的假阳性反应;与10份细粒棘球蚴病患者血清,5份并殖吸虫病患者血清和5份华支睾吸虫病患者血清均无交叉反应,总特异性为95.6％ （86/90）.该方法与ELISA法的符合率为99.2％,二者阳性检出率之间的差异无统计学意义（x2=0.12,P＞0.05）,二者特异性之间的差异也无统计学意义（x2=0.42,P＞0.05）. 结论 成功建立快速检测内脏利什曼病的胶体金免疫层析试条,该试条敏感性、特异性均较高.     

Visceral Leishmaniasis Eradication is a Reality: Data from a Community-based Active Surveillance in Bangladesh

More than 20 million people in Bangladesh are considered at risk of developing visceral leishmaniasis (VL). A community-based active surveillance was conducted in eight randomly selected villages in a highly endemic area of Bangladesh from 2006 to 2008. A total of 6,761 individuals living in 1,550 mud-walled houses were included in the active surveillance. Rapid rK39 dipstick tests were conducted throughout the study period to facilitate the case diagnosis. Individuals with previous or current clinical leishmaniasis were identified on the basis of the case definition of the VL elimination program. Untreated cases of suspected VL were referred to the hospital for treatment. Socioeconomic and environmental information including bed net use was also collected. In 2006, the annual incidence of clinical leishmaniasis in the study area was 141.9 cases per 10,000 population, which was significantly increased by the following year owing to community-based active surveillance for case detection and reporting. However, early case detection and early referral for treatment led to a significant decrease in incidence in 2008. This study suggests that community-based active surveillance using a simple diagnostic tool might play a role in achieving the goal of the VL elimination program.     

Drug policy for visceral leishmaniasis: a cost-effectiveness analysis

OBJECTIVE: To facilitate the choice of the best visceral leishmaniasis (VL) treatment strategy for first-line health services in (VL)-endemic areas, we compared in a formal decision analysis the cost and the cost-effectiveness of the different available options. METHODS: We selected four drug regimens for VL on the basis of frequency of use, feasibility and reported efficacy studies. The point estimates and the range of plausible values of effectiveness and cost were retrieved from a literature review. A decision tree was constructed and the strategy minimizing the cost per death averted was selected. RESULTS: Treatment with amphotericin B deoxycholate was the most effective approach in the baseline analysis and averted 87.2% of all deaths attributable to VL. The least expensive and the most cost-effective treatment was the miltefosine regimen, and the most expensive and the least cost-effective was AmBisome treatment. The cost of drug and medical care are the main determinants of the cost-effectiveness ranking of the alternative schemes. Sensitivity analysis showed that antimonial was competitive with miltefosine in the low-resistance regions. CONCLUSION: In areas with >94% response rates to antimonials, generic sodium stibogluconate remains the most cost-effective option for VL treatment, mainly due to low drug cost. In other regions, miltefosine is the most cost-effective option of treatment, but its use as a first-line drug is limited by its teratogenicity and rapid resistance development. AmBisome in mono- or combination therapy is too expensive to compete in cost-effectiveness with the other regimens.     

检测特异抗体胶体金免疫层析试条诊断内脏利什曼病患者现场评价

目的 在现场评价检测内脏利什曼病特异抗体的胶体金免疫层析试条诊断内脏利什曼病患者的效果。方法 2013年采集动物源型内脏利什曼病流行区(四川省、甘肃省)和人源型内脏利什曼病流行区(新疆喀什市)疾病预防控制中心门诊就诊的病人血样和骨髓样本,用镜检法、内脏利什曼病试条和rK39试条进行平行测试,以镜检法为金标准,比较两种试条法检测的敏感性和特异性有无差异。结果 内脏利什曼病试条和rK39试条检测镜检确诊的97例内脏利什曼病患者的敏感性分别为98.87%(96/97),97.94%(95/97),二者无统计学差异(χ²=0.34,P>0.05)。两种试条检测非内脏利什曼病病例145例, 均有2例假阳性反应,特异性为98.62(143/145)。对来自动物源型内脏利什曼病流行区和人源型内脏利什曼病流行区的内脏利什曼病患者分别统计阳性率,结果显示内脏利什曼病试条和rK39试条法检测动物源型和人源型流行区的内脏利什曼病患者血样之间阳性率的差异均无统计学意义(χ²=0.22 /0.01,P>0.05)。两种试条法检测动物源型和人源型内脏利什曼病流行区非内脏利什曼病患者血样之间特异性的差异也均无统计学意义(χ²=0.29,P>0.05)。结论 快速检测内脏利什曼病的胶体金免疫层析试条适用于检测动物源型内脏利什曼病流行区患者血样中的特异性抗体。     

Infection rates with Leishmania donovani and Mycobacterium tuberculosis in a village in eastern Sudan

BACKGROUND: Leishmania-tuberculosis co-infection is not uncommon in clinical practice in East Africa, but little is known about the epidemiology of this problem at population level. A cross-sectional household survey was carried out in an active visceral leishmaniasis (VL) focus in Eastern Sudan in February 2002. METHODS: All inhabitants of Marbata village in Atbara River Area, Gedarif State, who gave informed consent, underwent both a leishmanin skin test (LST) and a tuberculin test for infection with L. donovani and Mycobacterium tuberculosis. All subjects were clinically screened for VL and tuberculosis (TB). RESULTS: About 66% (252 of 382) were LST-positive, 26% (100 of 382) were tuberculin-positive and 20% (77 of 382) were positive for both tests. By the age of 15, more than 60% of inhabitants were LST-positive, but <20% were tuberculin-positive. By the age of 30, these percentages increased to 100 and 50%. No association was found at the individual level between leishmanial and tuberculous infection after controlling for age. CONCLUSION: In this community study, we found no association between the risk of infection with L. donovani and M. tuberculosis. However, the progression to active VL disease might be different in M. tuberculosis-infected than in non-infected persons and vice versa. Prospective studies are needed to document the prognosis of TB/VL co-infection.     

Visceral leishmaniasis in the early post‐transplant period after kidney transplantation: clinical features and therapeutic management

M. Veroux, D. Corona, G. Giuffrida, B. Cacopardo, N. Sinagra, T. Tallarita, A. Giaquinta, D. Zerbo, P.F. Veroux. Visceral leishmaniasis in the early post‐transplant period after kidney transplantation: clinical features and therapeutic management.
Transpl Infect Dis 2010: 12: 387–391. All rights reserved Abstract: Visceral leishmaniasis (VL) is a rare complication of kidney transplantation, with <100 cases reported in the literature. It is a life‐threatening condition and usually occurs as a late complication after transplantation, with a median delay of 18 months between transplantation and onset of disease. We report the clinical features and management of 5 kidney transplant recipients who presented with VL in the early post‐transplant period. All patients were successfully treated with liposomal amphotericin B (L‐AMB), but 2 patients experienced graft loss. VL should be considered in the differential diagnosis in kidney transplant recipients living in endemic areas, who present with unexplained fever and pancytopenia in the early post‐transplant period. Leishmania serology should be included in the screening of all transplant recipients, in order to identify a group of patients who could benefit from preemptive anti‐Leishmania therapy. Therapy with L‐AMB is highly effective and well tolerated in kidney transplant recipients with VL.     

Prospective evaluation and comparison of the direct agglutination test and an rK39-antigen-based dipstick test for the diagnosis of suspected kala-azar in Nepal

The diagnosis of visceral leishmaniasis (kala-azar) remains difficult in rural endemic areas and practical and reliable tests are badly needed. Two serological tests, the Direct Agglutination Test (DAT) and an rK39-antigen-based dipstick test, were compared to parasitological diagnosis in a group of 184 patients presenting at a tertiary care centre in south-eastern Nepal with a history of fever > or = 14 days and splenomegaly; 139 patients had a parasitologically proven kala-azar and 45 patients had a negative parasitological work-up. The rK39 dipstick showed a sensitivity of 97% and a specificity of 71%. The DAT was up to 99% sensitive with a low cut-off titre (1:400) but its specificity did not exceed 82% even with a high cut-off titre (1:51 200). Both tests could be used for screening suspect patients in endemic areas. However, their use as confirmatory tests should be restricted to situations where the proportion of kala-azar among clinical suspect patients is high. The rK39 dipstick is cheaper and easier to use than the DAT and could be used widely provided that both its performance and production remain stable.     

Comparative evaluation of freeze-dried and liquid antigens in the direct agglutination test for serodiagnosis of visceral leishmaniasis (ITMA-DAT/VL)

OBJECTIVE: The direct agglutination test (DAT) for visceral leishmaniasis (VL) with liquid (LQ) antigen is known to be only moderately reproducible because of inter-observer and batch-to-batch variability as well as its sensitivity to temperature and shaking during transport. We evaluated a DAT with freeze-dried (FD) antigen and compared it with the LQ antigen version. METHODS: Blood samples of clinical VL suspects and healthy endemic controls were collected in Sudan, Nepal and India. Both test versions were performed in duplicate in the respective countries and in the reference laboratory. Interbatch variability and stability tests were conducted and agreement was examined within and between centres on a dichotomic scale by Cohen's kappa as well as on a continuous scale through Bland-Altman plots. RESULTS: The FD antigen remains fully active even after storage at 45 degrees C for 24 months. Using a cut-off titre of 1:6400, the agreement between the FD and the LQ formats was excellent. CONCLUSION: The major advantages of FD antigen are its better stability at higher temperatures and its longer shelf life, which make it much more suitable than the LQ version for use in the field.     

新疆维吾尔自治区伽师县卧里托格拉克乡居民内脏利什曼病流行现况调查

目的 调查新疆维吾尔自治区伽师县内脏利什曼病流行现况.方法 采用回顾性调查和现况调查相结合,对伽师县卧里托格拉克乡20村1组所有居民进行入户调查.调查内容包括既往有无疑似内脏利什曼病病史,部分居民进行利什曼素皮内试验,对3岁以下婴幼儿皮内试验阴性者进行查体(触诊肝、脾)和rk39免疫层析试条检测.在居民住宅内、外捕集白蛉,解剖鉴定并检查前鞭毛体有无自然感染.结果 接受利什曼素皮内试验149人,阳性率为68.46%(102/149);3岁以下年龄组阳性率为11.76%(2/17),4～75岁年龄组阳性率为75.76%(100/132).3岁以下年龄组皮内试验阴性者有15人接受rk39免疫层析试条检测,1例阳性者(女,1岁),确认为临床诊断病例.2001-2008年7月有既往病史者52例,其中治愈50例,死亡2例.捕获的374只雌蛉,经解剖鉴定为吴氏白蛉(Phlebotomus wui),其中3只雌蛉体内查见自然感染的利什曼原虫前鞭毛体.结论 伽师县仍有内脏利什曼病流行.     

Evaluation of a new recombinant K39 rapid diagnostic test for Sudanese visceral leishmaniasis

A new rK39 rapid diagnostic dipstick test (DiaMed-IT-Leish) was compared with aspiration and a direct agglutination test (DAT) for diagnosis of visceral leishmaniasis (VL) in 201 parasitologically confirmed cases, 133 endemic controls, and in 356 clinical suspects in disease-endemic and -epidemic areas in Sudan. The sensitivity of the rK39 test in parasitologically confirmed VL cases was 90%, whereas the specificity in disease-endemic controls was 99%. The sensitivity of the DAT was 98%. In clinically suspected cases, the sensitivity of the rK39 test was 81% and the specificity was 97%. When compared with the diagnostic protocol based on the DAT and aspiration used by Médecins sans Frontières in epidemic situations, the positive predictive value was 98%, and the negative predictive value was 71%. This rK39 rapid diagnostic test is suitable for screening as well as diagnosis of VL. Further diagnostic work-up of dipstick-negative patients with clinically suspected VL is important. The ease and convenience of the dipstick test will allow decentralization and improved access to care in disease-endemic areas in Sudan.