Antigen Detection in Urine for Noninvasive Diagnosis and Treatment Monitoring of Visceral Leishmaniasis in Human Immunodeficiency Virus Coinfected Patients: An Exploratory Analysis from Ethiopia

Diagnosis of visceral leishmaniasis (VL) and assessment of treatment response in human immunodeficiency virus (HIV)–coinfected patients still relies on invasive tissue aspiration. This hampers scale-up and decentralization of care in resource-limited settings. Noninvasive diagnostics are urgently needed. KATEX is a frequently used latex agglutination test for Leishmania antigen in urine that has never been evaluated in HIV-coinfected individuals from Leishmania donovani–endemic areas. This was an exploratory sub-study embedded within the screening phase of a trial in highly endemic northwestern Ethiopia. All patients were HIV-positive and aspirate-confirmed VL cases. We assessed diagnostic accuracy of KATEX for VL diagnosis and as test of cure at end of treatment, using tissue aspirate parasite load as reference methods. We also described the evolution of weekly antigen levels during treatment. Most of the 87 included patients were male (84, 97%), young (median age 31 years), and had poor immune status (median cluster of differentiation type 4 count 56 cells/μL). KATEX had moderate sensitivity (84%) for VL diagnosis. KATEX had moderate sensitivity (82%) and a moderate negative predictive value (87%) but only low specificity (49%) and a low positive predictive value (40%) for the assessment of treatment outcomes. Weekly antigen levels showed characteristic patterns during treatment of patients with different initial parasite loads and treatment outcomes. Antigen detection in urine using KATEX can contribute to improved VL diagnosis in HIV-coinfected patients but has limited use for monitoring of treatment response. Better noninvasive diagnostics are needed to reduce reliance on invasive methods and thus to expand and improve clinical care for VL in resource-limited settings.

Are We Now Well Prepared for Another Major Visceral Leishmaniasis Epidemic in Sudan?

To minimize the chance for future visceral leishmaniasis (VL) epidemics such as the 1988-1991 epidemic in Sudan, several VL detection tools have been introduced. There are many VL diagnostics with excellent sensitivities, specificities, and ease of use reported. However, additional test characteristics should be considered for use in the detection of future VL epidemics. The potential for local production or uninterrupted availability, low production and application costs, and stability at ≥45°C are of the utmost importance. Of the antibody-, antigen-, or DNA-based methods introduced, only a liquid direct agglutination test (LQ-DAT) remains in routine use. The LQ-DAT test may be the ideal diagnostic for detection of VL epidemics due to its low cost ($0.50/patient), stability under frequent and long-duration electric failures, and high level of reproducibility. The improved reliability for VL detection achieved locally through incorporating autochthonous L. donovani strains in antigen processing and precluding toxicants in test execution provides optimal sensitivity and safety for routine and mass application.

Is urine a reliable clinical sample for the diagnosis of human visceral leishmaniasis? A systematic review and meta-analysis

Visualization of amastigotes in lymph nodes, bone marrow, and other tissues samples remains the gold standard method for the diagnosis of visceral leishmaniasis (VL) in humans. This gold standard diagnostic method uses a technically challenging microscopy procedure that is often not accessible in many places in the world where VL is endemic. Here, we report the current systematic review and meta-analysis to evaluate whether urine is a reliable clinical sample for diagnosis of human VL. Data were extracted from ten available databases during the period from 2002 to 2017. Overall, 29 articles fulfilled the inclusion criteria and were used for data extraction in this systematic review. Most studies (72.4%) using urine specimens were reported from five countries: India 6 (20.7%), Iran 5 (17.2%), Bangladesh 4 (13.8%), Japan 3 (10.3%) and Spain 3 (10.3%), respectively. The most common diagnostic tests performed on urine were Katex (62.1%), ELISA (24.1%), and the rK39 (17.2%) assays. In meta-analysis the sensitivity and specificity of the three most commonly used diagnostic assays were rK39 (97%; CI: 91-99; 98%;76-100), ELISA (91%; 82-95; 99%; CI: 94-100), and Katex (83%; 73-90; 98%; 98-100), suggesting that the rK39 assay provided the highest sensitivity and the ELISA assay provided the highest specificity for diagnosis of VL from urine samples. Our findings suggest that urine is a valuable clinical sample for the diagnosis of human VL, particularly in areas where the gold standard test for VL is not available.

A review of visceral leishmaniasis during the conflict in South Sudan and the consequences for East African countries

Background

Visceral leishmaniasis (VL), caused predominantly by Leishmania donovani and transmitted by both Phlebotomus orientalis and Phlebotomus martini, is highly endemic in East Africa where approximately 30 thousands VL cases are reported annually. The largest numbers of cases are found in Sudan - where Phlebotomus orientalis proliferate in Acacia forests especially on Sudan’s eastern border with Ethiopia, followed by South Sudan, Ethiopia, Somalia, Kenya and Uganda. Long-standing civil war and unrest is a dominant determinant of VL in East African countries. Here we attempt to identify the correlation between VL epidemics and civil unrest.

Objective and methodology

In this review, literature published between 1955 and 2016 have been gathered from MSF, UNICEF, OCHA, UNHCR, PubMed and Google Scholar to analyse the correlation between conflict and human suffering from VL, which is especially apparent in South Sudan.

Findings

Waves of forced migration as a consequence of civil wars between 1983 and 2005 have resulted in massive and lethal epidemics in southern Sudan. Following a comprehensive peace agreement, but especially with increased allocation of resources for disease treatment and prevention in 2011, cases of VL declined reaching the lowest levels after South Sudan declared independence. However, in the latest epidemic that began in 2014 after the onset of a civil war in South Sudan, more than 1.5 million displaced refugees have migrated internally to states highly endemic for VL, while 800,000 have fled to neighboring countries.

Conclusion

We find a strong relationship between civil unrest and VL epidemics which tend to occur among immunologically naïve migrants entering VL-endemic areas and when Leishmania-infected individuals migrate to new areas and establish additional foci of disease. Further complicating factors in East Africa’s VL epidemics include severe lack of access to diagnosis and treatment, HIV/AIDS co-infection, food insecurity and malnutrition. Moreover, cases of post-kala-azar dermal leishmaniasis (PKDL) can serve as important reservoirs of anthroponotic Leishmania parasites.

Novel Antigen Detection Assay to Monitor Therapeutic Efficacy of Visceral Leishmaniasis

Visceral leishmaniasis (VL) diagnosis is routinely performed by invasive liver, spleen, bone marrow, or lymph node biopsies, followed by microscopic identification of the parasites. Conventional serological tests cannot distinguish active disease from asymptomatic VL or from cured infection. Here, we report the initial validation of an enzyme-linked immunosorbent assay (ELISA) assembled to detect the Leishmania infantum/donovani antigens iron superoxide dismutase 1 (Li-isd1), tryparedoxin 1 (Li-trx1), and nuclear transport factor 2 (Li-ntf2) as a tool to monitor therapeutic efficacy of VL. The assembled ELISA detected the antigens in the urine samples from seven VL patients before initiation of therapy. Importantly, the antigens were no longer detected in all patients after completion of the treatment. These preliminary observations point to a promising tool to follow treatment efficacy of VL.

Leishmaniasis: diagnostic issues in Europe

Leishmaniasis is a parasitic disease with clinical presentations that vary from asymptomatic infection to cutaneous, mucocutaneous or visceral disease. Recent epidemiological studies have shown an increased prevalence in Europe largely caused by an increase in international travel, difficulty eradicating leishmanial infection in AIDS patients, and the use of immunosuppressive medications. Clinical diagnosis may be challenging, and parasitological diagnosis entails the use of invasive procedures which may be unrevealing in the immunosuppressed. A number of less invasive tests for the detection of anti-leishmanial antibodies or leishmanial antigen are available but their sensitivity and specificity may vary with the infective species and results have to be interpreted in light of the clinical presentation. The availability of polymerase chain reaction assays amplifying leishmanial genetic material has been a major step forward in improving the diagnosis of leishmanial disease and the response to treatment.

Systematic review of biomarkers to monitor therapeutic response in leishmaniasis

Recently, there has been a renewed interest in the development of new drugs for the treatment of leishmaniasis. This has spurred the need for pharmacodynamic markers to monitor and compare therapies specifically for visceral leishmaniasis, in which the primary recrudescence of parasites is a particularly long-term event that remains difficult to predict. We performed a systematic review of studies evaluating biomarkers in human patients with visceral, cutaneous, and post-kala-azar dermal leishmaniasis, which yielded a total of 170 studies in which 53 potential pharmacodynamic biomarkers were identified. In conclusion, the large majority of these biomarkers constituted universal indirect markers of activation and subsequent waning of cellular immunity and therefore lacked specificity. Macrophage-related markers demonstrate favorable sensitivity and times to normalcy, but more evidence is required to establish a link between these markers and clinical outcome. Most promising are the markers directly related to the parasite burden, but future effort should be focused on optimization of molecular or antigenic targets to increase the sensitivity of these markers. In general, future research should focus on the longitudinal evaluation of the pharmacodynamic biomarkers during treatment, with an emphasis on the correlation of studied biomarkers and clinical parameters.

Optimization of single-tube nested PCR for the diagnosis of visceral leishmaniasis

Conventional nested PCR is a very sensitive and specific method for the diagnosis of visceral leishmaniasis. However, this type of PCR is notorious for contamination problems related to the processing of the product between the first and the second PCR steps. In order to have a PCR method that is just as efficient but without the risk of contamination, we attempted the optimization of a single-tube nested PCR (STNPCR) method. During the first and the second PCR steps, we used the small subunit of ribosomal RNA (ssu rRNA) and the ribosomal internal transcribed spacer (ITS) as targets, respectively. The performances of STNPCR and nested PCR in detecting the DNA of Leishmania chagasi were compared. In the case of STNPCR, the inner primers were immobilized on the interior of the tube cap by means of adsorption microtubes and then were solubilized before the second reaction. This procedure eliminated the need to open the microtube, which could have led to false-positive results through cross-contamination. The detection limit for the purified L. chagasi DNA was 1 fg by using nested PCR and 10 fg by using STNPCR. We also tested the specificity of the system against other parasites, and observed that Trypanosoma cruzi DNA was amplified with a detection limit of up to 1 pg. This study not only presents a promising tool for the diagnosis of visceral leishmaniasis, but also provides a new tool for the diagnosis of Chagas disease, either in mono-infection by T. cruzi or in co-infection with Leishmania spp.

Rapid detection of human and canine visceral leishmaniasis: assessment of a latex agglutination test based on the A2 antigen from amastigote forms of Leishmania infantum

The diagnosis of visceral leishmaniasis (VL) in humans and animal reservoir hosts is difficult, particularly in rural areas where the disease is endemic and laboratory facilities are limited. This study aimed to develop a latex agglutination test (LAT) for the rapid detection of anti-Leishmania antibodies against the A2 antigen derived from the amastigote form as well as those against crude antigens derived from the promastigote form of an Iranian strain of Leishmania (Leishmania) infantum. The A2 antigen (42-100 kDa) was prepared from the amastigote form of L. infantum, purified with electroelution and compared with the crude antigen from the promastigote form of L. infantum. Both antigens showed appropriate intensity reactions, were selected using dot blotting of positive and negative pooled sera and used to sensitize 0.9-μm latex beads. The tests were carried out on sera from 43 symptomatic, human patients with VL confirmed by parasitological examination and direct agglutination test (DAT), 30 healthy controls and 32 patients with other infections but without VL. Canine sera were collected from 63 domestic dogs with VL confirmed using parasitological examinations and DAT and 31 healthy dogs from areas non-endemic for VL. Compared with the controls, human sera from DAT-confirmed patients yielded a sensitivity of 88.4% (95% CI, 82.1-94.5%) and specificity of 93.5% (95% CI, 87.0-99.7%) on A2-LAT (amastigote) when 1:3200 was used as the cut-off titre. A good degree of agreement was found between A2-LAT and DAT (0.914). LAT required 3-5 min to complete, versus the 12-18 h needed for DAT. Compared with the controls, A2-LAT of canine sera from DAT-confirmed cases yielded a sensitivity of 95.2% (95% CI, 95.0-95.4%) and specificity of 100% (95% CI 100%) when 1:320 was used as the cut-off titre. A good degree of agreement was found between A2-LAT and DAT (0.968). Similarly, the sensitivity and specificity of Pro.-LAT (promastigote) was calculated to be 88.4% and 91.9%, respectively for human sera and 96.8% and 90.3%, respectively for canine sera. No statistically significant differences were observed between A2-LAT and Pro.-LAT for the detection of human and canine L. infantum infections. In conclusion, A2-LAT and Pro.-LAT could be used in parallel to screen for L. infantum infections in humans and dogs in areas endemic for VL in Iran.

Quality of medical devices and in vitro diagnostics in resource-limited settings

The phenomenon of poor-quality medicines in resource-limited settings is well documented, and field observations reveal similar problems with medical devices (MDs) and in vitro diagnostics (IVDs). In scientific literature, however, there are only scarce reports and documents providing evidence of quality problems of MDs or IVDs in resource-limited settings. This discrepancy may be ascribed to (i) the poor regulatory oversight of MDs/IVDs in resource-limited settings, (ii) a general lack of awareness of the problem of poor-quality MDs/IVDs amongst the scientific community and decision-makers, and (iii) poor quality assurance in diagnostic laboratories in resource-poor settings, precluding tracing quality problems of IVDs from the other potential causes of diagnostic inaccuracy. The problem of poor-quality MDs/IVDs in resource-limited settings is a complex one to address. Firstly, operational definitions for substandard and counterfeit MDs/IVDs are required, as well as ad hoc field surveys, to ensure proper appraisal of the real extent of the problem. Investments are needed to reinforce the national regulatory oversights on MDs/IVDs in resource-limited settings, and to encourage a proactive and transparent exchange of information between Northern and Southern regulatory authorities. Industrialized countries can play a role by expanding and strengthening their regulatory oversight and quality labels to those MDs/IVDs that are frequently used in resource-poor settings. Hopefully, the combination of these measures will result in better protection of patients in resource-poor countries from the effects of being exposed to poor-quality MDs and IVDs.

Urine antigen detection by latex agglutination test for diagnosis and assessment of initial cure of visceral leishmaniasis

This prospective study evaluated the usefulness of the kala-azar latex agglutination test (KAtex) for the diagnosis and laboratory assessment of initial cure of visceral leishmaniasis (VL) (or kala-azar) patients following 30 days of sodium antimony gluconate treatment at Rajshahi Medical College Hospital (Bangladesh). KAtex detects a low molecular weight, heat-stable, carbohydrate antigen in the urine of VL patients. KAtex was performed using freshly voided urine samples obtained from 36 parasitologically confirmed cases of VL before and after treatment as well as from 40 healthy controls (20 each from kala-azar-endemic and non-endemic zones). KAtex was found to be positive in 27 (75%) of the 36 patients at diagnosis and was negative in all the controls. The diagnostic sensitivity and specificity of KAtex were 75% (95% CI 57-87%) and 100% (95% CI 89-100%), respectively. Following treatment, all 36 VL cases were negative for Leishman-Donovan bodies by splenic smear microscopy and 34 (94.4%) were negative by KAtex. This limited study suggests that KAtex is a satisfactorily sensitive, highly specific, rapid and completely non-invasive urine-based antigen detection test for the diagnosis of VL. Currently, this is the only non-invasive laboratory tool useful for the assessment of initial cure in VL patients.

Improvement of the newly developed latex agglutination test (Katex) for diagnosis of visceral lieshmaniasis

INTRODUCTION

Different methods are available for diagnosis of visceral leishmaniasis (VL), among them the urine-based antigen detection assay, latex agglutination test (Katex), is a recently developed one. The main drawback of the test is false-positive reactivity in some of healthy individuals. The false positivity of the test can be removed by boiling the urine sample for 5 min before testing. In this study an attempt was made to improve Katex by removing unpleasant boiling process, which also decreases field applicability of the test.

METHODS

False-positive and true-positive urine samples were collected from VL patients and healthy individuals. Both samples were then treated by reagents including, sodium dodecyl sulfate, trichloroacetic acid, dithiothreitol (DTT), sulphosalicylic acid and also heating at 56 degrees C.

RESULTS

Findings of this study showed that DTT pretreatment significantly reduced the rate of false-positive reactivity of Katex where 73% of false-positive urine samples changed to negative after DTT treatment. However, the DTT treatment reduced the rate of true positivity by 14%.

CONCLUSION

These data indicate that DTT can be used to eliminate nonspecific reactivity in the Katex. This will improve the performance of Katex and make it a more convenient and field applicable test.

The relationship between leishmaniasis and AIDS: the second 10 years

To date, most Leishmania and human immunodeficiency virus (HIV) coinfection cases reported to WHO come from Southern Europe. Up to the year 2001, nearly 2,000 cases of coinfection were identified, of which 90% were from Spain, Italy, France, and Portugal. However, these figures are misleading because they do not account for the large proportion of cases in many African and Asian countries that are missed due to a lack of diagnostic facilities and poor reporting systems. Most cases of coinfection in the Americas are reported in Brazil, where the incidence of leishmaniasis has spread in recent years due to overlap with major areas of HIV transmission. In some areas of Africa, the number of coinfection cases has increased dramatically due to social phenomena such as mass migration and wars. In northwest Ethiopia, up to 30% of all visceral leishmaniasis patients are also infected with HIV. In Asia, coinfections are increasingly being reported in India, which also has the highest global burden of leishmaniasis and a high rate of resistance to antimonial drugs. Based on the previous experience of 20 years of coinfection in Europe, this review focuses on the management of Leishmania-HIV-coinfected patients in low-income countries where leishmaniasis is endemic.