Diagnostic tests for kala-azar: a multi-centre study of the freeze-dried DAT, rK39 strip test and KAtex in East Africa and the Indian subcontinent.

Three diagnostic tests for visceral leishmaniasis (VL), the freeze-dried direct agglutination test (FD-DAT), the rK39 dipstick and a urine latex antigen test (KAtex), were evaluated for use in primary care in East Africa and the Indian subcontinent. Clinical suspects were prospectively recruited and tissue, blood and urine samples were taken. Direct microscopic examination of tissue smear, and FD-DAT, rK39 and KAtex were performed. Sensitivity and specificity with 95% credible intervals were estimated using Bayesian latent class analysis. On the Indian subcontinent both the FD-DAT and the rK39 strip test exceeded the 95% sensitivity and 90% specificity target, but not so in East Africa. Sensitivity of the FD-DAT was high in Ethiopia and Kenya but lower in Sudan, while its specificity was below 90% in Kenya. Sensitivity of the rK39 was below 80% in the three countries, and its specificity was only 70% in Ethiopia. KAtex showed moderate to very low sensitivity in all countries. FD-DAT and rK39 can be recommended for clinical practice on the Indian subcontinent. In East Africa, their clinical use should be carefully monitored. More work is needed to improve existing formats, and to develop better VL diagnostics.

Generic sodium stibogluconate is as safe and effective as branded meglumine antimoniate, for the treatment of tegumentary leishmaniasis in Isiboro Secure Park, Bolivia.

Human cutaneous leishmaniasis (CL) and mucous leishmaniasis (ML) are highly endemic in Isiboro Secure Park, which lies in the Bolivian department of Cochabamba--an area where branded meglumine antimoniate (Glucantime) is expensive and poorly distributed. The safety and efficacy of generic sodium stibogluconate (SSG), from Albert David Ltd, was therefore explored, in CL and ML cases from the park, who were treated with 20 mg/kg.day for 20 and 30 days, respectively. A questionnaire recording adverse effects was completed by a physician in each treatment centre. Efficacy of treatment was assessed at the end of treatment and at follow-ups 1 month and 3, 6 and 12 months later. Overall, 146 patients completed treatment with SSG in 2003-2004. No fatalities or severe adverse effects were reported but mild to moderate adverse effects were noted in 41 (28%) of the patients. The incidence of adverse effects was significantly higher among the cases of ML than among the cases of CL. Of the 86 patients with CL who completed 6 months of follow-up, 81 (94.2%) were considered to have been clinically cured; a comparable cohort of 69 CL cases who had been treated with Glucantime in 2001-2002 showed a similar frequency of clinical cure (90%). Generic SSG was shown to be safe and efficacious for the treatment of tegumentary leishmaniasis in Bolivia. Being several times cheaper than Glucantime, it could contribute to improving the access of CL and ML patients to treatment, not only in Bolivia but also in other countries of Latin America.

Leishmaniasis: current situation and new perspectives.

Leishmaniasis represents a complex of diseases with an important clinical and epidemiological diversity. Visceral leishmaniasis (VL) is of higher priority than cutaneous leishmaniasis (CL) as it is a fatal disease in the absence of treatment. Anthroponotic VL foci are of special concern as they are at the origin of frequent and deathly epidemics (e.g. Sudan). Leishmaniasis burden remains important: 88 countries, 350 million people at risk, 500,000 new cases of VL per year, 1-1.5 million for CL and DALYs: 2.4 millions. Most of the burden is concentrated on few countries which allows clear geographic priorities. Leishmaniasis is still an important public health problem due to not only environmental risk factors such as massive migrations, urbanisation, deforestation, new irrigation schemes, but also to individual risk factors: HIV, malnutrition, genetic, etc em leader Leishmaniasis is part of those diseases which still requires improved control tools. Consequently WHO/TDR research for leishmaniasis has been more and more focusing on the development of new tools such as diagnostic tests, drugs and vaccines. The ongoing effort has already produced significant results. The newly available control tools should allow a scaling up of control activities in priority areas. In anthroponotic foci, the feasibility of getting a strong impact on mortality, morbidity and transmission, is high.

Evaluation of a urinary antigen-based latex agglutination test in the diagnosis of kala-azar in eastern Nepal.

BACKGROUND: We evaluated the diagnostic accuracy as well as the reproducibility of the urine latex agglutination test 'KAtex' in the diagnosis of kala-azar in patients recruited at a tertiary care centre in Dharan, Nepal, between November 2000 and January 2002. METHODS: All patients presenting with fever of 2 weeks or more and splenomegaly were consecutively enrolled. Bone marrow and--if negative--spleen aspirates were examined for Leishmania donovani. Serum and urine samples were taken in duplicate for the Direct Agglutination Test (DAT) and KAtex. The reference laboratory determined sensitivity and specificity of KAtex. Reproducibility between both laboratories was assessed. RESULTS: KAtex was performed on urine from 155 parasitologically confirmed kala-azar and 77 non-kala-azar cases (parasitology and DAT-negative). KAtex showed a sensitivity of 47.7% (74/155, 95% CI: 39.7-55.9) and a specificity of 98.7% (76/77, 95% CI: 93.0-100.0). Reproducibility of KAtex showed a kappa of 0.684 (P < 0.001, n = 232). CONCLUSION: KAtex evaluation showed high specificity, low sensitivity and moderate reproducibility. A urine test for kala-azar could become a real breakthrough in kala-azar management if its reproducibility and sensitivity could be further improved.

Treatment of cutaneous leishmaniasis among travellers.

Leishmaniasis is endemic in 88 countries on five continents. There are 1-1.5 million cases of cutaneous leishmaniasis reported yearly worldwide. There has been a sharp increase in recorded cases over the last 10 years. Based on geographical distribution, cutaneous leishmaniasis is divided into Old World and New World leishmaniasis. In the past, species could be inferred from geographical setting or determined by performing culture and isoenzyme analysis. The recently developed and now widely available PCR technology allows a rapid diagnosis with determination of most species, and thus enables a species-orientated treatment. While the Old World species mostly cause benign and often self-limiting cutaneous disease, the American species cause a broad spectrum of conditions from benign to severe manifestations, including mucosal involvement. The response to treatment varies according to the species. Therefore, a species-specific approach is proposed. Drugs for systemic and topical treatment are presented and discussed with regard to their application, use and adverse effects. Indications for local or systemic treatment are proposed. Drugs under investigation are also mentioned. An overview of published treatment options and a treatment recommendation is given for each of the most important species. The level of evidence of the studies leading to these recommendations is given.

Leishmania/HIV co-infections: epidemiology in Europe.

As the AIDS pandemic spreads to rural areas and human visceral leishmaniasis (VL) becomes more common in suburban areas, there is an ever greater degree of overlap between the geographical distributions of the two diseases and, in consequence, an increasing incidence of Leishmania/HIV co-infection. Cases of the co-infection have been reported from 35 countries around the world but most have been recorded in south-western Europe. There has been a total of 1911 cases detected in Spain, France, Italy and Portugal. The incidence of Leishmania/HIV co-infection is expected to continue increasing in eastern Africa but to fall in south-western Europe as increasing numbers of HIV-positives in the latter region are given the new, highly active, antiretroviral therapy (HAART). In 1998, a world-wide network of surveillance for the co-infection, which now includes 28 member institutions, was established by the World Health Organization (WHO) and the Joint United Nations Programme on HIV/AIDS (UNAIDS). In south-western Europe, the surveillance system is based on 16 institutions and is already well established. The systematic use of standardized and recently computerized case-report forms, a central international registry at the WHO's headquarters in Geneva, and the use of a geographical information system (GIS) for mapping and monitoring the co-infections have together improved the overall quality of the epidemiological data-gathering. All member institutions of the global network report to the WHO on an annual basis. The data collected are then analysed and periodically disseminated through international publications. The GIS allows the relevant epidemiological and demographic data-sets to be integrated and permits all detected cases of co-infection to be mapped down to locality level. The system also allows the spatial distribution of cases to be visualised and analysed and the geographical spread of the co-infection to be monitored over time. The risk posed by co-infected patients, as a source of Leishmania infection for the sandflies feeding on them, has recently been confirmed. The parasites and HIV may also be transmitted as the result of needle-sharing among intravenous-drug users.

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.

Treatment of visceral leishmaniasis in south-eastern Nepal: decreasing efficacy of sodium stibogluconate and need for a policy to limit further decline.

Sodium stibogluconate (SSG) is the first-line therapy for visceral leishmaniasis (VL) in south-eastern Nepal. Recent studies from the neighbouring state of Bihar, India, have shown a dramatic fall in cure rates with treatment failure occurring in up to 65% of VL patients treated with SSG. A prospective study was conducted at a tertiary-level hospital located in south-eastern Nepal from July 1999 to January 2001. Parasitologically proven kala-azar patients with no previous history of treatment for VL were treated with SSG 20 mg/kg/d for 30 d which was extended to 40 d in those with persistent positive parasitology. Of the 110 patients who completed SSG therapy and were assessed at 1 and 6 months, definite cure was achieved in 99 patients (90%) and SSG failure occurred in 11 patients (10%). Except for the presence of hepatomegaly and a lower platelet count there was no clinical or laboratory baseline characteristic associated with treatment failure. A significantly lower cure rate (76%, P = 0.03) was observed in patients from the district of Saptari, which borders the antimony-resistant VL areas of Bihar. The efficacy of SSG as a first-line treatment for VL in south-eastern Nepal was still satisfactory, except for the patients living closer to the antimony-resistant VL areas of India. These findings indicate that the spread of resistance to antimonials is already taking place in Nepal and that a policy to control further spread should be urgently implemented.

[Co-infections of leishmania/HIV in south Europe]. / Co-infections à Leishmania/VIH dans le sud de l'Europe.

The Leishmania/HIV co-infection has emerged as a result of the increasing overlap between leishmaniasis (mainly visceral, more rarely cutaneous) and AIDS, which is due to the spread of the AIDS pandemic to rural areas and that of visceral leishmaniasis to suburban areas. Cases of co-infection have so far been reported from 33 countries around the world, most of the cases have been notified in south-western Europe. 1,627 cases have been notified from Spain, France, Italy and Portugal. While Leishmania/HIV co-infection is increasing in eastern Africa, cases of co-infection are expected to diminish in South-western Europe due to the new highly active anti-retroviral therapy (HAART). In 1998, a world wide WHO/UNAIDS surveillance network was established, which now includes 28 member institutions. In south-western Europe, the surveillance system based on 16 institutions is now well established. The systematic use of standardized and recently computerized case-report forms, the central international registry at WHO headquarters, and finally the use of a geographic information system (GIS) for mapping and monitoring co-infections have improved the overall quality of epidemiological data gathering. All member institutions of the network report to WHO on an annual basis. World wide information is analysed and periodically disseminated through international publications. The GIS integrates epidemiological and demographic data sets and allows for the mapping of co-infection cases down to locality level. The system can be used to easily visualise and analyse the spatial distribution of co-infection cases and to permit monitoring of the evolution of the distribution of the cases over time. The risk of co-infected patients, as carriers of Leishmania in the blood, to be a source of infection for the sandfly, has been recently confirmed. Moreover intravenous drug users also transmit the disease through the sharing of needles.

The increase in risk factors for leishmaniasis worldwide.

Economic development leads to changing interactions between humans and their physical and biological environment. Worldwide patterns of human settlement in urban areas have led in developing countries to a rapid growth of mega-cities where facilities for housing, drinking-water and sanitation are inadequate, thus creating opportunities for the transmission of communicable diseases such as leishmaniasis. Increasing risk factors are making leishmaniasis a growing public health concern for many countries around the world. Certain risk factors are new, while others previously known are becoming more significant. While some risk factors are related to a specific eco-epidemiological entity, others affect all forms of leishmaniasis. Risk factors are reviewed here entity by entity.

Domestic and peridomestic transmission of American cutaneous leishmaniasis: changing epidemiological patterns present new control opportunities.

Predictions that deforestation would reduce American cutaneous leishmaniasis incidence have proved incorrect. Presentations at a recent international workshop, instead, demonstrated frequent domestication of transmission throughout Latin America. While posing new threats, this process also increases the effectiveness of vector control in and around houses. New approaches for sand fly control and effective targeting of resources are reviewed.

Diagnosing visceral leishmaniasis with the recombinant K39 strip test: experience from the Sudan.

We compared a strip test employing recombinant K39 (rK39) antigen and protein A/colloidal gold as read-out agents with the rK39 ELISA for IgM and IgG antibodies and the direct agglutination test (DAT) using 55 sera from patients with parasitologically confirmed visceral leishmaniasis (VL). The rK39 strip test was positive in 37/55 (67%), the DAT in 50/55 (91%) at > or = 1 : 1600 cut-off value and in 47/55 (85%) at > or = 1 : 6400 cut-off value. The rK39-ELISA gave positive IgG results for all sera; those who had a positive strip test had significantly higher IgG levels than those with a negative strip test (31.1 (SD=3.6) and 17.7 U/ml (SD=9.8), respectively, P < 0.0001). A total of 31/55 (56%) sera showed a positive IgM result; of these 27 (49%) had a positive strip test. We tested 115 apparently cured VL patients with the strip test during follow-up; 68 were also tested with DAT. In the strip test, 25-43% of patients had a positive result at time points 3, 6, 9 and 12 months after treatment; for DAT (cut-off > or = 1 : 1600) these results were 67-83%. In neither test did a significant decrease in positivity rates occur over time (P=0.37 for the strip test, P=0.17 for the DAT). No correlation (P=0.33) was found between a positive strip test and a positive DAT result (cut-off > or = 1: 1600), indicating that the strip test and DAT are complementary rather than interchangeable. Of 61 endemic controls two (3%) had a positive strip test result; both had a positive leishmanin skin test. The rK39 strip test has the ideal format for use in the field, but its sensitivity is limited; like DAT, but to a lesser extent, it remains positive after treatment.

Emerging Leishmania/HIV co-infection in Africa.

The HIV/AIDS pandemic is spreading at an alarmingly high rate in Africa. Leishmaniasis is also highly prevalent in the continent. Despite the emergence of Leishmania/HIV co-infection in Africa, the numbers reported are disproportionately low. Moreover, the number of cases of co-infection is expected to rise in Africa owing to the simultaneous spread of the two infectious diseases and their increasingly overlapping geographical distribution.

HIV viral load and response to antileishmanial chemotherapy in co-infected patients.

OBJECTIVE: To investigate whether clearance of Leishmania parasites from tissue aspirate smears in patients with HIV and visceral leishmaniasis (VL) co-infection treated with pentavalent antimonials is influenced by initial HIV viral load and to assess the effect of active VL on HIV viral load and replication in vivo. METHODS: Leishmania parasites were identified in Giemsa-stained smears prepared from tissue aspirates. Parasite index was determined by quantifying Leishmania donovani bodies in smears. HIV-1 RNA was quantitated by using the nucleic acid sequence-based amplification technique with a limit of detection of 500 copies/ml. All patients were treated with pentavalent antimonials at 20 mg pentavalent antimony (Sb(V))/kg daily for a total of 28 days. None of the patients received specific anti-retroviral therapy. RESULTS: Seventeen patients (73.9%) showed good initial response to anti-leishmanial treatment and the remaining six (26.1%) had very poor response. Among the good responders, 11 (64.7%) had no demonstrable Leishmania donovani bodies in post-therapy tissue aspirate smear preparations, and in the remaining six (35.3%) their parasite loads were reduced to very low levels. Patients with poor response had persistently high parasite index despite completion of anti-leishmanial chemotherapy. Poor responders had pre-treatment median HIV viral load that was >160-fold higher than responders to anti-leishmanial chemotherapy; [410000 copies/ml (quartile range, 33000-530000) and 2500 copies/ml (quartile range 500-297500), respectively]. Furthermore, compared with pre-treatment viral concentrations, patients with good response showed marked reduction in post-treatment viral load. In contrast, post-treatment HIV viral concentrations were markedly increased among patients with poor response to anti-leishmanial therapy. CONCLUSIONS: The results suggest that pre-treatment HIV viral load influences response to anti-leishmanial chemotherapy and active VL is associated with increased viral replication in vivo, supporting the notion that dual infection plays an important role in the pathogenesis and disease progression of either infection.

Cost-effectiveness of competing diagnostic-therapeutic strategies for visceral leishmaniasis.

Reported are the results of a formal decision analysis which facilitated the choice of the most appropriate test-treatment strategy for visceral leishmaniasis in areas where the disease is endemic. The following strategies were compared: treatment of all suspects (strategy A); testing by means of parasitological investigation followed by treatment of positives (strategy B); two-step testing by means of the direct agglutination test (DAT) followed by treatment of patients with high titres as well as those with parasitologically confirmed borderline titres (strategy C); and DAT followed by treatment of positives (strategy D). The results for each strategy were expressed as costs in US$ per death averted. The effectiveness of strategies C and D was close to that of strategy A and far better than that of strategy B. The cost-effectiveness ratio for strategies C and D (US$ 465 per death averted) was not substantially higher than that of testing by means of parasitological investigation followed by treatment of positives (strategy B), which was the most cost-effective strategy at US$448 per death averted. At current prices of antimonial drugs, the cost of test-treatment strategies depends more on the cost of treatment than on that of testing. The use of a sensitive serological test such as the DAT is recommended as the basis of test-treatment strategies for visceral leishmaniasis in areas where the disease is endemic.

PIP: This paper reports the results of a formal decision analysis. This facilitates in choosing the most appropriate test-treatment strategy for visceral leishmaniasis in endemic areas. Four strategies were compared based on their cost-effectiveness expressed in US dollars per death averted. These strategies include: (A) testing by means of parasitological investigation followed by treatment of positives; (B) two-step testing by means of the direct agglutination test (DAT); (C) treatment of patients with high titers as well as those with parasitologically confirmed borderline titers; and (D) DAT followed by treatment of positives. The results showed that the effectiveness of strategies C and D was close to that of strategy A and far better than that of strategy B. The cost-effectiveness ratio for strategies C and D was US$465 per death averted, which is not substantially higher than that of strategy B, while strategy B is the most cost-effective at US$448 per death averted.