François Chappuis

Visceral leishmaniasis: what are the needs for diagnosis, treatment and control?

Visceral leishmaniasis (VL) is a systemic protozoan disease that is transmitted by phlebotomine sandflies. Poor and neglected populations in East Africa and the Indian sub-continent are particularly affected. Early and accurate diagnosis and treatment remain key components of VL control. In addition to improved diagnostic tests, accurate and simple tests are needed to identify treatment failures. Miltefosine, paromomycin and liposomal amphotericin B are gradually replacing pentavalent antimonials and conventional amphotericin B as the preferred treatments in some regions, but in other areas these drugs are still being evaluated in both mono- and combination therapies. New diagnostic tools and new treatment strategies will only have an impact if they are made widely available to patients.

Human African trypanosomiasis

Human African trypanosomiasis (sleeping sickness) occurs in sub-Saharan Africa. It is caused by the protozoan parasite Trypanosoma brucei, transmitted by tsetse flies. Almost all cases are due to Trypanosoma brucei gambiense, which is indigenous to west and central Africa. Prevalence is strongly dependent on control measures, which are often neglected during periods of political instability, thus leading to resurgence. With fewer than 12 000 cases of this disabling and fatal disease reported per year, trypanosomiasis belongs to the most neglected tropical diseases. The clinical presentation is complex, and diagnosis and treatment difficult. The available drugs are old, complicated to administer, and can cause severe adverse reactions. New diagnostic methods and safe and effective drugs are urgently needed. Vector control, to reduce the number of flies in existing foci, needs to be organised on a pan-African basis. WHO has stated that if national control programmes, international organisations, research institutes, and philanthropic partners engage in concerted action, elimination of this disease might even be possible.

Options for Field Diagnosis of Human African Trypanosomiasis

SUMMARY Human African trypanosomiasis (HAT) due to Trypanosoma brucei gambiense or T. b. rhodesiense remains highly prevalent in several rural areas of sub-Saharan Africa and is lethal if left untreated. Therefore, accurate tools are absolutely required for field diagnosis. For T. b. gambiense HAT, highly sensitive tests are available for serological screening but the sensitivity of parasitological confirmatory tests remains insufficient and needs to be improved. Screening for T. b. rhodesiense infection still relies on clinical features in the absence of serological tests available for field use. Ongoing research is opening perspectives for a new generation of field diagnostics. Also essential for both forms of HAT is accurate determination of the disease stage because of the high toxicity of melarsoprol, the drug most widely used during the neurological stage of the illness. Recent studies have confirmed the high accuracy of raised immunoglobulin M levels in the cerebrospinal fluid for the staging of T. b. gambiense HAT, and a promising simple assay (LATEX/IgM) is being tested in the field. Apart from the urgent need for better tools for the field diagnosis of this neglected disease, improved access to diagnosis and treatment for the population at risk remains the greatest challenge for the coming years.

A meta-analysis of the diagnostic performance of the direct agglutination test and rK39 dipstick for visceral leishmaniasis

Abstract Objective To compare the performance of the direct agglutination test and rK39 dipstick for the diagnosis of visceral leishmaniasis. Data sources Medline, citation tracking, January 1986 to December 2004. Selection criteria Original studies evaluating the direct agglutination test or the rK39 dipstick with clinical visceral leishmaniasis as target condition; adequate reference classification; and absolute numbers of true positive, true negative, false positive, and false negative observations available or derivable from the data presented. Results 30 studies evaluating the direct agglutination test and 13 studies evaluating the rK39 dipstick met the inclusion criteria. The combined sensitivity estimates of the direct agglutination test and the rK39 dipstick were 94.8% (95% confidence interval 92.7% to 96.4%) and 93.9% (87.7% to 97.1%), respectively. Sensitivity seemed higher and more homogenous in the studies carried out in South Asia. Specificity estimates were influenced by the type of controls. In phase III studies carried out on patients with clinically suspected disease, the estimated specificity of the direct agglutination test was 85.9% (72.3% to 93.4%) and of the rK39 dipstick was 90.6% (66.8% to 97.9%). Conclusion The diagnostic performance of the direct agglutination test and the rK39 dipstick for visceral leishmaniasis is good to excellent and seem comparable.

Urbanisation and infectious diseases in a globalised world

Summary The world is becoming urban. The UN predicts that the worlds urban population will almost double from 3·3 billion in 2007 to 6·3 billion in 2050. Most of this increase will be in developing countries. Exponential urban growth is having a profound effect on global health. Because of international travel and migration, cities are becoming important hubs for the transmission of infectious diseases, as shown by recent pandemics. Physicians in urban environments in developing and developed countries need to be aware of the changes in infectious diseases associated with urbanisation. Furthermore, health should be a major consideration in town planning to ensure urbanisation works to reduce the burden of infectious diseases in the future.

Influence of Leishmania (Viannia) Species on the Response to Antimonial Treatment in Patients with American Tegumentary Leishmaniasis

BACKGROUND Pentavalent antimonials (SbV) are the first-line chemotherapy for American tegumentary leishmaniasis (ATL). There are, however, reports of the occurrence of treatment failure with these drugs. Few studies in Latin America have compared the response to SbV treatment in ATL caused by different Leishmania species. METHODS Clinical parameters and response to SbV chemotherapy were studied in 103 patients with cutaneous leishmaniasis (CL) in Peru. Leishmania isolates were collected before treatment and typed by multilocus polymerase-chain-reaction restriction fragment-length polymorphism analysis. RESULTS The 103 isolates were identified as L. (Viannia) peruviana (47.6%), L. (V.) guyanensis (23.3%), L. (V.) braziliensis (22.3%), L. (V.) lainsoni (4.9%), L. (Leishmania) mexicana (1%), and a putative hybrid, L. (V.) braziliensis/L. (V.) peruviana (1%). L. (V.) guyanensis was most abundant in central Peru. Of patients infected with the 3 former species, 21 (21.9%) did not respond to SbV chemotherapy. The proportions of treatment failure (after 12 months of follow-up) were 30.4%, 24.5%, and 8.3% in patients infected with L. (V.) braziliensis, L. (V.) peruviana, and L. (V.) guyanensis, respectively. Infection with L. (V.) guyanensis was associated with significantly less treatment failure than L. (V.) braziliensis, as determined by multiple logistic regression analysis (odds ratio, 0.07 [95% confidence interval, 0.007-0.8]; P=.03). CONCLUSIONS Leishmania species can influence SbV treatment outcome in patients with CL. Therefore, parasite identification is of utmost clinical importance, because it should lead to a species-oriented treatment.

Gene Expression Analysis of the Mechanism of Natural Sb(V) Resistance in Leishmania donovani Isolates from Nepal

ABSTRACT Control of visceral leishmaniasis (VL) is being challenged by the emergence of natural resistance against the first line of treatment, pentavalent antimonials [Sb(V)]. An insight into the mechanism of natural Sb(V) resistance is required for the development of efficient strategies to monitor the emergence and spreading of Sb(V) resistance in countries where VL is endemic. In this work, we have focused on the mechanism of natural Sb(V) resistance emerging in Nepal, a site where anthroponotic VL is endemic. Based on the current knowledge of Sb(V) metabolism and of the in vitro trivalent antimonial [Sb(III)] models of resistance to Leishmania spp., we selected nine genes for a comparative transcriptomic study on natural Sb(V)-resistant and -sensitive Leishmania donovani isolates. Differential gene expression patterns were observed for the genes coding for 2-thiol biosynthetic enzymes, gamma-glutamylcysteine synthetase (GCS) and ornithine decarboxylase (ODC), and for the Sb(III) transport protein aquaglyceroporin 1 (AQP1). The results indicate that the mechanism for natural Sb(V) resistance partially differs from the mechanism reported for in vitro Sb(III) resistance. More specifically, we hypothesize that natural Sb(V) resistance results from (i) a changed thiol metabolism, possibly resulting in inhibition of Sb(V) activation in amastigotes, and (ii) decreased uptake of the active drug Sb(III) by amastigotes.

Travel-associated infection presenting in Europe (2008-12): an analysis of EuroTravNet longitudinal, surveillance data, and evaluation of the effect of the pre-travel consultation.

BACKGROUND Travel is important in the acquisition and dissemination of infection. We aimed to assess European surveillance data for travel-related illness to profile imported infections, track trends, identify risk groups, and assess the usefulness of pre-travel advice. METHODS We analysed travel-associated morbidity in ill travellers presenting at EuroTravNet sites during the 5-year period of 2008-12. We calculated proportionate morbidity per 1000 ill travellers and made comparisons over time and between subgroups. We did 5-year trend analyses (2008-12) by testing differences in proportions between subgroups using Pearsons χ(2) test. We assessed the effect of the pre-travel consultation on infection acquisition and outcome by use of proportionate morbidity ratios. FINDINGS The top diagnoses in 32 136 patients, ranked by proportionate morbidity, were malaria and acute diarrhoea, both with high proportionate morbidity (>60). Dengue, giardiasis, and insect bites had high proportionate morbidity (>30) as well. 5-year analyses showed increases in vector borne infections with significant peaks in 2010; examples were increased Plasmodium falciparum malaria (χ(2)=37·57, p<0·001); increased dengue fever (χ(2)=135·9, p<0·001); and a widening geographic range of acquisition of chikungunya fever. The proportionate morbidity of dengue increased from 22 in 2008 to 36 in 2012. Five dengue cases acquired in Europe contributed to this increase. Dermatological diagnoses increased from 851 in 2008 to 1102 in 2012, especially insect bites and animal-related injuries. Respiratory infection trends were dominated by the influenza H1N1 pandemic in 2009. Illness acquired in Europe accounted for 1794 (6%) of all 32 136 cases-mainly, gastrointestinal (634) and respiratory (357) infections. Migration within Europe was associated with more serious infection such as hepatitis C, tuberculosis, hepatitis B, and HIV/AIDS. Pre-travel consultation was associated with significantly lower proportionate morbidity ratios for P falciparum malaria and also for acute hepatitis and HIV/AIDS. INTERPRETATION The pattern of travel-related infections presenting in Europe is complex. Trend analyses can inform on emerging infection threats. Pre-travel consultation is associated with reduced malaria proportionate morbidity ratios and less severe illness. These findings support the importance and effectiveness of pre-travel advice on malaria prevention, but cast doubt on the effectiveness of current strategies to prevent travel-related diarrhoea. FUNDING European Centre for Disease Prevention and Control, University Hospital Institute Méditerranée Infection, US Centers for Disease Control and Prevention, and the International Society of Travel Medicine.

Tolerance and safety of nifurtimox in patients with chronic chagas disease.

BACKGROUND Nifurtimox has been used to treat Chagas disease for 40 years, but tolerance and safety data in adults are scarce. We aimed to evaluate nifurtimox tolerance and safety in a cohort of Trypanosoma cruzi-infected adult patients in a country of nonendemicity. METHODS This observational study included all consecutive adults patients who were given a diagnosis of T. cruzi infection from June through December 2008. Eligible patients received nifurtimox at 10 mg/kg/day for 60 days, with regular medical and biological follow-up. Adverse events (AEs) were recorded according to Common Terminology Criteria for Adverse Events, version 3.0. RESULTS Eighty-one patients received nifurtimox. Eight were lost to follow-up during treatment, and 41 (56.2%) completed the 60-day course. All premature treatment terminations were caused by AEs; 97.5% of patients suffered from AEs, mostly expected (90.5%) and not severe. Gastrointestinal symptoms predominated. Six (7.4%) patients presented with a suspected unexpected serious adverse reaction: drug reaction with eosinophilia and systemic symptoms (n = 3), Quincke edema (n = 1), acute myocarditis (n = 1), and anaphylaxis (n = 1). Patients with 3 or more AEs had an increased risk of premature treatment termination (hazard ratio, 8.42; 95% confidence interval, 1.6-45.5). CONCLUSION Nifurtimox is poorly tolerated among adults with chronic Chagas disease, resulting in a low treatment completion rate. Considering the significant risk of serious AEs, close monitoring is required, which may be difficult to implement in poor rural areas of countries of endemicity. The safety and efficacy of nifurtimox and benznidazole should be compared to improve current therapeutic recommendations, and pharmacovigilance systems should be enhanced.

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.