The phenomenon of visceral leishmaniasis and HIV (VL-HIV) co-infection is on the rise in India, Central and South America and is already a major issue in East Africa where it poses a new and difficult challenge to VL containment efforts. VL is an advanced form of leishmaniasis that occurs when this parasitic infection enters a host’s internal organs causing significant weight loss, fatigue, anemia and, in many cases, eventual death. As if infection by each of these diseases were not already dangerous enough, co-infection results in a deadly synergy: HIV infection of Leishmania exposed individuals dramatically increases the risk of progression from asymptomatic infection towards full VL; and conversely, VL accelerates HIV disease progression.
To highlight this emerging threat PLOS Neglected Tropical Diseases will dedicate a special collection to VL-HIV co-infection, kicking off with an accompanying editorial by Drs. Johan van Griensven, Ed Zijlstra and Asrat Hailu, leading researchers in this field. PLOS NTDs invite all authors to submit their work on VL-HIV to help address this emerging challenge and contribute to filling the knowledge gap and creating a momentum for enhancing research and disease control efforts.
PLOS NTDs Publication Manager Jeri Marie Wright recently spoke with Drs. van Griensven, Zijlstra and Hailu to discuss some of the most common questions about VL-HIV.
Q: What is the scope of the problem: how many people suffer from both VL and HIV worldwide and what are the risk factors for this co-infection?
A: There are no recent and exact estimates of the absolute number of VL-HIV co-infection cases at the global level. However, a high or increasing burden has been reported from several regions. In North-Ethiopia, 20-30% of VL cases are co-infected with HIV. Reports are increasing from Latin America; recent data from Bihar, India demonstrated co-infection rates of 3-4%. On the other hand, with the introduction of highly active antiretroviral treatment, the case load has decreased dramatically in the Mediterranean region. The risk factors for VL-HIV co-infection differ by region. In North-Ethiopia and India, VL-HIV co-infection is typically found in migrant workers.
As part of the collection on VL-HIV co-infection, four review papers have been commissioned focusing on VL-HIV co-infection in different regions (the Mediterranean, East-Africa, the Indian subcontinent, Latin America). These will also aim to provide updated regional estimates of the VL-HIV burden.
Q: What are the main challenges presented when a patient has both HIV and Visceral Leishmaniasis?
A: Similarly as tuberculosis-HIV co-infection, VL-HIV co-infection is characterized by a number of complexities including challenging diagnosis and treatment. The standard serological tests are often less reliable in HIV co-infection, atypical VL presentation is more common. In terms of treatment, VL-HIV co-infection is characterized by high mortality, increased drug toxicity and overall poor treatment response. Moreover, even with initiation of antiretroviral treatment, multiple VL relapses remain common. VL relapses tend to be associated with gradual loss in treatment responsiveness. There are also concerns that VL-HIV co-infected individuals could serve as a source and reservoir of drug resistant parasites.
Q: What prompted this new Collection, and what are you and PLOS NTDs hoping to achieve by it?
A: Although research on VL-HIV was conducted in Europe, following the emergence of VL-HIV co-infection in the nineties, the problem has now become global and shifted to low or middle income countries. Despite its important clinical and public health implications, research on VL-HIV co-infection is currently generally limited, especially in the hardest hit areas. However, there now appears to be an increasing interest in VL-HIV co-infection amongst researchers at the global level. Recent sessions on VL-HIV co-infection at international conferences consistently had high attendance rates. A number of VL-HIV research initiatives have emerged over the last few years. In that sense, this supplement is very timely.
With this supplement, we aim to give an overview of different aspects of VL-HIV co-infection at the global level, including currently ongoing or planned research. We hope this will contribute to creating a momentum for reflection on research priorities and enhancing research and disease control efforts. This will hopefully also assist in strengthening research networks and collaboration on VL-HIV co-infection and contribute to raising awareness.
Q: Can you tell us a little about the current research and initiatives?
A: We have been most involved with research initiatives in East Africa. One example is the AfriCoLeish Consortium, funded by the European community (http://www.africoleish.org). As part of the activities, two clinical trials (one focussed on secondary prophylaxis, one on VL combination therapy) will be conducted in HIV co-infected Ethiopian patients. A number of ancillary studies are foreseen, including immunological studies and studies on drug interactions between antiretroviral and antileishmanial drugs.
Q: Where do we need to go from here?
A: Research efforts and collaboration should be intensified; linking-up of research organisations, clinicians, implementers and other stakeholders will be required. At the basic level, we need to come to an improved understanding of the immunopathogenesis of VL-HIV co-infection and the complex parasite-virus-host interaction. We need more clinical research, not only to improve case management, but also to prevent overt VL-HIV co-infection. And we need more operational research to implement effective strategies or interventions.
Perhaps we should aim for an international VL-HIV network. Comprehensive research agendas and action plans could then be drafted, including basic, translational, clinical and operational research. Such wider collaboration could also create opportunities for improved global surveillance and exchange of expertise and experience. Efforts can be pooled to enhance advocacy and improve access to VL care and treatment in resource-limited settings.