Abstract
Leishmaniasis remains one of the world's most devastating neglected tropical diseases. It mainly affects developing countries, where it often co-exists with chronic malnutrition, one of the main risk factors for developing the disease. Few studies have been published, however, on the relationship between leishmaniasis progression and malnutrition. The present paper reports the influence of protein malnutrition on the immune response and visceral disease development in adult hamsters infected with Leishmania infantum fed either standard or low protein diets. The low protein diet induced severe malnutrition in these animals, and upon infection with L. infantum 33% had severe visceral leishmaniasis compared to only 8% of animals fed the standard diet. The infected, malnourished animals showed notable leukocyte depletion, mild specific antibody responses, impairment of lymphoproliferation, presence of parasites in blood (16.67% of the hamsters) and significant increase of the splenic parasite burden. Animals fed standard diet suffered agranulocytosis and monocytopenia, but showed stronger specific immune responses and had lower parasite loads than their malnourished counterparts. The present results show that protein malnutrition promotes visceral leishmaniasis and provide clues regarding the mechanisms underlying the impairment of the immune system.
Highlights
Malnutrition is a serious health problem that remains common in many parts of the world
It is clear that protection against L. infantum is dependent upon cellular immunity [8], which is known to be diminished by protein calorie malnutrition [9], the specific, cellmediated mechanisms compromised in malnourished persons with visceral leishmaniasis remain unclear
In the present study we evaluated for the first time haematological, biochemical, humoral and cellular immune responses, and parasitism in malnourished (3% protein diet) and well-nourished (14% protein diet) hamsters experimentally infected with L. infantum after 4 months post-infection
Summary
Malnutrition is a serious health problem that remains common in many parts of the world. Much of the excess morbidity and mortality associated with malnutrition is owed to the impairment of sufferers’ defence mechanisms, which predisposes them to infectious diseases [2]. Leishmaniasis, a vectortransmitted, poverty-related disease – the second and fourth most important among tropical diseases in terms of mortality and morbidity rates [3] – is commonly encountered where protein malnutrition is prevalent. It is clear that protection against L. infantum is dependent upon cellular immunity [8], which is known to be diminished by protein calorie malnutrition [9], the specific, cellmediated mechanisms compromised in malnourished persons with visceral leishmaniasis remain unclear. The impact of infection or protein malnutrition on the host immune response, as well as the progression of the infection towards chronic visceral disease, have never been addressed with standardized experimental models
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