Visceral leishmaniasis recrudescence in a patient with AIDS

Epidemiological review of Toxoplasma gondii infection in humans and animals in Portugal

Toxoplasmosis is a worldwide zoonosis. However, data from Portugal are limited and a considerable part of the literature is in Portuguese. Currently, the rate of congenital infection in Portugal is unknown, and almost nothing is known of sequelae of congenital toxoplasmosis. There is no recent general population-based serological survey of Toxoplasma gondii in humans in Portugal. In addition, there is little information on genetic characteristics of T. gondii in animals and humans. In the present paper, we review prevalence, clinical spectrum and epidemiology of T. gondii in humans and animals in Portugal. This knowledge should be useful to biologists, public health workers, physicians and veterinarians.

Leishmania and human immunodeficiency virus coinfection: the first 10 years

Over 850 Leishmania-human immunodeficiency virus (HIV) coinfection cases have been recorded, the majority in Europe, where 7 to 17% of HIV-positive individuals with fever have amastigotes, suggesting that Leishmania-infected individuals without symptoms will express symptoms of leishmaniasis if they become immunosuppressed. However, there are indirect reasons and statistical data demonstrating that intravenous drug addiction plays a specific role in Leishmania infantum transmission: an anthroponotic cycle complementary to the zoonotic one has been suggested. Due to anergy in patients with coinfection, L. infantum dermotropic zymodemes are isolated from patient viscera and a higher L. infantum phenotypic variability is seen. Moreover, insect trypanosomatids that are currently considered nonpathogenic have been isolated from coinfected patients. HIV infection and Leishmania infection each induce important analogous immunological changes whose effects are multiplied if they occur concomitantly, such as a Th1-to-Th2 response switch; however, the consequences of the viral infection predominate. In fact, a large proportion of coinfected patients have no detectable anti-Leishmania antibodies. The microorganisms share target cells, and it has been demonstrated in vitro how L. infantum induces the expression of latent HIV-1. Bone marrow culture is the most useful diagnostic technique, but it is invasive. Blood smears and culture are good alternatives. PCR, xenodiagnosis, and circulating-antigen detection are available only in specialized laboratories. The relationship with low levels of CD4+ cells conditions the clinical presentation and evolution of disease. Most patients have visceral leishmaniasis, but asymptomatic, cutaneous, mucocutaneous, diffuse cutaneous, and post-kala-azar dermal leishmaniasis can be produced by L. infantum. The digestive and respiratory tracts are frequently parasitized. The course of coinfection is marked by a high relapse rate. There is a lack of randomized prospective treatment trials; therefore, coinfected patients are treated by conventional regimens. Prophylactic therapy is suggested to be helpful in preventing relapses.

A simple method for quantifying Leishmania in tissues of infected animals

In experimental animals infected with Leishmania major, the size of cutaneous lesions of the parasite often does not correlate with the number of parasites within the lesion. Indeed, cutaneous lesions can heal, but still contain parasites. Thus, the ability to determine parasite burden in infected animals becomes important, especially when assessing vaccines that are intended to induce sterilizing immunity. Here, Hermenio Lima, Julie Bleyenberg and Richard Titus describe a simple technique for enumerating Leishmania in infected tissue. It is hoped that this technique will allow all researchers working with Leishmania (especially those in countries where leishmaniasis is endemic) to determine parasite burden easily in infected animals.

[Fatal visceral leishmaniasis associated with acquired immunodeficiency syndrome: report of a case with necropsy findings and immunohistochemical study]

A case of fatal visceral leishmaniasis associated with immunodeficiency syndrome in a 32 year-old male patient is reported. The protozoonosis was responsible for the patient's death. Visceral leishmaniasis showed itself in an atypical form, at necropsy, with an intense parasitation of the mononuclear phagocitic system and damaging organs not usually affected by the disease, such as the adrenals, the kidneys, the lungs and the brain. Parasitised cells were observed within small vessels in several tissues. An immunohistochemical study was done on samples from the spleen, lymph nodes and brain, showing strong reactivity with antibody directed against leishmania.

Role of T cell subsets during the recall of immunologic memory toLeishmania major

The contributions of different T cell subpopulations to the maintenance of immunity during secondary Leishmania major infections were analyzed in healed, resistant animals by depletion of T cell subsets in vivo. The strong delayed-type hypersensitivity mounted in immune genetically resistant mice upon challenge with viable promastigotes was mediated by both CD4+ and CD8+ T cells. Each T cell subpopulation alone contributes, although to a different extent, to the resolution of secondary lesions; both subsets, however, are required for an efficient and rapid healing of the secondary lesions and the decrease in the parasite burden in infected tissues. The results indicate that in immune, genetically resistant CBA mice, the activity of both T cell subsets is required for successful resistance to reinfection and an efficient maintenance of immunity.

Opportunistic infections in AIDS in developed and developing countries

The acquired immune deficiency syndrome (AIDS) is fundamentally the same disease in all parts of the world, but the prevalence of microorganisms in an environment governs the patterns of disease arising from reactivated latent infections, invading pathogens and opportunistic infections. AIDS in Africa has certain characteristic presentations. Enteropathic AIDS is most common: Cryptosporidium and Isospora belli are identified in up to 60% of patients, but it is uncertain whether they are the causes of diarrhoea. Pneumocystis carinii pneumonia is rare. Tuberculosis, both pulmonary and extrapulmonary, is the supreme complicating infection. Herpes zoster is frequently the first clinical presentation, and has a 95% positive predictive value for HIV positivity. Measles may be more frequent in infants born to HIV-infected mothers, and appears to be worse in HIV-infected children. There is accelerated progress of both diseases in patients infected by HIV and Mycobacterium leprae. Salmonellosis is frequent. There is no direct interaction between malaria and HIV, but, by being a potent cause of anaemia, malaria enhances transmission of HIV to children through blood transfusion. HIV-positive subjects are liable to new or reactivated visceral leishmaniasis with dissemination to unusual sites. Cerebral toxoplasmosis is common. There are no apparent interactions between HIV and helminths, although there is one report of hyperinfection with Strongyloides stercoralis. Cryptococcal meningitis has high frequency. Infections with Histoplasma encapsulatum are common in tropical America, but there has been no increase of frequency of H. duboisii in Africa since the advent of AIDS.

Experiences with vaccines against cutaneous leishmaniasis: of men and mice

The need for a vaccine(s) against cutaneous leishmaniasis and the populations at risk for whom such vaccines should be developed are briefly discussed. The current human vaccine studies are reviewed, as are some experimental mouse studies with emphasis on Leishmania major infection relevant to vaccine development. Based on the information available from the mouse model and those data which are being sought in human studies, the benign nature of the cutaneous disease, the ease with which L. major can be manipulated to yield the required material, and the ongoing practice of leishmanization which allows rapid evaluation of candidate vaccine(s), it is suggested that a vaccine, at least against L. major, is imminent in the not too distant future.