Human B19 parvovirus infetion: an example of multiple pathogenic effects determined by differences in host susceptibility

B19 infection offers some general lessons about human viruses and their possible effects on the human host, as follows: (1) Ubiquitous apparently benign viruses may have severe effects on a compromissed host. The virus may be invariable but the host can have diverse susceptibilities. (2) B19 and some other human viruses (through for none is the evidence so clear as for B19) have narrowly targetted effects. The host cell of B19 is a specialised progenitor of mature red cells: impairment of the function of this cell by B19 may cause profound anaemia. (3) The 'normal'host response to B19 may also cause disease, though this is slef limiting. (4) The effects of malfunction of the virus'target cell are exacerbated when the immune response is impaired by congenital or acquired immunodeficiency, immunosupressive therapy or, in the case of the fetus, developmental immaturity that allows the virus to persist.

Dried blood spots collected on filter paper: an international resource for the diagnosis and genetic characterization of human immunodeficiency virus Type-1

The collection of dried blood spots (DBS) on filter paper provides a powerful approach for the development of large-scale, population-based screening programs. DBS methods are particularly valuable in developing countries and isolated rural regions where resources are limited. Large numbers of field specimens can be economically collected and shipped to centralized reference laboratories for genetic and (or) serological analysis. Alternatively, the dried blood can be stored and used as an archival resource to rapidly establish the frequency and distribution of newly recognized mutations, confirm patient identity or track the origins and emergence of newly identified pathogens. In this report, we describe how PCR-based technologies are beginning to interface with international screening programmes for the diagnosis and genetic characterization of human immunodeficiency virus type 1 (HIV-1). In particular, we review recent progress using DBS specimens to resolve the HIV-1 infection status of neonates, monitor the genetic evolution of HIV-1 during early infancy and establish a sentinel surveillance system for the systematic monitoring of HIV-1 genetic variation in Asia.

Tuberculin Skin Test and CD4+/CD8+ T Cell Counts in Adults Infected with the Human Immunodeficiency Virus in Medellín, Colombia

To evaluate the effect of BCG vaccination and T lymphocyte subpopulations on the reactivity to the tuberculin skin test, 113 asymtomatic HIV+ individuals were tuberculin tested by intradermal injection of 5TU of purified protein derivative and the levels of circulating lymphocyte (CD3, CD4 and CD8) subpopulations determined by indirect immunofluorescence. Ninety-two percent of the subjects included in the study were males. The mean age of the group was 32.1±7.4 years. Sixty-two percent presented a BCG scar. However, only 22% exhibited positive tuberculin reactions (³5mm) irrespective of the presence of the BCG scar. Tuberculin positive individuals exhibited higher CD4+ cell counts (p=0.004) and CD4+/CD8+ ratios (p=0.006) than tuberculin negative (<5mm) HIV+ individuals. The number of individuals with positive tuberculin reactions was significantly higher in subjects with more than 500 CD4+ lymphocytes/ml (p=0.02) or CD4+/CD8+ ratios ³1.12 (p=0.002). These results suggest that a prior BCG vaccination does not influence the reactivity to the tuberculin skin test in HIV+ asymptomatic individuals and that the number of CD4+ lymphocytes and the CD4+/CD8+ ratio positively correlate with the tuberculin reactivity

Comparison between Human Immunodeficiency Virus Positive and Negative Patients with Tuberculosis in Southern Brazil

The objective of this study is to determine the different characteristics of human immunodeficiency virus (HIV) positive and negative patients treated for tuberculosis (TBC) in a tertiary hospital in Southern Brazil. We conducted a retrospective cohort study over a 5-year period, from January 1992 through December 1996. We reviewed medical charts of patients from our institution who received TBC treatment. We reviewed 167 medical charts of patients with confirmed TBC. HIV positivity was detected in 74 patients. There were statistically significant difference between HIV positive and negative patients in sex and age. HIV-infected patients showed significantly more signs of bacteremia than HIV-negative patients. Extra-pulmonary TBC was present respectively in 13 (17.6%) and 21 (22.6%) HIV positive and negative patients. There was a significant difference between chest radiograph presentation in HIV positive and negative patients. There were significantly lower hematocrit, hemoglobin, leukocyte and lymphocyte levels in HIV-positive compared to HIV-negative patients. Outcome was significantly different in the two groups with a death rate of 36.5% and 10.8% in HIV-positive and in HIV-negative patients. The difference between HIV positive and negative patients may have importance in the diagnosis, management and prognosis of patients with TBC.

Human Immunodeficiency Virus Seroprevalence among Inmates of the Penitentiary Complex of the Region of Campinas, State of São Paulo, Brazil

Six hundred and ninety three male inmates from three penitentiaries, two (A and B) maximum-security systems and one (C) minimum-security facility, located in Campinas, State of São Paulo, Brazil were studied for the presence of human immunodeficiency virus (HIV) antibodies, using a cross-sectional design. The search for anti-HIV antibodies in 693 samples of sera collected was carried out by two serological tests: (a) the Microparticle enzyme immunoassay-HIV-1 and HIV-2 (MEIA) (Abbott Laboratories) and (b) the Western Blot-HIV-1 (WB) (Cambridge Biotech Corporation) to confirm positive results with MEIA. Sera reactivity for HIV antibodies was 14.4%. The highest frequency of anti-HIV antibodies was found in the A and B maximum-security prisons: 17% and 21.5%, respectively. In prison C, the frequency of reagents was 10.9%. Seventy three inmates, initially negative in the MEIA test, were checked again five and seven months later. Three of them, all from the maximum-security facilities, became reactive in the MEIA test, with confirmation in the WB, suggesting that serological conversion had occurred after imprisonment.

Frequency of CCR5 Delta-32 Mutation in Human Immunodeficiency Virus (HIV)-seropositive and HIV-exposed Seronegative Individuals and in General Population of Medellin, Colombia

Repeated exposure to human immunodeficiency virus (HIV) does not always result in seroconversion. Modifications in coreceptors for HIV entrance to target cells are one of the factors that block the infection. We studied the frequency of Delta-32 mutation in ccr5 gene in Medellin, Colombia. Two hundred and eighteen individuals distributed in three different groups were analyzed for Delta-32 mutation in ccr5 gene by polymerase chain reaction (PCR): 29 HIV seropositive (SP), 39 exposed seronegative (ESN) and 150 individuals as a general population sample (GPS). The frequency of the Delta-32 mutant allele was 3.8% for ESN, 2.7% for GPS and 1.7% for SP. Only one homozygous mutant genotype (Delta-32/Delta-32) was found among the ESN (2.6%). The heterozygous genotype (ccr5/Delta-32) was found in eight GPS (5.3%), in one SP (3.4%) and in one ESN (2.6%). The differences in the allelic and genotypic frequencies among the three groups were not statistically significant. A comparison between the expected and the observed genotypic frequencies showed that these frequencies were significantly different for the ESN group, which indirectly suggests a protective effect of the mutant genotype (Delta-32/Delta-32). Since this mutant genotype explained the resistance of infection in only one of our ESN persons, different mechanisms of protection must be playing a more important role in this population.

Hepatitis B virus exposure in human immunodeficiency virus seropositive Cuban patients

In order to estimate the prevalence of serological markers of exposure to Hepatitis B Virus (HBV), 295 subjects were selected at random from the National Registry of human immunodeficiency virus positive subjects. Evidence of exposure to HBV was defined as: testing Hepatitis B surface antigen (HBsAg) and anti-Hepatitis B core antigen (anti-HBc) positive or anti-HBc positive only. Overall, 133 (45.5%) were positive for anti-HBc and 15 (5.1%) resulted positive to HBsAg. Significant statistical association was found between male sex and exposure to HBV (p<0.01). Homosexual or bisexual behavior was found to be strongly associated to HBV exposure (p<0.001). In conclusion, the prevalence of HBV serological markers is higher in Cuban HIV positive subjects compared to the Cuban general population.

Risk Factors for tuberculosis among human immunodeficiency virus-infected persons. A case-control study in Belo Horizonte, Minas Gerais, Brazil (1985-1996)

The objective of this study was to identify tuberculosis risk factors and possible surrogate markers among human immunodeficiency virus (HIV)-infected persons. A retrospective case-control study was carried out at the HIV outpatient clinic of the Universidade Federal de Minas Gerais in Belo Horizonte. We reviewed the demographic, social-economical and medical data of 477 HIV-infected individuals evaluated from 1985 to 1996. The variables were submitted to an univariate and stratified analysis. Aids related complex (ARC), past history of pneumonia, past history of hospitalization, CD4 count and no antiretroviral use were identified as possible effect modifiers and confounding variables, and were submitted to logistic regression analysis by the stepwise method. ARC had an odds ratio (OR) of 3.5 (CI 95% - 1.2-10.8) for tuberculosis development. Past history of pneumonia (OR 1.7 - CI 95% 0.6-5.2) and the CD4 count (OR 0.4 - CI 0.2-1.2) had no statistical significance. These results show that ARC is an important clinical surrogate for tuberculosis in HIV-infected patients. Despite the need of confirmation in future studies, these results suggest that the ideal moment for tuberculosis chemoprophylaxis could be previous to the introduction of antiretroviral treatment or even just after the diagnosis of HIV infection.

Visceral Leishmaniosis caused by Leishmania (L.) mexicana in a Mexican patient with human immunodeficiency virus infection

A 36 year old male was admitted in December 1997 to hospital with afternoon fever, malaise and hepatosplenomegaly. He also had a dry cough, dyspnoea and anaemia. Pneumonia caused by Pneumocystis carinii and human immunodeficiency virus (HIV) infection were documented. The HIV infection was confirmed in 1997 with 290,000 virus copies. The patient had been in the Mexican State of Chiapas which is known to be endemic for visceral leishmaniosis (VL) and localized cutaneous leishmaniosis (LCL). The visceral symptoms were diagnosed as VL and the causal agent was identified as Leishmania (L.) mexicana. Identification of Leishmania was carried out by the analysis of amplified DNA with specific primers belonging to the Leishmania subgenus and by dot blot positive hybridisation of these polymerase chain reaction derived products with kDNA from the L. (L.) mexicana MC strain used as probe. This is the first case in Mexico of VL caused by a species of Leishmania that typically produces a cutaneous disease form.

Sexually transmitted diseases in homosexual and bisexual males from a cohort of human immunodeficiency virus negative volunteers (Project Horizonte), Belo Horizonte, Brazil

Sexually transmitted diseases (STD) are very frequent in the whole world. Males who do not use a condom during their sexual relations are at great risk. We report cases of STD during six months of observation, among homosexual/bisexual males who participate in the Project Horizonte. There were 16 cases of genital warts, 6 cases of human immunodeficiency virus infection, 24 cases of unspecific urethritis, 28 cases of herpes simplex virus infection, 30 cases of syphilis, 58 cases of gonorrhea and 84 cases of pediculosis. We concluded that a condom must be used in all sexual relations and new counseling techniques are needed, to avoid this situation.

Microsporidia and acquired immunodeficiency syndrome

Microsporidia is a common term that has been used to refer to a group of eukaryotic, obligate intracellular protozoan parasites belonging to the phylum Microspora. They are important agricultural parasites, contaminating commercial insects; they are also important by infecting laboratory rodents, rabbits and primates. Ever since the early cases found by Magarino Torres, who reported the presence of Encephalitozoon in a patient suffering of a meningoencephalomyelitis, some human pathology caused by microsporidia has been described. However, only after the acquired immunodeficiency syndrome outbreak have these organisms appeared as significant etiological agents in different pathologies. Even so, they remain underestimated. In the present article, the importance of microsporidia for the human pathology in immunocompromised host has been stressed.

Immunocompromised host: from the early events until the impact of acquired immunodeficiency syndrome

The concept that microorganisms can modulate the host resistance was historically reviewed in the present article. The importance of African trypanosomiasis in the development of the research on immunosuppression as well as the impact of human immunodeficiency virus infection are discussed. Each day new opportunistic organisms establish a constant challenge for the correct diagnosis of concomitant infections in acquired immunodeficiency syndrome. The importance of parasite infection in the balance of host resistance in the third world was emphasized. Finally, some aspects of Leishmania as opportunistic organisms were presented.

Human immunodeficiency virus/acquired immunodeficiency syndrome and tropical diseases: a Brazilian perspective

The paper summarizes recent findings on the epidemiology and pathogenesis of human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/Aids), highlighting the role of co-infections with major tropical diseases. Such co-infections have been studied in the Brazilian context since the beginning of the Aids epidemic and are expected to be more frequent and relevant as the Aids epidemic in Brazil proceeds towards smaller municipalities and the countryside, where tropical diseases are endemic. Unlike opportunistic diseases that affect basically the immunocompromised host, most tropical diseases, as well as tuberculosis, are pathogenic on their own, and can affect subjects with mild or no immunossuppression. In the era of highly active anti-retroviral therapies (HAART), opportunistic diseases seem to be on decrease in Brazil, where such medicines are fully available. Benefiting from HAART in terms of restoration of the immune function, putative milder clinical courses are expected in the future for most co-infections, including tropical diseases. On the other hand, from an ecological perspective, the progressive geographic diffusion of Aids makes tropical diseases and tuberculosis a renewed challenge for Brazilian researchers and practitioners dealing with HIV/Aids in the coming years.