[Risk analysis of foodborne diseases: microbial risk assessment]. / Enfermedades transmitidas por los alimentos: Análisis del riesgo microbiológico.

The basic goals of risk assessment include the following: to identify potentially hazardous situations and apply appropriate methods to estimate the likelihood that a hazard occurs. In The uncertainty in that estimate, to provide alternative solutions to reduce the risk, estimate the effectiveness of those solutions, provide information to base a risk management decision, and estimate the uncertainty associated with the analysis. Risk analysis provides the rational framework for assembling and then analysing the evidence relating to risk and presenting the results in a form that is easy to understand and then act upon fairly and effectively. Progress made is no excuse for arrogance. The present review is definitely not designed as the last word on risk analysis for foodborne diseases. Rather, this review has been designed to continue an evolving and necessary process and to provide a reference point that indicates the state of development in 2010.

Strongyloides stercoralis hyperinfection in a patient with AIDS.

Strongyloides stercoralis is a prevalent cause of severe infection and death in many areas of the world where fecal contamination of soil or water is common. The nematode is endemic in tropical and subtropical regions of the world, including northeastern Argentina, where infection rates may exceed 30% of the population. Strongyloides infections are often light and associated with few or no signs and symptoms, particularly during initial migration through the body. However, certain persons are at risk of severe, clinically significant disease developing. The manifestations of hyperinfection syndrome are divided, based on the system of origin, into intestinal and extraintestinal disease mainly involving the respiratory tract. Unfortunately, S stercoralis hyperinfection is seldom diagnosed until late in the course of the disease, which contributes to a high death rate. In patients with the hyperinfection syndrome and massive Strongyloides infection, adult respiratory distress syndrome with pulmonary insufficiency that requires intubation and mechanical ventilation may also develop. We report a case of S stercoralis hyperinfection in an HIV-infected patient, which resulted in death.

[Radiation on the dining table]. / La radiación a la mesa.

Zero tolerance to bacterial contamination means considering the acceptance of "radiation on the table". The process of food irradiation has been extensively studied, nevertheless its use remains a matter of some controversy. Despite unanimous agreement within the medical community of the safety of this procedure, occasional concerns arise from the consumers. A common consumer misconception is that irradiation may turn the food "radioactive". A significant number of scientific studies on the topic were analyzed. We found no scientific study demonstrating that consumption of irradiated food might pose a risk to consumers. All studies conclude that food irradiation at the appropriate dose required to reduce contamination is safe and does not affect its nutritional value. In order to emphasize the issue we discuss the potential benefit vs harm of irradiation of food contaminated with E. coli 0157: H7. The association of this bacteria with severe disease and death has been clearly established in contrast with the lack of a demonstrated risk due to meat irradiation. We conclude that the risks of food irradiation remains "unknown" simply because, after four decades of research, none has been identified. In contrast to the risks of acquiring a food transmitted bacterial disease, the risk of irradiation is negligible.

[Epidemiology and risk factors associated to foodborne and infant botulism: where and when?]. / Epidemiología y factores de riesgo asociados al botulismo de los alimentos y al botulismo infantil: ¿Dónde y cuándo?

Foodborne botulism is caused by ingestión of a preformed toxin produced in food by C. botulinum. The most frequent source is home-canned foods, in which spores that survive an inadequate cooking and canning process germinate, reproduce, and produce this toxin in the anaerobic environment of the canned food. From 1992 to 2003, 34 cases of food-borne cases and 275 cases of infant botulism were reported in Argentina. The severity of symptoms depends on the amount of toxin ingested. Mild cases may not seek medical attention at all. A patient presenting only nausea and mild neurological symptoms may not raise the physician's attention and therefore the case will not be reported. It is important to make physicians aware of this potentially fatal disease. In Argentina, most botulism cases are related to home-canned food. Therefore, botulism can be prevented through the education of consumers in order to discourage the consumption of that kind of food.

[Listeria monocytogenes outbreaks: a review of the routes that favor bacterial presence]. / Brotes de infección por histeria monocytogenes: Una revisión de las vías que llevan a su aparición.

Listeria monocytogenes is a foodborne pathogen that causes serious invasive illness, mainly in certain well-defined high-risk groups, including immunocompromised patients, pregnant women and neonates. L. monocytogenes primarily causes abortion, septicaemia or infections of the central nervous systems. Listeriosis outbreaks have mostly been linked to consumption of raw milk or cheese made of unpasteurized milk. Previous outbreaks of listeriosis have been linked to a variety of foods especially processed meats (such as hot dogs, deli meats, and páté). The public health importance of listeriosis is not always recognized, particularly since listeriosis is a relatively rare disease compared with other common foodborne illnesses such as salmonellosis or botulism. However, because of its high case fatality rate, listeriosis ranks among the most frequent causes of death due to foodborne illness: second after salmonellosis. Changes in the manner food is produced, distributed and stored have created the potential for widespread outbreaks involving many countries. The pasteurization of raw milk, which destroys L. monocytogenes, does not eliminate later risk of L. monocytogenes contamination in dairy products. Extensive work has been ongoing in many countries during the last decade to prevent outbreaks and decrease the incidence of listeriosis. A marked reduction has occurred in its incidence in some of these countries during the 1990s, suggesting a relationship between preventive measures and reduction on human cases listeriosis.

Regional differences in astrocyte activation in HIV-associated dementia.

Since astrogliosis is a histological marker usually observed in HIV-associated dementia (HIV-D), we decided to investigate the potential relationship between the expression of glial fibrillary acidic protein (GFAP) and the regional distribution of cells positive (+) for this specific marker of astrocyte activation. Histological sections of brain tissues obtained at necropsy from 5 HIV-D patients and 5 age-matched controls without history of neuropsychiatric illness were immunostained with peroxidase. Mean numbers of GFAP(+) astrocytes were significantly increased in entorhinal cortex, hippocampus and subcortical white matter of patients, but values in frontal cortex and basal ganglia were similar to those of controls. In contrast, surface density of immunoreactive GFAP was significantly increased in all tested brain areas from all patients, including unusually affected regions such as entorhinal cortex and hippocampus. Therefore, such consistent finding of hypertrophic astrocytes, ranging from highest cell percentajes in subcortical white matter to lowest in basal ganglia indicates that quantification of surface density in GFAP (+) cells appears to be a more reliable approach to score gliosis than the counting of their cell nuclei. Because astrocyte activation involves both protective and detrimental effects on adjacent neuronal subsets, the evidence of regional differences in this reactive potential highlights the importance of accurately defining their contribution to the neuropathogenesis not only of HIV-D, but of a wide range of neurodegenerative disorders.

CNS cryptococcoma in an HIV-positive patient.

This is the first case of brain cryptococcoma in an AIDS patient reported in Argentina. The patient was a 28-year-old white heterosexual man with AIDS who presented with altered mental status, seizures, visual hallucinations, headache, and fever without significant focal neurological deficit. He had a lumbar puncture, and was treated for cryptococcal meningitis. Subsequent brain CT scanning and MRI disclosed a mass lesion in the occipital lobe. Histopathological examination of biopsy was compatible with cryptococcoma, and tissue culture revealed Cryptococcus neoformans. Resolution of the mass and edema resulted after treatment with intravenous amphotericin B for six weeks, which was followed with maintenance oral fluconazole. Intracranial mass is an uncommon complication in AIDS patients with cryptococcosis, and cryptococcoma should be considered as differential diagnosis of brain mass lesion in these patients. The etiologic diagnosis is necessary because central nervous system (CNS) toxoplasmosis, lymphoma, and tuberculoma can produce similar clinical syndromes and MRI or CT findings to cryptococcoma. Also, these pathologies may coexist with meningeal cryptococcosis.

Giemsa and Grocott in the recognition of Histoplasma capsulatum in blood smears.

OBJECTIVE: To facilitate the recognition of intracellular yeasts of Histoplasma capsulatum and differentiate it from Leishmania amastigotes and other parasites, using the combination of Giemsa and a rapid modification of Grocott stains to peripheral blood smears in a hematological study. METHODS: The combination of both stains was applied consecutively (first Grocott and then Giemsa) to previously fixed peripheral blood smears. Microscopy was performed with 400× and 1 000×, the latter using immersion oil. RESULTS: The yeasts of Histoplasma capsulatum were observed into the cytoplasm of leukocytes as brownish oval elements, with 3-4 µm in diameter. CONCLUSIONS: The combination of both techniques is a simple and fast method to facilitate recognition of intracellular yeasts and it is different from intracellular parasitic elements. Moreover, it allows distinguishing the cell elements that are in the microscopic preparations. It may be very helpful in those cases in which the presumptive diagnosis of histoplasmosis has not been established yet and where other more sophisticated methods are not available.

Rapid and biosecure diagnostic test for tuberculosis.

Early and rapid detection of the causative organism is necessary in tuberculosis. We present here an integrated and dedicated molecular biology system for tuberculosis diagnosis. One hundred and eighty-nine (189) biologic specimens from patients strongly suspected by clinical parameters of tuberculosis were studied by Ziehl-Neelsen staining, cultivation on a solid medium, and by a balanced heminested fluorometric PCR system (Orange G3TB) that preserves worker safety and produces a rather pure material free of potential inhibitors. DNA amplification was carried out in a low cost using a tuberculosis thermocycler-fluorometer. The double stranded DNA produced is fluorometrically detected. The whole reaction is carried out in one single tube which is never opened after adding the processed sample, thus minimizing the risk of cross contamination with amplicons. The assay is able to detect 30 bacilli/ml of sample having a 99.8 % inter-assay coefficient of variation. PCR was positive in 36 (18.9 %) tested samples (33 of them were smear-negative). In our study, it yields a preliminary overall sensitivity of 97.4 %. In addition, its overall specificity is 98.7 %. The total run time of the test is 4 h with two and a half real working hours. All PCR-positive samples also had a positive result by microbiological culture and clinical criteria. The results obtained showed that it could be a very useful tool to increase efficiency in detecting the tuberculosis disease in low bacillus inoculum samples. Furthermore, its low cost and friendly usage make it feasible to be used in regions with poor development.

Infections and inequalities: anemia in AIDS, the disadvantages of poverty.

OBJECTIVE: To study anemia in AIDS patients and its relation with socioeconomic, employment status and educational levels. METHODS: A total number of 442 patients who visited the Infectious Diseases University Hospital in Buenos Aires, Argentina were included in the study. Patients were dividied into two groups, i.e. one with anemia and the other without anemia. Anemia epidemiology and its relationship with educational level, housing, job situation, monthly income, total daily caloric intake and weekly intake of meat were evaluated. RESULTS: Anemia was found in 228 patients (54%). Comparing patients with or without anemia, a statistically significant difference was found (P<0.000 1) in those whose highest educational level reached was primary school, who lived in a precarious home, who had no stable job or were unable to work, whose income was less than 30 dollars per month, whose meat consumption was less than twice a week or received less than 8 000 calories per day. CONCLUSIONS: The high prevalence of anemia found in poor patients with AIDS suggests that poverty increases the risk to suffer from this hematological complication. The relationship between economic development policies and AIDS is complex. Our results seem to point to the fact that AIDS epidemic may affect economic development and in turn be affected by it. If we consider that AIDS affects the economically active adult population, despite recent medical progress it usually brings about fatal consequences, especially within the poorest sectors of society where the disease reduces the average life expectancy, increases health care demand and tends to exacerbate poverty and iniquity.

A case report of cutaneous larva migrans in Argentina.

Cutaneous larva migrans (CLM) represents the most common tropically acquired dermatosis. CLM is caused by infection with hookworm larvae in tropical and sub-tropical areas, and people who have a history of foreign travel and of walking barefoot on sandy soil or beaches are at a high risk of getting infected with it. The diagnosis is usually made on the basis of the typical appearance of the lesion, intense itching and history of foreign travel. CLM is a common parasitic skin disease that can be easily prevented by wearing 'protective' footwear. A case of CLM is described in this article.

Diagnosis of Mycobacterium tuberculosis using molecular biology technology.

OBJECTIVE: To present an integrated molecular biology dedicated system for tuberculosis diagnosis. METHODS: One hundred and five sputum specimens from patients strongly suspected by clinical parameters of tuberculosis were studied by Ziehl-Neelsen staining, by cultivation on solid medium and by a balanced heminested fluorometric PCR system (Orange G3TB) that could preserve worker safety and produce a rather pure material free of potential inhibitors. DNA amplification was performed in a low cost tuberculosis termocycler-fluorometer. Produced double stranded DNA was flurometrically detected. The whole reaction was conducted in one single tube which would not be opened after adding the processed sample in order to minimize the risk of cross contamination with amplicons. RESULTS: The assay was able to detect 30 bacillus per sample mL with 99.8% interassay variation coefficient. PCR was positive in 23 (21.9%) tested samples (21 of them were smear negative). In our study it showed a preliminary sensitivity of 94.5% for sputum and an overall specificity of 98.7%. CONCLUSIONS: Total run time of the test is 4 h with 2.5 real working time. All PCR positive samples are also positive by microbiological culture and clinical criteria. Results show that it could be a very useful tool to increase detection efficiency of tuberculosis disease in low bacilus load samples. Furthermore, its low cost and friendly using make it feasible to run in poor regions.

Prevention of foodborne listeriosis.

Listeria monocytogenes is a foodborne pathogen that can cause serious invasive illness, mainly in certain well-defined high-risk groups, including elderly and immunocompromised patients, pregnant women, newborns and infants. L. monocytogenes primarily causes abortion, septicemia or meningitis. Contaminated meats (such as hot dogs, delicatessen meats and patiota), dairy products and seafood have all been implicated in outbreaks of listeriosis. The public health importance of listeriosis is not always recognized, particularly because listeriosis is a relatively rare disease compared with other common foodborne illnesses such as salmonellosis or botulism. However, because of its high case fatality rate, listeriosis ranks among the most frequent causes of death due to foodborne illness, ranking second after salmonellosis. L. monocytogenes emerged as an important foodborne pathogen in the latter part of the 20th century. Extensive work has been performed in many countries during the last decade to prevent outbreaks and decrease the incidence of listeriosis. An important reduction occurred in listeriosis incidence in some of these countries during the 90s, suggesting a relationship between preventive measures and incidence decrease of human listeriosis.

Cutaneous myiasis due to Cochliomyia hominivorax in a drug user.

Myiasis is the condition resulting from the invasion of tissues or organs of man or animals by dipterous larvae. The blowflies (Calliphoridae) of Argentina comprise several species that may cause myiasis by colonizing wounds or infected body orifices, and one specific parasite: Cochliomyia hominivorax. This species often causes traumatic myiasis in cattle, dogs and cats, and it is not rare in humans. The larvae consume living tissues, so they are dangerous unless speedily removed. Immediate operative exploration along with the removal of larvae and primary defect closure is recommended in every case. Here we report a case of myiasis in a scalp wound caused by blunt force trauma to the area, in a male patient with a case history of alcohol and drug abuse. Seventy-one living larvae were extracted from the wound and determined as C. hominivorax in the Forensic Entomology Laboratory. Given the aggressiveness of these larvae, specific and quick diagnosis as well as the application of appropriate treatment is crucial.

Food-borne botulism in Argentina.

Botulism is a severe neuroparalytic disease caused by Clostridium botulinum toxins. Although the disease is uncommon it is a cause of great concern due to its high rate of mortality. Food-borne outbreaks of botulism occur worldwide and require immediate public health attention and acute care resources. Analysis of outbreaks showed that the food products most often involved were fermented fish products in Alaska; home-canned food, oil preservation and restaurant sauce in the rest of the United States (US) and in London and; and home-canned vegetables, airtight packed food with inappropriate refrigeration, and aerosols in Argentina. The diagnosis is based only on clinical findings matching the disease and previous exposure to suspicious food. Botulism must be immediately identified as even one case suggests the start of an epidemic and should be treated as a public health emergency. Therefore, the purpose of the following review is to recognize the risks associated with the consumption of potentially dangerous foods, and to encourage prevention by seeking to make all public health professionals aware of the dangers of this potentially lethal disease.

Atypical forms of Cryptococcus neoformans in CSF of an AIDS patient.

The microscopic recognition of typical rounded capsulated yeasts in centrifuged cerebrospinal fluid (CSF), stained with India ink, is a common, rapid and effective method for the diagnosis of cryptococcal meningitis among AIDS patients. The presence of atypical forms of Cryptococcus neoformans var. neoformans in samples of CSF of an AIDS patient with cryptococcosis treated at the University Hospital of Infectious Disease is presented. The India ink microscopy of three consecutive CSF samples revealed capsulated yeast with India ink particles in the deteriorated capsules and capsulated pseudohyophae. Clinically, the patient showed a subacute meningoencephalitis, with a clinical picture not particularly different from those commonly observed in patients with AIDS-associated cryptococcosis treated in our hospital. In all cases, the culture of the CSF showed colonies of C. neoformans with typical macro and micromorphology, and the in vitro susceptibility tests to amphotericin B, fluocitosine, itraconazole and fluconazole showed MIC values into the limits of sensitivity. The presence of atypical forms of C. neoformans, considered as an atypical finding, could be the consequence of an adaptive phenomenon of this fungal species to an impaired immunological status present in the host.