Evaluation of the double diffusion, enzyme immunoassay and immunoblotting techniques, for the diagnosis of human hydatid disease in tropical areas

Hydatid disease in tropical areas poses a serious diagnostic problem due to the high frequence of cross-reactivity with other endemic helminthic infections. The enzyme-linked-immunosorbent assay (ELISA) and the double diffusion arc 5 showed respectively a sensitivity of 73% and 57% and a specificity of 84-95% and 100%. However, the specificity of ELISA was greatly increased by using ovine serum and phosphorylcholine in the diluent buffer. The hydatic antigen obtained from ovine cyst fluid showed three main protein bands of 64,58 and 30 KDa using SDS PAGE and immunoblotting. Sera from patients with onchocerciasis, cysticercosis, toxocariasis and Strongyloides infection cross-reacted with the 64 and 58 KDa bands by immunoblotting. However, none of the analyzed sera recognized the 30 KDa band, that seems to be specific in this assay. The immunoblotting showed a sensitivity of 80% and a specificity of 100% when used to recognize the 30 KDa band.

Evaluation of the enzyme-linked-immuno-electro-diffusion-assay (ELIEDA) for the diagnosis of Schistosoma mansoni infection with low worm burden

An immunoprecipitation technique, ELIEDA (enzyme-linked-immuno-electro-diffusion assay), was evaluated for the diagnosis of Schistosoma mansoni infection with low worm burden. One hundred of serum samples from patients excreting less than 600 eggs per gram of feces (epg), with unrelated diseases and clinically healthy subjects were studied. In patients with egg counts higher than 200 epg, the sensitivities of IgM and IgG ELIEDA were 1.000 and 0.923, respectively, not differing from other Serologic techniques, such as indirect hemaglutination (IHAT), immunofluorescence (IFT) tests and immuno-electrodiffusion assay (IEDA). However in patients with low egg counts (< 100 epg), the IgG ELIEDA provided better results (0.821) than IgM ELIEDA (0.679), showing sensitivity that did not differ from that of IgG IFT (0.929), but lower than that of IgM IFT (0.964). However, its sensivity was higher than that found with IHAT (0.607) and IEDA (0.536). The specificity of IgG ELIEDA was comparable to that of other techniques. The data indicate that IgG ELIEDA might be useful for the diagnosis of slight S. mansoni infections, and the cellulose acetate membrane strips can be stored for further retrospective studies.

CONSTITUTIVE MELANIN IN THE CELL WALL OF THE ETIOLOGIC AGENT OF LOBO'S DISEASE

Lobo's disease is a chronic granulomatous disease caused by the obligate pathogenic fungus, whose cell walls contain constitutive melanin. In contrast, melanin does not occur in the cell walls of Paracoccidioides brasiliensis when stained by the Fontana-Masson stain.

The use of the antifungal agent miconazole as an inhibitor of Blastocystis hominis growth in Entamoeba histolytica/E. dispar cultures

In regions with high prevalence, Blastocystis hominis is frequently found in association with Entamoeba histolytica/E. dispar in xenic cultures. Its exacerbated growth is often superimposed on the growth of amebas, thus impeding the continuation of the amebas in the culture, within a few generations. The present study reports on the excellent efficacy (100%) of the antifungal agent miconazole in eliminating B. hominis from cultures of E. histolytica/E. dispar, thereby maintaining the integrity of the trophozoites of the amebas. Nystatin presented low efficacy (33.3%).

Cladophialophora carrionii: a rare agent of chromoblastomycosis in Rio de Janeiro State, Brazil

A 73 year-old male farm laborer from a rural area presented a 15 year history of extensive tumoral lesions over his left leg. Histological studies of skin biopsy showed pseudoepitheliomatous hyperplasia and granulomatous chronic inflammatory process with muriform cells, confirming chromoblastomycosis (CBM). Cladophialophora carrionii was isolated in culture. Treatment with itraconazole 400 mg/day for 12 months resulted in complete remission of lesions. As far we aware, this is the first case report of CBM caused by Cladophialophora carrionii in Rio de Janeiro State, Brazil.

Serological evidence of Rickettsia parkeri as the etiological agent of rickettsiosis in Uruguay

We report three new rickettsiosis human cases in Uruguay. The three clinical cases presented clinical manifestations similar to previous reported cases of Rickettsia parkeri in the United States; that is mild fever (< 40 ºC), malaise, headache, rash, inoculation eschar at the tick bite site, regional lymphadenopathy, and no lethality. Serological antibody-absorption tests with purified antigens of R. parkeri and Rickettsia rickettsii, associated with immunofluorescence assay indicated that the patients in two cases were infected by R. parkeri. Epidemiological and clinical evidences, coupled with our serological analysis, suggest that R. parkeri is the etiological agent of human cases of spotted fever in Uruguay, a disease that has been recognized in that country as cutaneous-ganglionar rickettsiosis.

SURVIVAL, INDUCTION AND RESUSCITATION OF Vibrio cholerae FROM THE VIABLE BUT NON-CULTURABLE STATE IN THE SOUTHERN CARIBBEAN SEA

The causative agent of cholera, Vibrio cholerae, can enter into a viable but non-culturable (VBNC) state in response to unfavorable conditions. The aim of this study was to evaluate the in situ survival of V. cholerae in an aquatic environment of the Southern Caribbean Sea, and its induction and resuscitation from the VBNC state. V. cholerae non-O1, non-O139 was inoculated into diffusion chambers placed at the Cuare Wildlife Refuge, Venezuela, and monitored for plate, total and viable cells counts. At 119 days of exposure to the environment, the colony count was < 10 CFU/mL and a portion of the bacterial population entered the VBNC state. Additionally, the viability decreased two orders of magnitude and morphological changes occurred from rod to coccoid cells. Among the aquatic environmental variables, the salinity had negative correlation with the colony counts in the dry season. Resuscitation studies showed significant recovery of cell cultivability with spent media addition (p < 0.05). These results suggest that V. cholerae can persist in the VBNC state in this Caribbean environment and revert to a cultivable form under favorable conditions. The VBNC state might represent a critical step in cholera transmission in susceptible areas.

Rickettsia typhi IN RODENTS AND R. felis IN FLEAS IN YUCATÁN AS A POSSIBLE CAUSAL AGENT OF UNDEFINED FEBRILE CASES

Rickettsia typhi is the causal agent of murine typhus; a worldwide zoonotic and vector-borne infectious disease, commonly associated with the presence of domestic and wild rodents. Human cases of murine typhus in the state of Yucatán are frequent. However, there is no evidence of the presence of Rickettsia typhi in mammals or vectors in Yucatán. The presence of Rickettsia in rodents and their ectoparasites was evaluated in a small municipality of Yucatán using the conventional polymerase chain reaction technique and sequencing. The study only identified the presence of Rickettsia typhi in blood samples obtained from Rattus rattus and it reported, for the first time, the presence of R. felis in the flea Polygenis odiosus collected from Ototylomys phyllotis rodent. Additionally, Rickettsia felis was detected in the ectoparasite Ctenocephalides felis fleas parasitizing the wild rodent Peromyscus yucatanicus. This study’s results contributed to a better knowledge of Rickettsia epidemiology in Yucatán.

HUMAN TOXOPLASMOSIS OUTBREAKS AND THE AGENT INFECTING FORM. FINDINGS FROM A SYSTEMATIC REVIEW

SUMMARY Toxoplasmosis, a worldwide highly prevalent zoonotic infection, is transmitted either by the oocysts, from water and soil, or the tissue cysts, in raw or undercooked infected meat, of Toxoplasma gondii. An ongoing debate is whether there are differences between the clinical and epidemiological characteristics of the outbreaks due to one or the other infective form of the agent. We performed a systematic review, recovering 437 reported outbreaks of which 38 were selected. They were complete reports containing ascribed Toxoplasma infecting form, and clinical and demographic data. There was no gender or age group selection in the outbreaks, which were described more often in the Americas. A large number of individuals were affected when oocysts, associated with soil and water contaminated with cat feces, were considered the transmission source. Onset of symptoms occurred early when the infection was ascribed to meat tissue cysts (11.4 ± 6.7 days) with sharpened temporal distribution of cases, while a broader and prolonged appearance of new cases was observed when oocysts in water were the source of the infection (20 ± 7 days, p < 0.001). Such information may be useful in the design and implementation of control strategies.

Leishmania infantum AS A CAUSATIVE AGENT OF CUTANEOUS LEISHMANIASIS IN THE STATE OF MATO GROSSO DO SUL, BRAZIL

Cutaneous leishmaniasis is caused by different species of theLeishmania genus. Leishmania(Leishmania) infantum, causing cutaneous leishmaniasis, has been described in patients living in areas where visceral leishmaniasis is endemic. In this study, it was possible to characterize this species in seven slides from cutaneous tissue imprints from patients with cutaneous leishmaniasis in the State of Mato Grosso do Sul, Brazil.