Treatment of swine wastewater with subsurface-flow constructed wetlands in Yucatán, Mexico: Influence of plant species and contact time

This study evaluates the capability of horizontal subsurface-flow constructed wetlands (SSF CWs) for treating pretreated swine wastewater as a function of contact time (CT) and type of macrophyte under the local conditions of Yucatán, Mexico. Experiments were conducted from July 2004 to November 2005 on a swine-fattening farm. The study had three stages: first, macrophytes were located and collected; second, plants were acclimatised; and third, a pilot plant with 6 wetlands was set up, operated and evaluated. The effectiveness of the wetlands was intensively tested over 2 periods (April and November 2005). The results indicate that treatment efficiency significantly improved with increased CT for most of the analysed contaminants. The highest removal rates were recorded at a CT of 3 d and ranged between 64 and 78% for total suspended solids, 52 and 78% for COD, 57 and 74% for BOD5, 57 and 79% for total nitrogen, 63 and 75% for ammonium nitrogen, 70 and 81% for nitrate, 0 and 28% for total phosphorus and 3.3 and 4.2 log-units for total coliforms. Results also suggest that the macrophyte species used did not significantly differ on their contribution to overall treatment efficiency. However, vegetated beds slightly improved water quality when compared to unplanted systems. Horizontal SSF CWs are a suitable technology for treating swine wastewater under the local conditions of Yucatán. Contact time should be given special attention in the design of future full-scale facilities

Risk factors for hepatitis B virus infection in Rio de Janeiro, Brazil

BACKGROUND: Despite international efforts to prevent hepatitis B virus (HBV) infection through global vaccination programs, new cases are still being reported throughout the world. METHODS: To supply data that might assist in improving preventive measures and national surveillance for HBV infection, a cross-sectional study was conducted among individuals referred to the Brazilian National Reference Center for Viral Hepatitis (Rio de Janeiro) during a two-year period. Reported risk factors among infected subjects ("HBV-positive") were compared to those of subjects never exposed ("HBV-negative") to HBV. Two subgroups were further identified within the HBV-positive group, "acute" infection and "non-acute" infection. RESULTS: A total of 1,539 subjects were tested for HBV, of which 616 were HBV-positive (79 acute infection and 537 non-acute infection). HBV-positive subjects were more likely to be of male gender (63% versus 47%); and to report multiple sexual partners (12% versus 6%) and illicit drug use (IDU and/or intranasal cocaine use) (6% versus 3%). Among the HBV-positive subgroups, age differed significantly, with 48% being under 30 years of age in subjects acutely infected compared to 17% in those with non-acute infection. CONCLUSIONS: The association of multiple sexual partners with past HBV infection and the age distribution of currently infected subjects suggest that sexual transmission played a major role in the transmission of HBV in this study population. Thus, vaccination during adolescence should be considered

Leishmaniose cutânea experimental: I - sobre a susceptibilidade do primata Cebus apella (Cebidae) a infecção pela Leishmania (Viannia) lainsoni Silveira, Shaw, Braga e Ishikawa, 1987

Foi investigada a susceptibilidade do primata Cebus apella (Cebidae) à infecção experimental pela Leishmaiua (Viannia) lainsoni, com o objetivo de estudara patogenia desse parasita, ainda pouco conhecido para o homem. Dessa forma, cinco espécimens jovens daquele primata, 2 machos e 3 fêmeas, foram inoculados, intraderme, em oito sítios diferentes da região dorsal da cauda com 3 x 10(6) de promastigotas do parasita (MHOMZBR/81/M6426, Benevides, Pará), obtidas de cultura da fase estacionária. Em seguida às inoculações, a infecção experimental nos animais foi comprovada, não só pela presença de amastigotas do parasita na pele dos animais inoculados, mas, também, pela concomitância desse achado associado ao desenvolvimento de lesão cutânea nos pontos da pele onde o parasita foi inoculado. Diante desses resultados, ficou demonstrada a susceptibilidade do primata Cebus apella à infecção experimental pela Leishmama lainsoni cujo período de infecção durou quase quatro meses, suficiente para testar drogas antileishmanióticas e estudar a patogênese da doença causada por este parasita.The susceptibility of the monkey Cebus apella (Cebidae) to experimental infection by Leishmania (Viannia) lainsoni has been investigated. For this purpose, five young monkeys, 2 males and 3 females, were intradermally, inoculated, in eight different places along the dorsal surface of the tail with 3 x 10(6) promastigotes of the parasite (MHOM/BR/81/M6426, Benevides, Pará), from stationary phase culture in Difco B45 medium. After inoculations, infection in the monkeys was indicated by the presence of amastigotes in the skin lesions produced in these animals at the points of inoculation, confirming the susceptibility of the monkey Cebus apella to experimental infection by Leishmania lainsoni, with an infection period of four months. This represents a suitable period for testing antileishmanial drugs or studying the pathogenesis of the disease caused by this parasite

Vaccines against toxoplasma gondii : challenges and opportunities

Development of vaccines against Toxoplasma gondii infection in humans is of high priority, given the high burden of disease in some areas of the world like South America, and the lack of effective drugs with few adverse effects. Rodent models have been used in research on vaccines against T. gondii over the past decades. However, regardless of the vaccine construct, the vaccines have not been able to induce protective immunity when the organism is challenged with T. gondii, either directly or via a vector. Only a few live, attenuated T. gondii strains used for immunization have been able to confer protective immunity, which is measured by a lack of tissue cysts after challenge. Furthermore, challenge with low virulence strains, especially strains with genotype II, will probably be insufficient to provide protection against the more virulent T. gondii strains, such as those with genotypes I or II, or those genotypes from South America not belonging to genotype I, II or III. Future studies should use animal models besides rodents, and challenges should be performed with at least one genotype II T. gondii and one of the more virulent genotypes. Endpoints like maternal-foetal transmission and prevention of eye disease are important in addition to the traditional endpoint of survival or reduction in numbers of brain cysts after challenge

Leishmaniose cutânea experimental: II - aspectos evolutivos da infecção no primata Cebus apella (Cebidae) pela Leishmania (V.) Braziliensis e L. (L.) Amazonensis

Objetivando avaliar o potencial do primata C. apella como modelo experimental da leishmaniose cutânea, produzida pela L. (V.) braziliensis e L. (L.) Amazonensis , inocularam-se, via intradérmica, 3 X 10(6) de promastigotas dessas leishmanias, em 8 sítios da cauda de 10 espécimens desse primata, 5 deles com a L. (V.) braziliensis e outros 5 com a L. (L.) Amazonensis . Posteriormente, às inoculações, o exame semanal dos animais e biópsias mensais, revelaram os seguintes resultados relativos a cada parasita: a) L. (V.) braziliensis : o período de incubação foi de 15-20 dias; aos 30 dias evidenciaram-se lesões pápulo-eritematosas, que evoluíram para nódulos ao fim de 60 dias; no 3.° mês, notou-se ulceração espontânea destas lesões e, no 4° mês, deu-se o início da reparação das lesões ulceradas, culminando com a cura em um dos animais após 5 meses, em dois após 6 meses, noutro após 7 meses e, no último, após 10 meses. Quanto ao parasitismo nas lesões, foi demonstrado nos 5 animais, até 90 dias; depois disto, somente em 2 até 120 dias e, por fim, até 180 dias apenas naquele que curou depois de 10 meses, b) L. (L.) Amazonensis : o período de incubação foi de 20 dias; aos 30 dias notou- se lesões pápulo-eritematosas, que também evoluíram para nódulos ao fim de 60 dias, porém, a partir do 3.° mês, estas lesões regrediram rapidamente ao fim de 90 dias, quando não mais detectou-se o parasita na pele dos animais. Em relação aos testes de Montenegro, somente 2 dos 5 animais infectados com a L. (V.) braziliensis reagiram ao teste, 60 e 90 dias após as inoculações. Os resultados observados permitiram confirmar a infectividade do C. apella a estas leishmanias e, também, reforçar a indicação desse primata como modelo experimental da leishmaniose cutânea causada por estes parasitas.As a means of assessing the usufulness of the monkey Cebus apella as an experimental model for the study of cutaneous leishmaniasis, 5 of these animals were inoculated intradermally at 8 sites along the tail with 3 X 106 promastigotes of L. (V.) braziliensis , while a further 5 monkeys received similar inoculations with 3 X 10(6) promastigotes of L. (L.) Amazonensis . Following the inoculations, weekly examinations and monthly biopsies showed evolution of resulting skin lesions to be as follows: a) L. (V.) braziliensis : lesions were first visible 15-20 days postinoculation (p.i), and at 30 days they were clearly of an etythematous-papular nature, which assumed a nodular form at 60 days; after 3 months a spontaneous ulceration of these lesions was noted and, at 4 months, the initiation of healing. In one animal total healing was apparent 5 months p.i; in two others at 6 months, in another monkey after 7 months, and in the last animal at 10 months p.i. Amastigotes were demonstrated in smears from the lesions of all monkeys up to 90 days p.i; up to 120 days in two animals, and at 180 days p.i. in the monkey which showed resolution of the lesions after 10 months, b) L. (L.) Amazonensis lesions were first apparent after 20 days p. i; at 30 days they were of an en'thematous-papular nature, developing into nodules at 60 days. From the third month of infection onwards, however, the lesions diminished rapidly and, at 90 days p.i. amastigotes were no longer detectable in the skin. With regards to the Montenegro (leishmanin) skin tests, only two of the monkeys (infected with L. (V.) braziliensis ) gave positive reactions, at 60 and 9 ) days p. i. These results confirm the susceptibility of C. apella to infections with both L. (V.) braziliensis and L. (L.) Amazonensis , and support previous indications that this monkey may serve as an useful experimental model for the study of cutaneous leishmaniasis caused by these parasites

Characterization of Leishmania spp. causing cutaneous leishmaniasis in Manaus, Amazonas, Brazil

In the State of Amazonas, American tegumentary leishmaniasis is endemic and presents a wide spectrum of clinical variability due to the large diversity of circulating species in the region. Isolates from patients in Manaus and its metropolitan region were characterized using monoclonal antibodies and isoenzymes belonging to four species of the parasite: Leishmania (Viannia) guyanensis, 73% (153/209); Leishmania (Viannia) braziliensis, 14% (30/209); Leishmania (Leishmania) amazonensis, 8% (17/209); and Leishmania (Viannia) naiffii, 4% (9/209). The most prevalent species was L. (V.) guyanensis. The principal finding of this study was the important quantity of infections involving more than one parasite species, representing 14% (29/209) of the total. The findings obtained in this work regarding the parasite are further highlighted by the fact that these isolates were obtained from clinical samples collected from single lesions