MARCOS AMAKU
Projetos de Pesquisa
Unidades Organizacionais
Departamento de Patologia, Faculdade de Medicina - Docente
LIM/01 - Laboratório de Informática Médica, Hospital das Clínicas, Faculdade de Medicina
LIM/01 - Laboratório de Informática Médica, Hospital das Clínicas, Faculdade de Medicina
46 resultados
Resultados de Busca
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- The risk of dengue for non-immune foreign visitors to the 2016 summer olympic games in Rio de Janeiro, Brazil(2016) XIMENES, Raphael; AMAKU, Marcos; LOPEZ, Luis Fernandez; COUTINHO, Francisco Antonio Bezerra; BURATTINI, Marcelo Nascimento; GREENHALGH, David; WILDER-SMITH, Annelies; STRUCHINER, Claudio Jose; MASSAD, EduardoBackground: Rio de Janeiro in Brazil will host the Summer Olympic Games in 2016. About 400,000 non-immune foreign tourists are expected to attend the games. As Brazil is the country with the highest number of dengue cases worldwide, concern about the risk of dengue for travelers is justified. Methods: A mathematical model to calculate the risk of developing dengue for foreign tourists attending the Olympic Games in Rio de Janeiro in 2016 is proposed. A system of differential equation models the spread of dengue amongst the resident population and a stochastic approximation is used to assess the risk to tourists. Historical reported dengue time series in Rio de Janeiro for the years 2000-2015 is used to find out the time dependent force of infection, which is then used to estimate the potential risks to a large tourist cohort. The worst outbreak of dengue occurred in 2012 and this and the other years in the history of Dengue in Rio are used to discuss potential risks to tourists amongst visitors to the forthcoming Rio Olympics. Results: The individual risk to be infected by dengue is very much dependent on the ratio asymptomatic/symptomatic considered but independently of this the worst month of August in the period studied in terms of dengue transmission, occurred in 2007. Conclusions: If dengue returns in 2016 with the pattern observed in the worst month of August in history (2007), the expected number of symptomatic and asymptomatic dengue cases among tourists will be 23 and 206 cases, respectively. This worst case scenario would have an incidence of 5.75 (symptomatic) and 51.5 (asymptomatic) per 100,000 individuals.
- Influence of the incubation conditions on culture media to optimize primary isolation of Mycobacterium bovis(2016) IKUTA, Cassia Yumi; MORATO, Flavia; SOUZA, Gisele Oliveira de; HEINEMANN, Marcos Bryan; AMAKU, Marcos; FERREIRA NETO, Jose SoaresThe isolation of Mycobacterium bovis is critical to a surveillance system for bovine tuberculosis based on detection of lesions in abattoirs. Thus, four solid culture media and three incubation conditions were investigated to elucidate which combination overcomes the others by assessing growth, time to the first appearance of colonies and their number. Ninety-seven samples of granulomatous lesions were submitted to the decontamination procedure by 1-hexadecylpyridinium chloride at 0.75% w/v, and inoculated on two egg-based media, Stonebrink's (ST) and Lowenstein-Jensen's with sodium pyruvate (LJp), and two agar-based media, tuberculosis blood agar (B83) and Middlebrook 7H11 medium (7H11). Each medium was incubated at 37 degrees C for 90 days in three incubation conditions: in air, in air containing 10% carbon dioxide (CO2), and in air in slopes closed with burned hydrophobic cotton and subsequently plugged with a cork to create a microaerophilic atmosphere. The colonies appeared faster and in higher number when incubated in air containing 10% CO2 (p < 0.01), independent of media. B83 showed a faster growth and detected more isolates at 30 days of incubation, when compared to ST (0.0178), LJp (p < 0.0001) and 7H11 (p < 0.0001), though there was no difference between B83, ST and LJp at 60 and 90 days of incubation. 7H11 presented the lowest number of isolates (p < 0.0001) and a longer period for the appearance of the first colony (p < 0.001). According to our findings, the concomitant use of ST and B83 media incubated in air containing 10% CO2 increases the isolation of M. bovis in a shorter period of time, which improves bovine tuberculosis diagnosis.
- The optimal age of vaccination against dengue in Brazil based on serotype-specific forces of infection derived from serological data(2021) MAIER, Sandra B.; MASSAD, Eduardo; AMAKU, Marcos; BURATTINI, Marcelo N.; GREENHALGH, DavidIn this paper, we study a single serotype transmission model of dengue to determine the optimal vaccination age for Dengvaxia. The transmission dynamics are modelled with an age-dependent force of infection. The force of infection for each serotype is derived from the serological profile of dengue in Brazil without serotype distinction and from serotype-specific reported cases. The risk due to an infection is measured by the probability of requiring hospitalization based on Brazilian Ministry of Health data. The optimal vaccination age is determined for any number and combination of the four distinct dengue virus serotypes DENv1-4. The lifetime expected risk is adapted to include antibody dependent enhancement (ADE) and permanent cross-immunity after two heterologous infections. The risk is assumed to be serostatus-dependent. The optimal vaccination age is computed for constant, serostatus-specific vaccine efficacies. Additionally, the vaccination age is restricted to conform to the licence of Dengvaxia in Brazil and the achievable and minimal lifetime expected risks are compared. The optimal vaccination age obtained for the risk of hospitalization varies significantly with the assumptions relating to ADE and cross-immunity. Risk-free primary infections lead to higher optimal vaccination ages, as do asymptomatic third and fourth infections. Sometimes vaccination is not recommended at all, e.g. for any endemic area with a single serotype if primary infections are risk-free. Restricting the vaccination age to Dengvaxia licensed ages mostly leads to only a slightly higher lifetime expected risk and the vaccine should be administered as close as possible to the optimal vaccination age.
- The impact of dry ageing vacuum-packed pork on the viability of Toxoplasma gondii tissue cysts(2020) ALVES, Bruna Farias; GENNARI, Solange Maria; OLIVEIRA, Solange; SOARES, Herbert Sousa; CONTE-JUNIOR, Carlos Adam; DUBEY, Jitender Prakash; AMAKU, Marcos; PENA, Hilda Fatima JesusThe present study evaluated the viability of Toxoplasma gondii tissue cysts in dry-aged pork loins (m. longissimus) after 14, 21 and 28 days under controlled temperature (0 degrees C +/- 1 degrees C). The pigs (n = 9) were orally inoculated with 3,000 T. gondii oocysts. The right loin of each pig was aged for a predetermined period, and the left loin was kept unprocessed as a control. Two experiments were performed. In Experiment 1, the loins of three pigs were aged for 14 days and then bioassayed in both cats and mice. In Experiment 2, the loins of six pigs were bioassayed only in mice, and the ageing periods were 14, 21, and 28 days. Toxoplasma gondii tissue cysts remained viable in loins aged up to 14 days, as confirmed by bioassays in cats and mice. Viable T. gondii was not recovered by bioassays in mice from loins that were aged for 21 or 28 days. These results demonstrate that T. gondii remained viable in vacuum-packed dry-aged pork loins for 14 days at controlled temperature but not for 21 days or longer.
- Spatio-temporal network analysis of pig trade to inform the design of risk-based disease surveillance(2021) CARDENAS, Nicolas Cespedes; VANDERWAAL, Kimberly; VELOSO, Flavio Pereira; GALVIS, Jason Onell Ardila; AMAKU, Marcos; GRISI-FILHO, Jose H. H.Network analysis is a powerful tool to describe, estimate, and predict the role of pig trade in the spread of pathogens and generate essential patterns that can be used to understand, prevent, and mitigate possible outbreaks. This study aimed to describe the network between premises such as production herds, slaughterhouses, and traders of pig movements and identify heterogeneities in the connectivity of premises in the state of Santa Catarina, Brazil, using social network analysis (SNA). We used static and temporal network approaches to describe pig trade in the state by quantifying network attributes using SNA parameters, such as causal fidelity, loyalty, the proportion of node-loyalty, resilience of outgoing contact chains, and communities. Two indexes were implemented, the first one is a normalized index based on SNA-farm level measures and other index-based SNA-farm level measures considering the swineherd population size from all premises, both indexes were summarized by a municipality to target and rank surveillance activities. Within Santa Catarina, the southwest region played a key role in that 80 % of trade was concentrated in this region, and thus acted as a hub in the network. Besides, nine communities were found. The results also showed that premises were highly connected in the static network, with the network exhibiting low levels of fragmentation and loyalty. Also, just 11 % of the paths in the static network existed in the temporal network which accounted for the order in which edges occurred. Therefore, the use of time-respecting-paths was essential to not overestimate potential transmission pathways and outbreak sizes. Compared to static networks, the application of temporal network approaches was more suitable to capture the dynamics of pig trade and should be used to inform the design of riskbased disease surveillance.
- The Optimal Age of Vaccination Against Dengue with an Age-Dependent Biting Rate with Application to Brazil(2020) MAIER, Sandra B.; MASSAD, Eduardo; AMAKU, Marcos; BURATTINI, Marcelo N.; GREENHALGH, DavidIn this paper we introduce a single serotype transmission model, including an age-dependent mosquito biting rate, to find the optimal vaccination age against dengue in Brazil with Dengvaxia. The optimal vaccination age and minimal lifetime expected risk of hospitalisation are found by adapting a method due to Hethcote (Math Biosci 89:29-52). Any number and combination of the four dengue serotypes DENv1-4 is considered. Successful vaccination against a serotype corresponds to a silent infection. The effects of antibody-dependent enhancement (ADE) and permanent cross-immunity after two heterologous infections are studied. ADE is assumed to imply risk-free primary infections, while permanent cross-immunity implies risk-free tertiary and quaternary infections. Data from trials of Dengvaxia indicate vaccine efficacy to be age and serostatus dependent and vaccination of seronegative individuals to induce an increased risk of hospitalisation. Some of the scenarios are therefore reconsidered taking these findings into account. The optimal vaccination age is compared to that achievable under the current age restriction of the vaccine. If vaccination is not considered to induce risk, optimal vaccination ages are very low. The assumption of ADE generally leads to a higher optimal vaccination age in this case. For a single serotype vaccination is not recommended in the case of ADE. Permanent cross-immunity results in a slightly lower optimal vaccination age. If vaccination induces a risk, the optimal vaccination ages are much higher, particularly for permanent cross-immunity. ADE has no effect on the optimal vaccination age when permanent cross-immunity is considered; otherwise, it leads to a slight increase in optimal vaccination age.
conferenceObject The risk of infectious diseases introduction into non-infected countries by travelers visiting endemic countries(2015) MASSAD, E.; LOPEZ, L. F.; AMAKU, M.; COUTINHO, F. A. B.; QUAM, M.; BURATTINI, M. N.; STRUCHINER, C. J.; WILDER-SMITH, A.- A Note on the Risk of Infections Invading Unaffected Regions(2018) AMAKU, Marcos; COUTINHO, Francisco Antonio Bezerra; ARMSTRONG, Margaret; MASSAD, EduardoWe present two probabilistic models to estimate the risk of introducing infectious diseases into previously unaffected countries/regions by infective travellers. We analyse two distinct situations, one dealing with a directly transmitted infection (measles in Italy in 2017) and one dealing with a vector-borne infection (Zika virus in Rio de Janeiro, which may happen in the future). To calculate the risk in the first scenario, we used a simple, nonhomogeneous birth process. The second model proposed in this paper provides a way to calculate the probability that local mosquitoes become infected by the arrival of a single infective traveller during his/her infectiousness period. The result of the risk ofmeasles invasion of Italy was of 93% and the result of the risk of Zika virus invasion of Rio de Janeiro was of 22%.
- The risk of urban yellow fever resurgence in Aedes-infested American cities(2018) MASSAD, Eduardo; AMAKU, Marcos; COUTINHO, Francisco Antonio Bezerra; STRUCHINER, Claudio Jose; LOPEZ, Luis Fernandez; COELHO, Giovanini; WILDER-SMITH, Annelies; BURATTINI, Marcelo NascimentoAedes aegypti, historically known as yellow fever (YF) mosquito, transmits a great number of other viruses such as Dengue, West Nile, Chikungunya, Zika, Mayaro and perhaps Oropouche, among others. Well established in Africa and Asia, Aedes mosquitoes are now increasingly invading large parts of the American continent, and hence the risk of urban YF resurgence in the American cities should because of great concern to public health authorities. Although no new urban cycle of YF was reported in the Americas since the end of an Aedes eradication programme in the late 1950s, the high number of non-vaccinated individuals that visit endemic areas, that is, South American jungles where the sylvatic cycle of YF is transmitted by canopy mosquitoes, and return to Aedes-infested urban areas, increases the risk of resurgence of the urban cycle of YF. We present a method to estimate the risk of urban YF resurgence in dengue-endemic cities. This method consists in (1) to estimate the number of Aedes mosquitoes that explains a given dengue outbreak in a given region; (2) calculate the force of infection caused by the introduction of one infective individual per unit area in the endemic area under study; (3) using the above estimates, calculate the probability of at least one autochthonous YF case per unit area produced by one single viraemic traveller per unit area arriving from a YF endemic or epidemic sylvatic region at the city studied. We demonstrate that, provided the relative vector competence, here defined as the capacity to being infected and disseminate the virus, of Ae. aegypti is greater than 0.7 (with respect to dengue), one infected traveller can introduce urban YF in a dengue endemic area.
- On the definition of the time evolution operator for time-independent Hamiltonians in non-relativistic quantum mechanics(2017) AMAKU, Marcos; COUTINHO, Francisco A. B.; TOYAMA, F. MasafumiThe usual definition of the time evolution operator e(-iHt/(h) over bar) = Sigma(infinity)(n-0) 1/h! (-i/(h) over bar Ht)(n), Where H is tha Hamiltonian of the system, as given in almost every book on quantum mechanics, causes problems in some situations. The operators that appear in quantum mechanics are either bounded or unbounded. Unbounded operators are not defined for all the vectors (wave functions) of the Hilbert space of the system; when applied to some states, they give a non-normalizable state. Therefore, if H is an unbounded operator, the definition in terms of the power series expansion does not make sense because it may diverge or result in a non- normalizable wave function. In this article, we explain why this is so and suggest, as an alternative, another definition used by mathematicians. (C) 2017 American Association of Physics Teachers.