RESUMO
The number of dengue epidemics in Brazil has increased dramatically in the last 15 years. In this study, we analysed the seasonal patterns in the incidence of hospitalisations due to dengue across the different states of Brazil and compared these with the corresponding climatic patterns. We discovered that the seasonality of dengue hospitalisations in Brazil has a clear zonal gradient, characterised by the progression of primary peaks from West to East during the first half of the year, which may be associated with the increased vapour pressure and rainfall during this period, leading to increased mosquito abundance and activity. We also found that the proportion of children among hospitalised individuals was especially high during the peak outbreaks in 2007/2008 and 2010. This may be due to the emergence and spread of the new DENV-2 Southeast Asian genotype lineage II from 2007, which has probably arrived from the Caribbean and may have caused an increase in incidence and severity of the disease, particularly among children. Our findings may allow health systems to improve control interventions and contribute to reducing dengue morbidity and mortality by using integrated vector control in conjunction with early diagnosis and prompt supportive care.
Assuntos
Dengue/epidemiologia , Hospitalização/estatística & dados numéricos , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Brasil/epidemiologia , Criança , Pré-Escolar , Bases de Dados Factuais , Vírus da Dengue/genética , Feminino , Análise de Fourier , Genótipo , Humanos , Incidência , Lactente , Masculino , Pessoa de Meia-Idade , Estações do Ano , Adulto JovemRESUMO
Diarrhoeal mortality rates in Mexican children dramatically declined during the 1980s and 1990s, concomitant with a temporal shift in peak deaths from summer to autumn-winter. The spatial dynamics of these patterns have not previously been studied. We first describe the seasonal features of paediatric diarrhoeal mortality in Mexico as a whole, then across individual states. While no geographical gradients in the magnitude of diarrhoeal mortality rates have been detected in recent years, we identified a distinct spatial pattern in the timing of peak mortality rate. In the 1980s the summer peak mortality was earliest around Mexico's capital and later in states to the southeast and northwest. Our results suggest that the direction and timing of those annual waves are related to the mean monthly precipitation and mean daily temperature. This pattern has disintegrated in recent years as the summer peak has diminished.
Assuntos
Clima , Diarreia/mortalidade , Criança , Pré-Escolar , Diarreia/epidemiologia , Análise de Fourier , Humanos , Lactente , Recém-Nascido , México/epidemiologia , Chuva , Estudos Retrospectivos , Estações do Ano , Estatísticas não Paramétricas , TemperaturaRESUMO
We studied the cyst production of 340 asymptomatic carriers with single or mixed infections of Entamoeba histolytica/Entamoeba dispar, Endolimax nana and Entamoeba coli. It was found that the main source of transmission was a small group of 37 (10.9%) carriers who produced 70.2% of all cysts. Gender was an important factor for cyst production of Ent. histolytica/Ent. dispar, since males produced 6-fold more cysts than females. Females produced 'large' (13-15 microns) Ent. histolytica/Ent. dispar cysts and males small (10-12 microns) cysts when concentration was > 2000 cysts/g. When concentration was < 2000 cysts/g, cysts were the same size for both sexes (11.6 +/- 0.3 microns). In Ent. coli infections, an inverse relationship between the number and size of cyst was found for both sexes. Cysts of End. nana were not affected by gender or cyst concentration. Following cyst production by a carrier infected with Ent. coli and Ent. histolytica for 28 days, we identified synchronized cycles of cyst production for both species. Altogether, these data suggest that cyst-mediated transmission is a highly regulated process in which synchronization among different species and gender of the host have an important role in transmission.
Assuntos
Amebíase/transmissão , Doenças do Colo/parasitologia , Endolimax , Entamoeba histolytica , Enteropatias Parasitárias/transmissão , Animais , Entamebíase/transmissão , Fezes/parasitologia , Feminino , Seguimentos , Humanos , Masculino , Caracteres SexuaisAssuntos
Países em Desenvolvimento/estatística & dados numéricos , Rickettsia typhi , Tifo Endêmico Transmitido por Pulgas/epidemiologia , Adulto , Feminino , Humanos , Masculino , México/epidemiologia , Prevalência , Testes Sorológicos , Distribuição por Sexo , Tifo Endêmico Transmitido por Pulgas/diagnóstico , População Urbana/estatística & dados numéricosRESUMO
In 1545, twenty-four years after the Spanish conquest of the Aztec empire, an epidemic of a malignant form of a hemorrhagic fever appeared in the highlands of Mexico. The illness was characterized by high fever, headache, and bleeding from the nose, ears, and mouth, accompanied by jaundice, severe abdominal and thoracic pain as well as acute neurological manifestations. The disease was highly lethal and lasted three to four days. It attacked primarily the native population, leaving the Spaniards almost unaffected. The hemorrhagic fevers remained in the area for three centuries and the etiologic agent is still unknown. In this report we describe, and now that more information is available, analyze four epidemics that occurred in Mexico during the colonial period with a focus on the epidemic of 1576 which killed 45% of the entire population of Mexico. It is important to retrieve such diseases and the epidemics they caused from their purely historical context and consider the reality that if they were to reemerge, they are potentially dangerous.
Assuntos
Surtos de Doenças/história , Febre Hemorrágica Americana/história , Febre Hemorrágica Americana/epidemiologia , História do Século XVI , História do Século XVII , História do Século XVIII , História do Século XIX , Humanos , México/epidemiologiaRESUMO
We used the polymerase chain reaction (PCR) to study the epidemiology of pathogenic and nonpathogenic Entamoeba histolytica in a rural community in Mexico. Formalin-fixed stool samples were used for extraction of DNA. The PCR amplifications were performed using two sets of primers that discriminate between pathogenic or non-pathogenic E. histolytica. A total of 201 randomly selected individuals were studied. Among them, 25 (12%) were diagnosed to be infected with E. histolytica by microscopy; PCR identified 24 of these as positive (sensitivity = 0.96) and of 176 negative individuals, only three were identified as positive (specificity = 0.98). The PCR analysis defined three populations: 14 cases were positive for both pathogenic and nonpathogenic E. histolytica, nine cases were positive for pathogenic and negative for nonpathogenic E. histolytica, and only one case was negative for pathogenic and positive for nonpathogenic E. histolytica. Infection by E. histolytica was strongly associated to infection with Entamoeba coli (odds ratio [OR] = 9.41, 95% confidence interval [CI] = 3.09, 28.65, P < 0.0004) and Endolimax nana (OR = 6.15, 95% CI = 2.03, 18.17, P < 0.0004). This new technique has high specificity and sensitivity; it is simple, reproducible, fast, avoids the need to culture trophozoites, and can be applied in the field for epidemiologic studies.