Analysis of historical data has strongly shaped our understanding of the epidemiology of pandemic influenza and informs analysis of current and future epidemics. Here, the authors analyzed previously unpublished documents from a large household survey of the "Spanish" H1N1 influenza pandemic, conducted in 1918, for the first time quantifying influenza transmissibility at the person-to-person le...

Variola minor 38 Clinical course 38 Variola sine eruptione and subclinical infection 40 Smallpox acquired by unusual routes of infection 40 Inoculation variola and variolation 40 Congenital smallpox 42 Effects of vaccination on the clinical course of smallpox 42 Effects of vaccination on toxaemia 43 Effects of vaccination on the number of lesions 43 Effects of vaccination on the character and e...

BACKGROUND Influenza infection does not always cause clinical illnesses, so serological surveillance has been used to determine the true burden of influenza outbreaks. This study investigates the accuracy of measuring cumulative incidence of influenza infection using different serological survey designs. METHODS We used a simple transmission model to simulate a typical influenza epidemic and ...

In order to assess the reliability of the thick smear in a Plasmodium infection area, 322 thick smears were examined by a trained microscopist in field conditions. Later, the same smears were examined by an experience microscopist in ideal laboratory conditions. Reliability was measured by the Kappa index. In symptomatic malaria patients the Kappa index was 0.91 (IC 95% 0.57-0.98 p<0.05) while ...

The objective of this study was to investigate risk factors for norovirus-associated infectious intestinal disease (IID) and asymptomatic norovirus infection. Individuals with IID and healthy controls were recruited in a community-based study in England (1993-1996). This is the first risk-factor study to use viral load measurements, generated by real-time RT-PCR, to identify cases of norovirus-...

Long known as a pathogen of poultry, Mycoplasma gallisepticum (MG) was first detected in house finches in 1994. The disease rapidly spread throughout the eastern United States and Canada and was associated with debilitating disease and high mortality in house finches. However, in the late 1990s, the proportion of infected finches dying as a result of infection with MG decreased, and asymptomati...

In addition to causing the disease called AI, these AIVs commonly cause asymptomatic or very mild infections that go undetected in the absence of an active laboratory-based virus surveillance program. These asymptomatic infections are important because they play a critical role in the epidemiology of AIV infections in birds and in the maintenance of AIVs in avian populations. The unique complex...

BACKGROUND An important issue associated with the control of visceral leishmaniasis is the need to identify and understand the relevance of asymptomatic infection caused by Leishmania infantum. The aim of this study was to follow the course of asymptomatic L. infantum infection in children in an area of Brazil where it is endemic. The children were assessed twice during a 12-month period. MET...

OBJECTIVE To compare a PCR assay and direct agglutination test (DAT) for the detection of potential markers of Leishmania infection in 231 healthy subjects living in a kala-azar endemic focus of Nepal. METHODS The sample was composed of 184 (80%) persons without any known history of KA and not living in the same house as known kala-azar cases (HNK), 24 (10%) Healthy Household Contacts (HHC) a...

Visceral leishmaniasis (VL) is a serious parasitic disease, causing high morbidity and mortality in the developing world. The pathogenesis of VL is complex, and the clinical presentation ranges from asymptomatic infection to severe and fatal disease. Despite a wealth of research on the full-blown "clinical VL" syndrome, asymptomatic leishmania infections remain poorly understood. Asymptomatic i...