No abstract

A cohort of convalescent Ebola hemorrhagic fever (EHF) patients and their household contacts (HHCs) were studied prospectively to determine if convalescent body fluids contain Ebola virus and if secondary transmission occurs during convalescence. Twenty-nine EHF convalescents and 152 HHCs were monitored for up to 21 months. Blood specimens were obtained and symptom information was collected from convalescents and their HHCs; other body fluid specimens were also obtained from convalescents. Arthralgias and myalgia were reported significantly more often by convalescents than HHCs. Evidence of Ebola virus was detected by reverse transcription-polymerase chain reaction in semen specimens up to 91 days after disease onset; however, these and all other non-blood body fluids tested negative by virus isolation. Among 81 initially antibody negative HHCs, none became antibody positive. Blood specimens of 5 HHCs not identified as EHF patients were initially antibody positive. No direct evidence of convalescent-to-HHC transmission of EHF was found, although the semen of convalescents may be infectious. The existence of initially antibody-positive HHCs suggests that mild cases of Ebola virus infection occurred and that the full extent of the EHF epidemic was probably underestimated.

Methods for obtaining blood samples from mice tend to be difficult, inhumane, or both. The authors describe an inexpensive, disposable, single-use lancet for submandibular bleeding of mice that allows investigators to quickly draw 0.2-0.5 ml of blood without the use of anesthesia.

Vesicular stomatitis is a disease of livestock caused by some members of the Vesiculovirus genus (Family Rhabdoviridae), two of which are called 'vesicular stomatitis virus'. Clinical disease presents as severe vesiculation and/or ulceration of the tongue, oral tissues, feet, and teats, and results in substantial loss of productivity. Except for its appearance in horses, it is clinically indistinguishable from foot-and-mouth disease. Unlike foot-and-mouth disease, it is very infectious for man and can cause a temporarily debilitating disease. Vesicular stomatitis occurs seasonally every year in the southeastern USA, southern Mexico, throughout Central America and in northern South America, and emerges from tropical areas to cause sporadic epidemics in cooler climates during the summer months. Other Vesiculoviruses are endemic in India and Africa. Vesiculoviruses are arthropod-borne and it is possible they are actually well adapted insect viruses that incidentally infect mammals. Vesiculoviruses are relatively simple, having a linear, single stranded, negative sense RNA genome encased in a bullet-shaped virion made from only five proteins. Upon infection of cultured cells, viral products turn off cellular gene expression and seize the entire metabolic potential of the cell. They also depolymerize the cytoskeleton to cause rapid tissue destruction. Virus infection in animals provokes interferon and nitric oxide responses, which quickly control viral replication, and an antibody response that prevents further viral replication. Vesiculovirus genome replication is error-prone, resulting in viral progeny containing many variants. This allows rapid adaptation. Nevertheless, vesicular stomatitis virus genomic sequences appear relatively stable within single endemic areas, and vary progressively on a North-South axis in the Western Hemisphere. Numerous important fundamental discoveries in immunology and virology have come from recent studies of vesicular stomatitis virus. However, these discoveries have not led to a safe and fully effective vaccine for man or beast. In the absence of a vaccine, the continual increase in rapid intercontinental travel, the increase in numbers and concentration of susceptible animals, the plasticity of the viral genome, and the underappreciation of vesiculoviruses as veterinary and zoonotic pathogens by regulators and biomedical researchers, are combining with potentially explosive consequences.

Ebola virus persistence was examined in body fluids from 12 convalescent patients by virus isolation and reverse transcription-polymerase chain reaction (RT-PCR) during the 1995 Ebola hemorrhagic fever outbreak in Kikwit, Democratic Republic of the Congo. Virus RNA could be detected for up to 33 days in vaginal, rectal, and conjunctival swabs of 1 patient and up to 101 days in the seminal fluid of 4 patients. Infectious virus was detected in 1 seminal fluid sample obtained 82 days after disease onset. Sequence analysis of an RT-PCR fragment of the most variable region of the glycoprotein gene amplified from 9 patients revealed no nucleotide changes. The patient samples were selected so that they would include some from a suspected line of transmission with at least three human-to-human passages, some from 5 survivors and 4 deceased patients, and 2 from patients who provided multiple samples through convalescence. There was no evidence of different virus variants cocirculating during the outbreak or of genetic variation accumulating during human-to-human passage or during prolonged persistence in individual patients.