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Biomedical subjects

P A Webb

Publications and source records attributed to P A Webb.

At least 37 records · Page 2Linked to original sources
PubMed1986

Lassa fever in children in Sierra Leone, West Africa.

A systematic study of Lassa fever in febrile children was undertaken over a four-year period, from August 1977 to August 1981, in the Eastern Province of Sierra Leone, West Africa. 479 patients were studied; of these, 245 had adequate specimens to confirm or exclude the laboratory diagnosis of Lassa fever. 51 cases of Lassa fever were identified (21% of patients from whom diagnosis was possible). Virus was isolated from 23 patients. All children had fever; cough and vomiting were present in over 60% of cases studied. The five to nine-year age group had the highest prevalence rate (41% of cases). Seasonal clustering occurred in April, May, and August. A significantly higher proportion of females than males had Lassa fever, a finding which remains to be explained. It is concluded that Lassa fever is a disease of significant concern in the paediatric age group.

Adolescent↗
PubMed1986

Lassa virus hepatitis: a study of fatal Lassa fever in humans.

In order to explore the significance of a previous observation that the most important pathologic changes in fatal Lassa fever are hepatic, we have studied postmortem liver biopsies from 19 patients with fatal Lassa fever. We observed a vigorous macrophage response to cellular damage, but we found no evidence of lymphocyte infiltration in infected hepatic tissues. Using semi-quantitative estimates of liver cell damage, we found a wide range in the severity and progression of Lassa virus hepatitis in our fatal cases. We have classified for descriptive purposes three general nosopoeitic phases: active hepatocellular injury (less than 20% necrosis), continued damage and early recovery, and mitotic activity representing hepatic recovery. We conclude that the liver goes through cellular injury, necrosis and regeneration and any or all may be present at death. In no instance was the degree of hepatic damage sufficient to implicate hepatic failure, and all three phases were represented among our cases. We conclude that the hepatitis of Lassa fever in humans is not the primary cause of death.

Hepatitis, Viral, Human↗
PubMed1985

Epiphyseal union of the anterior iliac crest and medial clavicle in a modern multiracial sample of American males and females.

Epiphyseal union of the anterior iliac crest and the medial clavicle is examined in 605 males and 254 females in a sample of modern Americans aged 11-40 years. The sample includes American whites, American blacks, Latin-Americans, and Orientals. This is the first skeletal investigation using a large sample of individuals of known age since the McKern and Stewart study of 1957. Epiphyseal union is analyzed in terms of four stages: 1) nonunion with no epiphyses, 2) nonunion with separate epiphyses, 3) partial union, and 4) complete union. The results provide broader age ranges for the stages of union than previous studies. Age ranges for males and females are similar or vary by only 1-2 years. Racially, no major distinguishing patterns are found except for greater variability in age distributions appearing to exist among American black females. The study furnishes valuable data on epiphyseal timing in the teenage years.

Adolescent↗
PubMed1985

Recent vesicular stomatitis virus infection detected by immunoglobulin M antibody capture enzyme-linked immunosorbent assay.

We developed an enzyme-linked immunosorbent assay (ELISA) that was capable of detecting immunoglobulin M (IgM) antibody to vesicular stomatitis virus (VSV) in the sera of experimentally and naturally infected cattle and horses. The detection of IgM in the sera of these animals permitted an estimate of the recency of infection by VSV serotype New Jersey. A VSV serotype New Jersey epizootic strain isolated from a horse and passed once in an Aedes albopictus cell line was used to infect a horse and a calf. Sera from these animals were used to standardize the ELISA. This assay was used to test sera from cattle and horses involved in the 1982 VSV epizootic. Comparative antibody titrations were performed by three systems: the serum-dilution plaque-reduction neutralization, complement fixation, and indirect immunofluorescent tests. The antibody titers by neutralization and the ELISA were comparable for the period that IgM was present; when IgM ELISA titers diminished, the neutralization titers remained high. The complement fixation and indirect immunofluorescent antibody titers followed closely the IgM pattern determined by the ELISA. The capture IgM ELISA is applicable for the rapid detection of IgM antibody to VSV in cattle and horses and is a useful assay of recent infection.

Animals↗
PubMed1983

Case-control study of Mastomys natalensis and humans in Lassa virus-infected households in Sierra Leone.

Lassa virus infection and antibodies were studied in households where Lassa fever cases occurred, and compared to those in nearest neighbor houses and "far" houses located across the village from case houses. Seventy-nine percent of all rodents caught in the houses were Mastomys, the natural reservoir of Lassa virus. Rodent infection was not randomly distributed, but rather focal. Thirty-nine percent of the Mastomys in case houses were viremic, compared to 3.7% in control houses. Human antibody prevalence in case houses was 30%, compared to 20% in non-case houses (P less than 0.05, chi-square test, df = 2). Neither seroconversions nor antibody prevalence rates were associated with household size or number of persons per room. Trapping of rodents in half of the case and control houses resulted in a Mastomys reduction ranging from 2.2- to 3.3-fold. This reduction failed to significantly reduce the seroconversion rate to Lassa virus in the people of trapped houses compared to those in untrapped ones. More complete trapping will be needed in order to better evaluate this procedure as a means of interruption of Lassa virus transmission in endemic villages.

Animals↗
PubMed1982

Pathologic and virologic study of fatal Lassa fever in man.

Postmortem examination of 21 virologically documented cases of Lassa fever, including 6 complete autopsies, was performed as part of a field study of community-acquired Lassa fever in Sierra Leone. The most consistently observed lesions were hepatocellular, adrenal, and splenic necrosis and adrenal cytoplasmic inclusions. Neither these lesions, nor other milder and less constantly observed lesions such as myocarditis, renal tubular injury, and interstitial pneumonia, appeared severe enough to explain the cause of death in Lassa fever. The central nervous system (CNS) contained no specific lesions. Viral titrations demonstrated high viral content in liver, lung, spleen, kidney, heart, placenta, and mammary gland. Clinical laboratory data included elevation of hepatic enzymes, creatine phosphokinase (CPK), and blood urea nitrogen (BUN). Because of the paucity of pathologic lesions in spite of widely disseminated viral infection, further investigation of humoral inflammatory mechanisms is indicated.

Adult↗
PubMed1980

Ebola hemorrhagic fever: Tandala, Zaire, 1977-1978.

Ebola virus was recovered from a nine-year-old girl who died of acute hemorrhagic fever in June 1977 at Tandala Hospital in northwestern Zaire, in the first reported recognized case of this disease since the discovery epidemics of 1976 in Zaire and Sudan. Investigations undertaken in the Tandala region revealed that two previous clinical infections with Ebola virus had occurred in 1972 and that about 7% of the residents had immunofluorescent antibodies to the virus. Females younger than 30 years of age had a higher prevalence of antibodies than males of comparable age, but above the age of 30 years there was no sex difference. No other clues to the still-mysterious natural reservoir of Ebola virus were uncovered.

Adolescent↗
PubMed1980

Nosocomial outbreak of viral hemorrhagic fever caused by Crimean Hemorrhagic fever-Congo virus in Pakistan, January 1976.

This paper describes the clinical, epidemiological, and laboratory investigations undertaken to isolate and identify the etiological agent of a nosocomial cluster of hemorrhagic fever cases due to Crimean hemorrhagic fever (CHR)-Congo virus. Since this virus is usually transmitted by ticks it was surprising that the index case, in a nomadic shepherd, occurred during the winter season when ticks are relatively inactive. These are the first cases of CHF-Congo virus found in humans in Pakistan. Investigations on other biological properties, particularly strain differences and virulence, are being continued at the Islamabad laboratory.

Adult↗
PubMed1980

Clinical observations in 42 patients with Lassa fever.

Under continuous observation of several months, 42 patients from the eastern province of Sierra Leone, Liberia (Lofa County), and neighbouring Guinea were identified as Lassa fever cases by indirect immunofluorescent antibody technique, indicating that the disease is endemic in these areas. The clinical course varied from mild disease to severe illness with haemorrhagic disorders. The fatality rate was 14%. The occurrence of only two possible secondary cases suggests that person-to-person spread of the disease is unimportant epidemiologically. There was a wide range of patients' ages, tribes, and occupations, including a 2 months old baby and a white US citizen. Clinical, laboratory, and histopathological investigations demonstrated the panorganotropism of Lassa virus. Haematological tests in few selected haemorrhagic cases with Lassa fever did not support coagulation disorders or thrombocytopenia as causing the bleeding tendency. The histopathologic changes bear resemblance to those observed in Argentinian and Bolivian haemorrhagic fever, both being caused by viruses of the Arena group. However, Lassa virus hepatitis may be differentiated from liver lesions occurring in yellow fever, Marburg virus disease, and Ebola (Maridi) haemorrhagic fever.

Adolescent↗
PubMed1980

Effectiveness of patient education and psychosocial counseling in promoting compliance and control among hypertensive patients.

Compliance with physician recommendations among long-term hypertensive patients can be a chronic and difficult treatment problem. This study evaluated the relative effectiveness of additional patient education and psychosocial counseling in improving patient compliance. At a family practice clinic, 123 low income, rural, black hypertensive patients were pretested on several psychological characteristics and randomly assigned to one of three groups: vigorous, group patient education and family physician appointments; supportive, individualized psychosocial counseling and family physician appointments; or family physician appointments only, which was the baseline medical care. Intervention and follow-up each lasted three months, and the intervention was in addition to the patients' baseline medical care. Compliance was measured by: keeping follow-up appointments; bringing antihypertension medications to each appointment; consuming these medications; and diastolic blood pressure. Analysis of variance of group mean and change scores, t tests, and chisquare analysis indicated that neither additional patient education nor additional psychosocial counseling improved compliance or blood pressure control significantly better than regular family physician visits alone.

Adult↗
PubMed1978

Interrelationships among arenaviruses measured by indirect immunofluorescence.

An evaluation of reciprocal indirect immunofluorescent antibody titers for at least one representative of each known arenavirus serotype leads to the conclusion that the Old World aranaviruses are more closely related to each other than to other members of the group. These relationships are particularly evident in evaluations of human convalescent sera. New World arenaviruses cross-react strongly with each other in most instances but only weakly with with Old World arenaviruses.

Animals↗
PubMed1977

The circular, segmented nucleocapsid of an arenavirus-Tacaribe virus.

The nucleocapsid structures of Tacaribe virus, a member of the Arenaviridae, were purified from detergent-treated virus particles by equilibrium density gradient centrifugation. Negative-contrast electron microscopy indicated that they were coiled, circular filaments. They had a mean diam. of 5 to 10 nm and two predominant length classes of 640 nm and 1300 nm were found.

Arenaviridae↗