The titer of antibody against core antigen of hepatitis B virus in the immunoglobulin M class (IgM anti-HBc) was determined by an IgM capture assay of reduced sensitivity (30 arbitrary units). The distribution of titers among 235 acute hepatitis patients who were hepatitis B surface antigen (HBsAg) positive suggested that 600 U forms a lower cutoff value for acute hepatitis B. Clinically apparent cases of acute hepatitis with high IgM anti-HBc and without HBsAg were rare (2.6%). Acute, non-B hepatitis in HBsAg carriers was more frequent (9.4%). In chronic hepatitis B, 39% of 174 biopsy-proven cases had moderate titers of 30 to 600 U, whereas healthy HBsAg carriers were rarely (4/84) positive. In mild or inapparent infections without HBsAg, titers were between 50 and 400 U. Thus, sufficiently accurate and sensitive quantitation of IgM anti-HBc allows for (i) differentiation of acute and nonacute hepatitis B virus infection in acute hepatitis, (ii) partial differentiation between clinically symptomatic and asymptomatic chronic infections, and (iii) identification of recent subclinical infections.
Exposure to and invasion by parasitic organisms may play an important part among many other intrinsic factors that guide the evolution of animal forms. Trypanosomes, two species of which cause African sleeping sickness today, are blood parasites of great antiquity. Their presence in Africa at the time of the first stages of human evolution may have been of great consequence, at first acting as a discriminating agent between resistant and non-resistant types of hominids, and later also in shaping migration routes and settlement patterns. As a possible clue as to why man arose in Africa, the author postulates that trypanosomes may have precluded the development of certain ground-dwelling faunas, allowing certain more resistant primates to fill the empty ecological niches. Some of these primates, thus becoming ground-dwellers, became the precursors of the hominid branch. The evolution of T. gambiense and T. rhodestense, the two human parasites, and their development in the tsetse fly, are debated. The epidemiological aspects and patterns of the disease are examined under the changing climatic conditions of the Pleistocene and during later times, when Africa was opened up by Western exploration.
Entomological investigations preliminary to a filariasis study were carried out over a period of eleven months in fourteen islands of the Seychelles group. Thirteen species of mosquitoes were found in collections of larvae from over 700 breeding places and occasional hand-catches of adults. These were: Aedes aegypti (L.), Ae. albopictus (Skuse), Ae. albocephalus (Theo.), Ae. (Skusea) sp. n., Ae. vigilax vansomerenae Mattingly ' Brown, Culex pipiens fatigans Wied., C. scottii Theo., C. simpsoni Theo., C. stellatus van Som., C. wigglesworthi Edw., Uranotaenia browni Mattingly, U. nepenthes (Theo.) and U. pandani (Theo.). Mansonia (Mansonioides)uniformis (Theo.), previously reported from the islands, was not found during the present survey.
1. The results of a survey of 194 Peruvian and Colombian primates for filarial infections are presented. Nine genera and 14 species of marmosets and monkeys are represented in the survey. A blood film survey revealed microfilariae in 82, of 42% of the animals. Adult worms were recovered from 21 of 61 dissected animals. The 209 adult worms belong to four species: Dipetalonema gracile, Dipetalonema caudispina, Tetrapetalonema marmosetae, and Tetrapetalonema tamarinae, a new species.2. New host records for Dipetalonema gracile are: Tamarinus nigricollis, Cebus albifrons, and Saimiri boliviensis. Saimiri boliviensis is a new host for Dipetalonema caudispina. New hosts for Tetrapetalonema marmosetae are: Oedipomidas oedipus, Saimiri sciurea, S. boliviensis, and Ateles paniscus.3. The adult worms and microfilaria of a new species of filarial worm, Teirapetalonema tamarinae, are described from a Peruvian tamarin marmoset, Tamarinus nigricollis.
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