Jordi Casals

Lassa fever Epidemiological aspects of the 1970 epidemic, Jos, Nigeria

Abstract A restricted, hospital-centred outbreak of Lassa fever involving 28 persons occurred early in 1970 in Jos, Nigeria. 24 patients were in hospital. Every patient, save the index, could be traced to some prior known human source of infection. Complement-fixing antibody to Lassa virus was detected in the sera of only 4 of 172 family and hospital contacts bled. These 4 persons had all been ill. Animal studies have so far failed to reveal a non-human host.

Antigenic similarity between the virus causing Crimean hemorrhagic fever and Congo virus.

Summary A viral strain isolated in the USSR from apatient suffering from Crimean hemorrhagic fever and reported to be etiologically related to the illness, has been shown to be antigenically indistinguishable from Congo virus.

The Nairovirus Genus: Serological Relationships

Serological relationships among viruses of the Nairovirus genus, family Bunyaviridae, were investigated. Relationships were found among viruses of the following serogroups: Congo-Cr

Bunyaviruses and Bunyaviridae

A new family is described, the Bunyaviridae, which contains a single genus, Bunyavirus. The main characteristics of the family are as follows: single-stranded RNA, total molecular weight about 7 X 10(6) daltons, probably in three segments. Virions spherical, enveloped particles 90-100 nm in diameter. Envelope contains at least one virus-specified glycopeptide. Develop in the cytoplasm, mature by budding into smooth-surfaced vesicles in the Golgi region or nearby. Internal ribonucleoprotein composed of long strands 2-2.5 nm broad. There are at least 150 members, 87 serologically related bunyaviruses and other probable bunyaviruses.

Amapari, a New Virus of the Tacaribe Group from Rodents and Mites of Amapa Territory, Brazil.

Summary Amaparí virus is a new member of the Tacaribe virus group which has been isolated on 5 occasions at Serra do Navio, Amapá Territory, Brazil, during 1964 and 1965. One strain was recovered from organs of Neacomys, 3 from organs of Oryzomys and 1 from mites combed from Oryzomys. The new virus is closely related in complement-fixation (CF) testing to the other 3 members of the group—Tacaribe, Junín and Machupo—but differs from them in neutralization testing. Limited studies revealed no neutralizing antibody in sera of human residents of Serra do Navio. Oryzomys captured in the area had CF but not neutralizing antibody.

Isolation of Dhori Virus from Hyalomma marginatum Ticks in Portugal

An agent pathogenic for mice was isolated from Hyalomma m. marginatum ticks collected from cattle in southern Portugal. Serologically, the agent was indistinguishable from Dhori virus, an antigenically ungrouped virus isolated in India.

Aride virus, a new ungrouped arbovirus infectingAmblyomma loculosum ticks from roseate terns in the Seychelles

SummaryA previously undescribed arbovirus, proposed name Aride virus, was recovered fromAmblyomma loculosum Neumann, collected from dead roseate ternsSterna dougallii arideensis Mathews in the Seychelles. Some important tick-virus-host associations are discussed.

Neutralization and hemagglutination-inhibition tests with Crimean hemorrhagic fever-Congo virus.

Summary The neutralization test by intracerebral inoculation of newborn mice can be satisfactorily carried out with at least 1 strain of Crimean hemorrhagic fever-Congo (CHF-C) virus; human sera showed no nonspecific antiviral activity and that of mouse sera was removed by acetone-ether extraction. An antigen usable in hemagglutination-inhibition (HI) tests has been developed with at least 2 strains of CHF-C virus. The cross-reactivity between CHF-C and Hazara viruses has been confirmed in the HI test. The authors are indebted to Professor M. P. Chumakov, Moscow, for the serum from a patient recovered from CHF; to Dr. G. W., Kafuko, Entebbe, for samples of sera from 2 patients recovered from Congo virus clinical infections; and to Dr. S. Saidi, Teheran, for the serum from a sheep presumably naturally exposed to CHF-C virus or a related agent.

Lassa virus antibodies in hospital personnel in western Liberia

The sera of 844 Liberian hospital staff memebers were positive for Lassa Virus (LV) antibodies in a survey using the indirect fluorescent antibody technique (IFAT). In two hospitals in Lofa County near the Sierra Leone border, the prevalence, 15.4%, was significantly higher than the 8.4% in seven others. There were near differences between the prevalence among laboratory workers, 15.3%, and other workers, 7.7%, and between midwifery students, 21.2%, and midwives, 4.2%, suggesting their infection from patients or their blood products. However, the over-all prevalence among those with patient contacts was the same as that among those without direct patient contact; most LV infections were apparently acquired from sources other than patients in hospital. This finding, the lack of evidence of hospital outbreaks and the presence of comparable prevalences in all age groups suggest that LV infections occur on a continuing basis in this population. In one hospital the comparison of the results of IFAT and complement fixation tests revealed some who reacted by one technique and not by the other. In one person the titre by IFAT had dropped from 1:32 to undetectable levels in two years. This finding prompts caution in the interpretation of results.

Arbovirus isolations from ixodid ticks infesting livestock, Kano Plain, Kenya

In a study conducted on the Kano Plain, Kenya, virus isolation attempts were made on ixodid ticks collected, over a 14-month period, from livestock held in family enclosures (bomas) before releasing the animals for daily foraging. 8735 Amblyomma variegatum (Fabricius) were tested, 98.6% of which were taken from cattle, yielding 36 strains of Dugbe (DUG), four strains of Nairobi sheep disease (NSD), three strains of Bhanja (BHA), one strain of Thogoto (THO) and five strains of virus which could not be characterized. 6549 Rhipicephalus spp. ticks were collected (60.3% from cattle). NSD, DUG and BHA viruses were each isolated twice from ticks taken from cattle. One BHA virus strain was recovered from ticks from a sheep. One strain recovered from ticks on cattle could not be characterized.