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Mortality trends of American missionaries in Africa, 1945-1985.

Mortality trends of missionary staff serving in sub-Saharan Africa were tracked for the period 1945-1985. For 1945-1970, when more complete incidence data were available, the missionary death rate was approximately 40% lower, after adjustment, than would be expected in a comparable US population. This trend persisted through 1985. Between 1945 and 1970, the largest number of fatalities was attributable to malignancy, atherosclerosis, accidents, and infectious disease, and the greatest mortality risks, compared with the US experience, were from homicides, the complications of pregnancy, and infections, notably malaria, hepatitis, and polio. Beginning in the late 1950s, motor vehicle accidents became the leading cause of death. Since the 1960s, accidental causes of death have been approximately 50% higher than in the US, and homicides have been four times higher. During this same period, the infectious disease death rate decreased to approximately that within the US. Currently, the leading causes of mortality are motor vehicle accidents, malignancy, and atherosclerosis, followed by other accidental causes, notably aircraft mishaps and drownings. Viral hepatitis is presently the leading infectious disease cause of death. Other contemporary lethal infections include malaria, rabies, typhoid, Lassa fever, and retroviral infection. It was concluded that missionaries in sub-Saharan Africa had a death rate approximately half that expected in a comparable domestic control population. Preventive strategies, particularly relative to accident and infectious disease prevention, could effectively reduce mortality risk further.

Accidents, Traffic↗

Sequence analysis of the small RNA segment of guinea pig-passaged Pichinde virus variants.

The established animal model for Lassa fever is based on the new world arenavirus Pichinde (PIC). Natural isolates of PIC virus are attenuated in guinea pigs, but serial guinea pig passage renders them extremely virulent in that host. We have compared the nucleotide sequences of the small RNA segments of two attenuated, low-passage variants of the PIC virus Munchique strain (CoAn 4763) and two virulent, high-passage derivatives. Missense mutations in the glycoprotein precursor (GPC) gene at codons GPC-119, GPC-140, and GPC-164 and the nucleoprotein gene (NP) codons NP-35 and NP-374 were most closely associated with virulence. Codon GPC-140 is predicted to represent a region of peak hydrophilicity of the glycoprotein 1 (GP1); it is conceivable that mutations at this site could influence virulence by altering B cell epitopes or virus attachment protein conformation.

Animals↗

[Progressive sensorineural hearing loss from infectious agents].

The progressive sensorineural hearing loss due to infectious causes can involve different etiological agents like bacteria, viruses, protozoons or mycetes. These infectious agents can act in various ways: directly through a labyrinthitis that may destroy the neuroepithelium; through an ischaemic process secondary to a septic embolus; or through a thrombus. In some cases the damage can occur in a meningitis context, because of the passage of the germ in the inner through the nerves, the vases or the labyrinthine liquids. Bacterial meningitis is one of the causes of progressive sensorinueral hearing loss. Among bacteria, the Mycobacterium Tuberculosis has nowadays acquired a remarkable importance which is also due to its considerable diffusion, despite modern therapy, and to its association with HIV infection. Bacteria can also cause a labyrinthitis acting directly on the inner ear: among these, Treponemas Pallidum, a spirochaete which causes syphilis and Borrelia Burgdorferi, a spirochaete that causes Lyme Disease, must be mentioned. The viruses that are certainly involved in the etiology of progressive sensorineural hearing loss are Cytomegalovirus and Rubella virus. The virus usually causes a labyrinthitis after the viraemia, wich may be due to the passage of the virus from the blood to the endolymph, through the stria vascularis with the consequent infection of the sensorial cells of the organ of Corti. Less frequently the viral damage to the inner ear can occur after a vasculitis, a meningitis or an alteration of the cell-mediated immunity. Progressive sensorineural hearing loss can also occur because of some congenital viral infections such as those caused by Cytomegalovirus and Rubella virus. More recently even the Human Parvovirus B19 seems to have been involved. This virus seems to act through autoimmune and/or immunologic processes, like that causing sudden hearing loss in Lassa fever. Another viral infection which can nowadays more frequently be considered among the cause of progressive hearing loss is HIV. In the HIV infection the neurological toxic lesions due to the administered ototoxic drugs are added up to the damages caused by the opportunistic infectious agents (virus, bacterium, protozoon mycete). However, in these patients HIV itself could be the cause of the auditory and vestibular lesions. More rarely, a progressive hearing loss may be due to the action of a protozoon or mycete only.

Disease Progression↗

The ecology of Praomys (Mastomys) natalensis in southern Africa.

The only non-human host of Lassa virus so far identified is the multimammate mouse, Praomys (Mastomys) natalensis, but its precise role in the natural Lassa fever cycle remains to be determined. This species is also an important link in the plague cycle in southern Africa and is one of the commonest rodents of Africa. It is a prolific breeder and can be kept and bred easily in captivity. It is thus an excellent laboratory animal, although it needs to be handled with care because it is aggressive towards man and bites readily. The current status of knowledge of its taxonomy, ecology, distribution, and role as a disease vector is reviewed, but attention is drawn to the possibly disastrous consequences of attempting to eradicate a vector species before the natural cycle of the disease and the ecology of the vector are fully understood.

Africa, Southern↗

Problems associated with the control of rodents in tropical Africa.

As elsewhere in the world, rodents are responsible for very considerable economic losses in tropical Africa because of their depredations on both growing crops and stored food products. Unfortunately, few accurate data are available on the extent of these losses but there is evidence that they are considerable. The public health importance of rodents, both as reservoirs and vectors of disease in tropical Africa, is also great; plague, leptospirosis, murine typhus, and Lassa fever are among the diseases associated with rodent hosts. Scientifically based rodent control programmes have been carried out in very few areas of Africa and there is urgent need for studies and demonstrations on rodent control in both urban and rural areas. The problems likely to be encountered are reviewed and methods of control proposed.

Africa↗

[Immunogenic and protective characteristics of recombinant Lassa virus NP protein].

Recombinant fragment of Lassa virus (strain Josiah) nucleocapsid protein (corresponding to amino acid residues 141 + 569) constructed by Dr. Jan ter Meulen (Tropenmedizine, Hamburg) was used for immunizing CBA/calac mice. The preparation was injected intraperitoneally twice with 2-week interval in a dose of 10 micrograms. The parameters of the resultant specific humoral and cell-mediated immunity were comparable to those in reference animals immunized with inactivated Lassa virus. Challenge with Lassa virus (10,000 PFU) resulted in 100% death of the reference animals, while of 15 animals immunized with the recombinant NP protein 8 survived.

Animals↗

[Lassa virus].

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Animals↗

[Antiviral properties of various pharmacologic groups of drugs].

Currently used cardiovascular drugs such as nicotinamide, strophanthin, corglycon, curantyl, cavinton, papaverin hydrochloride, nicotinic acid, xantinole nicotinate, isoptin, parmidin and halidor were studied by the program of antiviral drug screening. The majority of them (9 out of 11) were shown to have antiviral activity which was rather individual by its specificity and level. Laboratory strains of 9 viruses inducing the most common infections in man and animals, i.e. Herpes simplex, poxvaccine, influenza, vesicular stomatitis, respiratory syncytial infection, VEE, ECHO. Lassa fever and rotavirus infection were tested. The characteristic feature of the drugs was their high specific activity against the DNA-containing viruses and rotavirus. The three drugs papaverin hydrochloride, strophanthin and corglycon proved to be the most promising. Their antiviral activity was confirmed on a model of herpes infection in mice. The paper discusses whether the phenomenon discovered in the official drugs is important in the therapy of somatic patients.

Animals↗

[Lissavirus in bats residing in the South of West Siberia].

We caught, 2002-2003 in caves of Novosibirsk Region and Altai Territory, 52 bats (Myotis daubentoni, Myotis brandtii, Murina leucogaster, Plecotus auritus). Examinations of the animals' brain samples by fluorescence antibody microscopy and RT-PCR revealed lyssaviruses, genotype 1, which were close to strains provoking rabies in the local animals. According to the results, bats can be involved in keeping alive the rabies foci in Western Siberia, which must be taken into account in antiepizootic measures.

Amino Acid Sequence↗

[The interferon-inducing activity of the Lassa virus in the body of inbred mice].

The level and the time course of accumulation of endogenous interferon were studied in the blood sera of mice experimentally infected with Lassa virus by the intracerebral route. The level of interferon correlated with case-fatality rate of the animals which may be important for the understanding of the pathogenesis of arenavirus infections.

Animals↗

[Lassa and Mozambique viruses: cross protection in experiments on mice and action of immunosuppressants on experimental infections].

The pathogenicity of Mozambique virus for random-bred mice and CBA mice was studied. In contrast to Lassa virus, intracerebral inoculation of newborn zandom-bred mice with Mozambique virus (1000 PFU/mouse) results in death of the animals. The pathogenic properties of both viruses for adult CBA mice were found to be similar: intracerebral inoculation of the viruses caused death of the animals within 6-8 days, but not intraperitoneal inoculation. With the latter, they produced a population of immunocompetent cells protecting syngeneic recipient mice against the lethal intracerebral inoculation of the homologous virus. Cross-protection experiments demonstrated that intraperitoneal inoculation of Lassa virus protected 70% of mice against the lethal infection with Mozambique virus, and intraperitoneal inoculation of Mozambique virus protected 45% of mice against Lassa virus. Cyclophosphamide exerted no protective effect in Mozambique virus-infected mice. Cyclosporin A exerted no therapeutic effect in mice lethally infected with Lassa or Mozambique virus.

Animals↗

[Effect of immunosuppression on the development and outcome of an acute infection in mice caused by administration of the Lassa virus].

In experimental infection of mice with Lassa virus, the infectious virus could be detected in all the organs and brain tissues tested. Histopathological lesions were demonstrated in cerebral and spinal cord tissues only. Roentgen irradiation in a dose of 500 R and cyclophosphamide protected mice against a lethal Lassa virus dose. Cyclosporin A in various doses exerted no effect on the outcome of the acute infection. The adoptive transfer of splenocytes from mouse donors inoculated intraperitoneally prevented the development of lethal disease symptoms and death of mice-recipients. It is suggested that immunocompetent cells are involved in the development and outcome of experimental infection of mice with Lassa virus.

Acute Disease↗

The "mini-packer" syndrome. Fatal ingestion of drug containers in Baltimore, Maryland.

We report seven fatalities resulting from the ingestion of illicit drugs packaged in condoms, rubber balloons, or plastic bags which were observed in the last 4 years at the Office of the Chief Medical Examiner, State of Maryland. All the victims, with the exception of one, were men ranging in age from 19 to 37 years. There was no racial predominance. No drug paraphernalia was found at any scene. In two cases, seizure-like activity was documented. One victim had recently returned from Nigeria; therefore, Lassa fever was initially suspected. Two of the victims were "body packer" contrabanders who had just arrived from Africa. They used body cavities to hide large amounts of heroin to avoid U.S. Customs. The other five cases were "mini-packers," small-time illicit drug dealers who had swallowed a single bag of cocaine to avoid police detection. The possible mechanism of leaking or rupture of the latex container is discussed.

Adolescent↗

Recent advances in antiviral therapy.

Virus replication is described, and the clinical trials and indications for amantadine, rimantadine, vidarabine, vidarabine phosphate, acyclovir, ribavirin, and other promising antiviral agents are reviewed. Amantadine and rimantadine are useful for the treatment and prophylaxis of viral influenza A infections. Vidarabine is a second-line agent and is effective for the treatment of herpes simplex encephalitis, neonatal herpes simplex types 1 and 2, and varicella-zoster infections. Vidarabine phosphate (also known as vidarabine monophosphate) has a similar spectrum of activity and can be administered in smaller volumes than vidarabine. Acyclovir has demonstrated clinical efficacy for chickenpox, shingles (herpes zoster), genital herpes, and other herpes simplex infections. Acyclovir is also useful for the suppression of herpes infections. Systemically administered ribavirin is indicated for the treatment of Lassa fever. Aerosol ribavirin is effective for the treatment of respiratory syncytial virus pneumonia in children and infants and influenza A infections in adults. Only acyclovir, amantadine, ribavirin, and vidarabine are used in clinical practice. Vidarabine phosphate and investigational agents such as rimantadine, ganciclovir (DHPG, BW B759U), phosphonoformate, and bromovinyl-deoxyuridine (BVDU) need further investigation.

Antiviral Agents↗

[Pathogenicity of the Lassa virus for laboratory mice].

Pathogenicity for randombred and inbred mice of various age groups of the standard Lassa virus and the virus enriched with defective interfering particles (DIP) was studied. The standard Lassa virus inoculated intracerebrally caused 100% death of C3H/Sn mice aged up to 4 weeks and 60%-70% death of randombred white mice aged 3-4 weeks. BALB/C mice were found to be nonsusceptible to the virus, and its lethality for C57BL/6 and AKR mice varied within the range of 30%-60%. Lassa virus enriched with DIP caused no death of the susceptible animals and showed poor protective activity against the standard virus.

Aging↗