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Biomedical subjects

R N Davidson

Publications and source records attributed to R N Davidson.

79 records · Page 5Linked to original sources

Royal Society of Tropical Medicine and Hygiene joint meeting with Médecins Sans Frontières at Manson House, London, 20 March 2003: field research in humanitarian medical programmes. Médecins Sans Frontières interventions against kala-azar in the Sudan, 1989-2003.

Since 1989, Médecins Sans Frontières (MSF) has provided medical humanitarian assistance during outbreaks of visceral leishmaniasis (VL; kala-azar) in Sudan. First, in western Upper Nile in southern Sudan, where a VL epidemic occurred after the resumption of the civil war in Sudan in 1983, with an estimated 100,000 deaths. Later, MSF started interventions in eastern Upper Nile and Gedaref State. In these two endemic regions VL incidence has risen markedly since 2001, which could be the start of a new epidemic cycle. Outbreaks of VL in Sudan remain unpredictable, and access to affected populations in war-torn southern Sudan is often hampered by insecurity. Therefore, MSF takes a flexible approach, establishing treatment centres where patients can be accessed. From 1989 to 2002, MSF treated >51,000 VL cases in Sudan. Despite very basic field conditions, high cure rates of 95% are being achieved. Lack of diagnostics is a major obstacle to treatment, especially during epidemic situations. Therefore, development of simple and rapid technologies is required, allowing reliable diagnosis under field conditions. For treatment of VL there is a limited choice of effective, affordable drugs. There are strong indications of an emerging resistance to antimonials in Malakal. Introduction of combination therapies is urgently needed to prevent the further emergence and spread of resistance to antimonials, which are still the mainstay of VL treatment in eastern Africa. Experience with combination therapy with sodium stibogluconate (SSG) and paromomycin is promising, and combinations of SSg with liposomal amphotericin B and miltefosine are currently being explored.

Animals↗

Rapid diagnosis and determination of duration of viraemia in dengue fever using a reverse transcriptase polymerase chain reaction.

A rapid, simple diagnostic polymerase chain reaction (PCR) method for the diagnosis of dengue fever was developed using a pair of consensus oligonucleotide primers and validated with laboratory-derived strains of dengue serotypes 1-4 and other common flaviviruses. A cluster of 13 patients with clinical dengue fever admitted to a single infectious diseases unit over a period of 3 months allowed evaluation of this technology. The PCR was positive in all 11 acute dengue cases and negative in 2 convalescent cases and 10 febrile patients recently returned from the tropics in whom an alternative diagnosis was established. In some of the acute cases, viraemia was detected before the development of a diagnostic antibody response (indirect immunoglobulin (Ig) G enzyme-linked immunosorbent assay (ELISA) and capture IgM ELISA). In patients from whom sequential sera were taken, defervescence and recovery from thrombocytopenia coincided with the disappearance of dengue ribonucleic acid from the blood. Nucleotide sequencing of the PCR products was undertaken in 2 cases (from India and Guyana) and the results showed a close match with previously reported serotype 2 sequencies, suggesting a potential for use of this region of the genome in epidemiological studies.

Adult↗

Early efficacy of liposomal amphotericin B in the treatment of visceral leishmaniasis.

The rapidity and efficacy of a short course of liposomal amphotericin B was evaluated in 29 children affected by visceral leishmaniasis (Leishmania infantum). Their overall health status was assessed using the prognostic inflammatory and nutritional index (PINI), and their haematological status by the reticulocyte count and haemoglobin blood levels. All these quantities were measured on day 0, and 3 and 10 d after starting therapy. A significant decrease of inflammatory signs, associated with an improved reticulocyte count, was recorded after 3 d of therapy. A significant increase of haemoglobin levels was also observed 10 d after the start of treatment. The early reduction of inflammatory signs and the improvement of bone marrow function in most patients confirmed the validity of amphotericin B therapy. The PINI score is helpful in assessing the severity of visceral leishmaniasis and the follow-up of its treatment.

Adolescent↗