Search PubMed⌕ Search

Biomedical subjects

D A Warrell

Publications and source records attributed to D A Warrell.

282 records · Page 16Linked to original sources
PubMedDate not supplied

Snake bites in Kenya: a preliminary survey of four areas.

Primary data were collected on the incidence, severity and species responsible for snake bites in 4 areas of Kenya: (i) Kakamega and western Kenya, (ii) Lake Baringo and Laikipia, (iii) Kilifi and Malindi, and (iv) northern Kenya. The overall average frequency of snake bite was 13.8 per 100,000 population per year (range 1.9-67.9). The minimum rate of snake bite mortality was 0.45/100,000/year. Thirty-four of the 50 units visited reported no knowledge of death from snake bite in the last 5 years. Possible reasons for the low estimates are discussed. Traditional treatments were common, especially the use of herbal remedies and incisions at the wound site.

Antivenins↗
PubMedDate not supplied

Visual loss in immunocompetent patients with Cryptococcus neoformans var. gattii meningitis.

In Papua New Guinea cryptococcal meningitis occurs predominantly in immunocompetent patients in whom Cryptococcus neoformans var, gattii is implicated in 95% of cases. Ocular complications are common. We have reviewed ophthalmic findings in 82 immunocompetent patients and have attempted to identify those features of the disease that predict an unfavourable visual outcome. Visual loss occurred in 52.6% of survivors and was associated with optic atrophy following optic disc swelling in 60.9%. Progression of disc swelling to optic atrophy was predicted by the presence of an abducens palsy (P = 0.049) and cerebrospinal fluid (CSF) cryptococcal antigen titres > 1:1024 (P = 0.036). Raised intracranial pressure (defined as opening CSF pressure > or = 300 mm on admission) was not associated with visual loss. Vision deteriorated in 17.3% of patients despite anticryptococcal therapy and in 3.7% it followed curative therapy. The high rate of visual loss in immunocompetent patients with C. neoformans var. gattii infection contrasts with others' experience of immunosuppressed patients with C. neoformans var. neoformans infection, in whom visual loss was rare. This difference may reflect immune mediated optic nerve dysfunction in C. neoformans var. gattii meningitis caused by either compression due to arachnoid adhesions or oedema and inflammatory cell-mediated damage.

Adolescent↗
PubMedDate not supplied

The effect of corticosteroids on visual loss in Cryptococcus neoformans var. gattii meningitis.

In Papua New Guinea visual loss is a frequent sequal to Cryptococcus neoformans var. gattii meningitis in immunocompetent patients. We have previously postulated that visual loss may occur as a result of the immunological response to infection around the optic nerve. This retrospective study set out to explore the effect of corticosteroids on visual outcome. Sixteen patients received varying doses of corticosteroid (mainly 100-250 mg of hydrocortisone daily for the prevention of febrile reactions to amphotericin) and 10 received anticryptococcal therapy alone. Visual deterioration occurred less frequently in those treated with corticosteroids (2/16 [12.5%] vs. 7/10 [70%], P = 0.007), blindness was less frequent (1/16 [5.3%] vs. 5/10 [50%], P = 0.018), and in 3 patients vision improved. Corticosteroids may have a role in preventing or halting visual loss in C. neoformans var. gattii meningitis in immunocompetent patients.

Adolescent↗
PubMedDate not supplied

High incidence of early anaphylactoid reaction to SAIMR polyvalent snake antivenom.

During a prospective study of 147 patients with snakebite presenting to a rural South African hospital, 13 of 17 patients (76%) treated with South African Institute for Medical Research (SAIMR) polyvalent antivenom experienced potentially severe early (anaphylactoid) reactions. The most common reaction was generalized urticaria (12; 71%), but 3 cases of angio-oedema (18%), 2 of bronchospasm (12%), and 2 of hypotension (12%) were also observed. Reactions were controlled with adrenaline, antihistamines, and resuscitation. All patients fully recovered from envenoming although the full dose of antivenom was not given to most. Indications for the use of this antivenom should be reconsidered and patients should be given antivenom in a high care setting if possible. Use of antivenom by lay people outside hospital should be discouraged and antivenom manufacturing processes could usefully be reviewed.

Adolescent↗
PubMedDate not supplied

Human rabies and its prevention: an overview.

Human rabies is underreported, but it clearly is still a frequent medical problem that is virtually confined to tropical countries. Rabies encephalitis remains essentially incurable, and most patients die at home, their terrible symptoms unpalliated by sedatives or analgesics. Recent attempts to cure rabies in well-equipped intensive care units have failed, a situation reemphasizing the importance of preventive measures. The great advances that have been made in understanding the rabies virus and the associated improvements in rabies vaccines have had little or no impact in the tropical endemic zone. Most patients who have been exposed to rabies are still given nervous tissue vaccines for postexposure prophylaxis. An urgent priority is the development of a regimen using tissue culture vaccine that is sufficiently economical to replace nervous tissue vaccine. This has been achieved in China with primary hamster kidney cell vaccine.

Encephalitis↗
PubMedDate not supplied

The Jarisch-Herxheimer reaction in leptospirosis: possible pathogenesis and review.

The importance of treating leptospirosis with penicillin is emphasized by two case reports and a review documenting the occurrence of the Jarisch-Herxheimer reaction (JHR) in patients with this bacterial infection. The JHR is significant both as a cause of morbidity and mortality and as an indication of the therapeutic efficacy of penicillin. The possible etiology of the JHR is discussed, and comparisons with the changes occurring in septic shock are made; a study of either condition facilitates the understanding of the other. Tumor necrosis factor is hypothesized to play a key role in both. Current treatment of the JHR consists of general clinical support. Specific measures such as oxpentifylline therapy may play a role in the future.

Adult↗
PubMedDate not supplied

Quinine and quinidine: a comparison of EKG effects during the treatment of malaria.

We recorded electrocardiograms from 31 patients receiving quinine and 14 patients receiving quinidine for the treatment of Plasmodium falciparum malaria. Despite plasma quinine concentrations of up to 20 mg/L, there was no evidence of cardiotoxicity. QT prolongation was considerably greater in the quinidine-treated patients. The mean ratio of change in corrected QT interval to change in plasma concentration (delta QTc%/delta CQ) was 3.2% . mg-1 . L-1 for quinidine, compared to 0.74% . mg-1 . L-1 for quinine (p less than 0.001). T-wave flattening was observed in both groups. Plasma concentrations of quinine cannot be predicted from the EKG, because concentrations within the therapeutic range produced only minor and unpredictable abnormalities.

Adult↗
PubMedDate not supplied

Venomous bites and stings in the tropical world.

Snakes of the families Viperidae and Elapidae are responsible for the high incidence of morbidity and mortality after snake bites in countries of West Africa, the Indian subcontinent, South-East Asia, New Guinea and Latin America. Envenoming can cause local effects, notably tissue necrosis; and systemic effects, including paralysis, haemostatic disturbances, shock, increased capillary permeability, myocardial damage, rhabdomyolysis and acute renal failure. Specific hyperimmune serum (antivenom) is the mainstay of medical treatment for severe envenoming. Ancillary treatments such as assisted ventilation, repletion of circulating volume, renal dialysis and surgical debridement of necrotic tissues are needed in some cases. Scorpion stings are a common medical problem in middle and southern America, North Africa and the Middle East. Vasodilator drugs are important to counter the effects of massive catecholamine release. Bites by spiders and stings by hymenoptera and marine animals are responsible for deaths and morbidity in some tropical countries.

Animals↗
PubMedDate not supplied

'To search and studdy out the secrett of tropical diseases by way of experiment'.

William Harvey wrote about malaria, snake bite and rabies, three diseases now having their greatest impact in tropical developing countries. Global malarial mortality has not declined for 50 years. The most effective control measure would be a vaccine. Temporary immunity in humans, through hundreds of bites by irradiated infected mosquitoes, was achieved in the 1970s. A promising current strategy is effector T-cell vaccination directed at infected hepatocytes. RTS,S/(SB)ASO2, an adjuvanted fusion protein, produced transient protection in 70% of vaccines. Prime (DNA vaccine) boost (poxvirus recombinant) is particularly immunogenic. Pyrethroid-treated bed nets reduce childhood mortality and deplete the mosquito population, interrupting transmission. Chlorproguanil-dapsone is more effective than pyrimethamine-sulfadoxine in treating uncomplicated chloroquine-resistant malaria. Artemisinin derivatives are as effective as quinine in severe disease. Snake bite is an underestimated and neglected cause of morbidity and mortality in rural communities in tropical countries. Sutherland's pressure-immobilisation technique is recommended first-aid for victims of neurotoxic elapid snakes. Rabies post-exposure prophylaxis, using new generation cell culture vaccines, is now feasible in developing countries, employing an economical 8-site intradermal regimen. This Harveian Oration, the first in 350 years to be devoted to tropical medicine, emphasises the importance of this speciality in the twenty-first century.

Developing Countries↗
PubMedDate not supplied

Cell-mediated immunity in HIV seronegative patients recovered from Cryptococcus neoformans var. gattii meningitis.

Cell-mediated immunity was assessed in 37 HIV seronegative healthy patients cured of Cryptococcus neoformans var. gattii meningitis and compared with matched controls using a multitest device which simultaneously injects seven standardized common antigens intradermally. Responses in patients and controls were similar: however, male patients had significantly higher compound (average) scores than controls (P = 0.041). Male scores were higher than female scores in both patient (P = 0.002) and control (P = 0.017) groups. In eight patients with acute cryptococcal meningitis, seven were anergic to challenge with 5 IU of tuberculin on admission. Two of these patients had positive reactions after treatment. Three of four patients tested prior to treatment with the multitest device were anergic to all seven antigens but all three survivors showed improved responsiveness following cure. These data suggest that patients are immunosuppressed on presentation (due to overwhelming var. gattii infection) but that following cure, cell-mediated immunity improves to its premorbid state. A transient state of immunosuppression prior to the development of the disease cannot be excluded.

Adolescent↗