Factors contributing to fatal snake bite in the rural tropics: analysis of 46 cases in Thailand.

Records of 46 cases of fatal bites by identified snakes from 15 provincial hospitals throughout Thailand contained sufficient information for detailed analysis. Bungarus candidus and Calloselasma rhodostoma were each responsible for 13 deaths, Naja kaouthia for 12, Vipera russelli for 7 and B. fasciatus for one. Major causes of death among elapid victims were respiratory failure (26) and complications of prolonged mechanical ventilation (10), and among viper victims shock (12), intracranial haemorrhage (9), complications of local wound necrosis (7) including tetanus (2), and renal failure (2). Factors contributing to fatal outcome included inadequate dose of antivenom (15 cases), misidentification of the snake leading to use of the wrong antivenom (12), problems associated with mechanical ventilation (10), and delayed arrival in hospital after traditional (herbal) treatment (10). Similar problems have been identified in other tropical countries. Education of medical staff and the patient population at highest risk could reduce snake bite mortality

Magnetic resonance imaging of the brain in patients with cerebral malaria.

In a prospective study of cerebral malaria, 24 adults with this disease underwent magnetic resonance imaging (MRI) of the brain. Four patients died. Two of these patients (nos. 17 and 24) had breathing abnormalities requiring ventilatory support followed by clinical signs of brain death. Four days later MRI of patient 17 showed gross swelling of the brain, and 5 hours later MRI of patient 24 showed foramen magnum herniation. Twenty-two patients had no evidence of cerebral edema, but MRI revealed that brain volume during acute cerebral malaria was slightly greater than that during the convalescent phase of the disease. This difference was attributed to an increase in the volume of intracerebral blood. The cerebral volume was lower during early convalescence than several months later. The volume of the brain in patients with cerebral malaria is increased. This increased volume probably results from sequestration of parasitized erythrocytes and compensatory vasodilatation rather than from edema. Brain stem herniation may occur, but its temporal relation to brain death in cases of cerebral malaria remains uncertain

Antimalarial effects of rifampin in Plasmodium vivax malaria.

The antimalarial effects of rifampin in 60 adults with Plasmodium vivax malaria were assessed. There were three treatment groups: rifampin (20 and 15 mg/kg of body weight per day for 1 and 4 days, respectively; n = 5); rifampin followed by primaquine (15 mg of base per day for 14 days; n = 25), and chloroquine (25 mg of base per kg over 3 days) followed by primaquine (n = 30). All patients were hospitalized till clearance of fever and parasites, and 45 patients stayed in the hospital for 1 month. Despite initial clearance of fever in all patients and a > or = 6-fold reduction in parasitemia per 48-h life cycle, rifampin alone was not effective: all five patients had subsequent R2-like parasitological responses. All patients treated with rifampin-primaquine cleared both fever and parasitemia, but the therapeutic responses were slower than those following treatment with chloroquine-primaquine. Final fever clearance times were significantly longer (mean [standard deviation] = 43 [35] versus 27 [19] h; P = 0.046), and the parasite clearance times (to 50 and 90% of admission parasite counts and to a level undetectable in a peripheral blood smear) were also significantly greater (P = 0.053 to < 0.001). However, reappearance of infection occurred in only one patient treated with rifampin-primaquine. The results of this study suggest that rifampin at the usual therapeutic doses has partial activity against blood stages of P. vivax in humans but that used alone it is insufficient for cure. Rifampin might therefore be of value in combination antimalarial therapy

Detection of venom by enzyme linked immunosorbent assay (ELISA) in patients bitten by snakes in Thailand.

The ability of an enzyme linked immunosorbent assay (ELISA) to detect venom was evaluated in 251 patients bitten by four of the commonest poisonous snakes in Thailand. Serum was tested only from patients who brought the snakes that had bitten them. About one third of all bitten patients had detectable venom antigenaemia, though a smaller proportion were symptomatic. Serum venom concentrations on admission correlated with the severity of clinical manifestations. The test was sensitive and specific even for specimens that had been collected and stored under suboptimal conditions. The technique is suitable for forensic use in cases of suspected snakebite. The combination of snake identification and venom antigen detection should be a more reliable means of studying the epidemiology of snakebite than the measurement of venom antibodies in a population

Detection of venom by enzyme linked immunosorbent assay (ELISA) in patients bitten by snakes in Thailand.

The ability of an enzyme linked immunosorbent assay (ELISA) to detect venom was evaluated in 251 patients bitten by four of the commonest poisonous snakes in Thailand. Serum was tested only from patients who brought the snakes that had bitten them. About one third of all bitten patients had detectable venom antigenaemia, though a smaller proportion were symptomatic. Serum venom concentrations on admission correlated with the severity of clinical manifestations. The test was sensitive and specific even for specimens that had been collected and stored under suboptimal conditions. The technique is suitable for forensic use in cases of suspected snakebite. The combination of snake identification and venom antigen detection should be a more reliable means of studying the epidemiology of snakebite than the measurement of venom antibodies in a population

Antimalarial effects of rifampin in Plasmodium vivax malaria.

The antimalarial effects of rifampin in 60 adults with Plasmodium vivax malaria were assessed. There were three treatment groups: rifampin (20 and 15 mg/kg of body weight per day for 1 and 4 days, respectively; n = 5); rifampin followed by primaquine (15 mg of base per day for 14 days; n = 25), and chloroquine (25 mg of base per kg over 3 days) followed by primaquine (n = 30). All patients were hospitalized till clearance of fever and parasites, and 45 patients stayed in the hospital for 1 month. Despite initial clearance of fever in all patients and a > or = 6-fold reduction in parasitemia per 48-h life cycle, rifampin alone was not effective: all five patients had subsequent R2-like parasitological responses. All patients treated with rifampin-primaquine cleared both fever and parasitemia, but the therapeutic responses were slower than those following treatment with chloroquine-primaquine. Final fever clearance times were significantly longer (mean [standard deviation] = 43 [35] versus 27 [19] h; P = 0.046), and the parasite clearance times (to 50 and 90% of admission parasite counts and to a level undetectable in a peripheral blood smear) were also significantly greater (P = 0.053 to < 0.001). However, reappearance of infection occurred in only one patient treated with rifampin-primaquine. The results of this study suggest that rifampin at the usual therapeutic doses has partial activity against blood stages of P. vivax in humans but that used alone it is insufficient for cure. Rifampin might therefore be of value in combination antimalarial therapy

A prospective clinical and bacteriologic study of inguinal buboes in Thai men.

One-hundred thirteen men (mean age, 23 years) who presented with inguinal buboes to a government-operated hospital for sexually transmitted diseases (STDs) in Bangkok were studied between February 1987 and February 1989. The median duration of preceding symptoms was 7 days (range, 1-62 days). The majority of patients (74; 65%) had received treatment previously; 31 (27%) were febrile, 13 (12%) had extrainguinal lymphadenopathy, and 31 (27%) had concurrent active genital ulcers. There was no history of genital ulceration in 66 (58%) of the patients. Pus was obtained from 51 of the 110 buboes aspirated for culture; 21 (41%) of these cultures yielded Haemophilus ducreyi, and 2 (3.9%) were positive for Chlamydia trachomatis on immunofluorescence microscopy. Saline (1 mL) was injected and reaspirated from the buboes of 35 of the other 59 patients; 3 buboes yielded H. ducreyi and 9 were positive for C. trachomatis. All cultures for other aerobic and anaerobic bacteria and viruses in intact buboes were negative. Syphilis serology was positive in only one case. Patients attending STD clinics in this region who have large, fluctuant, edematous inguinal buboes containing pus should receive presumptive treatment for chancroid. If there is no pus, then the bubo is more likely to be caused by lymphogranuloma venereum

Arboreal green pit vipers (genus Trimeresurus) of South-East Asia: bites by T. albolabris and T. macrops in Thailand and a review of the literature.

In Thailand 29 patients were proved to have been bitten by arboreal green pit vipers: 24 by Trimeresurus albolabris and 5 by T. macrops. They were studied in order to define the clinical effects of envenoming, to characterize the haemostatic abnormalities and assess the efficacy of Thai Red Cross antivenom. T. macrops caused only local painful swelling, neutrophil leucocytosis and thrombocytopenia. T. albolabris caused more severe envenoming with local blistering and necrosis, shock, spontaneous systemic bleeding, defibrination, thrombocytopenia and leucocytosis. There was no evidence of disseminated intravascular coagulation, but fibrinolytic activity was increased. Platelet function was normal. The product of admission venom antigen concentration and the delay between bite and admission was significantly higher in defibrinated patients than in those without severe coagulopathy. Antivenom (5 ampoules intravenously) restored blood coagulability, but there was persistent venom antigenaemia, associated in some cases with recurrent coagulopathy. The literature on bites by south Asian green pit vipers of the genus Trimeresurus is reviewed; these bites are common medical problems and causes of morbidity. The identification of individual species is difficult, but may be important if antivenom is to be improved and used appropriately

Clinical significance of venom antigen levels in patients envenomed by the Malayan pit viper (Calloselasma rhodostoma).

Serial venom antigen levels were measured by enzyme-linked immunosorbent assay (ELISA) in 46 patients with systemic envenoming by the Malayan pit viper (Calloselasma rhodostoma), a major cause of snake bite in Southeast Asia. The principal effects of the venom are defibrination, hemorrhage and local tissue necrosis. Admission venom levels, which varied between 0 and 595 ng/ml, correlated with the incidence of spontaneous systemic bleeding, blood incoagulability and concentrations of plasma fibrinogen and serum fibrin degradation products. The presence or absence of nonclotting blood also correlated with the time elapsed between the bite and hospital admission. The development of nonclotting blood may be delayed by up to 72 hr after the bite even though circulating venom and raised FDP may be detected at presentation. This is probably explained by a temporary equilibrium between synthesis and consumption of fibrinogen. Venom antigenemia recurred in 12 patients (26%) suggesting continuous absorption of venom from the wound or saturation of extravascular binding sites. Admission venom levels also correlated with the extent of local swelling and the occurrence of tissue necrosis at the site of the bite. Venom was detected in 87% of wound aspirates and 88% of urine specimens taken on admission. Tourniquets, of the type used in rural Thailand, did not delay the absorption of venom into the circulation