Aniruddha Ghose

The greater black krait (Bungarus niger), a newly recognized cause of neuro-myotoxic snake bite envenoming in Bangladesh

Prospective studies of snake bite patients in Chittagong, Bangladesh, included five cases of bites by greater black kraits (Bungarus niger), proven by examination of the snakes that had been responsible. This species was previously known only from India, Nepal, Bhutan and Burma. The index case presented with descending flaccid paralysis typical of neurotoxic envenoming by all Bungarus species, but later developed generalized rhabdomyolysis (peak serum creatine kinase concentration 29,960 units/l) with myoglobinuria and acute renal failure from which he succumbed. Among the other four patients, one died of respiratory paralysis in a peripheral hospital and three recovered after developing paralysis, requiring mechanical ventilation in one patient. One patient suffered severe generalized myalgia and odynophagia associated with a modest increase in serum creatine kinase concentration. These are the first cases of Bungarus niger envenoming to be reported from any country. Generalized rhabdomyolysis has not been previously recognized as a feature of envenoming by any terrestrial Asian elapid snake, but a review of the literature suggests that venoms of some populations of Bungarus candidus and Bungarus multicinctus in Thailand and Vietnam may also have this effect in human victims. To investigate this unexpected property of Bungarus niger venom, venom from the snake responsible for one of the human cases of neuro-myotoxic envenoming was injected into one hind limb of rats and saline into the other under buprenorphine analgesia. All animals developed paralysis of the venom-injected limb within two hours. Twenty-four hours later, the soleus muscles were compared histopathologically and cytochemically. Results indicated a predominantly pre-synaptic action (β-bungarotoxins) of Bungarus niger venom at neuromuscular junctions, causing loss of synaptophysin and the degeneration of the terminal components of the motor innervation of rat skeletal muscle. There was oedema and necrosis of extrafusal muscle fibres in envenomed rat soleus muscles confirming the myotoxic effect of Bungarus niger venom, attributable to phospholipases A₂. This study has demonstrated that Bungarus niger is widely distributed in Bangladesh and confirms the risk of fatal neuro-myotoxic envenoming, especially as no specific antivenom is currently manufactured. The unexpected finding of rhabdomyolysis should prompt further investigation of the venom components responsible. The practical implications of having to treat patients with rhabdomyolysis and consequent acute renal failure, in addition to the more familiar respiratory failure associated with krait bite envenoming, should not be underestimated in a country that is poorly equipped to deal with such emergencies.

Randomized Controlled Trial of Levamisole Hydrochloride as Adjunctive Therapy in Severe Falciparum Malaria With High Parasitemia

Background. Cytoadherence and sequestration of erythrocytes containing mature stages of Plasmodium falciparum are central to the pathogenesis of severe malaria. The oral anthelminthic drug levamisole inhibits cytoadherence in vitro and reduces sequestration of late-stage parasites in uncomplicated falciparum malaria treated with quinine. Methods. Fifty-six adult patients with severe malaria and high parasitemia admitted to a referral hospital in Bangladesh were randomized to receive a single dose of levamisole hydrochloride (150 mg) or no adjuvant to antimalarial treatment with intravenous artesunate. Results. Circulating late-stage parasites measured as the median area under the parasite clearance curves were 2150 (interquartile range [IQR], 0–28 025) parasites/µL × hour in patients treated with levamisole and 5489 (IQR, 192–25 848) parasites/µL × hour in controls (P = .25). The “sequestration ratios” at 6 and 12 hours for all parasite stages and changes in microvascular blood flow did not differ between treatment groups (all P > .40). The median time to normalization of plasma lactate (<2 mmol/L) was 24 (IQR, 12–30) hours with levamisole vs 28 (IQR, 12–36) hours without levamisole (P = .15). Conclusions. There was no benefit of a single-dose of levamisole hydrochloride as adjuvant to intravenous artesunate in the treatment of adults with severe falciparum malaria. Rapid parasite killing by intravenous artesunate might obscure the effects of levamisole.

Pulmonary tuberculosis induces a systemic hypercoagulable state

OBJECTIVES Human tuberculosis (TB) remains an important cause of death globally. Bangladesh is one of the most affected countries. We aimed to investigate the impact of pulmonary TB on pro- and anticoagulant mechanisms. METHODS This prospective study was conducted in Chittagong, Bangladesh. We performed an in-depth analysis of coagulation activation and inhibition in plasma obtained from 64 patients with primary lung TB and 11 patients with recurrent lung TB and compared these with 37 healthy controls. Additionally, in nine patients coagulation activation was studied in bronchoalveolar lavage fluid (BALF) harvested from the site of infection and compared with BALF from a contralateral unaffected lung subsegment. RESULTS Relative to uninfected controls, primary and recurrent TB were associated with a systemic net procoagulant state, as indicated by enhanced activation of coagulation (elevated plasma levels of thrombin-antithrombin complexes, D-dimer and fibrinogen) together with impaired anticoagulant mechanisms (reduced plasma levels of antithrombin, protein C activity, free protein S, and protein C inhibitor). Activation of coagulation did not correlate with plasma concentrations of established TB biomarkers. Coagulation activation could not be detected at the primary site of infection in a subset of TB patients. CONCLUSIONS Pulmonary TB is associated with a systemic hypercoagulable state.

Correlation of biomarkers for parasite burden and immune activation with acute kidney injury in severe falciparum malaria

BackgroundAcute kidney injury (AKI) complicating severe Plasmodium falciparum malaria occurs in up to 40% of adult patients. The case fatality rate reaches 75% in the absence of renal replacement therapy (RRT). The precise pathophysiology of AKI in falciparum malaria remains unclear. Histopathology shows acute tubular necrosis with localization of host monocytes and parasitized red blood cells in the microvasculature. This study explored the relationship of plasma soluble urokinase-type plasminogen activator receptor (suPAR), as a proxy-measure of mononuclear cell activation, and plasma P. falciparum histidine rich protein 2 (Pf HRP2), as a measure of sequestered parasite burden, with AKI in severe malaria.MethodsAdmission plasma suPAR and Pf HRP2 concentrations were assessed in Bangladeshi adults with severe falciparum malaria (n = 137). Patients were stratified according to AKI severity based on admission creatinine clearance.ResultsA total of 106 (77%) patients had AKI; 32 (23%), 42 (31%) and 32 (23%) were classified into ‘mild, ‘moderate’ and ‘severe’ AKI groups, respectively. Plasma suPAR and Pf HRP2 concentrations increased with AKI severity (test-for-trend P <0.0001) and correlated with other markers of renal dysfunction. Admission plasma suPAR and Pf HRP2 concentrations were higher in patients who later required RRT (P <0.0001 and P = 0.0004, respectively). In a multivariate analysis, both increasing suPAR and Pf HRP2 were independently associated with increasing urine neutrophil gelatinase-associated lipocalin concentration, a marker of acute tubular necrosis (β = 16.54 (95% CI 6.36-26.71) and β = 0.07 (0.02-0.11), respectively).ConclusionsBoth sequestered parasite burden and immune activation contribute to the pathogenesis of AKI in severe falciparum malaria.

Clinically and Microbiologically Derived Azithromycin Susceptibility Breakpoints for Salmonella enterica Serovars Typhi and Paratyphi A

ABSTRACT Azithromycin is an effective treatment for uncomplicated infections with Salmonella enterica serovar Typhi and serovar Paratyphi A (enteric fever), but there are no clinically validated MIC and disk zone size interpretative guidelines. We studied individual patient data from three randomized controlled trials (RCTs) of antimicrobial treatment in enteric fever in Vietnam, with azithromycin used in one treatment arm, to determine the relationship between azithromycin treatment response and the azithromycin MIC of the infecting isolate. We additionally compared the azithromycin MIC and the disk susceptibility zone sizes of 1,640 S. Typhi and S. Paratyphi A clinical isolates collected from seven Asian countries. In the RCTs, 214 patients who were treated with azithromycin at a dose of 10 to 20 mg/ml for 5 to 7 days were analyzed. Treatment was successful in 195 of 214 (91%) patients, with no significant difference in response (cure rate, fever clearance time) with MICs ranging from 4 to 16 μg/ml. The proportion of Asian enteric fever isolates with an MIC of ≤16 μg/ml was 1,452/1,460 (99.5%; 95% confidence interval [CI], 98.9 to 99.7) for S. Typhi and 207/240 (86.3%; 95% CI, 81.2 to 90.3) (P < 0.001) for S. Paratyphi A. A zone size of ≥13 mm to a 5-μg azithromycin disk identified S. Typhi isolates with an MIC of ≤16 μg/ml with a sensitivity of 99.7%. An azithromycin MIC of ≤16 μg/ml or disk inhibition zone size of ≥13 mm enabled the detection of susceptible S. Typhi isolates that respond to azithromycin treatment. Further work is needed to define the response to treatment in S. Typhi isolates with an azithromycin MIC of >16 μg/ml and to determine MIC and disk breakpoints for S. Paratyphi A.

Magnetic resonance imaging of the brain in adults with severe falciparum malaria

BackgroundMagnetic resonance imaging (MRI) allows detailed study of structural and functional changes in the brain in patients with cerebral malaria.MethodsIn a prospective observational study in adult Bangladeshi patients with severe falciparum malaria, MRI findings in the brain were correlated with clinical and laboratory parameters, retinal photography and optic nerve sheath diameter (ONSD) ultrasound (a marker of intracranial pressure).ResultsOf 43 enrolled patients, 31 (72%) had coma and 12 (28%) died. MRI abnormalities were present in 79% overall with mostly mild changes in a wide range of anatomical sites. There were no differences in MRI findings between patients with cerebral and non-cerebral or fatal and non-fatal disease. Subtle diffuse cerebral swelling was common (n = 22/43), but mostly without vasogenic oedema or raised intracranial pressure (ONSD). Also seen were focal extracellular oedema (n = 11/43), cytotoxic oedema (n = 8/23) and mildly raised brain lactate on magnetic resonance spectroscopy (n = 5/14). Abnormalities were much less prominent than previously described in Malawian children. Retinal whitening was present in 36/43 (84%) patients and was more common and severe in patients with coma.ConclusionCerebral swelling is mild and not specific to coma or death in adult severe falciparum malaria. This differs markedly from African children. Retinal whitening, reflecting heterogeneous obstruction of the central nervous system microcirculation by sequestered parasites resulting in small patches of ischemia, is associated with coma and this process is likely important in the pathogenesis.

Serosurveillance of Orientia tsutsugamushi and Rickettsia typhi in Bangladesh.

Scrub and murine typhus infections are under-diagnosed causes of febrile illness across the tropics, and it is not known how common they are in Bangladesh. We conducted a prospective seroepidemiologic survey across six major teaching hospitals in Bangladesh by using an IgM enzyme-linked immunosorbent assay. Results indicated recent exposure (287 of 1,209, 23.7% seropositive for Orientia tsutsugamushi and 805 of 1,209, 66.6% seropositive for Rickettsia typhi). Seropositive rates were different in each region. However, there was no geographic clustering of seropositive results for both organisms. There was no difference between those from rural or urban areas. Rickettsia typhi seroreactivity was positively correlated with age. Scrub typhus and murine typhus should be considered as possible causes of infection in Bangladesh.

Temporal trends in severe malaria in Chittagong, Bangladesh

BackgroundEpidemiological data on malaria in Bangladesh are sparse, particularly on severe and fatal malaria. This hampers the allocation of healthcare provision in this resource-poor setting. Over 85% of the estimated 150,000-250,000 annual malaria cases in Bangladesh occur in Chittagong Division with 80% in the Chittagong Hill Tracts (CHT). Chittagong Medical College Hospital (CMCH) is the major tertiary referral hospital for severe malaria in Chittagong Division.MethodsMalaria screening data from 22,785 inpatients in CMCH from 1999–2011 were analysed to investigate the patterns of referral, temporal trends and geographical distribution of severe malaria in Chittagong Division, Bangladesh.ResultsFrom 1999 till 2011, 2,394 malaria cases were admitted, of which 96% harboured Plasmodium falciparum and 4% Plasmodium vivax. Infection was commonest in males (67%) between 15 and 34 years of age. Seasonality of malaria incidence was marked with a single peak in P. falciparum transmission from June to August coinciding with peak rainfall, whereas P. vivax showed an additional peak in February-March possibly representing relapse infections. Since 2007 there has been a substantial decrease in the absolute number of admitted malaria cases. Case fatality in severe malaria was 18% from 2008–2011, remaining steady during this period.A travel history obtained in 226 malaria patients revealed only 33% had been to the CHT in the preceding three weeks. Of all admitted malaria patients, only 9% lived in the CHT, and none in the more remote malaria endemic regions near the Indian border.ConclusionsThe overall decline in admitted malaria cases to CMCH suggests recent control measures are successful. However, there are no reliable data on the incidence of severe malaria in the CHT, the most endemic area of Bangladesh, and most of these patients do not reach tertiary health facilities. Improvement of early treatment and simple supportive care for severe malaria in remote areas and implementation of a referral system for cases requiring additional supportive care could be important contributors to further reducing malaria-attributable disease and death in Bangladesh.

Phase II study of magnesium sulfate in acute organophosphate pesticide poisoning

Background. Acute organophosphorus (OP) poisoning is relatively common and a major cause of death from poisoning in developing countries. Magnesium has been shown to be of benefit in animal models. Methods. We conducted a phase II study of bolus doses of (MgSO4) in 50 patients with acute organophosphate poisoning. Patients eligible for inclusion had ingested OP and had cholinergic symptoms consistent with moderate or severe poisoning. All patients received standard care of atropinization titrated to control muscarinic symptoms and pralidoxime. The trial was run in 4 sequential groups of patients. Participants in each group received a different total dose of MgSO4 (20%) administered as intermittent bolus doses infused over 10–15 min or placebo. There was one control patient for every 4 patients who received MgSO4. Group A (16 patients) received a total of 4 gm MgSO4 as a single bolus, group B (8 patients) received 8 gm (in two 4 gm doses q4H), group C (8 patients) received 12 gm (in three 4 gm doses q4H) group D (8 patients) received 16 gm (in four 4 gm doses q4H) and control (10 patients) received placebo). Patients were closely monitored for any adverse reaction like significant clinical neuromuscular disturbance and respiratory depression. Results. No adverse reactions to magnesium were observed. The 24 hour urinary magnesium concentration were statistically different between 16 gm (234.74 ± 74.18 mg/dl) and control (118.06 ± 30.76 mg/dl) (p = 0.019), while it was much lower than the 80% of the intravenous magnesium load. Six patients died in control group compared to 3 in 4 gm, 2 in 8 gm and 1 in 12 gm group. There was no mortality in 16 gm group. Conclusion. Magnesium was well tolerated in this study. Larger studies are required to examine for efficacy.

Sequestration and Red Cell Deformability as Determinants of Hyperlactatemia in Falciparum Malaria

Background. Hyperlactatemia is a strong predictor of mortality in severe falciparum malaria. Sequestered parasitized erythrocytes and reduced uninfected red blood cell deformability (RCD) compromise microcirculatory flow, leading to anaerobic glycolysis. Methods. In a cohort of patients with falciparum malaria hospitalized in Chittagong, Bangladesh, bulk RCD was measured using a laser diffraction technique, and parasite biomass was estimated from plasma concentrations of Plasmodium falciparum histidine-rich protein 2 (PfHRP2). A multiple linear regression model was constructed to examine their associations with plasma lactate concentrations. Results. A total of 286 patients with falciparum malaria were studied, of whom 224 had severe malaria, and 70 died. Hyperlactatemia (lactate level, ≥4 mmol/L) was present in 111 cases. RCD at shear stresses of 1.7 Pa and 30 Pa was reduced significantly in patients who died, compared with survivors, individuals with uncomplicated malaria, or healthy individuals (P < .05, for all comparisons). Multiple linear regression analysis showed that the plasma PfHRP2 level, parasitemia level, total bilirubin level, and RCD at a shear stress of 1.7 Pa were each independently correlated with plasma lactate concentrations (n = 278; R2 = 0.35). Conclusions. Sequestration of parasitized red blood cells and reduced RCD both contribute to decreased microcirculatory flow in severe disease.