Clinical presentation of type 1 and type 2 pyrethroid poisoning in humans.

Background: It is unclear if the clinical presentation of poisoning with type 1 and type 2 pyrethroid compounds is different. This study was undertaken to detail the clinical profile and outcome of patients presenting with pyrethroid poisoning and to quantify serum pyrethroid levels.
Patients and Methods: In this prospective study, patients were categorised as poisoning with type 1 pyrethroids or type 2 pyrethroids. Blood samples were sent for compound identification and quantification. Clinical features and outcomes were compared between the two groups. Factors associated with moderate and severe toxicity were explored using univariate logistic regression analysis and presented as odds ratio (OR) and 95% confidence intervals (CI).
Results: Type 1 pyrethroids were implicated in 16 patients and type 2 in 43 patients. The incidence of nausea and vomiting (81.2% vs. 81.3%) and tremor (37.5% vs. 32.6%) were similar in type 1 and type 2 poisoning; paraesthesia (6.2% vs. 32.6%, p  = 0.04), hypersalivation (0% vs. 20.9%, p  = 0.04), seizures (0% vs. 7%, p  = 0.29) and depressed sensorium (0% vs. 18.6%, p  = 0.03.) were observed more frequently in type 2 pyrethroid poisoning. Pyrethroids were detected in the serum samples of 24 patients; quantification was possible in 22 patients in whom serum levels ranged from 1.1 to 453 μg/ml. The compounds were undetectable in 35 patients. Two patients (lambda-cyhalothrin poisoning and cypermethrin poisoning) required intubation for low sensorium and respiratory distress. The median (interquartile range) duration of hospitalization was 12 (12-24) hours. All patients survived. Factors associated with moderate and severe toxicity included ingestion of a type 2 pyrethroid, lambda-cyhalothrin (OR 7.81, 95%CI 1.55-39.37, p  = 0.01) and volume ingested (OR 1.01, 95%CI 1.00-1.02, p  = 0.02).
Conclusion: Patients with pyrethroid poisoning present predominantly with mild to moderate symptoms. Paraesthesia and hypersalivation are more frequent in type 2 poisoning. A favourable outcome can be expected.