Parthenium weed: a growing concern in Pakistan

Abstract

Background Parthenium hysterophorus is a waste land weed which is hazardous to plantsand human beings.Objectives To find out the magnitude of parthenium spread and the adverse effects onagriculture and human beings.Patients and methods This multiphase study was designed in collaboration with theDepartment of Mycology and Plant Pathology (MAPP), Punjab University, Lahore. In phaseI, the plant itself was studied. In phase II, its effects on other plants were recorded. In phaseIII, patch test was performed in patients with allergic contact dermatitis visiting the medicalcamps at Jallo Park, and Johar town, Lahore and Changa Manga forest. Patch test was doneusing the leaf and flower of prthenium, as is, and 1% parthenin in petrolatum base.International Contact Dermatitis Research Group (ICDRG) guidelines and criteria were usedfor patch testing and interpreting the results at 48, 72 and 120 hours.Results In the first phase of the study, the weed was found growing unchecked in the abovementioned areas. In the second phase, it was found to invade crops like rice and maize. In thethird phase of the study, 511 patients suspected of allergic contact dermatitis were enrolledalong with 100 controls. Out of 511, 391 reacted positively. Only 5 from the control groupwere positive to parthenium.Conclusion Parthenium hysterophorus has replaced the main native flora in many parts ofPakistan including the big cities like Rawalpindi-Islamabad and Lahore. It has caused a majoroutbreak of airborne contact dermatitis. The rapid spread is probably due to its use inbouquets.