Because the COX-2 inhibitor SC-58125 tended to reduce the lung tissue levels of cysteinyl leukotrienes C4 and D4 and because 5-Lipoxygenase (5-LO) inhibitors had already been shown to reduce PH in the chronic hypoxia and monochrotaline models [11,13], we tested whether diethylcarbamazine [11] an inexpensive antihelminthic drug used in tropical zones to treat filariasis and a 5-LO inhibitor, would prevent or ameliorate PAH in the SuHx rat model. Here, ALOX5 is linked to filariasis.