[Coinfection between hepatitis B virus and malaria: clinical, serologic and immunologic aspects].

The Amazon region is known for a high prevalence of hepatitis B infection, and accounts for more than 90% of malaria cases in Brazil. It has been suggested that the occurrence of coinfections may be important, and may influence the natural history of both diseases. This study evaluated 545 patients with acute malaria, in Coari, Western Brazilian Amazon. 333 (61.1%) presented Plasmodium vivax malaria, 193 (35.4%) Plasmodium falciparum and 19 (3.5%) mixed infections. The HBsAg prevalence was 4.2% and total anti-HBc 49.7%. Patients with HBV serological markers presented no clinical differences than those with malaria only, nor showed any association with classic signs of hepatic disorder. Although showing no statistical significance, HBsAg reactive subjects presented lower parasitic load and higher antibody titers, suggesting the possibility that the immune response in a coinfected individual is differentiated and leads to a variation in the parasite load and antibody production.