Relapse/reinfection patterns of Plasmodium vivax infection: a four year study.

In an endemic area relapse and reinfection in Plasmodium vivax cases poses serious problems for the malaria control program. We have studied the relapse/reinfection patterns of P. vivax infection in 26 villages of District Shahjahanpur, a malaria endemic area of UP, India for a period of four years (May, 1986 to October, 1988). All the P. vivax cases were given a complete course of radical treatment and were followed-up for relapse/reinfection. There were 8,914, 2,484, 1,439 and 883 P. vivax cases in 1986, 1987 and 1989 respectively, our of which 2,066, 141, 58 and 18 cases in the respective years showed relapse/reinfection. The maximum number of relapse/reinfection was recorded from a 47 year old male patient, who suffered from P. vivax infection eight times. The percentage occurrence of relapse/reinfection was much higher (70.2%) in males compared with females (29.8%). Relapses were more common among 16-30 years old patients. In conclusion it was felt that in 1986 relapse/reinfection in vivax cases was higher due to improper treatment of these cases. This situation may have occurred due to lack of awareness among the public, poor surveillance by the National Malaria Program or higher density of the vector mosquitos in the area.