forward Infected(playerid);
public Infected(playerid)
{
    SetPlayerHealth(playerid,GetPlayerHealth(playerid)-2);
    SetTimerEx("Infected",1000,0,"i",playerid); // -2 hp per second
    return 1;
}

CMD:infect(playerid,params[])
{
    new targetid;
    if(sscanf(params, "uz", targetid)) return SendClientMessage(playerid, COLOR_WHITE, "USAGE: /Infect <playerid>");
    if(!IsPlayerConnected(targetid)) return SendClientMessage(playerid, COLOR_WHITE, "ERROR: Invalid ID.");
    else
    {
            new metin[512];
            new name[MAX_PLAYER_NAME];
            GetPlayerName(playerid, name, sizeof(name));
            new target[MAX_PLAYER_NAME];
            GetPlayerName(targetid, target, sizeof(target));
            SetTimerEx("Infected",100,0,"i",targetid);
            format(metin, sizeof(metin), "INFO: You have made %s infected!",target);
            SendClientMessage(playerid, -1, metin);
            format(metin, sizeof(metin), "WARNING: You have been infected by %s!",name);
            SendClientMessage(targetid, -1, metin);
    }
    return 1;
}

forward Infected(playerid);
public Infected(playerid)
{
    new Float:health; GetPlayerHealth(playerid,health);
    SetPlayerHealth(playerid,health-2);
    SetTimerEx("Infected",1000,0,"i",playerid); // -2 hp per second
    return 1;
}