Editing external vars from another script problem?

So I have a game where planes fly from one town to another, and they can carry disease with them. The disease is randomly given to a town at the start of the game, allowing it to spread to the rest of the towns. Here are the scripts I have right now.

City script (City creation.js)

 private var minimumpeople = 1000;                      //technical vars, determining the max and min # people in the city
 private var maximumpeople = 10000;
 
 var people = 0;            //the number of people in the town (randomly generated in function Start ())
 public var percentinfected = 0.0;       //the percent of people in the town that are infected
 
 var airplaneprefab : GameObject;         //the airplane prefab
 
 
 var dmanager : GameObject;
 var maincam : GameObject;
 
 var objectpos : Vector3;
 var cursorpos : Vector3;
 
 
 function Start () {           //things that happen only once, in the first frame
     people = Random.Range(minimumpeople, maximumpeople);        //the random generation of the number of people in the city
 
 
 
     dmanager = GameObject.FindGameObjectWithTag("Dmanager");                //seting the disease manager var
     maincam = GameObject.FindGameObjectWithTag("MainCamera");               //setting the main camera var
 
 }
 function Update () {    
     
     
     if(Random.Range(0, 1000) < 1) {        //the controller on how often a plane takes off
         var jsplane = Instantiate(airplaneprefab, transform.position, transform.rotation);        //creating the airplane
         jsplane.GetComponent("Airplane").takeoff = gameObject.name;                                //setting that the town that the plane is coming from
         
         if(percentinfected > 1) {
             jsplane.GetComponent("Airplane").infected = true;
         }
     }
     
     
     
     percentinfected = percentinfected * dmanager.GetComponent("DMscript").infectivity;             //retreiving the infectivity rate from the disease manager
     
     
     
     objectpos = maincam.camera.WorldToScreenPoint(transform.position);                            //calculating the locations of the mouse, and the positions of the cities on the screen
     cursorpos = Input.mousePosition;
 
     if(percentinfected > 1) {                                                                  //if the town is infected, then it will give off particals (this is for beta testing)
         particleSystem.emissionRate = 3;
     }
 }

Airplane script (Airplane.js)

 #pragma strict
 
 private var allcities : Array;              //an array of all the cities on the map
 var takeoff : String;              //where the plane has taken off from
 var landing : String;           //where the plane will land
 var landingcity : GameObject;
 public var infected : boolean = false;
 function Start () {
     allcities = GameObject.FindGameObjectsWithTag("City");    //putting all the cities on the map into an array
     landingcity = allcities[Random.Range(0, allcities.length)];
     landing = landingcity.gameObject.name;
 }
 
 function Update () {                           //part of the script that makes the plane actualy fly to the destination
     transform.LookAt(landingcity.transform);         //turn to face the landing city
     transform.Translate(0, 0, 0.025);           //proceed foreward
     
     
     
     if(Vector3.Distance(transform.position, landingcity.transform.position) < 0.3) {             //if the airplane is inside the city, it gets destroyed
         Destroy(gameObject);
     }
     
     
     if(Vector3.Distance(transform.position, landingcity.transform.position) < 0.4) {             //if the airplane is inside the city, it gets destroyed
         landingcity.GetComponent("City creation").percentinfected += 1;
     }
 }

And, finally, Disease manager (DMscript.js) (this one isn't quite as important, but I decided to include it anyway)

 var infectivity = 0.0;        //how easiliy the disease spreads
 var visibility = 0;           //how noticable the disease is
 var accessibility = 0;        //how easy the disease is to research
 var allcities : Array;              //an array of all the cities on the map
 private var firstinfected : GameObject;
 
 function Start () {
     infectivity = Random.Range(1.0, 1.001);              //randomizing the disease vars
     visibility = Random.Range(0, 100);
     accessibility = Random.Range(0, 100);
     
     
     allcities = GameObject.FindGameObjectsWithTag("City");
     
     firstinfected = allcities[Random.Range(0, allcities.length)];
     
     firstinfected.GetComponent("City creation").percentinfected = 1;
 }

I keep getting the error

Assets/Standard Assets/Scripts/Airplane.js(26,59): BCE0019: 'percentinfected' is not a member of 'UnityEngine.Component'.

which doesn't make any sense....