What implications does the period of infectiousness have for the control of transmission of these diseases? how are chronic earners of typhoid and hepatitis b managed?

The implications are epidemies, risk factors and disease burden.

When it comes to Typhoid, the cronic earners are treated with prescribed antibiotics, changes in sanitary habits and blood testing.

When it comes to hepatitis b, the cronic earners are treated with prescribed antivirals,  blood tests, liver ultrasound and biopsy.

Explanation:

Epidemies can occur because the sick population, might not be aware and contaminate the other amount who is not infected. That is the reason why the chronic earners must take the prescribed antibiotics for as long as the physician has prescribed, they must incorporate healthy sanitary habits like washing their hands with soap after using the bathroom, not preparing or serving food to other people. Because these actions will prevent others from getting the illness. And finally, they must get tested  so that the doctor can ensure that no Salmonella Typhi bacteria remain in their body. The best way to avoid Typhoid is by vaccine.

Hepatitis B epidemies, risk factors and disease burden happens when the chronic earner use illegal injected drugs and share the niddle, have unprotected sex with multiple partners, receive kidney dialysis or live with someone who has hepatitis B. So the best way of managing these patients is by lifetime treatment, which means that they will take antiviral medications, interferon injections or have a liver transplant.

The best way of preventing the hepatitis B is by vaccine, safe sex and no drugs.

this is true, assuming that the allele is completely recessive and incomplete dominance is not a factor.