Worms are common parasites in birds. There are several types of intestinal worms that affect birds.
Affected birds become weak and lose weight. It can be fatal if no measures are undertaken to get rid of the worms.
Cockatiels, budgies, and lovebirds are more susceptible to giardiasis than most species of birds. The parasite has also been found in some larger species of parrots. Birds can get the parasite from contact with infected material or from adult birds that are carriers. Symptoms of the infection include diarrhea, feather plucking, malnutrition, and skin itching, especially among cockatiels.
Trichomoniasis (also called canker) is caused by a protozoan parasite. Budgies appear to be the most common birds to be infected; and affected birds regurgitate food and salivate excessively. There are also whitish or yellowish lesions on the mouth, crop, and esophagus. Birds can get the parasite via contaminated food or water or by direct contact with an infected bird. Visit this website for additional knowledge.