One of the intestinal enzymes that are generally deficient in children following an attack of severe infectious enteritis is –
`Because Lactase activity in the mucosa is at best marginal, this enzyme is particularly likely to be depleted secondary to diffuse mucosal disease' - Nelson
Causes of Acquired Lactase deficiency
1. Acute Infective enteritis

Viral gastroenteritis   
Bacterial gastroenteritis       

2. Cystic fibrosis                                
3. Protein-energy malnutrition    
4. Cow's milk protein intolerance  
5. Prolonged use of drugs like Neomycin.
Lactase
Trypsin
Lipase
Amylase