What are the specific symptoms of typhoid fever in children?

Typhoid fever in children is a systemic infectious disease caused by infection with bacteria. Patients will experience varying degrees of fever, persistent high fever, vomiting and other symptoms. So what are the specific symptoms of typhoid fever in children?

The pathological changes of typhoid fever are mainly in the ileum wall of the small intestine. Initially, the collective lymph nodes and solitary lymph nodes on the intestinal wall swell, and then the swollen parts become necrotic due to nutritional disorders, and then ulcers are formed and may bleed or perforate. Finally, the ulcers heal without leaving scars. These changes may be mild in infants and young children, with only redness and swelling without ulcer formation, and the changes in the liver, kidneys, and heart are also much lighter than those in adults.

Since the above pathological changes are different from those in adults, typhoid fever in children is more atypical, especially in infants and young children. The incubation period of typhoid fever in children is 7-14 days, and the course of the disease is about 4 weeks. Most of the patients have an acute onset, and symptoms such as high fever, vomiting, and convulsions account for about 1/3 of the patients, among which convulsions in infants and young children are common. The patients are often misdiagnosed as upper respiratory tract infection, early pneumonia, or meningitis during the initial diagnosis. High fever may last for 5-6 days, often accompanied by headache, fatigue, loss of appetite, cough, sore throat, abdominal pain and nose bleeding. Diarrhea is common in infants and young children, and children who suffer from it frequently may develop symptoms of dehydration and acidosis.

Generally, the pulse rate speeds up during high fever, but in typhoid fever, the pulse rate slows down, which is inconsistent with the high fever. This slow pulse change is only seen in older children. Similarly, typhoid fever is often accompanied by mental symptoms, incoherent speech and movement, and is only seen in older children. Roseola occurs less frequently in children, accounting for only 6-15% of all cases. The rash appears on the abdomen, with several or more spots of varying sizes, is rose-colored, and raised above the skin. Most cases appear 4-15 days after onset of the disease. More than half of the children have enlarged liver and spleen, and enlarged liver is common. Most of the sick children have mild anemia and leukocytopenia. Whether or not the leukocytopenia occurs during infancy is not very helpful for diagnosis.

To confirm typhoid fever, blood culture should be performed in the early stage of the disease (within one week), from which Salmonella typhi can be cultured with a positive rate of 85%. 2-3 weeks after onset, Salmonella typhi can be cultured from feces, with a positive rate also reaching 80%. The positive rate of urine culture is only 20% when cultured 3 to 4 weeks later. Bone marrow fluid culture has the highest positive rate, but it can only be used when the diagnosis is difficult.

In addition, the positive rate of Widal reaction in the blood of children increased gradually with the extension of the onset time, reaching 90% in the fourth week. There are two types of Widal reaction, one is "O" agglutination reaction and the other is "H" agglutination reaction. Their titers should be above 1:160 to be meaningful. Generally speaking, "O" agglutination reaction appears early and lasts for a short time, while "H" agglutination reaction appears late and lasts for a long time. However, in infants and young children, "H" agglutination reaction may appear early. Recently, it has been found that in some cases, the Widal reaction may remain negative, but the blood culture is positive in the early stage, and the diagnosis of typhoid fever is undoubtedly certain.

Why is the Widal reaction negative during the course of the disease? After analysis and examination, two situations were found: one is that the child has congenital immune deficiency or low immune function, and the body has no immune response, so the result is negative; the other is that antibacterial drugs were used early, the typhoid Salmonella has disappeared but did not cause the body's immune response, so it is also negative. But such cases are rare. Therefore, when diagnosing typhoid fever in children, in addition to paying attention to clinical symptoms, blood culture and Widal reaction should also be tested.