In general, the mode of transmission of paratyphoid fever is the same as typhoid fever. However, compared to typhoid fever, paratyphoid fever presents with milder symptoms, a shorter duration of illness, fewer complications, and a better prognosis. Paratyphoid A is more common in older children, while Paratyphoid B and C are more prevalent in younger children.
The incidence of Paratyphoid A increases with age, and it is rarely seen in infants within their first year of life. Cases occur throughout the year. The onset of illness can be acute or gradual, and the duration of the disease can vary, averaging around three weeks. Among the paratyphoid fevers, the symptoms of Paratyphoid A are most similar to typhoid fever. It is difficult to distinguish typhoid fever from Paratyphoid A solely based on clinical manifestations.
Children with Paratyphoid B tend to be younger, with the majority being infants and toddlers under three years old. Boys are more affected than girls. More cases occur in summer and autumn. The onset of illness is more acute than that of Paratyphoid A, often leading to convulsions due to high fever. Another characteristic is diarrhea, which is present in almost all cases, and is mostly mucus-containing without pus or blood, lasting for an extended period. Despite the acute onset and severe symptoms, the prognosis is good.
Paratyphoid C is the most severe among the paratyphoid fevers, generally characterized by high and persistent fever. Pathogens are often present in the blood, and there are common purulent foci in the internal organs. There are also numerous bacterial toxins in the blood, leading to it being classified as "septicemia type," "pyemia type," and "toxemia type." In addition to high fever, systemic symptoms include chills, headache, lethargy or irritability, enlargement of the liver and spleen, and even jaundice. Conditions such as osteomyelitis, arthritis, pleurisy, and meningitis can also occur. The duration of illness is approximately one to three weeks. Severe cases are more common in frail infants and toddlers, with a poor prognosis.
