Pediatric Salmonella Infection

Updated: Jun 10, 2016
  • Author: Archana Chatterjee, MD, PhD; Chief Editor: Russell W Steele, MD  more...
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Overview

Background

Infections due to Salmonella species represent a major public health problem in many countries. In the United States, nontyphoidal Salmonella (NTS) is the most common pathogen implicated in food-borne gastroenteritis. [1] In most cases, NTS is a self-limiting disease that causes mild gastroenteritis; however, it can lead to a wide spectrum of complications including bacteremia, enterocolitis, and severe local infections such as meningitis and osteomyelitis. [2, 3, 4] Salmonella serotype typhi can cause serious and prolonged bacteremic illness referred to as enteric fever or typhoid fever. [5]

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Pathophysiology

The extension of the disease to various organs depends on the serotype, the size of the inoculum, and the status of the host. If large enough numbers of bacteria are ingested, they can survive in the normally lethal acidic pH of the stomach. Once ingested, Salmonella can gain access to the small intestine, producing diffuse mucosal inflammation, edema, and microabscesses. Generally, most NTS do not extend beyond the lamina propria and lymphatics of the gut. Exceptions include Salmonellacholeraesuis and Salmonelladublin, which can cause bacteremia with little intestinal involvement. [6] In individuals with S. typhi, areas of intestinal necrosis can ulcerate and result in perforation. In addition, this mucosal penetration allows uptake into the draining lymph nodes, contributing to blood stream infections (BSI) and subsequent invasion of the liver, spleen, and bone marrow. This process explains the delayed onset of symptoms in S.typhi. [7]

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Epidemiology

Frequency

United States

NTS caused an estimated 11% of the 9.4 million food-borne illnesses in the United States, second to norovirus. From 2006-2008, NTS was the leading cause of food-borne illnesses that resulted in hospitalization and death. [8] . Approximately 400 cases of typhoid fever are reported per year. Most of cases are a result of foreign travel, either US citizens traveling to developing countries or foreign travelers to the United States. Most cases are from travel to India or Pakistan. [9] However, over the last 10 years, US travelers to Asia, Africa, and Latin America have been especially at risk. [10]

The preliminary data from the Foodborne Diseases Active Surveillance Network (FoodNet) of the Centers for Disease Control and Prevention's (CDC's) Emerging Infections Program for 2011 revealed a steady increase in the reported incidence of Salmonella infections in the 10 US states in which active, population-based surveillance is performed. [11]

A study by Walters et al investigated turtle-associated salmonellosis outbreaks occurring in 2011-2013. The study identified 8 outbreaks totaling 473 cases from 41 states, Washington DC, and Puerto Rico. The median patient age was 4 years; 45% percent were Hispanic; and 28% were hospitalized. The study added that in the week preceding illness, 68% of case-patients reported turtle exposure and among these, 88% described small turtles. [12]

International

The past 2 decades have seen an increase in the incidence of NTS in Europe and North America. [13] A report from the GeoSentinel Surveillance Network revealed enteric fever as the leading cause of vaccine-preventable disease in international travelers. [14] Typhoid fever is endemic in many developing areas of the world, with incidence rates estimated to be 40-50 cases per 1,000,000 population in Pakistan and India. [15] Five Asian countries are considered to be endemic for typhoid: China, India, Indonesia, Pakistan, and Vietnam. [5] However, the CDC has removed 26 countries in Eastern Europe and the Middle East from the most current recommendations for typhoid vaccination. [15, 16] Annually, the World Health Organization (WHO) estimates 16-33 million cases of typhoid fever worldwide and 500,000-600,000 deaths.

Mortality/Morbidity

Enteric infections account for significant morbidity and mortality in young children (aged 1-4 y). Morbidity and mortality rates are highest in infants (most dangerous in infants < 3 mo with bacteremia), elderly patients, and patients with sickle cell disease, acquired immunodeficiency syndrome (AIDS), neoplasms, or other immunosuppressive conditions. [5, 17, 18] Substantial differences in outcomes have been noted based on varying serotypes. [19]

Race

The incidence of infection for all serotyped NTS is almost twice as high in blacks and Latinos, Salmonella typhimurium is the most common pathogen. [20]

Sex

No sex differences are noted. [20]

Age

Attack rates are highest in persons younger than 5 years or older than 70 years. [20, 5]

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