Do you know that non-typhoidal salmonellae are known to be the leading cause of diarrheal diseases worldwide? They cause an estimated 94 million cases of gastroenteritis and 115,000 deaths globally each year.  While this is a sad statistics, this disease is preventable.

Of the four major causes of diarrheal diseases globally, salmonella is one. Sometimes, cases of salmonellosis can be mild and it can be life-threatening. The severity is dependent on the immune system of the host and the serotype of Salmonella.

Antimicrobial resistance is a global public health concern and Salmonella is one of the microorganisms in which some resistant serotypes have emerged, affecting the food chain. As a preventive measure against salmonellosis however, basic food hygiene practices, such as cooking thoroughly is highly recommended.

 

THE DISEASE

Salmonellosis is a diarrheal disease usually characterized by acute onset of fever, abdominal pain, diarrhoea, nausea and sometimes vomiting.

The onset of the symptoms mostly occurs 6–72 hours after ingestion of the bacteria Salmonella. The illness may last 2–7 days.

Symptoms of salmonellosis are relatively mild and patients will make a recovery without specific treatment in most cases. However, in some cases, particularly in children and elderly patients, the associated dehydration can become severe and life-threatening.

Although large Salmonella outbreaks usually attract media attention, 60–80% of all salmonellosis cases is not recognized as part of a known outbreak and are classified as sporadic cases, or are not diagnosed as such at all.

 

INFECTIOUS AGENT

The disease is caused by Salmonella enterica, a gram-negative, rod-shaped bacillus. There are more than 2,500 Salmonella serotypes that have been identified. Non-typhoidal salmonellosis is caused by all serotypes of Salmonella except for Typhi, Paratyphi A, Paratyphi B (tartrate negative), and Paratyphi C.

 

MODE OF TRANSMISSION

Consumption of infected animal products such as milk, meat and poultry is the major route of transmission between human and the environment while faecal-oral route is the most common route of transmission between man to man.  The infected animals rarely show sign of any infection or disease. They are perfect vectors.

 

EPIDEMIOLOGY

Non-typhoidal salmonellae are known to be the leading cause of diarrheal disease worldwide. They cause an estimated 94 million cases of gastroenteritis and 115,000 deaths globally each year. The risk of Salmonella infection among travellers varies by region of the world visited. According to Centre for Disease Control and Prevention (CDC), in one analysis, the incidence of laboratory-confirmed infections from 2004 through 2009 was 7.1 cases per 100,000 among travellers to Latin American and Caribbean, 5.8 cases per 100,000 among travellers to Asia, and 25.8 cases per 100,000 among travellers to Africa. The true number of illnesses is much higher, because most ill people do not have a stool specimen tested.

 

SIGNS AND SYMPTOMS

The most common signs and symptoms of non-typhoidal Salmonella infection is the inflammation of the digestive tract. The incubation period is averagely from 6–72 hours, but illness usually occurs within 12–36 hours after exposure.  The commonly manifested symptoms are:

  • Acute diarrhea,
  • Abdominal pain,
  • Fever,
  • Nausea, and
  • Sometimes vomiting.

Usually the duration of the disease condition is from 4-7 days. Some people may recover without treatment. Approximately 5% of people develop bacteremia or focal infection (such as meningitis or osteomyelitis). The prognosis is determined by the. Some species may cause invasive infections which rate and death are generally higher among infants, older adults, and people with immunosuppressive conditions (including HIV), hemoglobinopathies, and malignant neoplasms.

 

DIAGNOSIS

Diagnosis of the disease is by isolating the causative organism, Salmonella. About 90% of isolates are obtainable from routine stool culture but can also be isolated from blood, urine. Isolates of salmonellae are needed for serotyping and antimicrobial susceptibility testing.

 

TREATMENT

Current treatment recommendation involves the treatment of those patients with mild salmonellosis with supportive therapy. this is because the antibiotics may not totally eliminate the micro-organisms and may lead to the development of resistance. Antimicrobial therapy is not recommended for mild to moderate infection. Antimicrobial therapy should be considered for patients who are severely ill (for example, those with severe diarrhea, high fever, or manifestations of extraintestinal infection) and for gastroenteritis caused by Salmonella species in people at increased risk of invasive disease (infants aged months, older adults aged ≥60 years, and the debilitated or immunosuppressed). Fluoroquinolones are used in the treatment of patients with severe travelers’ diarrhea; azithromycin and rifaximin are also commonly used. Resistance to antimicrobial agents varies by serotype and geographic region. First generation antimicrobials are non-effective against salmonella species (chloramphenicol, ampicillin, and trimethoprim-sulfamethoxazole), and resistance to both fluoroquinolones and third-generation cephalosporins has increased.

 

PREVENTIVE MEASURES

As there is no vaccine to prevent the development of the disease, the basic hygienic steps are highly recommended. According to World Health Organization (WHO), prevention requires control measures at all stages of the food chain, from agricultural production, to processing, manufacturing and preparation of foods in both commercial establishments and at home. Pet handlers need to employ a high standard of hygiene when handling their pets. Kids need to be closely monitored whenever they are handling pets that may be infected with the organisms. Below are some of the precautionary steps recommended for prevention:

  • Ensure food is properly cooked and still hot when served.
  • Avoid raw milk and products made from raw milk. Drink only pasteurized or boiled milk.
  • Avoid ice unless it is made from safe water.
  • When the safety of drinking water is questionable, boil it or if this is not possible, disinfect it with a reliable, slow-release disinfectant agent (usually available at pharmacies).
  • Wash hands thoroughly and frequently using soap, in particular after contact with pets or farm animals, or after having been to the toilet.
  • Wash fruits and vegetables carefully, particularly if they are eaten raw. If possible, vegetables and fruits should be peeled.
  • Separate raw and cooked.
  • Cook thoroughly.
  • Keep food at safe temperatures
  • Use safe water and raw materials.

 

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