Beware of Salmonella typhi: Microbiological Testing as Key to Identifying Salmonella typhi, the Cause of Typhus

• What is Salmonella typhi?
• How Typhoid Spreads and Its Symptoms?
• How to Prevent Typhoid
• The Importance of Microbiological Laboratory Testing to Prevent Typhoid Transmission

What is Salmonella typhi?

Salmonella typhi (S. typhi) is a Gram-negative bacterium that can cause typhoid fever (also called enteric fever). This bacterium can carry large plasmids, some of which make it resistant to antibiotics. Because it can infect humans and cause serious illness, S. typhi is considered a dangerous pathogen.

Typhoid infection is most common in areas with poor economic development and weak public health infrastructure. Communities without access to clean drinking water and proper sanitation are especially vulnerable. Globally, there are an estimated 11–21 million cases of typhoid and paratyphoid fever each year, causing 130,000–160,000 deaths. Most cases occur in South Asia, Southeast Asia, and Sub-Saharan Africa. In 2017, the highest numbers were recorded in India and Bangladesh, reaching 500–700 cases per 100,000 people.

How Typhoid Spreads and Its Symptoms?

The incubation period of S. typhi (time from infection to symptoms) ranges from 3 to 60 days. Typhoid spreads mainly through food and water contaminated with human feces or urine, or via flies that carry the bacteria. Although S. typhi can survive in the environment for weeks (4–140 days), it cannot multiply outside a living host.

There are two main ways of transmission:

• Short cycle: Food and water are directly contaminated because of poor hygiene—for example, eating street foods like milk products, ice cream, fruit, or juice.
• Long cycle: Human feces contaminate untreated water sources, which are then used for drinking or farming. This type of transmission is harder to trace.
  

When S. typhi enters the body through contaminated food or drinks, stomach acid may not always be strong enough to kill it. As a result, the bacteria can reach the intestines and spread throughout the body. Studies show that swallowing as few as 50–100 bacteria can cause typhoid.

Fatty or high-protein foods may protect the bacteria from stomach acid, making infection more likely. Common symptoms of typhoid include:

• Fever lasting more than a week and not improving with regular fever medicine
• Extreme fatigue and headache
• Muscle and joint pain
• Bloating, diarrhea, nausea, vomiting
• Cough and weight loss

The illness can last weeks to months depending on how many bacteria entered the body and when treatment begins. If untreated, typhoid can lead to serious complications like anemia, intestinal bleeding, a ruptured intestine, nerve problems, or blood clotting disorders.

How to Prevent Typhoid?

Effective prevention requires access to clean water, proper sanitation, and safe waste disposal. To reduce your risk:

• Wash your hands regularly
• Drink bottled or boiled water
• Avoid street food
• Get vaccinated before traveling to high-risk areas

In Western Europe and North America, typhoid cases have dropped significantly thanks to clean municipal water systems, milk pasteurization, and preventing food contamination. However, because S. typhi is becoming increasingly resistant to antibiotics, vaccination is now an important and practical way to prevent infection.

The Importance of Microbiological Laboratory Testing to Prevent Typhoid Transmission

If you work in the food, drinking water, or public service sectors, microbiological laboratory testing is a crucial step in preventing the risk of transmitting pathogenic bacteria like Salmonella typhi. This testing helps ensure that products and environments meet safety and hygiene standards. IML Research provides comprehensive and standardized microbiological testing services to accurately detect bacterial contamination. With valid test data, risk prevention and control decisions can be made more accurately. Protect your consumers and your business reputation through reliable microbiological laboratory testing.

Author: Safira
Editor: Sabilla

Reference:

Buzilă, E. R., Dorneanu, O. S., Trofin, F., Sima, C. M., & Iancu, L. S. (2025). Assessing Salmonella Typhi Pathogenicity and Prevention: The Crucial Role of Vaccination in Combating Typhoid Fever. International Journal of Molecular Sciences, 26(9), 3981. https://doi.org/10.3390/ijms26093981