10 Important Tropical Infections and Recommendations to Stay Safe on Your Journey

Most of us are familiar with the viruses that are rampaging through our own countries, but less so with the diseases affecting other parts of the world. Tropical infections, encompassing infections occurring in the tropical and subtropical regions, are a particular concern for travellers from temperate countries who might encounter these diseases during their explorations. 

Introduction of these infections to a country that is not endemic to the disease can lead to outbreaks, economic setbacks and even severe environmental consequences such as habitat loss. This article discusses the definition of tropical infections and the types of diseases they include.

What Are Tropical Infections?

Tropical infections commonly refer to diseases considered widespread — acquired in the tropics. This zone is located between the Tropic of Cancer and the Tropic of Capricorn, roughly 23 degrees latitude north and south of the equator¹. 

The tropics are generally humid, warm and experience frequent rainfall and consistently high temperatures. Such temperate conditions give rise to a range of infections caused by pathogens that thrive in these conditions, including certain bacteria, viruses, fungi and parasites. 

Types of Tropical Infections

Tropical infections can occur through various means such as food, water, insects, parasites, and small respiratory droplets. Contaminated food and water, especially, are major contributors to the spread of tropical diseases, largely because access to clean resources is often limited in developing countries². Below are the five main classifications of tropical infections, along with examples of diseases within each category.

Food-Borne Diseases

Food-borne illnesses are described as the illnesses that result from the contamination of food. In the context of tropical infections, food-borne diseases are often caused by bacteria, viruses and parasites.

  • Typhoid Fever: Typhoid is a potentially fatal disease caused by salmonella bacteria, prevalent in rural areas with inadequate sanitation³. It spreads when individuals consume food or drink contaminated with S. Typhi. Symptoms include persistent high fever, headache, fatigue, nausea, abdominal pain and more. 
  • Bacillary Dysentery: A more serious form of dysentery, an intestinal infection, bacillary dysentery often presents with fever, nausea, vomiting, abdominal pain, and diarrhoea containing blood or mucus. Shigella is the leading cause of dysentery⁴ (bloody diarrhoea associated due to gastroenteritis) in children in tropical regions. There is also amoebic dysentery — caused by Entamoeba histolytica, a water borne parasite.

Water-Borne Diseases

Water-related illnesses are transmitted via contaminated water, whether for recreational, drinking, food preparation or other purposes. Pathogenic microbes are behind water-borne diseases, often as a result of inadequate water treatment or poor hygiene. 

  • Cholera: Cholera is a bacterial disease that causes up to 143,000 deaths annually⁵. Characterised by watery diarrhoea, cholera can quickly escalate to dehydration and acidosis, renal failure, sometimes within hours of symptom onset. It is caused by the ingestion of water or food contaminated with Vibrio cholerae.
  • Leptospirosis: Leptospirosis can spread through contact with rat urine or contaminated water, primarily through broken skin, as well as the eyes, mouth and nose. Leptospira can infect both humans and animals. Symptoms of the blood infection include high fever, red eyes, headache, body aches, jaundice, renal failure and more.

Insect-Borne Diseases

Insect-borne diseases are a subset of vector-borne diseases, referring to infections carried by insects and transmitted to humans usually via a bite. Notably, mosquitoes are well-known vectors of a variety of diseases. The impact of insect-borne diseases is most pronounced in tropical and subtropical regions⁶.

  • Dengue Fever: Dengue fever is an illness transmitted through the bite of an infected Aedes mosquito. While it is most common in tropical and subtropical areas, about half of the world’s population is at risk of dengue⁷ today. Common signs include high fever, severe headache, pain behind the eyes and body aches. Severe dengue can lead to more serious symptoms such as shortness of breath, bleeding gums and nose, persistent vomiting and shock
  • Malaria: Malaria is classified as both an insect-borne and parasitic disease. It spreads through the bite of an infected Anopheles mosquito, which carries the malaria parasite. The parasites enter the bloodstream and travel to the liver to reproduce before reentering the bloodstream to infect red blood cells, leading to fever, flu-like symptoms and even anaemia. 

Parasitic Diseases

The transmission methods of parasitic diseases vary according to the type of parasite. Parasitic diseases can be caused by vectors, contaminated food and water, direct contact, and other means. These infections result from organisms that depend on the host’s body for survival and reproduction.

  • Hookworm: Hookworm infections are regarded as one of the most neglected and underfunded tropical diseases⁸. This infection involves parasites called hookworms, which enter through the skin then reside in the intestines, feeding on the host’s blood.
  • Chagas Disease: Chagas disease, also known as American trypanosomiasis, is caused by a protozoan parasite found in various environments, including our food and water; but most get it through contact with the faeces of triatomine bugs. While it’s possible to eliminate the parasite during the acute phase of the disease, individuals suffering from the chronic (long-term) phase have to adapt to managing their symptoms. Acute Chagas disease symptoms include localised swelling, fever, rashes and more.

Airborne Diseases

Pathogenic microbes that are small enough to be expelled through sneezing, coughing and talking are classified as airborne diseases. Due to the aerosol nature of these infections, simply breathing in contaminated air can put you at risk of contracting them.

  • Meningococcal Meningitis: Meningococcal meningitis is a rare but dangerous bacterial infection that affects the meninges, which is the membranes that cover and protect the brain and spinal cord. It is passed on through respiratory droplets and saliva.
  • Tuberculosis: Commonly shortened as TB, tuberculosis often attacks the lungs, although it can also affect other parts of the body. There are three stages of tuberculosis, namely primary, latent and active TB infection. Active TB is characterised by a cough (sometimes accompanied by mucus or blood), chest pain, fever, fatigue and others. The majority of the TB burden is concentrated in tropical countries, accounting for 98% of the deaths⁹. TB is also not uncommon in some communities in temperate countries including homeless people, immigrants and HIV-injected individuals.

Health Recommendations for Travellers

Here are some guidelines to help travellers reduce their risk of contracting tropical diseases. These preventive measures, coupled with good hygiene practices, can make travelling to or living in tropical areas safer.

Pre-Travel Preparation

Check for available vaccinations and conduct health checkups to ascertain your condition before visiting high-risk areas. While some diseases such as malaria do not have vaccines, others like cholera and typhoid do. Research the health implications associated with your destination and ensure you pack appropriate medications and supplies to protect and care for yourself, like mosquito repellents and personal hygiene products.

During Travel

Think twice before engaging in risky behaviours such as swimming in unfamiliar rivers and lakes. Always practise good hygiene, including proper hand washing, and ensure your food is cooked thoroughly to eliminate the risk of foodborne illnesses. Stay alert for local health advisories and remain mindful of your surroundings. Remember, in areas with soil-borne parasites, even walking barefoot can pose a danger.

Emergency Preparedness

Familiarise yourself with the location and contact details of local health facilities, and seek prompt medical attention if you feel something is amiss, such as if you experience any symptoms — no matter how mild. Don’t delay seeking help until the situation becomes dire. Early treatment is crucial for effectively managing most diseases. 

For more information on tropical infections, visit our page here.

References

  1. About Tropical Infections. ID Specialists. https://idspecialists.sg/infections-treatments/tropical-infection/. Accessed August 27, 2024.
  2. Tropical Diseases. American Society of Tropical Medicine & Hygiene. https://www.astmh.org/education-resources/tropical-medicine-q-a/major-tropical-diseases. Accessed August 27, 2024.
  3. Typhoid Fever: Causes, Symptoms & Treatment. Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/17730-typhoid-fever. Accessed August 27, 2024.
  4. Dejkam A, Hatam-Nahavandi K. Dysentery in Children. Iranian Journal of Public Health. https://doi.org/10.18502/ijph.v50i9.7082. Accessed August 27, 2024.
  5. World Health Organization. Cholera. https://www.who.int/health-topics/cholera. Accessed August 27, 2024.
  6. World Health Organization. Vector-borne diseases. https://www.who.int/news-room/fact-sheets/detail/vector-borne-diseases. Accessed August 27, 2024.
  7. World Health Organization. Dengue and severe dengue. https://www.who.int/news-room/fact-sheets/detail/dengue-and-severe-dengue. Accessed August 27, 2024.
  8. Ghodeif AO, Jain H. Hookworm. PubMed. https://www.ncbi.nlm.nih.gov/books/NBK546648/. Accessed August 27, 2024.
  9. Zammarchi L, Bartalesi F, Bartoloni A. Tuberculosis in Tropical Areas and Immigrants. https://www.researchgate.net/publication/263431595_Tuberculosis_in_Tropical_Areas_and_Immigrants. Accessed August 27, 2024.