Introduction

Tularemia is a condition commonly known as ‘rabbit fever’. It is caused by an infectious bacterium known as Francisella tularensis. Tularemia is a zoonotic disease, which means it is spread from animals such as rodents and rabbits.¹ Although rare, it is still able to affect a wide population of individuals. Therefore, it has been advised for travellers to take proper precautions. For example, those engaged in outdoor activities such as hiking, camping, or hunting are particularly at risk. Without proper precautions, exposure to this bacterium can lead to severe illness, making it crucial for travellers to take proactive measures to protect themselves.² 

This article aims to address the transmission of tularemia, symptoms and preventative measures. 

Understanding tularemia 

Tularemia can be contracted in various ways, including:

• Skin-to-skin contact with infected animals, such as rabbits
• Drinking contaminated water that has been contaminated with infected animal faeces 
• Inhaling airborne bacteria
• Insect bites, e.g. from mosquitoes or ticks³ 

The symptoms of tularemia begin with common manifestations such as a fever, headache, loss of appetite, fatigue and/or joint pain. These symptoms usually take 3-5 days to appear after initial exposure to the bacteria^. There are also some specific symptoms dependent on the way the individual was infected.⁴

For example, 

• If bitten by a mosquito:

When bitten, the area surrounding the bite may have a rash or begin to swell. This can also have effects on the lymph nodes, where the lymph nodes become swollen and painful. These cases account for 75% of tularemia cases. Although, there is also another form whereby there are no skin symptoms before the lymph node is affected. ⁴

• If infected through inhalation:

If inhaled, the bacteria may cause an infection to manifest in the lungs, leading to complications such as fluid around the lungs, breathing problems and pneumonia. However, symptoms such as pneumonia only occur in very severe cases.

• If infected via consumption or contact of contaminated water or meat:

Contact with contaminated water can lead to eye irritation and inflammation of the eye membrane, commonly known as conjunctivitis. The infection may also spread to nearby lymph nodes, resulting in swelling and discomfort. 

Common areas 

Tularemia is most commonly found in regions with rural, wooded, or water-rich environments that support large populations of animals and insects capable of transmitting the Francisella tularensis bacterium. 

Common areas that harbour the bacterium include North American states such as Arkansas, Missouri and Oklahoma. This is due to the vast rural areas and interactions with wildlife. There is also risk in areas such as South Dakota, Nebraska, and Kansas, as well as parts of the western U.S., including Montana, Wyoming, Colorado, New Mexico, and Utah.⁵

In Europe, there have been reports of cases in Sweden and Finland where the transmission of tularemia is due to bites by either ticks or mosquitoes.⁶ Other European countries, including Austria, Hungary, Slovakia, and the Czech Republic, frequently report cases due to the presence of wildlife and extensive forestry. There have also been reports in countries such as France and Spain, however, these are quite sporadic and usually related to agriculture. However, Turkey is a known hotspot for tularemia infections due to an increased risk of water contamination in rural and agricultural areas.⁷

These high-risk areas all share common factors that increase the likelihood of tularemia transmission, such as abundant wildlife (particularly rabbits and rodents), insect vectors like ticks and mosquitoes, and outdoor activities in rural, forested, or agricultural environments. Exposure to untreated water sources also poses a risk in these regions

Preventative measures

Anyone travelling to these areas should ensure to take appropriate precautions in order to protect themselves from any potential infection. These include checking the WHO website for any precautions or vaccinations needed before travelling, wearing insect repellents, avoiding contact with wild animals, and ensuring that the food and water they consume are clean and properly treated to reduce any risk of infection.⁸ 

Further measures

Avoiding direct animal contact

Since tularemia can be transmitted through contact with animals like rabbits and rodents, travellers should exercise caution when handling these animals, whether alive or dead, as the bacteria can survive in the animal’s body even at low temperatures. To minimise the risk of infection, it is strongly recommended that individuals wear gloves when handling wildlife.⁹

Preventing insect bites

In order to prevent insect bites from carriers such as mosquitoes and ticks, travellers should wear an appropriate amount of insect repellent, particularly containing picaridin, DEET or Oil of Lemon Eucalyptus (OLE). Individuals are also advised to perform a tick check after being in heavily wooded areas. If found, the ticks should be removed with fine tweezers. To further reduce risk, travellers should avoid areas with thick vegetation. If avoiding these areas is not feasible, such as when working outdoors or camping, minimising skin exposure by wearing protective clothing such as long sleeves, long trousers, and long socks is recommended.¹⁰

Having safe food and water sources

As tularemia can be transmitted through the consumption of contaminated food and water, travellers should avoid drinking from lakes or rivers, which may be a risk of contamination. It is advisable to carry bottled water when visiting rural areas. Additionally, any game meat caught should be thoroughly cooked to eliminate any bacteria to reduce the risk of infection.

Protecting respiratory health

In some cases, tularemia can be contracted by inhaling the bacteria. This is especially a concern when engaging in tasks or activities that stir up contaminated soil or plant material, such as digging, mowing or farming in areas where tularemia is prevalent. To minimise this risk, travellers should wear masks in situations where exposure to potentially contaminated dust is likely.¹⁰

​​By taking these preventive steps, travellers can significantly reduce the risk of infection when travelling or participating in certain activities. 

Seeking medical attention

Travellers visiting tularemia-endemic areas should be aware of the importance of seeking prompt medical attention if they suspect exposure to the bacteria or begin experiencing symptoms. This is due to the early symptoms of tularemia, which include fever and swollen lymph nodes, which can appear as large bumps on the body and be mistaken for more common and less serious illnesses. Another important reason for seeking medical care urgently is that tularemia can progress rapidly, potentially leading to severe complications such as pneumonia or sepsis. Therefore, recognising the common signs and symptoms in order to obtain medical attention as soon as possible is essential.¹¹ 

When seeking medical care, it is important to inform your healthcare provider about any recent activities that involve high-risk regions. This is because by knowing this information, the healthcare provider can come to a quicker diagnosis to run the correct tests. 

In order to diagnose tularemia, healthcare professionals may carry out a series of tests. The tests conducted may include a blood test in order to look for signs of tularemia in your blood. However, the bacteria that cause tularemia may not appear in the early stages, hence, a blood test may need to be repeated. If your lymph nodes are swollen, a biopsy may be taken. This is when a sample of your tissue is taken to be analysed in the lab for the presence or growth. Additionally, a nasal or throat swab may be taken depending on the way it may have been contracted.⁵

Treatment 

The first line of treatment for tularemia involves the use of antibiotics, which are most effective when administered early in the course of the infection. Commonly prescribed antibiotics include streptomycin, gentamicin, doxycycline, and tetracycline.¹² The choice of antibiotic depends on the severity of the infection. Streptomycin is the first-line medication administered by intravenous injection when presenting with tularemia symptoms. Depending on the patient's response and the severity of infection, the duration of antibiotic treatment generally ranges from 10 to 21 days.¹⁰

At present, there are no approved vaccination programs for tularemia, however, research and clinical trials are ongoing to make it more applicable to the wider population.¹¹  

Summary

Tularemia is an infection caused by the bacteria Francisella tularensis (F.tularensis). This condition is transmitted through insect bites, contact with infected animals, both alive and dead or through the consumption of contaminated food or water. Endemic areas include North America and parts of Europe, and Asia. Individuals travelling to these areas are advised to take preventative measures. For example, using insect repellent, avoiding direct contact with wild animals that are known to carry the bacteria, as well as ensuring food and water are clean and safe for consumption. 

As soon as symptoms like fever or swelling of lymph nodes or ulceration of the skin appear after possible exposure to a F.tularensis, prompt medical attention is essential, as antibiotics like streptomycin can prevent serious complications. Therefore, taking the appropriate precautions and knowing the signs and symptoms of infection can aid in reducing the risk of tularemia infection.