Fever at Sea

Dr Benjamin Dunton / Rural Generalist Registrar / Kavieng, New Ireland Province, Papua New Guinea

Ben is currently working in remote primary and emergency healthcare in Papua New Guinea. The location is popular with adventurous surfers, divers, and billionaires arriving on superyachts. On occasion, they become unstuck and require emergency healthcare. Ben describes a recent case of acute febrile illness.

Abstract

This case review examines the diagnosis and management of a traveller experiencing an acute febrile illness in tropical Papua New Guinea. The case underscores the critical role of thorough pre-departure evaluation and adept management of febrile conditions in tropical environments.

The case describes a patient experiencing severe headaches, fever, and rigours on a luxury yacht cruise without appropriate malaria prophylaxis or knowledge of the risks associated with mosquito-borne diseases. The detection of malaria through a positive rapid diagnostic test (RDT) led to a treatment plan incorporating intramuscular artemether in addition to empirical antibiotics before private jet transfer to an overseas healthcare facility.

The review examines the literature on the diagnostic challenges of tropical medicine. It highlights the greater prevalence of non-tropical diseases in travellers compared to tropical diseases, while emphasising the significant burden of malaria to febrile illness and mortality in these situations. Furthermore, the review evaluates the accuracy of rapid diagnostic tests (RDTs) for diagnosing tropical diseases such as malaria, dengue, and typhoid in areas with limited resources. It outlines a management strategy for undifferentiated acute febrile illness in tropical locations.

Introduction

As the world’s population grows and the collective desire for adventure increases, more holidaymakers are exploring destinations worldwide. Many of these destinations are idyllic tropical settings, which offer an escape from the bitter cold of winter and the monotony of urban life. However, travel to these areas presents unique challenges. These include the risk of tropical infectious diseases, extreme environmental conditions that stress unacclimatised bodies, and often remote locations with limited access to medical care. As a result it is now essential for all healthcare professionals to understand the common causes and management strategies for acute febrile illnesses in tropical environments. Those working in non-tropical regions must be equipped to conduct pre-departure assessments as well as evaluate and manage febrile patients returning from travel. Similarly, health professionals in tropical areas must be adept at caring for febrile travellers, particularly in isolated and resource-limited settings.

Case Presentation

Patient Information

This case concerns a male in his late sixties of European descent, with a medical history including obesity, dyslipidaemia, hypertension, mild fatty liver disease, and benign prostatic hypertrophy. His medications comprised of antihypertensives, a statin, and tamsulosin-dutasteride for prostate management. He had no reported allergies.

Situation

The patient had embarked on a 14-day luxury superyacht cruise around Papua New Guinea’s remote islands. The 168-foot vessel hosted approximately eight guests and twelve crew members. The vessel was equipped with a comprehensive medical kit, which did not meet all of the requirements for Category A vessels as outlined by the UK Maritime and Coastguard Agency (MCA).¹  This discrepancy was likely due to a provision which permits adjustments based on the recommendations of a qualified health professional to suit the crew’s needs and the voyage’s specifics. The captain was responsible for medical care and had access to international maritime medical support. A private plane was utilised to transport guests to the yacht and was stationed on standby in Northern Australia for the duration of the cruise.

The cruise offered guests yacht-based activities such as snorkelling, diving, jet skiing, and occasional land-based adventures such as jungle hikes and white-water rafting. Throughout the journey, the health of all staff and the other guests remained stable, and no acute illnesses were reported. However, despite the voyage’s location and occasional land excursions into dense jungle, no malaria prophylaxis was provided to guests or crew, underestimating the mosquito exposure risk during onshore activities in Papua New Guinea. Furthermore, preventative measures against insect bites were not taken for land excursions, and guests were not informed about the risks of mosquito-borne diseases prevalent in this tropical region.

Clinical Assessment

The focus of this case, a male in his late sixties, started experiencing a mild headache and lethargy the evening before seeking medical care. Upon return from a remote health patrol, an Australian doctor volunteering in the province received a phone call informing them that the vessel was en route to port for medical care due to the patient’s worsening condition. Over the day, the patient’s headache intensified, becoming severe, accompanied by high fevers peaking at 39.8°C, rigours, and sinus tachycardia with heart rates ranging from 100-120 beats per minute. He remained normotensive. The patient reported no other symptoms in the previous three days, and neither the guests nor the crew had observed any further symptoms before this deterioration.

Upon boarding the yacht, a thorough examination and history revealed numerous mosquito bites within the past 14 days. The individual reported no respiratory, urogenital, cutaneous or gastrointestinal symptoms. They had not recently started any new medications. There was no reported recreational drug use or high risk sexual activity. The examination confirmed the patient’s account, noting only subtle suprapubic tenderness and persistence of the tachycardic but normotensive state, with fevers slightly reduced to the 38°C range after paracetamol.

Diagnostic Assessment

Before boarding the yacht, the doctor prepared a list of differential diagnoses, aiming to refine them through clinical evaluation and bedside testing. The primary considerations for fever in a visitor to Papua New Guinea included acute tropical and non-tropical infectious diseases and rare non-infectious causes such as medication side effects, hypermetabolic states like thyroid storm, or inflammatory conditions such as vasculitis.

The doctor requested and reviewed the yacht’s medical supplies list, noting an absence of malaria rapid diagnostic tests (RDTs) and antimalarial medications. This review enabled them to gather these crucial supplies, an intravenous cannula, and fluids before heading to the yacht. This ensured preparedness for as many potential diagnoses as possible. The doctor directed the crew to give the patient paracetamol and promote oral hydration to control fever and maintain fluid balance while they made it to the yacht.

In this remote part of Papua New Guinea, diagnostic options were limited. The absence of urine analysis, dengue and typhoid RDTs, and non-operational x-ray equipment at the local hospital further constrained diagnostic capabilities. The primary differential diagnosis in a man in his late sixties, presenting with severe headache, fever, and rigours after a 14-day trip to Papua New Guinea, was malaria. This was supported by a weakly positive RDT. Differential diagnoses included urinary tract infection, dengue, typhoid, and rickettsial infection. However, the lack of specific tests for these conditions required reliance on clinical judgment and the patient’s response to empirical treatment.

Management

Initial management involved administering paracetamol for fever and promoting oral hydration. Following assessment, targeted interventions began, including 3.2mg/kg of intramuscular artemether for suspected malaria. This was chosen for its once-daily dosing effectiveness and the practicalities of administration in a human resource-limited setting.²  Concurrently, to cover potential bacterial infections, 2g of ceftriaxone was given intramuscularly, empirically addressing alternative causes of fever, including urinary and respiratory infections, typhoid, rickettsial diseases, and meningococcal infections.^3-6 Oral artemether/lumefantrine was also supplied to allow continued treatment once a higher-level medical facility was reached, in anticipation of potential delays in accessing malaria treatment in non-endemic regions.

In the absence of glucose monitoring, the patient was advised to consume one glass of sugar-added fluids for every two of water to prevent hypoglycemia. The yacht crew monitored the patient every six hours for signs of deterioration, with thresholds set for seeking further medical assistance. Arrangements were made for expedited transfer the following morning to an overseas tertiary healthcare facility using the patient’s private plane, ensuring timely and safe transportation.

Follow-up and Outcomes

The patient showed improvement overnight, with reduced fever and tachycardia, but remained in a suboptimal location for ongoing management. Given the patient would arrive at the tertiary hospital within 24 hours and the continued effect of the administered artemether and ceftriaxone, no further doses were given pre-transfer. Stable and afebrile, he was deemed fit for travel without medical escort on his private plane from Papua New Guinea. He remained stable during the flight and recovered sufficiently at the tertiary facility. Unfortunately the precise cause of his fever, with its wide differential, was never communicated back to Papua New Guinea.

Discussion

This case required the doctor to navigate various diagnostic and therapeutic decisions with limited support and access to resources. Reflecting on this experience, a thorough review of the diagnostic and management processes has shed light on potential improvements and modifications to this doctors clinical practice while working in remote tropical locations. These insights aim to improve patient outcomes in similar situations encountered in the future. The details in the subsequent sections aim to share this knowledge with other healthcare professionals working in or aspiring to work in similar tropical environments.

Febrile Illness in Tropical Environments

This case underscores the difficulties in diagnosing and treating acute febrile illnesses in remote tropical settings like Papua New Guinea, highlighting the need for a comprehensive list of differential diagnoses for travellers with fever and nonspecific symptoms. In such cases, non-tropical infectious diseases, including respiratory and urinary tract infections, are the most prevalent cause, accounting for 39% of cases.⁷ Tropical infectious diseases follow closely at 33%, whereas non-infectious causes of fever represent a mere 0.5% of febrile illnesses in travellers to tropical regions.⁷ Malaria stands out as the predominant organism to cause fever in travellers to tropical regions (22%). It has a mortality rate of 0.2-0.5%, causing 25-55% of infectious disease related deaths among travellers, hence testing for and treating malaria is essential.^6-10

Dengue fever is the second most common organism to cause fever among travellers to tropical areas, constituting 5.2% of cases. However it does presents a significantly lower mortality and complication rate compared to malaria.^6-9  Other significant tropical diseases include enteric fever (typhoid and paratyphoid) and rickettsial infections.^6,7,9  Less common causes, accounting for under 2% of cases, include schistosomiasis, helminthic infections, amebiasis, viral haemorrhagic fevers, brucellosis, melioidosis, and borreliosis.⁷

To summarise, the primary causes of a fever in a traveller on a short, less than two week, tropical holiday include; ^6-17

• 39% non-tropical infectious diseases, such as respiratory and urinary tract infections
• 33% tropical infectious diseases
• 0.5% non-infectious diseases, such as vasculitides

The five most common tropical infectious diseases are listed in the table below.^6-17

Field Diagnosis of Tropical Infectious Diseases

Rapid Diagnostic Tests (RDTs) have revolutionised the diagnosis of acute febrile illnesses in resource-limited tropical settings. They provide accurate in-field confirmation of major causes like malaria, dengue, and typhoid. For malaria, RDTs show remarkable sensitivity and specificity, particularly for Plasmodium falciparum, with rates exceeding 95%. This helps facilitate immediate and targeted treatment, which significantly improves patient outcomes in remote areas.^6,13,18  Dengue RDTs demonstrate a sensitivity range of 76-93% and impressive specificity over 98%. Furthermore, Typhoid RDTs, such as Typhidot, achieve sensitivity of 95-97% and specificity above 89%.¹³ By minimising the necessity for complex laboratory tests and streamlining the diagnostic workflow, RDTs have expedited the delivery of disease-specific treatments, significantly reducing the morbidity and mortality linked to these infectious diseases.

Field Management of Acute Febrile Illness in a Tropical Environment

Managing undifferentiated fever in travellers to tropical regions involves a systematic evaluation for various potential diagnoses, emphasising identifying localising symptoms to quickly narrow down the differential.⁹ The Quick Sepsis-related Organ Failure Assessment (qSOFA) and similar tools are crucial for identifying patients at risk of severe sepsis and rapid deterioration, who need urgent care and empirical antibiotics.⁹

Malaria testing using RDTs or blood smears is mandatory for all travellers to endemic areas, with positive cases treated immediately with artemisinin-based therapies.⁹  If malaria is ruled out, available dengue and typhoid RDTs should be performed, and positive results should be treated accordingly.

After ruling out malaria, dengue, and typhoid fever, if possible, consider commencing empirical antibiotic therapy with ceftriaxone (100mg/kg/day IV or IM) and doxycycline (5mg/kg/day), with the option to add azithromycin (10mg/kg/day), pending transfer for further assessment and management.¹³  Upon reaching a suitable healthcare facility, repeat malaria testing is essential to ensure no missed diagnosis. If the patient’s condition worsens in the field, empirical malaria treatment should be started with parenteral artemisinin-based therapy and empiric antibiotics, including azithromycin, until transfer to a well-equipped healthcare facility.

Learning Points

1. Seek pre-departure health assessments, vaccinations, and travel advice from a tropical medicine specialist.
2. Non-tropical infections are the leading cause of fever in travellers to tropical areas.
3. Malaria is the most common tropical disease that causes fever in travellers.
4. Dengue, Typhoid, and Rickettsial infections are other significant causes of fever in these travellers.
5. Tropical diseases often initially present with non-specific symptoms, including headache, fever, rigours, and malaise.
6. Use rapid diagnostic tests for malaria, dengue, and typhoid when available. Plan to secure a supply in advance.
7. Diagnosing illnesses in tropical environments can be challenging. When faced with uncertainty, severely ill, or deteriorating patient, opt for broad treatment. This should include artemisinin-based therapy for malaria and antibiotics, including ceftriaxone and doxycycline, with azithromycin as an optional addition to the regimen if necessary.
8. Initiate early communication with transportation, retrieval services, referral hospitals, and global health agencies. The optimal care location is typically elsewhere for unwell travellers in tropical areas. Prompt transfer of the patient to a suitable medical facility is crucial for improving outcomes.

Conclusion

This case highlights the challenges of delivering medical care in remote tropical locations, where the range of possible illnesses expands but access to diagnostic testing diminishes, complicating accurate diagnosis. A broad understanding of potential causative agents enables the implementation of wide-ranging treatment protocols to optimise patient outcomes. The key to improving patient outcomes in this setting is the early identification and treatment of malaria, coupled with swift transfer. However, clinicians must remember that most acute febrile illnesses in these regions are caused by infections common to non-tropical areas.

Optimising care for acutely febrile travellers in remote tropical settings requires a broad knowledge base and skill set, foresight in planning and anticipatory decision-making, effectively utilising limited resources and evacuation coordination for at-risk or deteriorating patients.

References

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