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Concurrent mixed infection with malaria, dengue and scrub typhus in a 5-year-old child: A rare paediatric case report
*Corresponding author: T. Sriram, Department of Pharmacy Practice, PGP College of Pharmaceutical Science and Research Institute affiliated with The Tamil Nadu Dr. M.G.R. Medical University, Namakkal, Tamil Nadu, India. drsriram2001@gmail.com
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Received: ,
Accepted: ,
How to cite this article: Sriram T, Gladia Jenifer B. Concurrent mixed infection with malaria, dengue and scrub typhus in a 5-year-old child: A rare paediatric case report. Karnataka Paediatr J. doi: 10.25259/KPJ_52_2025
Abstract
Diagnosing febrile illnesses in children from tropical regions poses significant clinical challenges due to overlapping symptoms of endemic infections such as malaria, dengue and scrub typhus. Although coinfections are uncommon, they can complicate clinical management and delay targeted therapy. We report the case of a 5-year-old boy of Odisha origin, living in Tamil Nadu, who presented with a seven-day history of high-grade, intermittent fever. Initial clinical and laboratory investigations revealed severe anaemia and thrombocytopenia. Rapid diagnostic tests confirmed co-infection with Plasmodium falciparum, P. vivax and dengue virus. The child received antimalarial drugs and supportive therapy. However, there was limited clinical improvement. Although the characteristic eschar typically associated with scrub typhus was absent, the persistent febrile course and inadequate response to treatment raised clinical suspicion of an additional co-infection. Considering the regional endemicity of scrub typhus, IgM serology was performed and tested positive. The patient was then treated with a combination of antimalarials, doxycycline, and supportive measures, including blood transfusion for anaemia. Marked clinical and haematological improvement occurred within days of initiating the revised treatment plan. This case underscores the need to consider co-infections in paediatric patients presenting with prolonged fever in endemic regions. Early clinical suspicion, prompt diagnostic workup and appropriate therapy are essential for achieving favourable outcomes in such challenging scenarios.
Keywords
Concurrent mixed infection
Dengue
Malaria
Quadruple mixed infection
Scrub typhus
INTRODUCTION
Febrile diseases in paediatric populations in tropical and subtropical countries present a considerable therapeutic challenge due to the wide range of aetiological agents and the vague characteristics of early symptoms.[1] In India, malaria remains a pressing public health issue, particularly in vulnerable populations such as infants and young children, who are at increased risk due to their underdeveloped immunity. Human malaria is primarily caused by five Plasmodium species, with Plasmodium falciparum and Plasmodium vivax being the most widespread; P. falciparum in particular is known for its association with serious clinical outcomes, including neurological involvement and multiorgan dysfunction. According to the World Malaria Report 2023, India contributes to nearly 66% of all malaria cases, underscoring the need for sustained surveillance, early diagnosis and region-specific control strategies to mitigate the disease burden.[2] In Tamil Nadu, both P. falciparum and P. vivax are reported, with seasonal peaks during and after the monsoon, contributing to a substantial proportion of paediatric febrile admissions in endemic districts.
Dengue fever, induced by one of four serotypes of the dengue virus and vectored by Aedes aegypti, has experienced a significant increase in prevalence throughout India in the past 20 years.[3] Paediatric dengue typically initiates with fever, vomiting and rash; nevertheless, it may swiftly advance to severe dengue, accompanied by complications such as vascular leakage or haemorrhage, particularly in young children from endemic areas.[4] Hepatomegaly, plasma leakage and thrombocytopenia are typical symptoms that might be confused with other infections, making early identification challenging.[5] The zoonotic disease scrub typhus, resulting from Orientia tsutsugamushi infection through chigger mite vectors, is emerging as a prominent cause of acute febrile illness in central and eastern India.[6] Scrub typhus is marked by acute fever with back pain, chills, cephalgia, emesis, myalgia, profuse perspiration and lymph node enlargement. Scrub typhus, marked by fever, eschar, lymphadenopathy and occasionally organ involvement, is frequently underdiagnosed owing to its generic symptoms and insufficient knowledge among healthcare professionals. If not promptly treated with doxycycline or azithromycin, it may result in severe consequences, including pneumonitis, meningoencephalitis, renal impairment or multiorgan failure.[7] A paediatric scrub typhus study conducted in Chennai identified six cases with co-infections, two with malaria and four with dengue, emphasising the concurrent transmission of multiple vector-borne diseases in Tamil Nadu.[8] Although these infections are commonly observed individually in endemic regions, their simultaneous occurrence in a single paediatric patient is rare and poses a significant diagnostic challenge. The overlapping clinical features often make it difficult for physicians to distinguish between them accurately.
In this report, we describe an unusual and diagnostically complex case involving a 5-year-old boy diagnosed with concurrent infections of P. falciparum, P. vivax, dengue virus and scrub typhus, successfully managed at a tertiary care centre in South India. This case report illustrates the importance of a systematic diagnostic approach, awareness of regional epidemiology and early initiation of targeted treatment to prevent adverse outcomes in paediatric patients presenting with persistent febrile illness.
CASE REPORT
Initial presentation and workup
A 5-year-old boy from Odisha, residing temporarily in Tamil Nadu, presented to the Paediatric Department of Namakkal Government Medical College Hospital with a 7-day history of high-grade intermittent fever. The fever was not associated with vomiting, cough, cold or abdominal pain. There was no history of bleeding, rashes or altered sensorium. Past medical history included anaemia and prior dehydration episodes.
On general examination, the child was awake, alert, febrile and pale. During the time of admission, the vital signs were temperature 97.6°F, pulse rate 92/min, blood pressure 90/60 mmHg and respiratory rate within normal limits. Abdominal examination revealed right hypochondriac tenderness with a palpable spleen. Central nervous system examination was normal. Initial investigations revealed severe anaemia with haemoglobin of 5.1 g/dL and thrombocytopenia (platelet count 50,000/μL), with normal total white blood cell (WBC) count. Biochemical evaluation indicated that renal parameters and hepatic enzymes remained within physiological limits. Ultrasound of the abdomen showed minimal free fluid in the hepatorenal pouch. Urine examination was unremarkable. Peripheral smear and rapid antigen testing were positive for both P. falciparum and P. vivax. Dengue non-structural protein 1 antigen was also positive.
First-line management
Based on these findings, the child was started on intravenous (IV) fluids, injection ceftriaxone 850 mg IV three times a day (TDS), injection paracetamol 17 mL every six hours (Q6H), capsule doxycycline 100 mg and tablet chloroquine 250 mg. Supportive therapy included IV ranitidine and close monitoring of vitals and fluid status.
Persistent symptoms and re-evaluation
Despite receiving appropriate antimalarial and antibiotic therapy, the patient continued to have persistent fever, and platelet counts remained low. By day 3, haemoglobin had declined further to 4.9 g/dL, with platelets decreasing to 47,000/μL and packed cell volume to 16.5%. On day 5, the child received a 170 mL packed red blood cell transfusion, after which haemoglobin increased to 8.3 g/dL and platelets rose to 2.41 lakh/μL by day 6. Although haematological indices improved, the sustained fever despite adequate therapy prompted a broader diagnostic re-evaluation. No eschar was identified on repeated examinations. Given the unresolved febrile state, suboptimal clinical response and the high endemicity of scrub typhus in the region, further investigation for possible co-infection was undertaken. Serological testing for O. tsutsugamushi immunoglobulin M returned positive, confirming scrub typhus as an additional diagnosis.
Final diagnosis and recovery
On day 6, a final diagnosis of mixed infection involving malaria (P. falciparum and P. vivax), dengue and scrub typhus was established. The treatment regimen included artesunate 50 mg, sulphadoxine–pyrimethamine 525 mg and primaquine 2.5 mg on the first day, followed by artesunate 50 mg and primaquine 2.5 mg for the next 3 days and primaquine 2.5 mg alone for the subsequent 10 days. Capsule doxycycline 100 mg had been initiated empirically at the time of admission; however, significant clinical improvement was observed only after the initiation of targeted antimalarial therapy, alongside altering doxycycline 250 mg (½–0–½) for confirmed scrub typhus. Supportive care comprised IV pantoprazole 17 mg once daily and paracetamol as needed. Within 48–72 h, the child demonstrated marked clinical improvement: Fever subsided, splenic tenderness resolved and appetite returned. Physical examination findings, including chest auscultation and abdominal assessment, were normalised and serial laboratory investigations confirmed restoration of haemoglobin, WBC and platelet counts to normal ranges. Table 1 shows the trends of hematological parameters, including haemoglobin levels, white blood cell (WBC) counts and platelet counts, over the course of admission. The data indicate that haemoglobin gradually increased from 5.1 grams per deciliter on day 1 to 11.2 grams per deciliter by day 14. Similarly, WBC counts initially decreased from 5100 cells per micro liter to 3000 cells per micro liter by day 2, followed by a progressive rise to 6100 cells per micro liter by day 14. Platelet counts showed a significant improvement from a critically low count of 50,000 cells per micro liter on day 1 to 250,000 cells per micro liter by day 14, reflecting clinical recovery. The child made a complete recovery and was discharged upon completion of the prescribed treatment regimens.
| Day of admission | Haemoglobin (g/dl) | White Blood Cells (cells/µl) | Platelets (cells/µl) |
|---|---|---|---|
| Day 1 | 5.1 | 5100 | 50,000 |
| Day 2 | 5.2 | 3000 | 48,000 |
| Day 3 | 4.9 | 4000 | 47,000 |
| Day 4 | 5.3 | 5000 | 93,000 |
| Day 8 | 8.3 | 5900 | 241,000 |
| Day 14 | 11.2 | 6100 | 250,000 |
DISCUSSION
Although individual infections with Plasmodium spp., dengue virus and O. tsutsugamushi are common in endemic tropical regions such as South India, their concurrent presence in a single paediatric patient is exceedingly rare and poses significant diagnostic and therapeutic challenges. Co-infections may not only exacerbate disease severity but also confound clinical judgment due to overlapping symptomatology, such as persistent fever, thrombocytopenia, hepatosplenomegaly and deranged haematological parameters. At presentation, the child was categorised under acute febrile illness, a broad clinical syndrome in tropical paediatric practice that necessitates consideration of multiple infectious aetiologies. The absence of eschar in this patient further complicated the diagnosis. Although eschar is recognised as a pathognomonic feature of scrub typhus, it is not universally present, particularly in paediatric populations. Potential reasons for its absence include subtle or atypical lesion morphology, localisation to concealed anatomical sites such as the scalp, groin or axilla and variations in host immune response or skin sensitivity compared to adults. Notably, co-infection with P. falciparum, P. vivax and scrub typhus has previously been reported in young adult male patients from central India[9] and coinfection of malaria and scrub typhus in paediatric cases from Pondicherry, India.[10] Published literature on quadruple infections involving P. falciparum, P. vivax, dengue virus and scrub typhus without external eschar co-existing in a single paediatric patient is extremely limited. To the best of our knowledge, this case represents one of the first documented reports from India describing such a rare combination in a 5-year-old child, successfully diagnosed and treated at a government tertiary care centre, Tamil Nadu.
CONCLUSION
This case underscores the importance of maintaining a high degree of clinical suspicion when assessing febrile illnesses in paediatric patients residing in endemic regions, particularly during the pre- and post-monsoon periods. While dengue, malaria and scrub typhus are frequently encountered individually in tropical regions, their simultaneous manifestation is unusual and presents considerable diagnostic and therapeutic complexity due to overlapping clinical signs and laboratory findings. Timely identification of such co-infections, comprehensive diagnostic evaluation and early initiation of appropriate therapy are essential to optimise patient outcomes and prevent complications. Strengthening diagnostic capabilities and enhancing the clinical competence of healthcare providers at the primary and secondary care levels is crucial for the early recognition and effective management of these multifaceted cases, particularly in settings with limited resources.
Ethical approval:
Institutional review board approval is not required.
Declaration of patient consent:
The authors certify that they have obtained all appropriate patient’s consent.
Conflicts of interest:
There are no conflicts of interest.
Use of artificial intelligence (AI)-assisted technology for manuscript preparation:
The authors confirm that there was no use of artificial intelligence (AI)-assisted technology for assisting in the writing or editing of the manuscript and no images were manipulated using AI.
Financial support and sponsorship: Nil.
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