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Year : 2017  |  Volume : 35  |  Issue : 3  |  Page : 402--405

Evaluation of concurrent malaria and dengue infections among febrile patients

Parul D Shah, Tanmay K Mehta 
 Department of Microbiology, Smt. N.H.L. Municipal Medical College, Ahmedabad, Gujarat, India

Correspondence Address:
Tanmay K Mehta
M-4-67-521, Shastrinagar Shopping Centre, Naranpura, Ahmedabad - 380- 013, Gujarat
India

Abstract

Context: Despite a wide overlap between endemic areas for two important vector-borne infections, malaria and dengue, published reports of co-infections are scarce till date. Aims: To find the incidence of dengue and malaria co-infection as well as to ascertain the severity of such dengue and malaria co-infection based on clinical and haematological parameters. Setting and Design: Observational, retrospective cross-sectional study was designed including patients who consulted the tertiary care hospital of Ahmedabad seeking treatment for fever compatible with malaria and/or dengue. Subjects and Methods: A total of 8364 serum samples from clinically suspected cases of fever compatible with malaria and/or dengue were collected. All samples were tested for dengue NS-1 antigen before 5 days of onset of illness and for dengue IgM after 5 days of onset of illness. In all samples, malaria diagnosis was based on the identification of Plasmodium parasites on a thin and thick blood films microscopy. Results: Only 10.27% (859) patients with fever were tested positive for dengue and 5.1% (434) were tested positive for malaria. 3.14% (27) dengue cases show concurrent infection with malarial parasites. Hepatomegaly and jaundice 37.03% (10), haemorrhagic manifestations 18.51% (5) and kidney failure 3.7% (1), haemoglobin <12 g/dl 100% (27) and thrombocytopenia (platelet count <150,000/cmm) 96.29% (26) were common in malaria and dengue co-infections and were much more common in Plasmodium falciparum infections. Conclusion: All febrile patients must be tested for malaria and dengue, both otherwise one of them will be missed in case of concurrent infections which could lead to severe diseases with complications.

How to cite this article:
Shah PD, Mehta TK. Evaluation of concurrent malaria and dengue infections among febrile patients.Indian J Med Microbiol 2017;35:402-405

How to cite this URL:
Shah PD, Mehta TK. Evaluation of concurrent malaria and dengue infections among febrile patients. Indian J Med Microbiol [serial online] 2017 [cited 2020 Apr 1 ];35:402-405
Available from: http://www.ijmm.org/text.asp?2017/35/3/402/216611

Full Text

 Introduction



Vector-borne infections such as malaria and dengue are of major public health concern worldwide. The former is a parasitic disease transmitted by Anopheles mosquito, and the latter is a viral disease transmitted by Aedes mosquito.

In a geographical area where both the vectors coexist, simultaneous occurrence of malaria and dengue in an individual cannot be ruled out. The two diseases share many clinical features and may be clinically indistinguishable. It is important; however, to differentiate between the two conditions, otherwise, it may result in a poor outcome.

Despite a wide overlap between endemic areas for these vector-borne infections, published reports of co-infections are very scarce till date. Very few publications described proven or suspected associations, but always as isolated cases.[1],[2],[3],[4],[5],[6]

Objective

The aim of our study was to find out the incidence of dengue and malaria co-infection as well as to ascertain the severity of such dengue and malaria co-infection based on clinical and haematological parameters.

 Subjects and Methods



We carried out an observational retrospective cross-sectional study on patients who consulted the tertiary care hospital of Ahmedabad for fever compatible with malaria and/or dengue during 1.5 years period, from June 2013 to November 2014.

A total of 8364 blood samples were collected from clinically suspected cases of fever compatible with malaria and/or dengue. All samples were tested for dengue NS-1 antigen ELISA on or before 5 days of onset of illness and for dengue IgM ELISA after 5 days of onset of illness. Malaria diagnosis was based on the identification of Plasmodium parasites on a thin and thick blood films microscopy in all samples.

All demographic, clinical, haematological and other laboratory parameter data were collected and analysed.

 Results



Only 10.27% (859) patients with fever were tested positive for dengue, and 5.1% (434) were tested positive for Plasmodium parasite. Only 3.14% (27) cases show concurrent infection with dengue virus and Plasmodium parasites. Of these, 62.96% (17) were positive for Plasmodium vivax, 33.33% (9) were Plasmodium falciparum and 3.7% (1) case of mixed infection with P. vivax and P. falciparum. As per recent (2009) WHO classification for dengue cases, out of 859 dengue-positive cases, 50.6% (435) were dengue without warning signs (D), 37.6% (323) were dengue with warning signs (DW) and 11.8% (101) cases were severe dengue (SD). Out of total malaria and dengue concurrent infections, 11.11% (3) were dengue without warning signs, 55.55% (15) were DW signs and 33.33% (9) cases were SD cases [Table 1].[7],[8] All the co-infection cases presented after 5 days of febrile illness and were positive for dengue IgM ELISA.{Table 1}

Complications such as hepatomegaly and jaundice 37.03% (10); haemorrhagic manifestations 18.51% (5) and kidney failure 3.7% (1) are common in malaria and dengue co-infections. These complications are more common if P. falciparum infection is present [Table 2]. Important haematological parameters in dengue and malaria co-infection cases are summarised in [Table 3] showing haemoglobin <12 g/dl in 100% (27) and thrombocytopenia (platelet count <150,000/cmm) in 96.29% (26) cases. No mortality was detected in dengue and malaria co-infection cases.{Table 2}{Table 3}

 Discussion



Dengue and malaria, both are preventable vector-borne diseases. Coexistence of both is very important to understand as both have almost similar signs and symptoms but entirely different treatment protocols. Simultaneous presence of both the infections in one individual can easily be missed as detection of any one of them in an acute febrile patient can mask the diagnosis of other.

In the present study, the incidence of concurrent dengue and malaria infection was 3.14%. The incidence of concurrent infection in other studies has been quite variable and range from 1% in French Guiana[2] to 6% in India and 27% in Pakistan.[3],[4] Classical concept of malaria occurring in rural areas and dengue in urban areas has been challenged in many reports from different countries due to overlap of mosquito biotypes.[9] As only hospitalised patients were included in the study, this co-infection incidence does not represent incidence in community or local population. We could not determine the vector load which would have been helpful in determining the concurrent infection in a locality. Other published studies also had similar limitation.[10],[11]

In published case reports, the diagnosis of dengue infection is usually made based on positive dengue IgM; however, this cannot confirm recent dengue with certainty because IgM can persist for months and cross-react with other arboviruses.[][1],[2],[3],[4],[5],[6],[12],[13] In our study, the presence of both malaria and dengue in a patient at one point of time was presented after 5 days of febrile illness, and all these cases were positive for dengue IgM ELISA. This could be a concurrent infection of patients with dengue virus and Plasmodium parasite. Another possibility could be an infection of malarial parasites in a previously infected dengue patient with persistent dengue IgM in their serum. Dengue patients can have poor immunity during convalescence which makes them susceptible to other infections. Beyond 1 week of fever, if dengue infection shows no signs of improvement to conservative treatment, consider other possibilities of co-infections most importantly malaria.

In the present study, P. vivax was present in the majority of the cases (62.96%) similar to study done in French Guiana and Pakistan showing P. vivax in 63.9% and 96.2% cases.[10],[11] This can be attributed to the species prevalent in a particular geographical region.

The clinical features of dengue and malaria co-infection were more like dengue mono-infection than malaria mono-infection. Therefore, clinically, it is difficult to diagnose concurrent dengue and malaria. As 89% of total concurrent malaria and dengue concurrent infection belong to DW signs and SD implicating the role of malaria in increasing severity of dengue cases, especially when P. falciparum is implicated. Complications such as hepatomegaly and jaundice 37.03% (10), haemorrhagic manifestations 18.51% (5) and kidney failure 3.7% (1) are common in malaria and dengue co-infections with maximum cases in P. falciparum infected cases. Therefore, screening for malaria is essential after clinical and haematological correlation in dengue-positive cases and vice versa. Anaemia, thrombocytopenia, altered liver and renal function tests were observed in malaria and dengue co-infection cases with higher number of cases in P. falciparum infection. Similar findings were found in study done in Pakistan.[11] Deranged liver function was also found in that study.[11] It is interesting to note that haemorrhagic manifestations are uncommon in falciparum malaria whereas in dengue, they are common. As both malaria and dengue can cause thrombocytopenia, it is difficult to decide which one is responsible for the haemorrhagic manifestation. Therefore, malaria with bleeding manifestations are considered as severe malaria and treated accordingly.[14] The biological influence of dengue virus, which affects the endothelium, a major protagonist of severe malaria pathophysiology, on the eventual severity of falciparum malaria, needs to be studied.[15]

Although severity and complications are more in co-infection cases, especially with P. falciparum infection, no mortality was detected in such cases. The increased severity could result from longer evolution duration or increased virulence or both. Our study was retrospective so the results should be interpreted with caution. Prospective studies with homogeneous diagnosis methods and patient groups should be tried to confirm the higher severity of co-infection, but the usefulness of such a study is questionable because of the very low prevalence of dual infection. The benign outcome has also been observed in other two studies.[10],[11] The good outcome was attributed to early medical treatment of co-infection cases.[5],[6] The distinction between SD and severe malaria must be made in an emergency department or hospital setting because in both situations, early diagnosis is essential for patient care.

The present study showed three notable findings. First, it showed that malaria and dengue co-infection is not uncommon in a geographical area where both the mosquito vectors coexist. Second, in concurrent infection, the clinical features of dengue fever are predominant over malaria. Third, DW signs and SD cases are found more in dengue and malaria co-infection cases especially when P. falciparum is implicated.

Malaria and dengue must be suspected in febrile patients living in or returning from areas endemic for these infections. If malaria is confirmed first, then dengue should not be ruled out without testing for it. If first dengue is confirmed, then all such cases also should be sought for malaria. All clinicians treating febrile patients in or returning from endemic areas should systematically order examinations for both malaria and dengue diagnoses, even if one or the other is positive.

 Conclusion



All febrile patients must be tested for both malaria and dengue otherwise one of them can be missed in case of concurrent infections which could lead to severe disease with complications.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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