Prevalence of malaria and selected arboviral infections in patients presenting with undiagnosed febrile illness in Rusinga Island, Kenya

Onset of uncomplicated malaria is characterized by fever, headache, joint pains, myalgia and lack of appetite. These non-specific signs and symptoms also present in patients with arthropod borne viral (arboviral) infections complicate differential diagnoses. The lack of diagnostics that can detect arboviral infections in Kenyan public hospitals coupled with malaria diagnostic tools incapable of detecting low Plasmodiumparasitemia,has led to diagnosis based on clinical symptoms only,favouring malaria diagnosis at the expense of arboviral infections detection.Investigations were conducted to detect Plasmodiumparasites undetected by microscopy and rapid diagnostic tests (RDTs) and determine Sindbis and Bunyamwera viruses neutralizing antibodies among undiagnosed febrile ill patients in Rusinga Island. Human blood and serum samples (n=92) were collected from patients without malaria (as confirmed by microscopy and RDTs) from Tom Mboya Hospital in the island. The blood samples were screened for Plasmodium parasites by nested PCR coupled to high resolution melting analysis (nPCR-HRM), and serum samples screened for neutralizing antibodies by plaque reduction neutralization test (PRNT). Association between risk factors and exposure to infections was determined by Chi square and Logistic multivariate analyses. Plasmodium parasites were detected in 36 (39.1%) of the 92 patients. Out of these 36 patients with Plasmodium infections, only 16 (44.4%) were correctly treated with antimalarial medication with the rest being treated with antibiotics, antihelminthes and amoebicides. Conversely, a majority of non-malaria febrile patients (n=32) were treated with antimalarial medication. Plasmodium falciparum was the major malaria-causing parasite detected in Rusinga Island (29 out of 36).Individuals involved in outdoor activities (farmers and fishermen) were 2.24-2.43 folds more likely to get malaria infections than those involved in indoor-based (teachers/students)occupations.Neutralizing antibodies against Sindbis virus were detected in five (5.4%) patients, three of whom had malaria co-infection. No antibodies against Bunyamwera virus were detected. These results demonstrate limitations of differential diagnostics of febrile illness in rural malaria endemic settings that under mine proper acute febrile illness management and patient care. The under-appreciation of arboviral infections is of great concern, in a country where active arbovirus circulation has been demonstrated, resulting in poor health outcomes for non-malaria febrile patients. This study highlights the need for improved diagnostics deployable in rural malaria endemic settings to counter the increasing challenges of low parasitemia malaria and non-malaria undiagnosed acute febrile illnesses.