نبذة مختصرة : The common theme and aim for this thesis was to explore the epidemiology and thediagnostic possibilities of patients with non-malarial febrile infections of tropical origin, withboth the individual patient perspective and the more general public health aspects in focus.Analysis from two study areas, Sweden and Mozambique, are presented in the project.The infectious disease panorama in Mozambique has to a large extent been a blind spot.Further epidemiological studies, aiming at more knowledge to guide decisions on preventivemeasures, are needed. We performed two prospective investigations. The first one was a pilotsero-epidemiological study on vector-borne viral zoonoses, in which we screened serumsamples from patients attending a health care clinic in the suburb of the capital Maputo. In theanalysis we found that 29% of the patients screened had an antibody response against one ormore of the viral pathogens. Our conclusion, based on these results, was that exposure tochikungunya virus (CHIKV), dengue virus (DENV) and Rift Valley fever virus (RVFV) hadtaken place, and that these viruses are circulating in the country. The second study was aninvestigation of the DENV outbreak in the cities Pemba and Nampula. We analysed serumsamples for DENV by PCR from patients seeking medical attention for fever during 2015-2016. The results including PCR positive samples, serotyping and sequencing of strains,confirmed that DENV serotype 2 is now endemic in northern Mozambique.In the Swedish multicentre study we prospectively included febrile travellers returning toSweden from tropical areas defined as malaria endemic. Epidemiological data fromquestionnaires and clinical diagnoses given to patients by their attending doctors were firstcompared with results from a panel of extended laboratory diagnostics, primarily onconvalescent samples. We then focused on the possibilities for early diagnostics with PCR,particularly for cases where no relationship between the febrile illness and a microbialpathogen had been identified. We also developed a universal PCR for diagnosis of earlyphase DENV infection. This universal single probe real time RT-PCR for DENV was thenused for the DENV analysis on acute samples. The results showed that infectious diseaseclinicians in Sweden, when taking care of febrile travellers returning from the tropics, were ingeneral able to establish a diagnosis based on laboratory diagnostics for relevant pathogens.That being said, we also noted that 30 % of the patients included in the study were dismissedwith the diagnosis fever of unknown origin. It was also apparent from the results thatinfluenza virus infection was a frequent, and often missed, diagnose among febrile travellers,regardless of the time of year. The antibody screening also identified several additional casesof dengue infection. When including the PCR for DENV in the diagnostic kit, it was possibleto reduce even further the number of cases with diagnosis of unknown fever. This confirmsthat the universal PCR for DENV is a sensitive, specific and valuable diagnostic tool to useduring the first 5 days in the acute phase of illness. Apart from influenza and DENV,Rickettsia and Leptospira infections stood out as differential diagnoses that needed to beaddressed.
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