Table 1 Study sites and participants from whom stored samples were obtained

Recruitment sites

Paediatric hospital

Two provincial hospitals in northwest and southern Laos

Migrant and refugee clinics on the Thai/Myanmar border

Enrolment dates

October 2009 to October 2010

May 2008 to December 2010; September 2008 to December 2010

March 2011 to March 2013

Patients recruited

n = 1180

n = 1938

n = 1029

Patient demographics

<16 years (69 % < 5); 45 % female; All inpatients

5–49 years (37 % < 15); 42 % female; 44 % inpatients

≥5 years (45 % < 15 years); 36 % female; clinic attendants

Symptoms/syndromes used for inclusion/exclusion

Documented axillary temperature ≥38 °C within 48 h of admission. All febrile inpatients were eligible irrespective of symptoms/syndromes but excluding post-surgical cases

Fever (tympanic ≥38 °C) with no obvious cause < 8 days and eligible for a malaria test by Laos national guidelines (patients with obvious causes of fever such as abscess or severe diarrhoea were excluded)

Documented fever ≥38 °C of up to seven days duration with no obvious cause. Patients with a clear clinical diagnosis such as chickenpox, pneumonia (based on clinical criteria), skin/soft tissue infection (e.g. cellulitis), or urinary tract infection were excluded

Documented mortality

5.6 %

0.5 %

0.1 %

Organisms tested for

Plasmodium spp, Leptospira spp, O tsutsugamushi, R typhi, spotted-fever-group rickettsia, agents of conventional bacteraemia, dengue fever, Japanese encephalitis virus, influenza

Plasmodium spp, Leptospira spp, O tsutsugamushi, R typhi, spotted-fever-group rickettsia, causes of community bacteraemia, dengue fever, Japanese encephalitis virus, influenza (in one of the two sites)

Plasmodium spp, Leptospira spp, O tsutsugamushi, R typhi, spotted-fever-group rickettsia, causes of community bacteraemia, dengue fever, Japanese encephalitis virus