Non-malaria febrile illness

In Cambodia, the number of reported malaria cases, as well as case
fatality rates, continue to decrease since the implementation of
large scale malaria programs in the country 10 years ago. However,
with the introduction and wide distribution of rapid diagnostic
tests (RDTs) for malaria, it also turned out that in many of the
clinically suspected malaria cases, no malaria parasites could be
detected. As a first step towards developing an algorithm for
malaria-RDT negative fever management at peripheral health posts, a
cross-sectional, prospective, observational study was designed to
investigate the causes of acute malaria-negative febrile illness in
rural areas of Cambodia. From January 2008 to December 2010, 1475
study subjects were recruited in three different sites throughout
the country. Among the study subjects, 1193 were febrile
out-patients and 282 were non-febrile individuals who have been
recruited as a control group. A battery of test was run on the
samples in the central laboratory in Phnom Penh. In 73.2% of the
1193 febrile outpatient samples, at least one pathogen was
identified. In 26.8% of these samples the etiology of the fever
remained unknown. Most frequent pathogens detected by molecular
diagnostics were P. vivax (26.4%), P. falciparum (20.7%),
Leptospira (9.5%), Dengue Virus (5.4%), Influenza Virus A (5.9%),
O. tsutsugamushi (3.7%), Influenza Virus B (1.8%), Rickettsia
(0.2%) and bacteria from blood culture (Salmonella spp., E. coli,
S. pneumoniae, E. cloacae) (0.8%). Conclusions: Malaria is still
amongst the principal causes of undifferentiated fever in this
setting, even though RDTs did not prove sufficient to diagnose
cases of low parasitemia and infections with P. vivax. RDT-negative
fever cases should be tested for malaria using microscopy or
ideally PCR. If malaria is ruled out, diagnostic tools are needed
to distinguish between either viral or bacterial etiology of the
fever. Leptospirosis and rickettsial diseases showed to play an
important role and are easily treatable with the right antibiotics.
However, more research and better diagnstic tools are needed to
understand and map the incidence of these diseases in Cambodia.