Page 73 - JSOM Fall 2024

Sandfly fever is often referred to colloquially as “three-day fe- and one person was antibody-positive for both Sicilian virus
4
ver” and “papataci fever.” As the former name would suggest, and Brucella species bacteria. 9
the clinical course of the disease normally spans about 3 days,
with patients exhibiting a prodromal phase consisting of fa- In 2013, Shiraly et al. conducted serologic examinations for
tigue, chills, abdominal pain, and possibly facial flushing and sandfly fever antibodies in 201 Iranian military personnel based
tachycardia. Disease onset is marked by hyperpyrexia, myal- in the city of Mehran, in the Ilam province. All soldiers had
6
gia, and arthralgia. The incubation period is 3–5 days, with been posted in Mehran (on the western border of Iran, north of
3
viremia in humans lasting typically less than 1 week. Sandfly Al Kut, Iraq) for more than 1 year. A total of 37 serum samples
fever is listed as ICD-10 A93.1 within the International Classi- (18.4%) contained IgG antibodies to sandfly fever virus; the
fication of Diseases system. 1 most common serotypes identified were Sicilian and Naples. 10
Several dozen phlebovirus subspecies exist, the most virulent In 2008, 26 cases of “Helmand fever” at a British hospital in
of which is Toscana (within the Naples virus complex). The Helmand province, Afghanistan, underwent serologic test-
Toscana phlebovirus incubates within the human host from ing for causative organisms. The cases occurred between the
a few days to 2 weeks before abrupt onset of disease marked months of May and October (the time during which Phlebot-
by fever, nausea, vomiting, headache, and possibly myalgia. omus sandflies are most active). Out of the 23 cases in which
Neck rigidity and Kernig’s sign (difficulty in straightening the the causative organisms were identified, 52% (12) were identi-
legs) may also be present. Ten percent of those infected with fied as sandfly fever virus, 26% (6) were identified as Q fever,
Toscana virus may also present with decreased mental status, and 22% (5) were identified as rickettsial infections. 11
tremors, nystagmus, and limb paresis. The mean duration of
Toscana virus disease is 7 days. 3 A 1996 study reported the presence of sandfly fever antibodies
in 27%–70% of a total of 570 adult patients (divided into 3
Recently published literature sheds light on the epidemiology cohorts) treated for febrile illnesses in northern Pakistan. 12
of both sandflies and the viruses they harbor within Algeria,
Israel, Saudi Arabia, Iraq, Iran, Afghanistan, Pakistan, China, In 2019, Wang et al. reported on the characteristics and feed-
and Panama. 3,6–14 A summary of these data follows. ing habits of Phlebotomus sandflies collected in Yangquan
County, China. It was noted that the sandfly population (Phle-
A 2021 study from Algeria describes the occurrence of vari- botomus chinensis) peaked in June, and chiefly preyed upon
ous species of Phlebotomus sandflies primarily within the Tell both humans and chickens for their blood meals. The article
Atlas mountains and the highlands area and the presence of also noted that a study conducted in Sichuan County, China,
Phlebotomus perniciosus throughout all of Algeria. 7 found pigs to be the preferred source of blood meals. The
Wuxiang sandfly virus serotype was isolated from the sand-
In 1999, Cohen et al. reported on the presence of IgG and flies collected in this region. 13
IgM antibodies to sandfly fever and West Nile virus (using
ELISA) in 1,019 healthy Israeli soldiers. The highest preva- The preeminent Hunter’s Tropical Medicine text discusses New
lence of sandfly fever antibodies occurred in the 40–55-year World sandfly viruses and their vectors. In Panama, the highly
age group (n=285), with a 23.7% antibody rate to the Sicilian anthropophilic (human host-preferring) Lutzomyia tropi doi
virus species, and a 30.8% antibody rate to the Naples virus and Lutzomyia ylephilator sandflies are known to vector the
species. 8 Chagres and Punta Toro sandfly viruses. Sandflies in Brazil
have been shown to harbor Candiru and Alenquer sandfly vi-
A 2023 study examined the seroprevalence of sandfly fever ruses. The Hunter’s text cites the sandfly fever virus antibody
virus in both livestock animals and humans in Jeddah, Saudi prevalence among Panamanians as 17%–35%. 3
Arabia. Neutralizing antibodies to the Sicilian virus were found
in 53.3% of cows (45 animals tested), 27.5% of sheep (51 an- In their 2019 report, Markowitz et al. stated that sandfly
imals tested), 2.2% of goats (44 animals tested), and 10% of populations in the vicinity of the Panama Canal were great-
camels (88 tested). Positive tests among these animals for the est within forested areas. This is thought to be a function of
virulent Toscana sandfly fever virus subspecies occurred as fol- both the abundance of leaf litter and animal burrows in which
lows: 4.4% of cows, 7.8% of sheep, 0% of goats, and 2.3% of sandflies rest as well as the increased humidity in which the
camels. Archived human blood donor serum (n=705) collected eggs of the sandfly thrive. 14
between 2012 and 2016 in Jeddah was tested for sandfly fever
antibodies, of which 6.4% were positive for the Sicilian virus, Diagnosis
and 0.7% were positive for Toscana virus. In 2019 the serum
samples of 313 Saudi animal handlers were collected and simi- The symptomology of sandfly fever (fever, chills, arthralgia,
larly tested; 16% were positive for the Sicilian virus, while 1% and myalgia) is by no means pathognomonic but should be
were positive for the Toscana virus. 6 examined against other disease etiologies presenting a similar
constellation of signs and symptoms. Barring access to a de-
A 2008 article reported on an acute flu-like syndrome that finitive diagnosis via reverse transcription polymerase chain
swept through a U.S. Military patrol base outpost south of reaction (RT-PCR), a field medical practitioner may arrive at a
Baghdad, Iraq, in September 2007. An examination of con- working diagnosis of sandfly fever based solely on clinical pre-
valescent serum in all 14 cases revealed that 92.9% (all but sentation, geographic exposure, history of sandfly bites, and
1 case) were IgM/IgG antibody-positive for Sicilian sandfly exclusion of other diagnoses.
fever virus antibodies. Incidentally, three individuals were
antibody-positive for Coxiella burnetii (Q fever); two individ- The three lists below offer a starting point for differentiating
uals were antibody-positive for both Sicilian virus and Q fever; sandfly fever from other infectious etiologies.

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