Specimens from 975 of 1464 subjects were evaluated using the Rickettsia diagnostic panels. Rickettsia was identified as the etiology of febrile illness in 103/975 (10.6%) cases (Figure 1). None of these patients were diagnosed with Rickettsia upon clinical presentation. One case was clinically diagnosed as Rickettsia during hospitalization but was not laboratory confirmed.
Characteristics of patients with acute rickettsial infection at enrollment are shown in Table 1. Of 103 subjects, 69 (67%) were male and 34 (33%) female. Median age was 35 years (range: 1-75 years), with the majority 53/103 (51.4%) in patients 19 to 45 years. Underlying diseases were documented in 30 subjects, including diabetes (8), hypertension (8), liver disease (3), respiratory diseases (3), anemia (3), malnutrition (3), HIV (1), and osteoarthritis (1).
Table 1. Demographics and Outcomes (n=103 subjects)
Median age (range) y.o.
|
35 (1-75)
|
Male: female
|
69 : 34
|
Distribution of cases in age group†, N(%)
|
|
1 - ≤5 years
|
2/153 (1.3%)
|
6 - ≤18 years
|
19/190 (10%)
|
19 - ≤45 years
|
53/378 (14%)
|
>45 years
|
29/254 (11.4%)
|
Day of onset (median, range), days
|
5 (1-12)
|
Length of stay (median, range), days
|
6 (1-36)
|
Antibiotics use from 90 subjects with documented history, N (%)
|
76 (84%)
|
Ceftriaxone
|
17(22.4%)
|
Ciprofloxacin
|
9 (11.8%)
|
Levofloxacin
|
9 (11.8%)
|
Cefixime
|
2 (2.6%)
|
Cefotaxime, Amoxicillin, Ampicillin, Cefadroxil, Meropenem, Chloramphenicol, Cefoperazone, Sulbactam, Cotrimoxazole
|
1 (1.3%), each
|
Combination 2-3 antibiotics
|
30 (39.5%)
|
Outcomes, N (%)
|
|
Recovered
|
72 (69.9%)
|
Recovered with sequelae§
|
24 (23.3%)
|
Died
|
7 (6.8%)
|
By sites, N/subjects enrolled (1464) (%)
|
|
Bandung
|
22/189 (11.6%)
|
Denpasar
|
16/101 (15.8%)
|
Jakarta
|
7/87 (8%)
|
Makassar
|
5/131 (3.8%)
|
Semarang
|
21/191 (10.9%)
|
Surabaya
|
26/156 (16.7%)
|
Yogyakarta
|
6/120 (5%)
|
†from 975 subjects tested for Rickettsia typhi
§Lethargy, arthralgia, anorexia, headache, dizziness, cough
Confirmation of rickettsial infections
The distribution of 103 acute R typhi infection cases by site ranged from 5/131 (3.8%) in Makassar to 26/156 (16.7%) in Surabaya. Amongst 872 subjects with no evidence of R typhi infection, R. typhi IgG was detected in 269 (30.8%) subjects. Spotted fever IgG and O. tsutsugamushi IgG were less common (36/634 (5.7%) and 19/504 (3.8%)), respectively. Geographical distribution of IgG prevalence and acute cases is shown in Figure 2. In 65 of the 103 subjects with acute R typhi infection, confirmation was by Rickettsia sp and/or R. typhi DNA and sero-conversion or 4-fold increase titers of IgM and/or IgG IFA. In 36 subjects, diagnosis was based on sero-conversion or 4-fold incrase IgM/IgG by IFA. In one subject, R. typhi was confirmed by detection of Rickettsia sp and sero-conversion of IgM, IgG by IFA. In the one R. felis case, increasing IgG titers to R. typhi were detected and R. felis DNA was identified by R. felis PCR using Rickettsia sp and R. felis primers.
Sequencing of R. typhi DNA was conducted in 19 specimens. All revealed 99% sequence identity with R. typhi from Myanmar and Thailand (Figure 3).
Clinical Characteristics
Subjects averaged 5 days (range 1-12 days) of fever before hospital admission (Table 1). Other reported symptoms included nausea (72%), headache (69%), vomiting (43%), lethargy (33%), anorexia (32%), arthralgia (30%), myalgia (28%), chills (28%), and epigastric pain (28%). The clinical triad of R. typhi infection (fever, headache and rash) was found in 11%. The three most frequent confirmed diagnoses in the study cohort, dengue, typhoid and leptospirosis demonstrated overlap with rickettsial infection. Details are shown in Table 2.
Table 2. Characteristics of R. typhi cases, compared to dengue, S. typhi, and leptospira cases
Clinical signs and symptoms
|
R. typhi
cases
|
Dengue
cases
|
Salmonella cases
|
Leptospira cases
|
N =102†
|
N=468
|
N=103
|
N=48
|
Symptoms, N (%)
|
|
|
|
|
Fever
|
102 (100)
|
468 (100)
|
103 (100)
|
48 (100)
|
Nausea
|
73 (72)
|
345 (74)
|
74 (72)
|
38 (76)
|
Anorexia
|
33 (32) b
|
153 (33)
|
49 (48)
|
16 (33)
|
Headache
|
70 (69) ab
|
261 (56)
|
45 (44)
|
26 (54)
|
Vomiting
|
44 (43)
|
249 (53)
|
52 (50)
|
29 (60)
|
Lethargy
|
34 (33) a
|
102 (22)
|
46 (45)
|
14 (29)
|
Arthralgia
|
31 (30)
|
139 (30)
|
25 (24)
|
19 (40)
|
Myalgia
|
29 (28)
|
103 (22)
|
20 (19)
|
20 (42)
|
Chills
|
29 (28) a
|
65 (14)
|
35 (34)
|
20 (42)
|
Epigastric pain
|
29 (28)
|
112 (24)
|
32 (31)
|
12 (25)
|
Cough
|
24 (24) b
|
79 (17)
|
48 (47)
|
16 (33)
|
Diarrhea
|
15 (15) bc
|
47 (10)
|
41 (40)
|
20 (42)
|
Skin rash
|
17 (17) b
|
85 (18)
|
3 (3)
|
3 (6)
|
Constipation
|
19 (19) a
|
23 (5)
|
15 (15)
|
6 (13)
|
Altered mental status
|
4 (4) a
|
6 (1)
|
3 (3)
|
1 (2)
|
Dysuria
|
4 (4)
|
9 (2)
|
1 (1)
|
3 (6)
|
Icterus
|
5 (5)
|
2 (0.4)
|
1 (1)
|
6 (13)
|
Rickettsia Triad: fever, headache and rash
|
11 (11)b
|
57 (12)
|
2 (2)
|
1 (2)
|
Hematology profiles: Mean (SD)
|
Hb (mg/dl)
|
14.04 (1.89) bc
|
13.9 (1.84)
|
12.4 (1.79)
|
13.3 (2.06)
|
Hematocrit (%)
|
40.8 (5.18) b
|
41 (5.21)
|
36.3 (5.42)
|
38.9 (6.16)
|
Leukocyte count: /mm3
|
7,354
(2,975) ac
|
4,225
(2,608)
|
6,902
(2,974)
|
10,924 (4,246)
|
Platelet count
|
123,426 (61,746) ab
|
107,720 (67,522)
|
158,402 (74,784)
|
138,333 (75,491)
|
N (%)
|
|
|
|
|
Leukopenia
|
14 (14) ac
|
312 (66.7)
|
21 (20)
|
2 (4.2)
|
Leukocytosis
|
17 (17) a
|
9 (1.9)
|
12 (11.7)
|
25 (24.5)
|
Platelet <100,000/mm3
|
41 (40) ab
|
266 (57)
|
22 (21)
|
13 (27)
|
Platelet <150,000/mm3
|
74 (73)
|
373 (8)
|
52 (50)
|
26 (54)
|
Thrombocytopenia (150,000) AND
leukopenia (<5000)
|
19(19) ac
|
318 (68)
|
22 (21)
|
0
|
Leucocyte cell types; Mean (SD)
|
Neutrophil (%)
|
70.34
(10.87) abc
|
60.59
(16.41)
|
64.8
(14.2)
|
84.2
(7.9)
|
Neutrophil count
|
5,329
(2,741) abc
|
2,672
(2,227)
|
4,373
(2,216)
|
9,001
(3,453)
|
Lymphocyte (%)
|
21.9 (9.85) abc
|
28.5 (15.1)
|
26.5 (12.2)
|
9.5 (6.4)
|
Lymphocyte absolute
|
1,388
(484-4,489)
|
888
(192-7,104)
|
1,521
(348-10,900)
|
729
(243-2,783)
|
N (%)
|
|
|
|
|
Neutropenia
|
9 (9)
|
99 (21)
|
17 (17)
|
0
|
Neutrophilia
|
12 (12) c
|
41 (9)
|
14 (14)
|
22 (46)
|
Lymphocytopenia
|
31 (30)
|
110 (24)
|
26 (25)
|
32 (67)
|
Lymphocytosis
|
8 (8)
|
84 (18)
|
17 (17)
|
0
|
|
|
|
|
|
Biochemistry profiles: Median (range)
|
Bilirubin (mg/dl)
|
0.55
(0.12-12)
|
0.37
(0.08-3.46)
|
0.37
(0.1-2.09)
|
0.69
(0.13-16.83)
|
ALT (IU)
|
82 (12-604)
|
83 (1-6570)
|
66 (14-542)
|
38 (15-207)
|
AST (IU)
|
69 (0.71-466)
|
34 (1-1286)
|
40 (5-339)
|
32 (10-141)
|
Urea (mg/dl)
|
26 (9-181.2)
|
17 (0.3-121)
|
19 (6-59)
|
53 (13-459)
|
Creatinine (mg/dl)
|
0.9
(0.4-9.92)
|
0.85
(0.05-98)
|
0.7
(0.3-1.7)
|
1.2
(0.5-8.8)
|
N/available data (%)
|
Bilirubin >1 mg/dl
|
21/98 (21) abc
|
10/409 (2)
|
5/96 (5)
|
17/46 (37)
|
Direct bilirubin >0.4 mg/dl
|
36/98 (37) abc
|
27/409 (7)
|
13/96 (14)
|
26/46 (56)
|
Indirect bilirubin>0.6 mg/dl
|
7/98 (7) c
|
17/409 (4)
|
2/96 (5)
|
10/46 (22)
|
Direct > Indirect bilirubin
|
66/98 (67)a
|
147/409 (36)
|
55/97 (57)
|
34/46 (74)
|
ALT >45 IU
|
76/97 (78)
|
326/409 (80)
|
65/95 (68)
|
16/45 (36)
|
ALT >100 IU
|
35/97 (36) c
|
147/409 (36)
|
26/95 (27)
|
7/45 (16)
|
AST >35 IU
|
75/97 (77)
|
197/409 (48)
|
54/97 (56)
|
16/45 (36)
|
AST >100 IU
|
28/97 (29) abc
|
60/409 (15)
|
7/97 (7)
|
2/45 (4)
|
Urea N >40 mg/dl
|
4/31 (13) ac
|
10/409 (2)
|
4/44 (9)
|
24/44 (55)
|
Creatinine >1.2 mg/dl
|
15/98 (15) bc
|
44/409 (11)
|
5/94 (5)
|
25/46 (54)
|
Note : Significant (p <0.05) a between R. typhi and dengue , b between R. typhi and S. typhi, c between R. typhi and leptospira. †One Rickettsia felis case is not included.
Most subjects presented with normal hematocrit (median 40.8%) and leukocyte count (median 7,354/mm3). The majority had low lymphocyte proportion (median 21.9%) and platelets (median 123,426/mm3). Mildly increased liver enzymes were found in 77%, with bilirubin increases primarily attributable to direct bilirubin. During hospitalization, no clinically relevant changes were observed.
The hematologic profile of R. typhi cases was similar to typhoid, but distinguishable from dengue and leptospirosis. Dengue showed lower leukocyte and platelet counts. Leptospirosis showed higher leukocyte and neutrophil counts, but lower absolute lymphocyte counts. Increased total bilirubin and direct bilirubin were more prevalent than in dengue or typhoid, while increased total and indirect bilirubin were more frequent in leptospirosis. AST above 100 IU was more common in R. typhi cases compared to the three diseases, whereas creatinine >1.2 mg/dl was more common in leptospirosis.
Clinical Diagnoses:
For the 103 rickettsioses patients, discharge diagnoses were: typhoid fever (44), dengue fever (20), leptospirosis (6), respiratory infections (1 upper, and 6 lower), unidentified fever (6), sepsis (6), hepatobiliary infections (3), unidentified viral infections (3), UTI (3) and others (one each: HIV, chikungunya, enteritis, meningoencephalitis, and diabetic neuropathy).
In all cases of Rickettsia initially suspected to be leptospirosis, typhoid fever, chikungunya, or dengue fever, diagnostic assays for those pathogens at the reference laboratory were negative, except in one R. felis case where leptospira PCR was positive and leptospira IgM and IgG sero-converted, suggesting co-infection. Clinicians diagnosed typhoid despite negative or weak positive S. typhi IgM rapid tests in 24 presumed typhoid cases; in 4 other cases rapid tests were not performed. In the remaining cases (16), positive results from the rapid test were not supported as blood culture, PCR and ELISA IgM tests for Salmonella were negative. In these 16 cases, R. typhi was confirmed by PCR and/or serological assays. Fifteen dengue diagnoses were not supported by rapid dengue antigen or antibody tests. In contrast, 6 presumed leptospirosis cases had positive rapid tests, but PCR and ELISA at the reference laboratory were negative except in the R. felis case above. Details of the diagnostic tests to confirm Rickettsia infection and to exclude S. typhi, dengue, and Leptospira infections are shown in Supplement 1.
Management and Outcomes
Antibiotics were taken prior to hospitalization in 23 subjects, including amoxicillin (8), cephadroxil (4), cotrimoxazole (3), chloramphenicol (2), cefixime (1), spiramycin (1), and a combination of antibiotics (4). Antibiotics were given at hospitals in 76 of 90 (84%) subjects with documented treatment data as shown in Table 1. The majority received ceftriaxone (17), ciprofloxacin (9) and levofloxacin (9), or a combination of antibiotics (30). The drug of choice for Rickettsia infection, doxycycline was given to 2 patients, one in combination with ceftriaxone and one with amoxicillin. 14 (58%) subjects with suspected viral infections received antibiotics at hospital several days after no clinical improvement with symptomatic treatment. The median hospital stay was 6 days (range 1-36).
Twenty-four subjects (23.3%) recovered with sequelae and 72 (69.9%) recovered without sequelae. Seven (6.8%) patients (median 54.7 years, range 36.1-75 years) died. Of these, 5 had underlying disease (stroke, HIV and chronic liver disease, HIV and TB, DM, and COPD). Six deaths were attributed to sepsis; in one HIV positive patient with meningoencephalitis, death was attributed to cardiogenic shock. All patients who died received antibiotics, however none received doxycycline. Contribution of rickettsial infection to these deaths could not be ascertained.