INTRODUCTION
Schistosomiasis is a parasitic disease caused by blood flukes (trematodes) of the
genus Schistosoma, it is the third most devastating tropical disease in the world
after malaria and intestinal helminthiasis.[1]
It can present as acute or chronic illness.
We report a case of schistosomiasis that shows how the acute infection (Katayama syndrome)
in an endemic country can be misdiagnosed at the time of presentation, with the diagnosis
made only after development of chronic complications of schistosomiasis.
CASE REPORT
A 29-year-old male, engineer, living in Khartoum state, presented with a 1-week history
of fever, headache, fatigue, myalgia, excessive sweating, and abdominal cramps. He
underwent thorough investigations that showed a high eosinophil count of 4.96 × 103
cell/μL, C-reactive protein (CRP) of 287.9 mg/L, erythrocyte sedimentation rate (ESR)
of 90 mm/h, serum IgE of 841.5 IU/ml, and a strongly positive A/Scl 70 [Table 1]. He was seen by a rheumatologist who considered him as a case of systemic sclerosis;
the patient was admitted to hospital and started on prednisolone 40 mg daily. After
9 days, he was discharged with much improvement clinically and biochemically. In spite
of that, he continued to have fatigability, myalgia, and mild abdominal cramps. He
consulted a second rheumatologist who suggested the diagnosis of Churg–Strauss syndrome
in view of eosinophilia and a history of wheezy chest in childhood. This time he was
put on azathioprine 50 mg twice daily orally, in addition to the previously prescribed
dose of prednisolone.
Table 1
Laboratory investigations of the patient on initial presentation with acute febrile
illness
|
Test
|
Patient values
|
Normal values
|
|
ANA=Antinuclear antibody
|
|
Hemoglobin concentration
|
15.4
|
11.0-16.0 mg/dl
|
|
White blood cell count
|
11.45×103
|
4.0-11.0×103 µL
|
|
Neutrophils
|
3.55
|
1.8-6.8×103 µL
|
|
Lymphocytes
|
2.24
|
1.2-4.9×103 µL
|
|
Platelet count
|
209×103
|
150-450×103µL
|
|
Eosinophil
|
4.96×103
|
0.1-0×103µL
|
|
Erythrocyte sedimentation rate
|
90
|
5-20 mm/1 h
|
|
IgE
|
841.5
|
0-100 IU/ml
|
|
C-reactive protein
|
287.9
|
<5 mg/L
|
|
Blood urea
|
23.9
|
10-50 mg/dl
|
|
Serum creatinine
|
0.8
|
0.7-1.2 mg/dl
|
|
Liver function test
|
Normal
|
-
|
|
ANA profile
|
Strongly positive A/Scl 70
|
-
|
One week later, he presented to the gastroenterology department with bright red bleeding
per rectum which lasted for 3 days without associated change in bowel habits, fever,
or weight loss. He was a nonsmoker and had no family history of inflammatory bowel
disease or bowel malignancy. The patient denied any contact with contaminated water.
Physical examination was unremarkable. Laboratory investigations revealed a high eosinophil
count of 1.5 × 103 cell/μL, ESR of 60 mm/h, and CRP of 45 mg/L, and trace protein
in urinalysis. He had a normal stool examination with no red blood cells, ova, or
parasites, and normal urea and creatinine level [Table 2].
Table 2
Laboratory investigations of the patient after development of schistosomal colitis
|
Test
|
Patient values
|
Normal values
|
|
Hemoglobin concentration
|
15.2
|
11.0-16.0 mg/dl
|
|
White blood cell count
|
9.8×103
|
4.0-11.0×103 µL
|
|
Neutrophil
|
5.2
|
1.8-6.8×103µL
|
|
Lymphocytes
|
2.8
|
1.2-4.9×103 µL
|
|
Platelet count
|
270×103
|
150-450×103 µL
|
|
Eosinophil
|
1.5×103
|
0.1-0.4×103 µL
|
|
Erythrocyte sedimentation rate
|
60
|
5-20 mm/1 h
|
|
C-reactive protein
|
45
|
<5 mg/L
|
|
Blood urea
|
18
|
10-50 mg/dl
|
|
Serum creatinine
|
1.2
|
0.7-1.2 mg/dl
|
|
Urine analysis
|
Trace protein
|
-
|
|
Stool analysis
|
No ova or parasites
|
-
|
Colonoscopy revealed moderate colitis noted distally with edematous, inflamed mucosa
up to mid-transverse colon, inflammation was most severe in the rectum. Histopathological
examination of the colonic mucosa sections showed normal crypt architecture. Several
viable schistosome ova associated with aggregates of eosinophils were noted; features
of active colonic schistosomiasis [Figure 1].
Figure 1: (a and b) Two histology slides of the colonic mucosa of a 29-year-old male with distal
colitis due to Schistosoma mansoni infection. In the center of the field (arrow) is
a viable Schistosoma mansoni egg (intact miracidial nuclei) in the lamina propria
associated with aggregates of eosinophils
He was treated with praziquantel 40 mg/kg, the dose was repeated after 6 weeks, he
showed immediate marked clinical improvement and most of his symptoms disappeared
within the 1st week. He showed complete resolution of symptoms on follow-up visits.
His repeat complete blood count showed normal eosinophil count.
DISCUSSION
Acute schistosomiasis can present as swimmer's itch or as Katayama fever, the latter
is a systemic hypersensitivity reaction against the migrating parasites, which occurs
between 2 and 8 weeks after exposure.[2],[3]
Symptoms are more likely to occur in travelers and other nonimmune hosts,[4] these include sudden onset of fever, chills, myalgia, arthralgia, dry cough, diarrhea,
and headache, often resembling serum sickness. Lymphadenopathy and hepatosplenomegaly
may be prominent findings on physical examination. The symptoms usually resolve spontaneously
over a period of a few weeks, but neck stiffness and coma can occur and occasional
deaths have been reported related to intense infection.[5] Patients may develop eosinophilia and patchy infiltrates on chest X-ray.[3]
The diagnosis of Katayama fever relies upon appropriate epidemiology for potential
exposure and consistent clinical findings. The diagnosis can be complicated by the
fact that eggs are rarely excreted in detectable amounts during this stage and antibody
tests are usually negative. However, a peripheral eosinophilia will usually be present
and often serves as an important clue.[6]
Due to the lack of clinical trials in nonimmune populations, the optimal treatment
regimen for Katayama syndrome is not known.[7] Praziquantel is not particularly effective in early infection, so therapy for Katayama
fever is mostly supportive. Glucocorticoids (e.g., prednisolone 40 mg daily for 5
days) can be considered to ameliorate significant symptoms related to hypersensitivity.[7],[8]
The optimal timing of praziquantel therapy is unclear; if it is not instituted immediately,
it should be administered within 6–10 weeks when the infection is established and
adult worms have developed. An alternative approach is to commence praziquantel at
the time of diagnosis as this may decrease the worm load and reduce the risk of ectopic
localization.[4]
The pathology of chronic schistosomiasis, which is far more common than the acute
form of the infection, results from egg-induced immune response, granuloma formation,
and associated fibrotic changes.
The symptoms of colonic schistosomiasis are nonspecific and may mimic other gastrointestinal
problems.[9] Severe complications have been reported with schistosomiasis such as hemorrhagic
diarrhea, obstruction secondary to an inflammatory mass, acute appendicitis, intestinal
intussusception arising from a mucocele of the appendix, and ischemic colitis.[10],[11],[12],[13],[14]
For a patient coming from an endemic country with a suspected light infection, the
reasonable approach for diagnosis would be serum antibody titer or polymerase chain
reaction assay.[6] Other investigations include serologic tests for the detection of the parasite antigens.[15] Another means involve the demonstration of parasite eggs in the stool by microscopic
examination (Kato-Katz smear).[16]
The treatment of choice for all schistosome species is praziquantel.[17],[18]
As maturing schistosomes are less susceptible to therapy than adult worms, a second
course of treatment is necessary. This is given several weeks after the first course
of therapy.[19]
This patient presented first with an acute illness, Katayama syndrome, which was misdiagnosed
as connective tissue disease owing to the nonspecific clinical presentation. Patients
with acute Schistosoma mansoni infection have been diagnosed at times as having typhoid
fever, hepatitis, pancreatitis, and appendicitis, only to be cured when infection
with schistosomiasis has been discovered after a long search.[14] In this case, the patient's illness was complicated by acute colonic schistosomiasis,
confirmed by the finding of viable ova on histopathological examination of colonic
mucosa specimens. The absence of ova in stools does not rule out schistosomiasis since
it has been estimated that thousands of eggs per day must be excreted to be readily
visualized on routine microscopic examination of stools.[20]
CONCLUSION
Compared to chronic schistosomiasis, Katayama syndrome is rather an uncommon acute
presentation of the disease, especially in endemic areas. Clinical symptoms and laboratory
tests are nonspecific, so the diagnosis could be missed till the time of appearance
of features of specific organ involvement. Colonic mucosa is one of the common sites
of ova deposition, giving rise to colonic schistosomiasis, again with nonspecific
clinical symptoms and laboratory tests, as well as endoscopic features, but only in
conjunction with the histopathological findings, the correct diagnosis can be revealed.
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