in august 2013 , a 9-year - old girl who was returning to france after a 1-month stay with her family in casablanca , morocco , was admitted to lille university hospital in lille .
symptoms started in casablanca 3 days before hospital admission and included fever , severe diarrhea ( > 10 liquid defecations / day ) , vomiting , and abdominal pain in the hypogastric area and in the right and left lower quadrants associated with bilateral dorsal pain , anorexia , and weakness .  
blood count showed 13,850/mm leukocytes ( 75.4% neutrophils , 15.9% lymphocytes , 8.5% monocytes ) .
c - reactive protein level was increased at 266 mg / l ( low risk : < 1.0mg / l ; average risk : 1.03.0 mg / l ; high risk > 3.0 mg / l )
. traveler s gastroenteritis was diagnosed , and symptomatic treatment with acetaminophen , phloroglucinol glucoside , and acetorphan was prescribed . however , abdominal pain increased , and total food intolerance occurred in the following hours .  
an abdominal ultrasound was performed , revealing appendicitis with suppuration in the recto - uterine pouch and a reflex ileus .
parasitologic examination of fecal matter revealed only abundant blastocystis vacuolar forms , with > 5 parasites per field .
we further confirmed absence of cryptosporidium spp . using glycerin assay and real - time pcr .
yeasts and a multimicrobial flora were present in the fecal material , but other infectious agents such as salmonella spp . , shigella spp .
similarly , multimicrobial flora , but no pathogenic bacteria , were detected in the peritoneal liquid and recto - uterine pouch ( table ) .
histopathologic observation revealed acute suppurative appendicitis with ulcerations extending deep into the muscularis , which was covered with a suppurative and fibrinous exudate .
we observed infiltration by numerous neutrophils , eosinophils , plasma cells , and lymphocytes through all layers and into the serous membrane ( figure , panel a ) .  
micrographs showing histopathologic examination of appendix samples from a child who had peritonitis , casablanca , morocco , 2013 .
a ) ulceration ( u ) covered with suppurative and fibrinous exudates ( se ) ( hematoxylin - eosin stain ) .
b ) blastocystis parasites ( arrows ) in the lumen ( l ) , and at the surface of the epithelium ( e ) ( hematoxylin - eosin stain ) .
c ) blastocystis parasites ( arrows ) in the lumen , at the surface of the epithelium and in the lamina propria ( lp ) of the mucosa ( immunofluorescence labeling with anti - blastocystis paraflorb antibody ) .
after hematoxylin - eosin staining and immunofluorescence labeling by using the anti - blastocystis paraflor b monoclonal antibody ( boulder diagnostics , marlborough , ma , usa ) , we detected parasitic forms in the lumen and in the lamina propria of the mucosa ( figure , panels b , c ) .
we used real - time pcr for blastocystis parasite detection as described ( 4 ) , using dna extracted from stools , appendix , peritoneal liquid , and the recto - uterine pouch , which all tested positive .
we subsequently performed small subunit rdna ( ssu rdna ) amplification , then cloned the pcr product and sequenced 5 clones from all the dna samples to subtype ( st ) blastocystis isolates and detect mixed infections ( 5 ) .
the ssu rdna gene sequences obtained in this study have been deposited in genbank under accession nos .
the child completely recovered after an appendectomy , removal of a stercolith from the appendix lumen , and treatment with tinidazole , 20 mg / kg / d , and ceftriaxone , 50 mg / kg / d for 10 days , together with gentamicin , 5 mg / kg / d for 5 days .
although tinidazole is not the first line medication for treatment of blastocystis infection , the child recovered completely and showed total clearance of parasites at day 73 : using microscopy and real - time pcr on fecal samples , we found negative results for blastocystis .
data obtained from the child s mother revealed simultaneous cases of gastroenteritis in 26 family members : 13 adults , 3498 years of age , and 13 children , 18 months15 years of age , who lived in the same building at the residential  mohammadi  area of casablanca .
adults had mild or moderate diarrhea but symptoms were more severe in children , who all had abundant diarrhea , vomiting , and weight loss .
repatriation in france of an 18-month - old baby was considered , but his condition improved .
unfortunately , no explorations were performed , therfore the diagnosis could not be microbiologically documented .
reports of blastocystis infection associated with diarrhea and clinical symptoms in immunocompetent and immunocompromised patients have increased during the past 2 decades ( 2 ) .
tissue invasion of blastocystis parasites in the appendix ( 6 ) or in the colon mucosa ( 3 ) , associated with acute or chronic inflammation , has been reported . however , controversy still exists over whether this parasite is commensal or pathogenic ; this case further supports its invasive and inflammatory potential .
previous reports regarding the presence of blastocystis parasites in 4 of 100 appendix specimens from patients with acute appendicitis ( 7 ) , and of pseudoappendicular illness , which led to appendectomies in children with intestinal infection caused by this parasite ( 8) , suggest that blastocystis infection could be associated with appendicitis .
nevertheless , the actual role of blastocystis in the pathogenesis of appendicitis remains inconclusive . in this report , the presence of a stercolith , which can be found in 50%80% of appendicitis cases , suggested mechanical obstruction of the appendix s lumen , which is the main etiology of appendicitis .  
here , we report dissemination of blastocystis into the lumen , the mucosa , and the recto - uterine pouch exudate , associated with appendicular acute inflammation , and no other infectious agent was detected .
these observations , together with the well - documented acute or chronic inflammation occurring in humans or animals with blastocystis infections ( 3,9 ) , likely support the contribution of this infection to the inflammatory process .
indeed , the presence of pathogenic strains among st3 has been confirmed through experimental infections in rats ( 9 ) .
additionally , a substantial inflammatory reaction and an increased propagation of human colorectal cancer cells exposed to blastocystis st3 antigens has been demonstrated in vitro ( 10 ) .
for humans , the pathogenicity of different sts is unclear and remains a debatable issue .
st1 isolates were found to be more prevalent among symptomatic patients in lebanon ( 5 ) , but st3 was found to be the only st that showed pathogenic potential in malaysian patients when compared with st1 and st2 ( 11 ) .
st3 was also found to be significantly associated with diarrhea in libya ( p = 0.008 ) ( 12 ) .
for this case , the fact that only st3 was detected in all analyzed samples , whereas a mixed infection with st2 and st3 was found in the child s stools , further supports the high invasive potential of st3 .
st3 is the most common st in europe , but , in african countries , its frequency varies from 17.8% in libya ( 12 ) to 61.9% in egypt ( 13 ) . in morocco ,
a 28.7% prevalence of blastocystosis has been reported , but data concerning the st distribution of the parasite are not available ( 14 ) .
furthermore , although blastocystis infection could not be confirmed among the child s relatives , the simultaneous occurrence of gastroenteritis cases in the same family and the absence of other infectious agents in the child s stools suggest a potential outbreak of blastocystis infection
. blastocystis parasites could have spread within the child s family , as previously reported in italy , where 2 adopted children originating from india and the cte divoire transmitted blastocystis parasites to their adoptive parents and grandmother ( 15 ) .
possible acquisition of this parasite from a common source such as contaminated water could also explain family transmission in this report .
altogether , these data highlight 1 ) the need for both systematic parasitologic examinations of stools in patients with invasive infections who are traveling from countries with high blastocystis prevalence and 2 ) the need for routine provision of imidazoles for empiric treatment of peritonitis .
 despite increasing reports that blastocystis infection is associated with digestive symptoms , its pathogenicity remains controversial . 
 we report appendicular peritonitis in a 9-year - old girl returning to france from morocco . 
 only blastocystis parasites were detected in stools , appendix , peritoneal liquid , and recto - uterine pouch . 
 simultaneous gastroenteritis in 26 members of the child s family suggested an outbreak . 
The Study
Conclusions