humans are infected naturally by 3 species of hookworms ; necator americanus , ancylostoma duodenale , and ancylostoma ceylanicum .
individual people can be infected with 1 species , 2 species , or all 3 species of hookworms [ 1 - 5 ] . although a. ceylanicum is often considered to be a zoonotic pathogen , since it is also found in dogs and cats , its importance as a significant soil - transmitted helminth of humans is increasingly being recognized .
two haplotypes of a. ceylanicum have been identified ; one largely found in humans and another that infects humans , dogs , and cats .
a. ceylanicum is considered to be of emerging importance as a helminth of humans in the asia pacific region .
a fourth hookworm also reported from humans , ancylostoma caninum represents a canine species with zoonotic potential .
this species has mainly been recorded as causing eosinophilic enteritis in people in tropical australia , but never establishes a patent infection and hence humans are regarded as accidental hosts .
human hookworm is common in the solomon islands , with an estimated 192,000 people ( 36% of the population ) infected , but the different species involved are yet to be determined [ 9 - 11 ] .
the report to the rockefeller hookworm campaign in 1928 described only n. americanus as being present on these islands .
the only previous report of a. ceylanicum from the solomon islands was a 5-year - old boy who imported the species in 1938 from the shortland island group of the solomon islands to australia .
the solomon islands is a small pacific nation to the north east of australia , with a predominantly melanesian population .
the regional assistance mission to solomon islands ( ramsi ) occurred between 2003 and 2013 , at the request of the solomon island s government , to assist in stabilizing internal troubles occurring within the nation .
ramsi consisted of 2,200 police and soldiers from many pacific island nations and was led by australia .
this case report describes the finding of a. ceylanicum in an australian soldier who developed symptomatic disease after returning from a deployment in solomon islands with ramsi .
the patient was a 26-year - old male living in townsville , north queensland , australia who presented in march 2004 with central poorly defined abdominal pain of 4 weeks duration and increased frequency of defecation .
a peripheral eosinophilia had been noted on blood tests in february prior to symptom development , and in march , when eosinophils were 6.2010/l whilst red blood cell indices were normal ( hemoglobin 146 g / l , mcv 93 fl , hematocrit 0.44 , red cell count 4.710/l ) .
the patient had served with ramsi in the solomon islands from late july to early december 2003 .
his duties involved travel to various remote areas and provided multiple opportunities to become infected with hookworms .
routine treatment with albendazole had been given by the australian defense force on return to townsville in december , 2 months prior to development of symptoms .
initially , in march 2004 no parasite eggs were detected in feces by formalin - ethyl acetate concentration , but infective larvae of hookworms were found on harada - mori culture .
infective larvae were sheathed , had inconspicuous buccal spears , the intestine was narrower than the esophageal bulb , and inconspicuous transverse striations were noted on the sheath in the tail region .
the infective larvae , measured after preservation in hot formalin , had the following dimensions , meansd ( range ) : length 657.19.6 m ( 633 - 669 m ) , width 21.40.9 m ( 20.2 - 22.2 m ) , esophagus 156.73.5 m ( 151 - 162 m ) , tail 77.93.8 m ( 69 - 81 m ) , length of sheath 763.78.6 m ( 779 - 746 m ) ; esophagus / length 23.80.5% , and tail / length 11.90.6% . due to the failure of single dose post - deployment albendazole therapy to eradicate this infection , the patient was treated with 100 mg of mebendazole twice daily for 3 days .
twelve adult hookworms ( 6 females and 6 males ) were recovered by dissection of stools passed during the 48 hr immediately following treatment . the en face view revealed a robust ventral cutting plate bilaterally with a prominent point on the dorsal end and less obvious point on the ventral end ( fig .
the width of the bursa in lateral view was greater than its length , and the mediolateral and posteriolateral bursal rays were parallel ( fig .
the morphology of the adult hookworms was consistent with a. ceylanicum with key features being : the large ventral cutting plates terminating at the dorsal end in a large single tooth ; and in the male the parallel mediolateral and posteriolateral bursal rays .
although the morphology and dimensions of the infective larvae are more consistent with a. ceylanicum than n. americanus , differentiating them from infective larvae of a. duodenale is unreliable .
although molecular taxonomy is valuable in identifying hookworm species , it was not available in this case and , as the specimen was subsequently accidentally disposed of , molecular taxonomic studies can not be performed now . however , the morphological features were sufficient to identify this species as a. ceylanicum .
this represents only the second report of human a. ceylanicum infection having been acquired in this nation , with the first being made almost 80 years ago .
this finding not only expands the known range of human a. ceylanicum infection but also raises the question of whether a. ceylanicum is in fact a common cause of human hookworm infection in some regions of the solomon islands , as it has recently been described as being in many parts of asia . the only previous reported description of hookworm species in the country was almost 80 years ago and was anecdotal , not providing descriptions of number of people tested or how the species identifications were arrived at .
a. ceylanicum infection has recently been reported from two people in western australia . prior to this , a. ceylanicum had been reported from dogs and cats in northern australia , including those from townsville .
hence , the infection could have been acquired in north queensland or while deployed with ramsi .
the likelihood of infection with ancylostoma from humans in the solomon islands is high , but negligible in north queensland since human feces are disposed of safely .
however , since a. ceylanicum is present in dogs and cats in north queensland , there is a possibility of a zoonotic australian source even though this infection has not been seen in humans in this region .
many ramsi personnel were infected with hookworms during their mission to the solomon islands , and an isolated case of a. ceylanicum infection had been reported from this area early in the 20th century .
this adds to the likelihood that the case presented here was acquired in the solomon islands and not elsewhere .
the clinical symptoms displayed by our patient were consistent with the phase of hookworm infection during which the host attempts to eliminate the parasite using an allergic response , manifesting morphologically as eosinophilic enteritis . for n. americanus
this response begins about 10 days after infection and persists for up to a month .
a. caninum and a. duodenale have a more complicated life cycle in which some infective larvae can enter a state of hypobiosis ( arrested development ) and can orchestrate entry to the intestine to coincide with the wet season and physiological events [ 23 - 26 ] . whether a. ceylanicum has
the failure of a routine post - deployment albendazole treatment to eliminate the infection in our patient supports a hypothesis that the current infection was due to hypobiotic larvae activated after the anthelmintic was given .
acute enteritis has been described previously in soldiers with a. ceylanicum acquired in west papua ( formerly dutch new guinea )   and in a traveller returning from myanmar to france .
treatment with albendazole in the latter patient cleared the gut infection but symptoms and parasites recurred after 3 months adding evidence for hypobiosis in a. ceylanicum .
our patient was treated after diagnosis with mebendazole due to its far greater tissue penetration and therefore greater capacity to kill hypobiotic larvae in the tissue .
the key points from this case report are : a. ceylanicum should be considered as a cause of acute eosinophilic enteritis in returned travellers , workers , or defense force personnel who have lived or visited tropical and subtropical countries ; laboratory confirmation may require persistence to make the diagnosis of hookworms and will require special tests ( morphology of adults after treatment ; molecular taxonomy on stools or infective larvae ) to identify the species ; and human infection with a. ceylanicum is probably endemic in the solomon islands and further study of the prevalence of different hookworm species present in this country is warranted .
 a 26-year - old male member of the australian defense force presented with a history of central abdominal pain of 4 weeks duration and peripheral eosinophilia consistent with eosinophilic enteritis . 
 acute hookworm disease was diagnosed as the cause . 
 adult worms recovered from feces after therapy with albendazole were morphologically consistent with ancylostoma ceylanicum . 
 as the patient had been deployed with the regional assistance mission to solomon islands for 6 months prior to this presentation , it is very likely that the a. ceylanicum was acquired in solomon islands . 
 until now , it has been assumed that any ancylostoma spp . recovered from humans in solomon islands 
 is a. duodenale . 
 however , this case demonstrates that human hookworm infection acquired in the solomon islands could be caused by a. ceylanicum . 