fascioliasis , a snail - borne parasitic zoonosis , has been recognised for a long time because of its major veterinary impact . it is caused by two trematode species of the fasciola genus : f. hepatica , present in europe , africa , asia , the americas , and oceania and f. gigantica , mainly distributed in africa and asia . fascioliasis is currently the vector - borne disease with the widest known latitudinal , longitudinal , and altitudinal distribution . it has been generally acknowledged that f. hepatica was introduced into the caribbean region in general and cuba in particular by the infected livestock of spanish conquistadors between 1500 and 1865 [ 24 ] . however , the first autochthonous cases of human fascioliasis were not reported in cuba until 1931 . fascioliasis was therefore considered to be a public health problem relatively early in the history of cuba . although data on human fascioliasis remained rare in the very similar neighbouring island , hispaniola ( haiti , dominican republic ) or even nonexistent as in haiti , animal fascioliasis was well documented in this country [ 7 , 8 ] . a relatively recent case of fascioliasis was reported in a 26-year - old woman native of dominican republic , and living in usa , demonstrating the existence of human fascioliasis in hispaniola . however , to the best of our knowledge , no cases of human fascioliasis have been reported in haiti , although zoonotic infection of man is known to occur in cuba , the dominican republic and puerto rico . moreover , in haiti , f. hepatica is present in animals and watercress ( nasturtium officinale ) , commonly consumed by the human population . the present study was therefore designed to screen for possible cases of asymptomatic human f. hepatica infection in haiti . a retrospective , cross - sectional , serological survey , testing sera provided by workers , was conducted in port - au - prince . two hundred and sixteen serum samples , provided by workers ( 1835 years old ) seen in the context of periodic occupational medicine visits , were retrospectively tested ( after storage by freezing at 20c ) using a western blotting test ( ldbio diagnostics , lyon , france ) . the enzyme - linked immunoelectrotransfer blot ( eitb ) techniques with fasciola hepatica excretory - secretory antigens have been appropriately evaluated for fascioliasis diagnosis in humans [ 10 , 11 ] . eitb was performed with strips and reagents provided with the kit , according to the manufacturer 's instructions . briefly , the strips were incubated with serum diluted to 1  :  50 in tris - nacl sample buffer for 90  min . after a washing step with tris - nacl washing buffer , the strips were incubated with an antihuman immunoglobulin g - alkaline phosphatase conjugate for 60  min . after another washing step , the protein fractions recognised by the serum were revealed by the corresponding substrate a test was considered to be positive when the strip presented 2 or more specific bands including the p27 - 28  kda band . fourteen serum samples were positive on the f. hepatica western blot assay test , each reacting at two to three specific antigenic bands . under these study conditions , 6.5% of the study population had been in contact with the parasite . as shown in table 1 , the immunodominant bands most frequently recognised by western blot were 27 - 28  kda ( 100% ) and 42  kda ( 64% ) . f. hepatica is a frequently neglected parasitic trematode infecting almost 17 million people worldwide [ 12 , 13 ] . recent observations indicate that fascioliasis is gradually expanding and constitutes a serious threat to human and animal health . indeed , this disease has a great potential for expansion due to the considerable colonisation capacities of its causal agents and vector species . for example , fascioliasis has been detected at very high altitudes ( 35004200 meters ) in various andean regions . the highest prevalence and egg outputs in humans have been observed in these very high altitude zones of bolivia and peru [ 15 , 16 ] . this means that not only snails and parasites are able to successfully colonise the extreme conditions of very high altitude , but also that they have been able to develop various strategies resulting in higher parasite transmission rates . however , the extent of this public health threat is not well known due to poor reporting of cases of fascioliasis worldwide . according to a study conducted by the pan american health organization , fascioliasis is known to cause major losses to the meat industries in cuba , the dominican republic , haiti , and jamaica . the extent of losses can be partially quantified by examining the prevalence of bovine liver condemnation , an indicator of morbidity produced by liver - fluke infestation . in the 1960s , liver condemnation rates ranged from 11 to 33% in cuba , 10 to 23% in saint lucia , 0 to 3% in puerto rico , and 60% of all livers were condemned in one haitian slaughterhouse . in addition to its veterinary and economic impact , potential transmission of f. hepatica to humans must not be neglected . surprisingly , zoonotic infection of man appears to be truly absent from haiti , as , to our knowledge , there have been no reported cases of human fascioliasis , despite the fact that environmental conditions and eating habits are in favour of human infection . as in other caribbean countries , watercress , which is known to be a potential source of human f. hepatica infection , is grown extensively and eaten with nearly every meal in haiti . it is called  poor man 's lettuce  because it is affordable for the majority of the population . furthermore , sewage systems are rare , and outdoor defecation is common , facilitating human participation in transmission via egg shedding . the absence of case reports of human fascioliasis therefore can not indicate the absence of this disease in haiti . based on variables such as poverty and physician / patient ratio , human fascioliasis should logically be prevalent in haiti , as supported by the available data , with up to 23% of cattle infected in haiti [ 7 , 8 ] . as enzyme - linked immunoelectrotransfer blot is recognised to be a highly sensitive and specific method for the immunodiagnosis of parasite infections , this test was used in the present serological survey . tests were performed by the same experienced staff to reduce the risk of handling and reading errors . the frequency of antibodies in serum samples of the study population was 6.5% ( 14/216 ) . however , due to the study design , this result may not indicate the true endemic level of human fascioliasis in haiti , as fascioliasis is a water - linked disease characterized by a patchy geographical distribution . haiti , although a relatively small country , has a very heterogeneous geography , ranging from lowlands to highlands , plains to mountains and valleys , and urban and periurban areas to rural areas . on the basis of these results , haiti could be wrongly considered to be a mesoendemic country on the list established by who and other agencies . in other words , the positive serology rate of 6.5% should not be applied to the entire country but may correspond to hyperendemic foci diluted in the total of 216 samples . all infected subjects of this study population may be derived from only one or two villages , as geographical data were not available . however , further studies including human stool examination surveys are needed to provide public health authorities with data on the incidence and epidemiology of human fascioliasis in this country . recent malacological investigations are also needed to identify other potential vectors among snails present in haiti and to initiate control measures . however , for the first time , this study provides data on human fascioliasis in haiti . it is a preliminary report that opens the way for further studies designed to obtain reliable epidemiological data on human fascioliasis in haiti . correlation of antibody levels with other features of the disease , such as ova counts in stools , may help to clarify whether asymptomatic infection is due to mild primary infection or to other immune - related factors . in haiti , these results reinforce the urgent need for control and prevention measures by local public health services . updated information on diagnosis and management of fascioliasis is required , especially for clinicians who are unfamiliar with the multiple clinical presentations of this disease .
fasciola hepatica , the aetiological agent of fascioliasis in the caribbean region , occurs throughout the major islands of the greater antilles and in localised zones on two islands ( martinique and saint lucia ) of the lesser antilles . 
 however , apart from puerto rico , information regarding human fascioliasis in islands of the caribbean is out of date or unavailable , or even nonexistent as in haiti . 
 the authors conducted a retrospective , cross - sectional serological survey in port - au - prince using a western blotting test ( ldbio diagnostics ) on human fascioliasis in haiti . 
 a total of 216 serum samples obtained from apparently healthy adults were tested . 
 the frequency of antibodies in serum samples of the study population was 6.5% ( 14/216 ) . 
 the immunodominant bands recognised in western blots were 27 - 28  kda ( 100% ) , 42  kda ( 64% ) , 60  kda , and 8 - 9  kda ( 28% ) . 
 this is the first survey to reveal a relatively low proportion of asymptomatic f. hepatica - infected humans in haiti .