Long-Standing International Cooperation in Parasitology Research: A Summary of 35 Years of Activities in the Bolivian Chaco.

The Bolivian Chaco is a semiarid region with a low population density, situated in the southeast part of the Plurinational State of Bolivia. Here, despite the improvements of the last 15 years, poverty remains high in rural areas, where social vulnerability is widespread. The Guaraní ethnic group often lives in isolated communities with a low standard of hygiene and sanitation. This epidemiological scenario favors the spread of transmissible diseases, including several parasitic infections belonging to the neglected tropical diseases (NTDs) group. In this area, a long-standing research activity, built upon the synergism between local and foreign institutions, has been established since the late 1980s and helps to fill in the knowledge gap about the epidemiology dynamics of soil-transmitted helminths, vector-borne parasites, and other parasitic diseases. A 35-year history of cooperation programs in parasitology research has contributed to informing local health authorities of the NTD burden in the Bolivian Chaco and, ultimately, supports local healthcare providers in the management of parasitic diseases.

Trypanosoma cruzi infection in the human population of the Bolivian Chaco: four serosurveys over a 26-year period (1987-2013).

INTRODUCTION: Chagas disease (CD) remains a public health concern in several Latin American countries. At global level, Bolivia has the highest CD burden and the Chaco region, in the southeast of the country, is the most affected area. We report the results of four serosurveys for Trypanosoma cruzi antibodies, carried out approximately ten years apart from each other, during the lapse 1987-2013, in different localities of the Bolivian Chaco. METHODOLOGY: Four cross-sectional surveys were conducted in various localities, mostly rural, of the Bolivian Chaco, during the period 1987-2013. RESULTS: Although a reliable analysis of CD epidemiological trend is challenging, a partial reduction of anti-T. cruzi seroprevalence over the past four decades in the Bolivian Chaco may be assumed. In particular, in 1987 the exposure to T. cruzi in rural setting was universal since the first years of life, while it resulted gradually lower and age-dependent thereafter. Moreover, T. cruzi seroprevalence among women of reproductive age (15-45 years) has been persistently high in rural areas. CONCLUSIONS: T. cruzi transmission is still active and CD remains a concern throughout the Bolivian Chaco. More efforts are needed in order to achieve a sustainable interruption of vector-borne CD transmission in this area.

Decline in Total Serum IgE and Soluble CD30 in the Context of Soil-Transmitted Helminth Decline in Bolivia.

In the Bolivian Chaco, recent surveys documented a dramatic decrease in the prevalence of soil-transmitted helminth (STH) infections as compared with the 1980s after thirty years of preventive chemotherapy (PC). Concomitant immunological rearrangements are expected. Because nematode infections are associated with increased levels of circulating IgE and glycoprotein CD30 soluble form (sCD30), this study aims to evaluate changes in serological markers of T helper (Th)2-cells activity between 1987 (high STH prevalence) and 2013 (low STH prevalence) in rural communities in the Bolivian Chaco area. We collected 151 sera during two different surveys in 1987 (n = 65) and 2013 (n = 86) and measured the concentration of total IgE and sCD30 by immunoassays. We found a statistically significant age-independent decrease in the total IgE (P < 0.0001) and sCD30 (P < 0.0001) from 1987 to 2013. The significant decrease in serological Th2 markers (IgE and sCD30) between 1987 and 2013 is consistent with the drop in STH prevalence in this geographical area during the same period of time. Further studies might elucidate the clinical and epidemiological impact of these serological rearrangements.

Canine Trypanosoma cruzi infection in the Bolivian Chaco.

A cross-sectional study on Trypanosoma cruzi was carried out in 2013 to evaluate the role of dogs as possible source of infection for humans in two rural communities of the highly endemic Bolivian Chaco (Bartolo, Chuquisaca Department, n = 57 dogs; and Ivamirapinta, Santa Cruz Department, n = 48 dogs). Giemsa-stained thick and thin smears, rapid immunochromatographic test (ICT) (Chagas Quick test, Cypress Diagnostic, Belgium) and polymerase chain reaction for T. cruzi on dried blood spots were performed. All smears proved negative by microscopic examination, whereas 23/103 (22%) were positive by ICT and 5/105 (5%) blood samples contained T. cruzi DNA, evidencing the potential role of dogs in the domestic transmission of the parasite.

Hymenolepis nana-An Emerging Intestinal Parasite Associated with Anemia in School Children from the Bolivian Chaco.

Tropical anemia can have multiple causes, whether socioeconomic, dietary, or infectious. In the Bolivian Chaco, soil-transmitted helminthiases (STH), malaria, and Chagas disease are potential infectious causes of anemia among school-aged children (SAC). Following years of preventive chemotherapy with mebendazole, the prevalence of STH among SAC living in that area is now negligible, whereas protozoan infections are still highly prevalent (81%); Hymenolepis nana is the most frequent intestinal helminth (∼13%). We present results of hemoglobin (Hb) assessment and the association between parasitic infections and Hb levels of that SAC population. Overall, 511 SAC (girls:boys ratio 1:1, mean age 9.4 years [95% confidence interval {CI}: 9.3-9.5]) had Hb levels measured by using a point of care testing (HemoCue® Hb 301 System; HemoCue, Angelhome, Sweden). The prevalence of anemia was 23% (117/511), with mean and median Hb level = 12.2 g/dL (95% CI: 12.1-12.3; range 9.2-15.4 g/dL). By multivariate analysis, H. nana infection was associated with an increased risk of anemia (odds ratio 2.9, 95% CI: 1.5-5.7, P = 0.002). Two samples (0.5%) were positive for Trypanosoma cruzi and none for Plasmodium spp. by polymerase chain reaction of the 439 children tested. Anemia is still a concern among SAC living in the Bolivian Chaco. Our findings call for a greater attention to fecal-oral emerging pathogens, such as H. nana, and highlight the importance of water, sanitation, and hygiene improvements for disadvantaged population such as those living in the Bolivian Chaco.

Scaling down of a deworming programme among school-age children after a thirty-year successful intervention in the Bolivian Chaco.

OBJECTIVE: Preventive chemotherapy is the WHO-recommended control method for soil-transmitted helminthiases. In the Bolivian Chaco, 6-monthly single-dose mebendazole delivery to school-age children achieved a dramatic decrease in soil-transmitted helminthiases prevalence between 1987 and 2013. Consequently, in September 2016, preventive chemotherapy delivery was interrupted in nine rural communities. In compliance with WHO recommendations, we intensified surveillance to monitor soil-transmitted helminthiases prevalence and detect potential changes that would require interventions. METHODS: We conducted two cross-sectional parasitology surveys 12 months apart (September 2016-2017) among school-age children living in the communities where preventive chemotherapy delivery had been halted. Study design, methods of sampling and sample analysis technique (direct microscopy, Kato-Katz technique) followed WHO recommendations, aiming to obtain data representative of the Bolivian Chaco ecological zone. RESULTS: We collected 426 samples in 2016 and 520 in 2017. Soil-transmitted helminthiasis prevalence was unremarkable: 0.7% (95% CI 0-1.5%) in 2016 and 0.8% (0-1.5%) in 2017. Conversely, the prevalence of tapeworms (13% in 2016, 12% in 2017) and intestinal protozoan infections (81% in 2016 and 75% in 2017) continued to be high. CONCLUSIONS: Our findings support the role of preventive chemotherapy in reducing soil-transmitted helminthiases transmission, as otherwise poor hygienic and health conditions persist in the Bolivian Chaco. A national survey, involving areas from all the ecological zones of Bolivia, is now warranted.

Seroepidemiological trend of strongyloidiasis in the Bolivian Chaco (1987-2013) in the absence of disease-specific control measures.

OBJECTIVES: The prevalence of Strongyloides stercoralis infections is grossly underestimated because infections go mostly undetected, although they can persist for a lifetime due to the auto-infective cycle. In the Bolivian Chaco, the prevalence of soil-transmitted nematodes dropped dramatically in the past 25 years, but the mebendazole used for preventive chemotherapy has no effect on S. stercoralis. Meanwhile, the prevalence of intestinal protozoan infections remains unchanged. We compared S. stercoralis seroprevalence in rural communities of the Bolivian Chaco from 1987 to 2013. METHODS: Sera collected during two previous serosurveys, conducted in the Chaco region in 1987 and 2013, were tested for S. stercoralis using a commercial assay (Bordier-ELISA, Bordier Affinity Products, Switzerland). RESULTS: Overall, 355 sera were analysed, 122 from the 1987 survey and 233 from the 2013 survey. Seropositivity for S. stercoralis was significantly more prevalent in 1987 (19/122, 16% in 1987 vs. 15/233, 6% in 2013, P = 0.006), accounted for by a drop from 17% to 3% in people under 26 years of age. Multivariate analysis showed a significant association between seropositivity for S. stercoralis and age in the 2013 population (OR 1.03 for each one-year increase, 95%CI 1.00-1.05, P = 0.04), but none in 1987. CONCLUSIONS: The significant reduction in S. stercoralis seroprevalence in Bolivian Chaco cannot be explained by preventive chemotherapy or improved social-sanitary conditions. As the drop is seen in younger generations, it is consistent with little transmission occurring. However, the risk of transmission still exists, as prevalence is persistently high in older individuals, who present a potential reservoir due to the lifelong nature of S. stercoralis infections.

An appraisal of canine and human cases reveals an endemic status of dirofilariosis in parts of Serbia.

Dirofilaria immitis and D. repens are mosquito-borne nematodes that primarily infect canids, and can also cause mild to serious superficial or visceral infection in humans. In the present survey, peripheral blood from 150 asymptomatic dogs from Serbia were examined using the modified Knott's technique. Dirofilaria immitis, identified based on morphological and morphometric characteristics, was prevalent in dogs not receiving preventative treatment (in 44% and 60% of pound and pet dogs, respectively). These results, together with findings of autochthonous cases of subcutaneous D. repens infection in human patients from Southeastern Serbia emphasize the need for further investigations of this veterinary and public health problem.

Seroprevalence and Risk Factors for Toxocara canis Infection in Serbia During 2015.

We report data on the Toxocara seroprevalence evidenced in 2015 from samples of 40 children and 298 adults of the population living in different areas of Serbia, and on possible association of certain variables with infection. Detection of specific antibodies was performed using an enzyme-linked immunosorbent assay; all ambiguous results and part of the positive and negative sera were further analyzed by confirmatory Western blot test. An overall 23.5% seroprevalence was noticed, which was confirmed in 13.0% of the examined population with no significant difference regarding the age (children = 10.0%; adults = 13.4%) or by country area (East = 18.2%; North = 15.5%, Southeastern = 9.5%; p = 0.005). In contrast, the group of adult women proved more reactive than men (p = 0.001), and subjects both who spend spare time in square/parks (p = 0.041) and with positive onychophagy (p = 0.001) habit turned out more exposed to the infection. Possible reasons of these differences were analyzed, and the medical, veterinary, and economic impact of this soil-transmitted zoonosis were discussed.

Intestinal parasitic infections and associated epidemiological drivers in two rural communities of the Bolivian Chaco.

INTRODUCTION: In 2013 a coproparasitological survey was carried out in two rural communities of the Bolivian Chaco to determine the prevalence of intestinal parasitic infections (IPIs) and to investigate on possible infection drivers through a questionnaire interview. METHODOLOGY: Faecal samples were examined by microscopy. Samples positive for Entamoeba histolytica complex and Blastocystis were molecularly examined to identify the species/subtypes involved. RESULTS: The overall infection rate was 86%, identical in both communities and mostly due to protozoa. Soil-transmitted helminths were detected in <3% of children and adults. DISCUSSION: The protozoa detected, including Blastocystis subtypes, indicate faecal contamination of the environment by both humans (as confirmed by the presence of Hymenolepis nana) and animals. Nested-PCR identified E. histolytica, thus signalling the possible occurrence of invasive amoebosis. Lack of safe water, environmental contamination, poor sanitation and hygiene, shared by both communities, are the main drivers of IPIs. In addition, unlike gender and socioeconomic factors, childhood (only for some species), crowding and cohabitation with animals proved to be further significant protozoon infection risk factors. CONCLUSIONS: These results highlight the need for the promotion of access to clean water, improved sanitation and better hygiene, thus reducing the frequency of preventive chemotherapy for STHs while continuing to monitor the population for possible recrudescence.

Human Babesiosis, Bolivia, 2013.

To investigate human babesiosis in the Bolivian Chaco, in 2013 we tested blood samples from 271 healthy persons living in 2 rural communities in this region. Microscopy and PCR indicated that 3.3% of persons were positive for Babesia microti parasites (US lineage); seroprevalence was 45.7%. Appropriate screening should mitigate the risk for transfusion-associated babesiosis.

Dirofilaria repens microfilariae from a human node fine-needle aspirate: a case report.

BACKGROUND: Human dirofilariosis is still a little known infection even in endemic areas. Dirofilariosis is zoonotic infection usually abortive in humans; instead, we report a very rare case (the 4th in the world), the first in Italy, in which at least two infective larvae became mature adults that mated and produced active microfilariae even though they did not reach peripheral blood. CASE PRESENTATION: A 30-year-old Italian woman presented with a transient oedematous swelling on the left abdominal wall with a creeping eruption followed by the occurrence of a subcutaneous nodular painless mass in the iliac region. One month later, a similar temporary swelling appeared on the contralateral inguinal region associated with intermittent joint discomfort in both knees. The patient had recently travelled abroad, therefore many possible diagnoses were to be ruled out. Routine laboratory investigations revealed eosinophilia. An ultrasound examination of the iliac swelling evidenced a well-defined cyst with a big filamentous formation in continuous movement. A fine-needle aspiration of the lesion was performed for parasitological, cytological and histological exams. The prompt microscopic examination of the aspired material showed the presence of numerous microfilariae that were initially morphologically attributed to Mansonella ozzardi. Subsequently, the revision of the Giemsa stained film and molecular analyses of the biological material, allowed to identify Dirofilaria repens as etiological agent of infection. CONCLUSIONS: We report of a case in whom microfilariae were detected in fine-needle aspirate of subcutaneous node, without evidence of microfilaraemia, and the infection failed to become fully patent. Therefore we confirm that complete development and fertilization of D. repens worms in human hosts may occur, at variance with what is commonly believed, that Dirofilaria worms cannot fully develop in humans.

Eyeworm infections in dogs and in a human patient in Serbia: A One Health approach is needed.

Thelazia callipaeda eyeworm has been frequently reported parasitizing humans in Asia. In Europe, the parasite is endemic in wild and domestic carnivores and only eight cases have been reported in humans so far. We describe the first case of human thelaziosis in Serbia, along with two cases in dogs from the same area. A One Health approach, based on cooperation amongst veterinarians and physicians, is strongly advised for this emerging infection in order to assess the risk for and prevent of the zoonotic infection.

Malaria in children of Tshimbulu (Western Kasai, Democratic Republic of the Congo): epidemiological data and accuracy of diagnostic assays applied in a limited resource setting.

BACKGROUND: The literature data on malaria in Western Kasai, DRC, are limited and inadequate. A recent molecular survey there has detected Plasmodium ovale and Plasmodium malariae as mixed infections with Plasmodium falciparum. In Tshimbulu, Western Kasai, during a humanitarian initiative designed to provide children with free preventive screening and to reduce the local high malaria death rate, accurate species identification was performed, in order to collect unambiguous epidemiological data and to evaluate the reliability of locally applied diagnostics. METHODS: Finger pricks provided fresh blood for microscopic analysis (MA), for rapid diagnostic test (RDT) and for molecular diagnostics (MD). MA and RDT were first performed by the local team and then a re-interpretation of the results (on the same slides and on RDT's taken pictures) was conducted in Italy, where MD were performed. RESULTS: The analysis was conducted on 306 children; RDT found 80.9 % as P. falciparum-positive (37.4 % as two-band positive, P. falciparum single infection). MA identified a further four children as positive to P. falciparum and six co-infections with P. ovale. The second RDT evaluation confirmed a similar infection rate (78.2 %) but interpreted as two-band positive a significantly higher share of tests (56.8 %). MA confirmed 80.0 % of the children as malaria positive and, in addition to P. falciparum, identified P. malariae (13.8 %), P. vivax (3.4 %) and P. ovale (2.4 %), and detected Babesia microti in 19 smears. MD confirmed all of the species found (Babesia microti included), classified as mono-infection with P. falciparum a rate of spots comparable to MA revision, and identified all P. ovale as Plasmodium ovale wallikeri. The RDT used locally proved 93.1 % sensitive and 92.1 % specific for P. falciparum. CONCLUSIONS: The malaria prevalence among the children and the presence of four Plasmodium species, highlighted in this study, identified a sanitary issue which proved to be more alarming than expected, as it was worsened by the unpredictable presence of P. vivax and Babesia microti (never before reported in DRC). Each diagnostic tool showed its point of weakness. Therefore, the most correct approach is by the combined use of different, locally available, diagnostic tools.

Canine Babesioses in Noninvestigated Areas of Serbia.

During the years 2012-2014, a total of 158 outdoor dogs from Pancevo and Durdevo (northern Serbia) and Nis and Prokuplje (southern Serbia) were submitted to molecular analyses (PCR and sequencing) for canine babesioses. An overall prevalence of 21.5% was found, due to the species Babesia sp. 'spanish dog' (10.1%), B. gibsoni (5.7%), B. canis vogeli (1.9%), B. caballi (1.9%), and B. microti (1.9%). In addition, sequence analysis showed the presence of Hepatozoon canis in a dog from Nis. No significant difference between infected and noninfected dogs was found by age, sex, and place of residence, whereas there was difference regarding the presence of ticks (p<0.005) and application of preventive measures such as applying of antitick drugs/devices. Moreover, a significant difference was established by area: Dogs from Prokuplje showed infection rates (59.1%) higher than dogs from Pancevo (11.9%), Nis (4.5), and Durdevo (where infected dogs were not found), and a different geographical distribution of the species was found. The presence of so many Babesia species and the first identification of H. canis will allow investigations on the pathogenic role played by each one and suggests entomological studies on the tick species that are more suitable vectors for each of them. Finally, the presence of so many infected dogs offers the opportunity of evaluating the hypothesis of a possible zoonotic role of babesial species affecting dogs.

Molecular detection of Rickettsia, Borrelia, and Babesia species in Ixodes ricinus sampled in northeastern, central, and insular areas of Italy.

The aim of the present study was to provide insight into the diversity of tick-borne pathogens circulating in Italy, carried/transmitted by Ixodes ricinus, one of the most abundant tick species in the country. A total of 447 specimens sampled in five areas of northeastern, central and insular Italy were analysed by polymerase chain reaction and sequencing for the presence of rickettsiae, borreliae and babesiae. Several rickettsial species of the spotted fever group of zoonotic concern and other zoonotic pathogens were found, such as Borrelia burgdorferi s.s., Borrelia afzelii, Borrelia garinii, and Babesia venatorum. These findings confirm a wide distribution of tick-borne bacterial and protozoan species in Italy, and highlight the sanitary importance of I. ricinus, often recorded as feeding on humans.

Dramatic decrease in prevalence of soil-transmitted helminths and new insights into intestinal protozoa in children living in the Chaco region, Bolivia.

We assessed the prevalence of intestinal parasites among 268 2-12-year-old children living in rural areas, small villages, and semi-urban areas of the Chaco region, south-eastern Bolivia. The overall parasitism was 69%. Only protozoa, helminths, or co-infections were observed in 89.2%, 5.9%, or 4.9% of the positive children, respectively. A significant progressive increase in overall parasite prevalence was found when passing from rural areas to small villages and semi-urban areas. The most commonly found species were Entamoeba coli (38.4%), Giardia intestinalis (37.7%), and Blastocystis spp. (16%). Hymenolepis nana was the most prevalent helminth (5.6%), followed by Ascaris lumbricoides and hookworms (1.5% and 0.4%) evidenced only in rural areas and in villages. Molecular diagnostics identified Blastocystis subtypes 9 and 2, and 5 infections by Entamoeba histolytica and 4 by Entamoeba dispar. The dramatic decrease in prevalence of soil-transmitted helminths with respect to that observed about 20 years ago (> 40%) evidences the success of the preventive chemotherapy intervention implemented in 1986. Health education and improved sanitation should be intensified to control protozoan infections.

Chronic polyarthritis associated to Cercopithifilaria bainae infection in a dog.

Despite the widespread distribution of Cercopithifilaria bainae among canine and tick populations worldwide, this filarioid is currently considered of 'minor importance' in veterinary medicine, particularly when compared to related filarioids, such as Dirofilaria immitis and Dirofilaria repens. To date, only a single case of dermatological alterations possibly associated to infection by C. bainae had been reported in a dog. In the present study, we describe the first case of systemic alterations associated to C. bainae infection in a dog suffering from diffused chronic polyarthritis. The animal had a previous history of reluctance to move and stiff gait and displayed multiple joint pain during manipulation of limbs. No biochemical, haematological and X-ray alterations were detected; microfilariae were observed in the synovial fluids collected from the joints. In spite of the morphological and molecular identification of these microfilariae as C. bainae, the dog did not respond to multiple microfilaricidal treatments with milbemicyn oxyme. The potential role of C. bainae in the pathogenesis of this clinical condition is discussed. Given the potential pathogenicity of this parasite, improved knowledge of this little known tick-borne nematode is warranted in order to assist the development of novel and effective treatment strategies.

Human oestriasis acquired in Florence and review on human myiasis in Italy.

Myiases-causing flies are widely observed in tropical countries, whereas in Italy, a temperate country, their epidemiology and clinical presentation are poorly known. We report three cases of human conjunctival myiasis recently observed at our hospital, and the results of a review of the literature on human myiasis in Italy. In August 2012, a case of Oestrus ovis conjunctival myiasis acquired in the city centre of Florence, Italy was diagnosed at our hospital. In the early fall of 2013, two additional cases, acquired in the neighbouring areas, occurred. The review of literature showed that, up to the middle of 1990s, myiasis in Italy was mainly an occupational disease of shepherds, caused by O. ovis. Recently, cases of travel acquired furuncular myiasis emerged, together with "opportunistic" autochthonous cases of wound myiasis in patients with underlying health conditions. Considering the causative agents of human of myiasis in Italy, among the 703 autochthonous cases reported, 98.1% were caused by O. ovis, while among the 42 imported cases described, 59.5% were due to Cordylobia spp. and 40.5% to Dermatobia hominis. Our findings suggest that O. ovis conjunctival myiasis may still be observed in urban setting in Italy. Health care providers should know and implement the basic rules of entomoprophylaxis for myiasis in the facilities where they are working and use these indications to educate patients and care givers in both pretravel care and geriatric outpatient settings.

Human exposure to piroplasms in Central and Northern Italy.

TA serosurvey has been conducted in Northern and Central Italy to investigate the presence in humans of antibodies against zoonotic Babesia and Theileria species. The study focused on a total of 432 volunteers, of which 290 were persistently exposed to tick bites because of their jobs (forester employees, livestock keepers, veterinary practitioners, farmers and hunters) and 142 resident in the same area less frequently exposed. An indirect fluorescent antibody test (IFAT) for humans was used to detect antibodies to Babesia microti, IFAT tests for veterinary use were modified to detect reactivity to Babesia bovis, Babesia canis and Theileria equi. A laboratory-derived ELISA was employed to detect antibodies to Babesia divergens. Both reactive and 10 negative sera were analysed against plasmodial antigens to evaluate possible aspecificity. A high reactivity to piroplasm antigens was found, showing significant difference between the sera of the two groups of volunteers (24% vs 7.%; p<0.001). No cross-reactivity was observed, while each professional group showed reactivity that would fit with the professional risk exposure. In particular, a high reactivity to B. microti and B. divergens antigens was observed in foresters and hunters (32% and 12%, respectively). This is the first report on the human seroreactivity to piroplasms in Italy; it also provides additional epidemiological information on these tick-borne zoonoses in Europe. Our findings suggest the possible occurrence of piroplasm infections in Italy and alert physicians to consider these otherwise neglected parasitic diseases when dealing with any febrile illness, especially in subjects exposed to tick bites.