Microfilaremic Dirofilaria repens Infection in Patient from Serbia

We report a case of Dirofilaria repens infection causing microfilaremia in a patient from Serbia. Serum samples tested positive for D. repens IgG by ELISA. Our findings and those of others suggest the parasite's progressive adaptation to humans. Clinicians should be aware that microfilaremia can develop during Dirofilaria spp. infections.

Persistence of onchocerciasis and associated dermatologic and ophthalmic pathologies after 27 years of ivermectin mass drug administration in the middle belt of Ghana

OBJECTIVES

There is a pressing need to regularly evaluate the progress of onchocerciasis elimination programmes to timely identify and mitigate potential risks hindering the reaching of the 2030 targets proposed by the World Health Organization (WHO) in its roadmap on neglected tropical diseases (NTDs). We determined the prevalence of onchocerciasis and associated dermatological and ophthalmological manifestations in six endemic communities in the Bono Region of Ghana after 27 years of ivermectin mass treatment.

METHODS

In a cross-sectional study, 564 participants aged ≥5 years were enrolled (49.1% females), with a median age of 26 (range: 5-89) years. In 54% and 47%, skin-snip microscopy and Ov16 rapid diagnostic tests were performed, respectively. Skin disease was determined using the WHO Skin NTD App. Visual function assessments included tests of visual acuity.

RESULTS

The overall microfilarial prevalence was 12.5% (38/305) and Ov16 seroprevalence was 24.2% (64/265). Severe itching was recorded in 24.3%, acute papular onchodermatitis in 52.8%, chronic papular onchodermatitis in 12.5%, lichenified onchodermatitis in 0.7%, skin atrophy in 11.3%, depigmentation in 1.7% and palpable nodules in 5.3%. Of the 301 persons in which visual acuity was examined, 17% were visually impaired and 5.3% were blind and 47.3% presented with cataract. Chronic papular onchodermatitis, lichenified onchodermatitis, depigmentation and visual impairment were significantly associated with the presence of skin microfilariae and Ov16 seropositivity.

CONCLUSIONS

The persistence of Onchocerca volvulus infection and onchocerciasis-associated dermatological and ophthalmological pathologies after prolonged treatment is of concern. There is a need to include morbidity management in onchocerciasis elimination programmes and understand better patterns of treatment coverage, adherence and actual intake of ivermectin.

Procedure for Handling and Storage of Onchocerca volvulus Microfilariae Obtained from Skin Snips for Downstream Genetic Work

WHO and endemic countries target elimination of transmission of Onchocerca volvulus, the parasite causing onchocerciasis. Population genetic analysis of O. volvulus may provide data to improve the evidence base for decisions on when, where, and for how long to deploy which interventions and post-intervention surveillance to achieve elimination. Development of necessary methods and tools requires parasites suitable for genetic analysis. Based on our experience with microfilariae obtained from different collaborators, we developed a microfilariae transfer procedure for large-scale studies in the Democratic Republic of Congo (DRC) comparing safety and efficacy of ivermectin, the mainstay of current onchocerciasis elimination strategies, and moxidectin, a new drug. This procedure is designed to increase the percentage of microfilariae in skin snips suitable for genetic analysis, improve assignment to metadata, and minimize time and materials needed by the researchers collecting the microfilariae. Among 664 microfilariae from South Sudan, 35.7% and 39.5% failed the mitochondrial and nuclear qPCR assay. Among the 576 microfilariae from DRC, 16.0% and 16.7% failed these assays, respectively. This difference may not only be related to the microfilariae transfer procedure but also to other factors, notably the ethanol concentration in the tubes in which microfilariae were stored (64% vs. ≥75%).

Dogs infected by Dirofilaria immitis: a threat to the health of human and non-human animals in Rio de Janeiro, Brazil

This study aimed to investigate the presence of Dirofilaria immitis microfilaremia in dogs from two regions of the state of Rio de Janeiro, Brazil, where heartworm infections are highly prevalent. Blood samples were collected from dogs aged > 12 months, independent of the use of preventatives. All samples obtained and analyzed using Knott's modified test by the investigators. A total of 133 blood samples were tested, and D. immitis microfilariae were detected in 29 of them, resulting in an occurrence of 21.8%. The percentage of dogs with microfilaremia detected raises concerns for pet families, one health professionals, and small animal practitioners. Microfilaremic dogs are the richest source of infection for the mosquitoes, increasing the risk of transmission. Therefore, the stakeholders in One Health must raise concerns regarding the health of wild animals, as wild canids and other species of wild animals are exposed to the risk of D. immitis infection. In addition, humans can get infected and develop human pulmonary dirofilariasis. In conclusion, the presence of dogs with microfilaremia potentiates opportunities for D. immitis transmission, exposing all animals, wild or domestic, human or non-human to the disease.

Assessing Onchocerca volvulus Intensity of Infection and Genetic Diversity Using Mitochondrial Genome Sequencing of Single Microfilariae Obtained before and after Ivermectin Treatment

Onchocerciasis is a neglected tropical disease targeted for elimination using ivermectin mass administration. Ivermectin kills the microfilariae and temporarily arrests microfilariae production by the macrofilariae. We genotyped 436 microfilariae from 10 people each in Ituri, Democratic Republic of the Congo (DRC), and Maridi County, South Sudan, collected before and 4-5 months after ivermectin treatment. Population genetic analyses identified 52 and 103 mitochondrial DNA haplotypes among the microfilariae from DRC and South Sudan, respectively, with few haplotypes shared between people. The percentage of genotype-based correct assignment to person within DRC was ~88% and within South Sudan ~64%. Rarefaction and extrapolation analysis showed that the genetic diversity in DRC, and even more so in South Sudan, was captured incompletely. The results indicate that the per-person adult worm burden is likely higher in South Sudan than DRC. Analyses of haplotype data from a subsample (n = 4) did not discriminate genetically between pre- and post-treatment microfilariae, confirming that post-treatment microfilariae are not the result of new infections. With appropriate sampling, mitochondrial haplotype analysis could help monitor changes in the number of macrofilariae in a population as a result of treatment, identify cases of potential treatment failure, and detect new infections as an indicator of continuing transmission.

Lymphatic Filariasis Elimination Status: Wuchereria bancrofti Infections in Human Populations after Five Effective Rounds of Mass Drug Administration in Zambia

Lymphatic filariasis (LF), also commonly known as elephantiasis, is a neglected tropical disease (NTD) caused by filarial parasites. The disease is transmitted via a bite from infected mosquitoes. The bites of these infected mosquitoes deposit filarial parasites, Wuchereria or Brugia, whose predilection site is the lymphatic system. The damage to the lymph system causes swelling in the legs, arms, and genitalia. A mapping survey conducted between 2003 and 2011 determined LF as being endemic in Zambia in 96 out of 116 districts. Elimination of LF is known to be possible by stopping the spread of the infection through large-scale preventive chemotherapy. Therefore, mass drug administration (MDA) with diethylcarbamazine citrate (DEC) (6 mg/kg) and Albendazole (400 mg) for Zambia has been conducted and implemented in all endemic districts with five effective rounds. In order to determine whether LF prevalence has been sufficiently reduced to levels less than 2% antigenemia and less than 1% microfilaremia, a pre-transmission assessment survey (pre-TAS) was conducted. Therefore, post-MDA pre-TAS was conducted between 2021 and 2022 in 80 districts to determine the LF prevalence. We conducted a cross-sectional seroprevalence study involving 600 participants in each evaluation unit (EU) or each district. The study sites (sentinel and spot-check sites) were from districts that were the implementation units (IUs) of the LF MDA. These included 80 districts from the 9 provinces. A total of 47,235 people from sentinel and spot-check locations were tested. Of these, valid tests were 47,052, of which 27,762 (59%) were females and 19,290 (41%) were males. The survey revealed in the 79/80 endemic districts a prevalence of Wb antigens of 0.14% and 0.0% prevalence of microfilariae. All the surveyed districts had an optimum prevalence of less than 2% for antigenaemia, except for Chibombo district. The majority of participants that tested positive for Wuchereria bancrofti (Wb) Antigens (Ag) were those that had 2, 3, and 4 rounds of MDA. Surprisingly, individuals that had 1 round of MDA were not found to have circulating antigens of Wb. The study showed that all the surveyed districts, except for Chibombo, passed pre-TAS. This further implies that there is a need to conduct transmission assessment surveys (TASs) in these districts.

Microfilaria in cervicovaginal Pap smears: A common parasite hiding in an unusual site: Short series of four cases with literature review

In India, filariasis is a severe and significant public health problem. It has been reported to be present in any potential site. However, cervicovaginal Pap smear cytology rarely contains microfilariae despite the widespread occurrence. The occurrence of microfilariae in cervicovaginal smears has seldom been reported, even as an accidental finding. In our retrospective study, four cases of clinically asymptomatic filariasis were diagnosed on a routine cervicovaginal Pap smear from January 2019 to July 2022. All microfilariae were characterized as Wuchereria bancrofti. In the present study, the majority of the cases present vaginal discharge, and the diagnosis was made by cytopathology. Therefore, it is crucial to consider and look for microfilariae in areas where they are not endemic.

First Report of Acanthocheilonema reconditum Outbreak in Canines with Clinical Signs of Anemia from Southwestern Colombia

Different nematodes affect canines, however Acanthocheilonema reconditum was considered mostly a non-pathogenic parasite. Climate change, animal migration, and other factors transformed the dynamics of vector-borne diseases, including filariasis. Since 2016, a sudden increase in the number of dogs with microfilaremia was reported by different veterinary centers in Cali, southwest Colombia. The objective of this study was to molecularly identify the etiologic agent of this filariasis outbreak detected in this city, using PCR−RFLP and evaluating dogs’ clinical signs. From 2018−2019, canine filariasis cases were prospectively evaluated after a microscopic test, recruiting 82 cases and 43 healthy controls from 2971 samples. Acanthocheilonema reconditum (Nematoda, Onchocercidae) was identified in 61.3% of the cases (49/82) by PCR−RFLP. Sanger sequencing of the 5.8S ribosomal RNA gene and internal transcribed spacer-2 fragment was additionally performed on seven cases, confirming A. reconditum in all of them. The filariasis cases are statistically associated with male dogs who have clinical signs of anemia, low levels of hemoglobin and hematocrit (p < 0.0001), and high levels of plasma proteins (p < 0.001). This emerging canine disease constitutes an important public health concern among veterinarians and active surveillance is advised to explore its zoonotic potential.

Detection of Mansonella ozzardi in peripheral blood in two malaria-endemic areas in Panama

Introduction:

Studies conducted in 1984 demonstrated the presence of Mansonella ozzardi in the Darien and Colon provinces. Since then, there have not been further reports of this parasitic infection in Panama.

Methodology:

We conducted a cross-sectional assessment of peripheral blood samples of individuals across Panama over a 4-year period (2013–2016) as part of malaria surveillance activities.

Results:

We identified microfilaria in 96 cases. Most of these cases were found in East Panama (78%) followed by the Darien region (22%). Mansonella ozzardi was the filarial parasite identified by morphological features in all cases.

Conclusion:

After 36 years of epidemiological silence, we identified human cases of Mansonella ozzardi infection in Panama. This is, however, the first report of this filarial parasite’s presence in the Eastern region of Panama. There is a need for further surveillance efforts to elucidate the epidemiology associated with Mansonella infections in Panama.

ILC2s Control Microfilaremia During Litomosoides sigmodontis Infection in Rag2-/- Mice

Group 2 innate lymphoid cells (ILC2s) are inducers of type 2 immune responses, but their role during filarial infection remains unclear. In the present study, we used the Litomosoides sigmodontis rodent model of filariasis to analyze ILC2s during infection in susceptible BALB/c mice that develop a chronic infection with microfilaremia and semi-susceptible C57BL/6 mice that eliminate the filariae shortly after the molt into adult worms and thus do not develop microfilaremia. ILC2s (CD45⁺ Lineage^- TCRβ^- CD90.2⁺ Sca-1⁺ IL-33R⁺ GATA-3⁺) were analyzed in the pleural cavity, the site of L. sigmodontis infection, after the infective L3 larvae reached the pleural cavity (9 days post infection, dpi), after the molt into adult worms (30dpi) and during the peak of microfilaremia (70dpi). C57BL/6 mice had significantly increased ILC2 numbers compared to BALB/c mice at 30dpi, accompanied by substantially higher IL-5 and IL-13 levels, indicating a stronger type 2 immune response in C57BL/6 mice upon L. sigmodontis infection. At this time point the ILC2 numbers positively correlated with the worm burden in both mouse strains. ILC2s and GATA-3⁺ CD4⁺ T cells were the dominant source of IL-5 in L. sigmodontis-infected C57BL/6 mice with ILC2s showing a significantly higher IL-5 expression than CD4⁺ T cells. To investigate the importance of ILC2s during L. sigmodontis infection, ILC2s were depleted with anti-CD90.2 antibodies in T and B cell-deficient Rag2^-/- C57BL/6 mice on 26-28dpi and the outcome of infection was compared to isotype controls. Rag2^-/- mice were per se susceptible to L. sigmodontis infection with significantly higher worm burden than C57BL/6 mice and developed microfilaremia. Depletion of ILC2s did not result in an increased worm burden in Rag2^-/- mice, but led to significantly higher microfilariae numbers compared to isotype controls. In conclusion, our data demonstrate that ILC2s are essentially involved in the control of microfilaremia in Rag2^-/- C57BL/6 mice.

Description and Molecular Characterization of Two Species of Avian Blood Parasites, with Remarks on Circadian Rhythms of Avian Haematozoa Infections

Avian blood parasites are remarkably diverse and frequently occur in co-infections, which predominate in wildlife. This makes wildlife pathogen research challenging, particularly if they belong to closely related groups, resulting in diagnostic problems and poor knowledge about such infections as well as the patterns of their co-occurrence and interactions. This is particularly true due to the periodicity (circadian rhythms) of parasitemia, which means that different parasitemia and parasite stages might be found throughout the day. We analysed blood samples from a Eurasian blackbird (Turdus merula) and a Song thrush (Turdus philomelos). This study aimed to describe a new avian Lankesterella species and molecularly characterize and redescribe Splendidofilaria mavis, a common avian filarioid nematode. Additionally, it was possible to investigate the circadian rhythms of the avian blood parasites belonging to Plasmodium, Haemoproteus, Leucocytozoon, and Trypanosoma, which occurred in co-infection in the same avian host individuals. Different circadian rhythms were seen in different parasites, with Plasmodium sp. peaks occurring at midday, Leucocytozoon spp. peaks mainly during the evening and night, and Trypanosoma spp. and microfilariae peaks at midnight. No periodicity was seen in Haemoproteus and Lankesterella species infections. The time of parasitemia peaks most likely coincides with the time of vectors' activity, and this should be beneficial for transmission. Knowledge about the circadian rhythms is needed for better understanding patterns in host-parasite interactions and disease transmission.

IL-10 and Its Related Superfamily Members IL-19 and IL-24 Provide Parallel/Redundant Immune-Modulation in Loa loa Infection

BACKGROUND

Interleukin-10 (IL-10) has been implicated as the major cytokine responsible for the modulation of parasite-specific responses in filarial infections; however, the role of other IL-10 superfamily members in filarial infection is less well studied.

METHODS

Peripheral blood mononuclear cells from loiasis patients were stimulated with or without filarial antigen. Cytokine production was quantified using a Luminex platform and T-cell expression patterns were assessed by flow cytometry.

RESULTS

All patients produced significant levels of IL-10, IL-13, IL-5, IL-4, and IL-9 in response to filarial antigen, indicating a common infection-driven response. When comparing microfilaria (mf)-positive and mf-negative patients, there were no significant differences in spontaneous cytokine nor in parasite-driven IL-10, IL-22, or IL-28a production. In marked contrast, mf-positive individuals had significantly increased filarial antigen-driven IL-24 and IL-19 compared to mf-negative subjects. mf-positive patients also demonstrated significantly higher frequencies of T cells producing IL-19 in comparison to mf-negative patients. T-cell expression of IL-19 and IL-24 was positively regulated by IL-10 and IL-1β. IL-24 production was also regulated by IL-37.

CONCLUSION

These data provide an important link between IL-10 and its related family members IL-19 and IL-24 in the modulation of the immune response in human filarial infections.

CLINICAL TRIALS REGISTRATION

NCT00001230.

Effect of Clinical, Biochemical, and Genetic Variations on Medical Management in Filarial Chyluria: A Prospective Study at a Tertiary Care Centre in North India

Objective To analyze the effect of clinical, biochemical factors, and Mannose Binding Lectin 2 (MBL2) gene variations on medical management in filarial chyluria (FC) patients. Material and methods We conducted a study between March 2013 and April 2016. MBL2polymorphisms were genotyped in confirmed 101 medically-treated cases of FC. Demographic, clinical, and biochemical variables were compared between remission and failure groups. Genotyping of MBL2 codon 54 and promoter -221 were undertaken by polymerase chain reaction. Genotype frequencies were compared with clinical and biochemical variables and medical treatment outcomes (remission/failure). The association between genotypes and treatment response was estimated by OR and 95% CI and generated by the chi-square test. Results The mean age was 36.9±10.28-years and the male-female ratio was 3:1.2. Sixty-six patients had remission (Group-A) while 35 had recurrence (Group-B) at a mean follow-up of 21 months. The success rate for medical therapy was 65.35%. There was no statistical difference observed in the demographic profile of the two groups. On multivariate analysis, patients in Group-B had a higher grade of chyluria (p=0.005), had experienced greater number of disease attacks in the past (p=0.022), and had higher urinary triglyceride levels (TG) (p<0.001) as compared to Group-A patients. A significant association of MBL2 codon 54 genotypes was observed with the recurrent presentation of chyluria (p=0.044), grade of chyluria (p=0.028), and urinary TGs (p=0.001). However, genotype distribution at -221 did not show association with clinical and biochemical parameters of FC patients. The distribution of genotypes at codon 54 differed significantly between remission and failure/recurrence group; the variant genotype BB was significantly higher in the recurrence or failure group (OR:6.00; 95%CI, 1.00-35.91; p=0.050). However, frequencies of variant genotype YX and recessive group YX+XX of MBL2 -221 promoter was higher in remission group (OR:2.97;95%CI, 1.23-7.13; p=0.018 and OR:2.76; 95%CI, 1.80-6.50; p=0.020), respectively, showing that genetic variant may be associated with response to medical therapy. Conclusion Higher grade of chyluria, a higher number of disease attacks in the past, and higher urinary TGs levels were clinical predictors of poor response to medical treatment. Our results showed that the variants of MBL2 genes have an impact on treatment outcomes in FC patients. These observations may be limited by sample size.

Recurrent Swelling and Microfilaremia Caused by Dirofilaria repens Infection after Travel to India

Human subcutaneous dirofilariasis is an emerging mosquitoborne zoonosis. A traveler returning to Germany from India experienced Dirofilaria infection with concomitant microfilaremia. Molecular analysis indicated Dirofilaria repens nematodes of an Asian genotype. Microfilaremia showed no clear periodicity. Presence of Wolbachia endosymbionts enabled successful treatment with doxycycline.

Immunization with Brugia malayi Calreticulin Protein Generates Robust Antiparasitic Immunity and Offers Protection during Experimental Lymphatic Filariasis

Lymphatic filariasis causes permanent and long-term disability worldwide. Lack of potent adulticidal drugs, the emergence of drug resistance, and the nonavailability of effective vaccines are the major drawbacks toward LF elimination. However, immunomodulatory proteins present in the parasite secretome are capable of providing good protection against LF and thus offer hope in designing new vaccines against LF. Here, we evaluated the immunogenicity and protective efficacy of B. malayi calreticulin protein (BmCRT) using in vitro and in vivo approaches. Stimulation with recombinant BmCRT (rBmCRT) significantly upregulated Th1 cytokine production in mouse splenocytes, mesenteric lymph nodes (mLNs), and splenic and peritoneal macrophages (PMΦs). Heightened NO release, ROS generation, increased lymphocyte proliferation, and increased antigen uptake were also observed after rBmCRT exposure. Mice immunized with rBmCRT responded with increased Th1 and Th2 cytokine secretion and exhibited highly elevated titers of anti-BmCRT specific IgG at day 14 and day 28 postimmunization while splenocytes and mLNs from immunized mice showed a robust recall response on restimulation with rBmCRT. Infective larvae (L3) challenge and protection studies undertaken in Mastomys coucha, a permissive model for LF, showed that rBmCRT-immunized animals mounted a robust humoral immune response as evident by elevated levels of total IgG, IgG1, IgG2a, IgG2b, and IgG3 in their serum even 150 days after L3 challenge, which led to significantly reduced microfilariae and worm burden in infected animals. BmCRT is highly immunogenic and generates robust antiparasitic immunity in immunized animals and should therefore be explored further as a putative vaccine candidate against LF.

Dirofilaria repens infection of the eye with concomitant microfilaremia in a traveller

Dirofilaria repens is the main causative agent of human and canine dirofilariosis. This form of zoonotic parasitosis usually manifests with an involvement of the skin or the eye. Human dirofilariosis is considered as an emerging infectious disease. We report the first case of proven microfilariemic dirofilariosis in peripheral blood in Germany.

Incidental Detection of Onchocerca Microfilariae in Donkeys (Equus asinus) in Italy: Report of Four Cases

This paper reports the occurrence for the first time in Italy of autochthonous Onchocerca infection in donkeys. Four jennies, bred on the same farm, were referred to the Veterinary Teaching Hospital of Pisa for a check-up on ovarian activity (n = 3) or for veterinary support during the delivery (n = 1). Microfilariae were incidentally detected during the blood smear examination of one jenny. Peripheral blood samples were then collected from the other three jennies and the presence of microfilariae was investigated by Knott's test. Circulating unsheathed microfilariae were identified in all the animals. The level of microfilaraemia was between 1 and 31 microfilariae in 2 mL of blood. Hematological changes showed moderate eosinophilia in one case or both remarkable eosinophilia and basophilia in another case. Based on molecular findings by PCR and sequencing, the microfilariae showed 98% sequence similarity with Onchocerca sp. in the NCBI GenBank database (Accession No.: MK541848.1). The present report provides evidence that Onchocerca is an etiological agent of parasitic infection in donkeys in Italy. Our findings highlight the importance of screening in donkeys for Onchocerca even in the absence of clinical indications.

Microfilariae in bone marrow aspirate of a case of myelofibrosis: A cause or coincidence?

Filariasis is among the common parasitic infestations found in India, with Wuchereria bancrofti being the most common causative organism. Presentation ranges from clinically asymptomatic to profound elephantiasis. It is also detected incidentally in diagnostic samples such as body fluids, fine needle aspirates, peripheral blood smears, and other cytological smears. Its detection in bone marrow aspirates with an associated hematolymphoid neoplasm is rare, with only a few case reports. We report one such case of young male who presented with leukocytosis of 253 × 10⁹/L with basophilia and massive splenomegaly. Bone marrow aspirate smears showed the presence of microfilariae along with other features of a myeloproliferative neoplasm (MPN). The present case is probably the first case of finding a microfilaria in a case of MPN.

Comparison of Diagnostic Tests for Onchocerca volvulus in the Democratic Republic of Congo

Onchocerciasis is diagnosed by detecting microfilariae in skin snips or by detecting OV16 IgG4 antibodies in blood by either enzyme linked immunosorbent assay (ELISA) or a rapid diagnostic test (RDT). Here, we compare the sensitivity and specificity of these three tests in persons with epilepsy living in an onchocerciasis endemic region in the Democratic Republic of Congo. Skin snips and blood samples were collected from 285 individuals for onchocerciasis diagnosis. Three tests were performed: the OV16 RDT (SD Bioline) and the OV16 ELISA both on serum samples, and microscopic detection of microfilariae in skin snips. The sensitivity and specificity of each test was calculated with the combined other tests as a reference. Microfilariae were present in 105 (36.8%) individuals, with a median of 18.5 (6.5–72.0) microfilariae/skin snip. The OV16 RDT and OV16 ELISA were positive in, respectively, 112 (39.3%) and 143 (50.2%) individuals. The OV16 ELISA had the highest sensitivity among the three tests (83%), followed by the OV16 RDT (74.8%) and the skin snip (71.4%). The OV16 RDT had a higher specificity (98.6%) compared to the OV16 ELISA (84.8%). Our study confirms the need to develop more sensitive tests to ensure the accurate detection of ongoing transmission before stopping elimination efforts.

Prevalence and Correlates of Lymphatic Filariasis Infection and Its Morbidity Following Mass Ivermectin and Albendazole Administration in Mkinga District, North-Eastern Tanzania

Lymphatic filariasis (LF) is a neglected tropical disease targeted for elimination as public health problem through morbidity management and preventive annual mass drug administration (MDA). This cross-sectional community-based surveillance assessed the prevalence and correlates of LF infection in Mkinga district, Tanga-region, Tanzania. A total of 4115 individuals (49.7% males, 35.2% children) were screened for circulating filarial antigens (CFA), microfilaremia (mf) and disease manifestations in 15 villages between November 2018 and January 2019. MDA uptake in the previous year was assessed. Overall prevalence of CFA-positivity was 5.8% (239/4115; 95% CI: 5.1–6.6), with significant heterogeneity between villages (range 1.2% to 13.5%). CFA-positivity was higher in males (8.8%) than females (3.3%), and correlated with increasing age (p < 0.001). Prevalence of mf among CFA-positives was 5.2%. Only 60% of eligible inhabitants in the study area took MDA in the previous year, and CFA-positivity was 2-fold higher in those who missed MDA (p < 0.0001). Prevalence of scrotal enlargement, hydrocele, arms or legs swelling, lymphoedema and lymphadenopathy was 6.4%, 3.7%, 1.35%, 1.2% and 0.32%, respectively. Compared to baseline data, 16 years of MDA intervention significantly reduced LF transmission and morbidity, although the intended elimination target of <1% mf and <2% antigenemia to level where recrudescence is unlikely to occur by the year 2020 may not be attained. The finding of hotspots with ongoing transmission calls for intensified control measures.

Microfilaria in achylous hematuria: Can it imitate urolithiasis?

Wuchereria bancrofti is the major species resulting in filarial cases in India. Filariasis may present with various clinical presentations: asymptomatic, microfilaremia, lymphedema, acute adenolymphangitis and chronic lymphatic disease. Microfilariae of W. bancrofti have been detected in various clinical samples, but incidental detection of microfilaria in achylous urine is a rare finding with unexplained pathology. We report a case of microfilaria in achylous urine of a 30-year-old female who presented with pain abdomen and ureteric calculus on ultrasonography.

Use of Slow-Release Injectable Moxidectin for Treatment of Dirofilaria immitis Infection During Pregnancy

Canine heartworm disease is a life-threatening disease caused by Dirofilaria immitis and is prevalent in Brazil. The standard drug for its treatment, melarsomine dihydrochloride, is a fast-killing organic arsenical chemotherapeutic agent not approved in Brazil. Therefore, an alternative strategy, such as macrocyclic lactone in combination with a tetracycline antibiotic, has to be used. The alternative method is a long-term therapy that could lead to compliance issues during treatment. The aim of this case report is to present a preliminary assessment on the efficacy and safety of an off-label biannual administration of slow-release moxidectin (0.5 mg/kg every 6 months), which is formulated for annual administration (0.5 mg/kg annually). This overdose was chosen to test if moxidectin serum levels could be maintained high enough to harm the worms. It was administered to a 4-year-old female dog in combination with a 30-day doxycycline course. The second dose of moxidectin was administered approximately a week before she gave birth to three healthy puppies. Microfilariae were not detected on day 180 of treatment. Serological tests showed that the worms were eliminated, as two negative antigen tests were obtained 6 months apart (at day 180 and day 360 of treatment). Therefore, the off-label biannual use of moxidectin in combination with doxycycline was effective in eliminating D. immitis in 360 days and was harmless for the pregnant dog and her offspring, suggesting that this strategy is promising. Although these results are encouraging, further studies are needed to confirm safety and efficacy issues.

Fine-needle aspiration of axillary swelling: Cytodiagnosis of an unusual presentation of filariasis

Lymphatic filariasis is a major public health problem in tropical and subtropical countries. Fine-needle aspiration cytology (FNAC) is not routinely used for its identification. However, it has been detected incidentally, while doing FNAC for the evaluation of other lesions. We describe a presentation of occult filariasis with microfilariae (mf) in an isolated axillary swelling wherein FNAC was helpful in establishing the diagnosis.

Diagnostic Identification and Differentiation of Microfilariae

The morphologic similarities of the microfilariae and their infrequency in clinical specimens in settings of endemicity present challenges to clinical laboratories in maintaining competence for accurate identification and differentiation. We present here a review of the primary filarial nematodes causing human infection, including an illustrated key, which we hope will improve the diagnostic capabilities of hematologists, microbiologists, medical technologists, and similarly qualified laboratorians.

Litomosoides sp. (Filarioidea: Onchocercidae) Infection in Frugivorous Bats (Artibeus spp.): Pathological Features, Molecular Evidence, and Prevalence

Bats can host pathogenic organisms such as viruses and fungi, but little is known about the pathogenicity of their parasites. Hemoparasites are frequently recorded in Neotropical bats, particularly Litomosoides (Filarioidea: Onchocercidae), but their pathogenic effect on bats is scarcely known. In this work, Litomosoides microfilariae were identified in four (8%) out of 51 sampled frugivorous bats belonging to three different species: Artibeus aztecus, Artibeus jamaicensis, and Artibeus lituratus, which are located in Yautepec, Morelos, Mexico. Two infected animals showed weakness, tachypnoea, and ecchymosis on their wings. In these animals, histopathology revealed microfilariae in the blood vessels of the lung, liver, and spleen. Both animals presented exudative pneumonia with congestion and concomitant edema, in addition to moderate arterial hypertrophy. Parasitemia was quantified in blood samples of the infected animals (>3000 parasites/mL). Phylogenetic analysis placed the obtained sequence inside the Litomosoides genus, reaching over 98% identity to the related species. Due to the relevance of bats in ecosystems, any new record of their parasite repertoire offers noteworthy insights into our understanding of the ecology and impact of new parasite species in bats.

Dirofilaria repens Nematode Infection with Microfilaremia in Traveler Returning to Belgium from Senegal

We report human infection with a Dirofilaria repens nematode likely acquired in Senegal. An adult worm was extracted from the right conjunctiva of the case-patient, and blood microfilariae were detected, which led to an initial misdiagnosis of loiasis. We also observed the complete life cycle of a D. repens nematode in this patient.

Epizootiological observations on canine microfilaremia in Gujarat state, India

Aim

The present investigation was conducted to study the prevalence of microfilaremia in dogs in Gujarat.

Materials and Methods

A total of 418 adult dogs aged between 2 and 14 years with signs of weakness and non-specified complaints, presented at TVCC, Deesa (North Gujarat), Nandini Veterinary Hospital, Surat (South Gujarat), and Private Clinics, Ahmedabad (Central Gujarat), were included in the present investigation for studying the prevalence of microfilaremia from July 2016 to May 2017.

Results

A total of 418 dogs were screened, of which 33 were found positive for circulating microfilariae with the prevalence rate of 7.89% in the population. Among microfilaremic dogs, the finding of microfilariae of Dipetalonema (Acanthocheilonema) reconditum was more common (23 cases; 69.69%) than Dirofilaria immitis (10 cases; 30.30%) making their prevalence in the population of 418 dogs as 5.50% and 2.39%, respectively. Breed-wise distribution of microfilaremic dogs revealed that 12 (36.36%), 8 (24.24%), 5 (15.15%), 4 (12.12%), 2 (6.06%), 1 (3.03%), and 1 (3.03%) cases were observed in Pomeranian, non-descript, German Shepherd, Labrador, Great Dane, Lhasa Apso, and Pug dogs, respectively. Of 10 cases of D. immitis, 5, 2, 2, and 1 were observed in Pomeranian, Labrador, non-descript, and Great Dane dogs, respectively. Cases of Dipetalonema reconditum were highest in Pomeranian (7), followed by non-descript (6), German Shepherd (5), Labrador (2), Great Dane (1), Lhasa Apso (1), and Pug (1). Age-wise distribution recorded significantly (p≤0.01) higher number of cases in adult dogs (4-14 years) for D. immitis (30.30%) and D. reconditum (39.39%). Sex-wise distribution of microfilaremic dogs showed that male (22/33, 66.66%) was more predisposed to microfilaremia rather than females (11/33, 33.34%). It is apparent from the study that the number of dogs with microfilaremia due to D. reconditum was significantly (p≤0.01) higher than that of D. immitis.

Conclusion

The present study revealed that microfilaremia due to D. immitis and D. reconditum is prevalent in the state of Gujarat. The infection with D. immitis was associated with severe lung and cardiac pathological manifestations.

Tropical pulmonary eosinophilia masquerading as asthma in a 5-year-old girl

Tropical pulmonary eosinophilia (TPE) is an exaggerated immunological response to filarial antigens mainly seen in adults in endemic areas and is uncommonly reported in children. The diagnosis is frequently delayed as it mimics asthma clinically, while the chest radiograph might show miliary mottling which is often confused with that in pulmonary tuberculosis. A 5-year-old girl presented with episodes of nocturnal cough, wheeze, low grade fever and breathlessness for the previous 4 months and was being treated for asthma. The absolute eosinophil count was markedly raised (53 × 10⁹/L) with prominent bilateral infiltrates on the chest radiograph. Serology for microfilaria and a test for microfilaria antigens were positive and the patient showed a dramatic response to diethylcarbamazine, which confirmed the diagnosis of TPE. TPE is an important differential diagnosis of asthma especially in endemic areas.

Immunopathological response of leukocytes against microfilariae and adult worms in white rats infected with Setaria cervi

Aim:

Aim of this study was to see the immunopathological changes against the microfilariae (Mf) and adult worms of a bovine filarid, Setaria cervi in the tissues of vital organs of experimentally infected white rats. The effect of diethylcarbamazine (DEC) was also observed on the Mf, as leukocytes especially lymphocytes produce immunoglobulins which opsonize and increase the efficacy of DEC against circulating Mf. Effect of this drug was also assessed on liver enzymes in the microfilaremic rats.

Materials and Methods:

Microfilaremia was established by implanting adult worms intraperitoneally and by the infusion of Mf recovered from the uterus of gravid female worms. DEC was administered orally for six consecutive days in the rats having patent infection. Differential leukocyte count was recorded every 3^rd day, and liver enzymes were estimated every 10^th day in both treated and untreated rats. Pathological changes were observed in HE stained sections of vital organs where Mf or adult worms were trapped.

Results:

Destruction and reduction in microfilarial density were noticed in microfilaremic rats treated with DEC. Trapped Mf and embedded worms revealed heavy cellular infiltrations by defensive cells which surrounded and attached with the body surface of the Mf as well as adult worms for their destruction and piece meal clearance. Immune-mediated pathology was observed in the tissue sections of lungs, spleen, and liver. Liver enzymes were elevated during the period of higher parasitemia.

Conclusions:

There was a moderate level of immunopathology against the Mf and adult worms by the leukocytes in experimentally infected microfilaremic rats. Mf were in the process of degeneration where they got trapped. Moderate increase in liver enzyme was noticed which was slightly more in untreated group. Although a fraction of Mf gets killed in the peritoneum, majority of them successfully enter the systemic circulation and survive for about 54 days, which is sufficient enough for conducting immunological and chemotherapeutic studies.

Keratitis due to microfilariae in dogs: a newly recognized disease

Parasitic agents have been associated with keratitis, but a diagnosis of parasitic keratitis has not been commonly made in domestic animals. The purpose of this study was to describe the clinical and histopathological findings in seven dogs with chronic keratitis caused by microfilariae diagnosed in Brazil. All dogs presented with superficial corneal opacities of varying degrees affecting the perilimbal and central regions of the cornea, with other opaque areas appearing as crystalline deposits and corneal vascularization. The lesions were bilateral and were associated with mild-to-moderate conjunctival hyperemia. There was no history of blepharospasm or pruritus, and no subjects presented with epithelial erosions. Corneal biopsy revealed free microfilariae in the corneal stroma, with varying degrees of inflammation and collagen fiber destruction. The microfilariae were also found in skin lesions by skin snip technique. No adult worms were found in these dogs, and no dogs were on heartworm preventative before diagnosis. Monthly doses of oral ivermectin improved ocular and dermal lesions. One dog showed complete remission with the treatment. The species of the microfilariae was not identified.

Nodular presentation of Dirofilaria repens infection in a cat mimicking a fibrosarcoma

A cat with multiple subcutaneous nodules suggesting a soft tissue sarcoma by physical and computed tomographic examination was diagnosed as being affected by subcutaneous filariosis based on cytologic and ultrasonographic assessments. Nodules were surgically removed and extracted nematodes were identified by PCR as Dirofilaria repens. Furthermore, DNA of Dipetalonema dracunculoides (syn. Acantocheilonema dracunculoides) was detected by PCR, with no evidence of circulating microfilariae. To the best of the authors' knowledge, this represents the first report describing adults of D repens in multiple subcutaneous nodules in a cat. Cytopathologic examination allowed characterization of the parasitic nature of the nodules. Veterinary practitioners should be aware of the possible nodular presentation of D repens in cats and should include D repens in the differential diagnosis of subcutaneous neoformations in the cat.

Patency of Litomosoides sigmodontis infection depends on Toll-like receptor 4 whereas Toll-like receptor 2 signalling influences filarial-specific CD4(+) T-cell responses

BALB/c mice develop a patent state [release of microfilariae (Mf), the transmission life-stage, into the periphery] when exposed to the rodent filariae Litomosoides sigmodontis. Interestingly, only a portion of the infected mice become patent, which reflects the situation in human individuals infected with Wuchereria bancrofti. Since those individuals had differing filarial-specific profiles, this study compared differences in immune responses between Mf(+) and Mf(-) infected BALB/c mice. We demonstrate that cultures of total spleen or mediastinal lymph node cells from Mf(+) mice produce significantly more interleukin-5 (IL-5) to filarial antigens but equal levels of IL-10 when compared with Mf(-) mice. However, isolated CD4(+) T cells from Mf(+) mice produced significantly higher amounts of all measured cytokines, including IL-10, when compared with CD4(+) T-cell responses from Mf(-) mice. Since adaptive immune responses are influenced by triggering the innate immune system we further studied the immune profiles and parasitology in infected Toll-like receptor-2-deficient (TLR2(-/-)) and TLR4(-/-) BALB/c mice. Ninety-three per cent of L. sigmodontis-exposed TLR4(-/-) BALB/c mice became patent (Mf(+)) although worm numbers remained comparable to those in Mf(+) wild-type controls. Lack of TLR2 had no influence on patency outcome or worm burden but infected Mf(+) mice had significantly lower numbers of Foxp3(+) regulatory T cells and dampened peripheral immune responses. Interestingly, in vitro culturing of CD4(+) T cells from infected wild-type mice with granulocyte-macrophage colony-stimulating factor-derived TLR2(-/-) dendritic cells resulted in an overall diminished cytokine profile to filarial antigens. Hence, triggering TLR4 or TLR2 during chronic filarial infection has a significant impact on patency and efficient CD4(+) T-cell responses, respectively.

An unusual presentation of filariasis in a nonendemic country

Introduction: Filariasis is an endemic disease with worldwide distribution in tropical and subtropical regions. It is uncommon in Qatar. The conventional diagnostic procedure is the demonstration of microfilaria in blood smears. Even with its high incidence, it is unusual to detect microfilaria in fine needle aspiration cytology (FNAC) smears. Although the ‘filarial dance sign’ is rarely documented, it remains a classical ultrasonographic sign in lymphatic filariasis. Case presentation: We present a case of a 38-year-old male patient with fever, chills, shortness of breath and a tender warm swelling on his right thigh. Ultrasound of the thigh lesion showed the classical filarial dance sign. Subsequently FNAC from the lesion documented microfilaria in spite of absent peripheral blood eosinophilia and microfilaria. The patient underwent an incision and drainage of the thigh lesion and was treated with ivermectin and diethylcarbamazine. He was subsequently admitted to the medical ward and discharged home after two weeks in a stable condition. Conclusion: This case report illustrates the importance of diagnostic tools like ultrasound and FNAC along with a high index of clinical suspicion while evaluating patients presenting with unusual signs and symptoms. We would like to highlight the rarity of filarial presentation in a nonendemic country like Qatar. This case is unique since microfilaria was demonstrated in the pus aspirated from the thigh abscess and showed the filarial dance sign by ultrasound along with involvement of the pleura and pericardium.

Reductions in microfilaridermia by repeated ivermectin treatment are associated with lower Plasmodium-specific Th17 immune responses in Onchocerca volvulus-infected individuals

BACKGROUND

37 million individuals are currently infected with Onchocerca volvulus (O. volvulus), a parasitic nematode that elicits various dermal manifestations and eye damage in man. Disease control is primarily based on distributing ivermectin in mass drug administration (MDA) programmes which aim at breaking transmission by eliminating microfilariae (MF), the worm's offspring. The majority of infected individuals present generalized onchocerciasis, which is characterized by hyporesponsive immune responses and high parasite burden including MF. Recently, in areas that have been part of MDA programmes, individuals have been identified that present nodules but are amicrofilaridermic (a-MF) and our previous study showed that this group has a distinct immune profile. Expanding on those findings we determined the immune responses of O. volvulus-infected individuals to a Plasmodium-derived antigen MSP-1 (merozoite surface protein-1), which is required by the parasite to enter erythrocytes.

METHODS

Isolated PBMCs from O. volvulus-infected individuals (164 MF(+) and 46 a-MF) and non-infected volunteers from the same region (NEN), were stimulated with MSP-1 and the resulting supernatant screened for the presence of IL-5, IL-13, IFN-γ, TNF-α, IL-6, IL-17A and IL-10. These findings were then further analyzed following regression analysis using the covariates MF, ivermectin (IVM) and region. The latter referred to the Central or Ashanti regions of Ghana, which, at the time sampling, had received 8 or 1 round of MDA respectively.

RESULTS

IL-5, IL-13 and IFN-γ responses to MSP-1 were not altered between NEN and O. volvulus-infected individuals nor were any associations revealed in the regression analysis. IL-10, IL-6 and TNF-α MSP-1 responses were, however, significantly elevated in cultures from infected individuals. Interestingly, when compared to a-MF individuals, MSP-induced IL-17A responses were significantly higher in MF(+) patients. Following multivariable regression analysis these IL-10, IL-6, TNF-α and IL-17A responses were all dominantly associated with the regional covariate.

CONCLUSIONS

Consequently, areas with a lowered infection pressure due to IVM MDA appear to influence bystander responses to Plasmodium-derived antigens in community members even if they have not regularly participated in the therapy.

Incidental detection of microfilariae in a lymph node aspirate: A case report

Lymphatic filariasis is a global health problem endemic in Nigeria. Peripheral blood smears are frequently negative for microfilariae in a significant number of infected patients in whom conventional diagnostic methods may also fail to identify the disease. In such cases, fine needle aspiration cytology may play an important role in disease identification. A 49-year-old South-western male Nigerian farmer, presented with a one-year history of a right groin swelling, which became painful 2 weeks before coming to the hospital. A clinical assessment of lymphogranuloma venereum was made to rule out a non-Hodgkin lymphoma. Initial laboratory investigations only showed mild eosinophilia and haematuria. However, fine needle aspiration cytology performed on the swelling showed microfilariae of Wuchereria bancrofti for which appropriate treatment was instituted with excellent outcome. This case demonstrates that lymphatic filariasis should be considered in the differential diagnosis of lymph node swellings in the groin and that aspiration cytology may play an important role in its diagnosis, especially in an endemic resource poor country.

Tropical pulmonary eosinophilia--a review

Tropical pulmonary eosinophilia (TPE) is a syndrome of wheezing, fever and eosiniphilia seen predominantly in the Indian subcontinent and other tropical areas. Its etiological link with Wuchereria bancrofti and Brugia malayi has been well established. The pathogenesis is due to an exaggerated immune response to the filarial antigens which includes type I, type III and type IV reactions with eosinophils playing a pivotal role. Peripheral blood eosinophilia is usually striking with levels over 3000/μl being common. High serum levels of IgE and filarial-specific IgE and IgG are also found. The pathology may vary from an acute eosinophilic alveolitis to histiocytic infiltration depending on the stage of the disease. While earlier studies had suggested that the disease runs a benign course, more recent work has shown that untreated TPE could result in a fair degree of respiratory morbidity. Pulmonary function tests may show a mixed restrictive and obstructive abnormality with a reduction in diffusion capacity. The bronchoalveolar lavage (BAL) eosinophil count has a negative correlation with the diffusion capacity. Treatment consists of diethylcarbamazine (DEC) for at least three weeks. Despite treatment with DEC, about 20 per cent of patients may relapse. Steroids have shown to have a beneficial effect but the exact dose and duration is yet to be confirmed by randomized controlled trials. A specific and easily available marker is required for TPE in order to distinguish it from other parasitic and non-parasitic causes of pulmonary eosinophilia.

Relevance of the eosinophil blood count in bancroftian filariasis as a screening tool for the treatment

BACKGROUND

Lymphatic filariasis constitutes a major public health issue in French Polynesia. Diagnosis has been revolutionized with the availability of circulating filarial antigen (CFA) tests which are easy to perform but are costly. Filariasis is responsible for acquired eosinophilia and eosinophil blood count (EBC) is commonly used as a screening tool.

METHODS

We retrospectively analysed all the results of EBCs and CFA tests performed in our laboratory over a 2-year period. We calculated the prevalence of antigenemia for nine different eosinophil cutoffs. We calculated the number of patients detected by CFA testing and the number of estimated CFA-positive patients according to their EBC.

RESULTS

Over a 2-year period, we detected 7503 eosinophilic patients. For an EBC above 500/mm(3), the prevalence of positive CFA was 25·78% and the estimated number of positive CFA patients was 1934. During the same period, as CFA determination is not routinely performed, only 141 patients were detected and treated.

CONCLUSION

Our current strategy against lymphatic filariasis which combines annual mass drug administration, systematic treatment of antigenemic and microfilaraemic patients, and vector control; failed to reach the target of 1% prevalence. Unfortunately, mainly for economical reasons, the antigenemia cannot be determined for all patients. In complement to existing strategy, we propose an additional action based on the treatment of eosinophilic patients in order to reduce the filariasis prevalence in our country.

Theoretical potential of passerine filariasis to enhance the enzootic transmission of West Nile virus

Vertebrate reservoirs of arboviruses are often infected with microfilariae (MF). Laboratory studies have shown that MF can enhance the infectivity of arboviruses to mosquitoes. Soon after being ingested, MF penetrate the mosquito midgut. If the host blood also contains virus (i.e., vertebrate is dually infected), penetrating MF may introduce virus into the hemocoel. This can transform otherwise virus-incompetent mosquito species into virus-competent species and simultaneously accelerate viral development, allowing mosquitoes to transmit virus sooner than normal. This phenomenon is termed microfilarial enhancement of arboviral transmission. The prevalence of MF is very high in many passerine populations in North America. Therefore, we investigated if microfilarial enhancement could have facilitated the establishment and rapid spread of West Nile virus (WNV) across the mid-western United States. Our investigations revealed that mosquitoes, WNV, and passerine MF do interact in nature because; 1) 17% of 54 common grackles (Quiscalus quiscula L.), 8% of 26 American robins (Turdus migratorius L.), and 33% of three eastern kingbirds (Tyrannus tyrannus L.) were concurrently microfilaremic and seropositive to WNV; 2) feeding activities of mosquitoes overlapped temporally with the appearance of MF in the blood of common grackles; 3) mosquitoes fed on common grackles and American robins in nature; and 4) mosquito ingestion of two taxonomically distant species of passerine MF (i.e., Chandlerella quiscali and Eufilaria spp.) resulted in penetration of mosquito midguts. To estimate the theoretical effect that MF enhancement could have on WNV transmission in areas of high MF prevalence, vectorial capacity values were calculated for Culex mosquitoes feeding on common grackles, whereby MF enhancement was either invoked or ignored. For Cx. pipiens, vectorial capacity increased over three-fold when potential effects of MF were included in the calculations. For Cx. tarsalis, the effect was less (i.e., 1.4-fold increase). Closer attention should be paid to the potential of MF to enhance mosquito transmission of arboviruses.

Microfilaria in a patient of achylous hematuria: A rare finding in urine cytology

Filariasis is a widespread public health problem seen commonly in tropical countries. Microfilariae have been reported in aspiration smears from various sites. However, it is very rare to detect these organisms in voided centrifuged urine cytology. We, report this rare finding in a 25-year-old patient who presented with achylous hematuria.

Cytological diagnosis of microfilariae in filariasis endemic areas of eastern Uttar Pradesh

BACKGROUND

Filariasis is a major health problem in tropical countries including India. Fine needle aspiration cytology plays an important role in prompt recognition of disease.

AIM

To assess the role of fine needle aspiration cytology (FNAC) in diagnosis of filariasis at all possible sites.

MATERIALS AND METHODS

Total 250 cases of superficial swellings at various sites were subjected to fine needle aspiration cytology.

RESULTS

Out of 250 cases, 24 cases of filariasis were detected which include breast lumps (8 cases), lymph nodes (6 cases), scrotal swellings (4 cases), thyroid swellings (3 cases), soft tissue swellings (2 cases) and ascitic fluid (1 case). Eosinophilia was present in 8 out of 24 cases with a percentage ranging from 12-24%. Significant adherence of inflammatory cells and macrophages to microfilariae was present in 3 out of 24 cases.

CONCLUSIONS

In endemic areas, it should be considered one of the differential diagnoses of a superficial swelling. Careful screening of FNAC smears help in detecting microfilaria even in asymptomatic patients and thus plays a significant role in recognition of the disease and institution of specific treatment.