Prevalence of onchocerciasis and associated clinical manifestations in selected hypoendemic communities in Ghana following long-term administration of ivermectin

Background

Onchocerciasis is a neglected tropical disease which is still of immense major public health concern in several areas of Africa and the Americas. The disease manifests either as ocular or as dermal onchocerciasis with several symptoms including itching, nodules, skin thickening, visual impairment and blindness. Ivermectin has been an efficient microfilaricide against the causative agent of the disease (Onchocerca volvulus) but reports from some areas in Africa suggest the development of resistance to this drug. The aim of this study was to determine the prevalence of onchocerciasis and associated clinical conditions frequently associated with the disease in three endemic communities in Ghana which have been subjected to 18 to 20 rounds of mass drug administration of ivermectin. This was to help determine whether or not onchocerciasis persists in these communities.

Methods

A cross-sectional study design was adopted. Three communities (Tanfiano, Senya and Kokompe) in the Nkoranza North District of Ghana where mass drug administration of ivermectin had been ongoing for more than two decades were selected for the study. The population was randomly sampled and 114 participants recruited for the study based on the eligibility criteria. The study participants were examined for the presence of parasites and clinical manifestations of onchocerciasis following established protocols.

Results

The study showed that the prevalence of microfilaria in the Tanfiano, Senya, Kokompe communities were 13.2, 2.4, and 2.9%, with nodule prevalence being 5.3, 4.9 and 14.3% respectively. Females in the study communities had a higher prevalence of microfilaria carriers (5.17%) relative to males (2.44%), but this difference was not statistically significant (p = 0.2800, unpaired t test). The most frequent clinical manifestation observed in this study among all participants was dermatitis (25.4%), followed by visual impairment & nodules (7.9% each) and then by blindness (4.4%).

Conclusion

The study showed that despite several years of mass drug administration with ivermectin, infection with onchocerciasis and the commonly associated clinical manifestations of the disease still persist in the study communities. This calls for a greater urgency for research and development aimed at discovering new or repurposed anti-filarial agents which will augment ivermectin if global onchocerciasis eradication targets are to be achieved.

Long-Term Storage of Cryptosporidium parvum for In Vitro Culture

The long-term storage of Cryptosporidium life-cycle stages is a prerequisite for in vitro culture of the parasite. Cryptosporidium parvum oocysts, sporozoites, and intracellular forms inside infected host cells were stored for 6-12 mo in liquid nitrogen utilizing different cryoprotectants (dimethyl sulfoxide [DMSO], glycerol and fetal calf serum [FCS]), then cultured in vitro. Performance in vitro was quantified by estimating the total Cryptosporidium copy number with quantitative polymerase chain reaction (qPCR) in 3- and 7-day-old cultures. Although few parasites were recovered either from stored oocysts or from infected host cells, sporozoites stored in liquid nitrogen recovered from freezing successfully. More copies of parasite DNA were obtained from culturing those sporozoites than sporozoites excysted from oocysts kept at 4 C for the same period. The best performance was observed for sporozoites stored in Roswell Park Memorial Institute (RPMI) medium with 10% FCS and 5% DMSO, which generated 240% and 330% greater number of parasite DNA copies (on days 3 and 7 post-infection, respectively) compared to controls. Storage of sporozoites in liquid nitrogen is more effective than oocyst storage at 4 C and represents a more consistent approach for storage of viable infective Cryptosporidium aliquots for in vitro culture.

Interleukin-10 and soluble tumor necrosis factor receptor II are potential biomarkers of Plasmodium falciparum infections in pregnant women: a case-control study from Nanoro, Burkina Faso

Background

Diagnosis of malaria in pregnancy is problematic due to the low sensitivity of conventional diagnostic tests (rapid diagnostic test and microscopy), which is exacerbated due to low peripheral parasite densities, and lack of clinical symptoms. In this study, six potential biomarkers to support malaria diagnosis in pregnancy were evaluated.

Methods

Blood samples were collected from pregnant women at antenatal clinic visits and at delivery. Microscopy and real-time PCR were performed for malaria diagnosis and biomarker analyses were performed by ELISA (interleukin 10, IL-10; tumor necrosis factor-α, TNF-α; soluble tumor necrosis factor receptor II, sTNF-RII; soluble fms-like tyrosine kinase 1, sFlt-1; leptin and apolipoprotein B, Apo-B). A placental biopsy was collected at delivery to determine placental malaria.

Results

IL-10 and sTNF-RII were significantly higher at all time-points in malaria-infected women (p < 0.001). Both markers were also positively associated with parasite density (p < 0.001 and p = 0.003 for IL-10 and sTNF-RII respectively). IL-10 levels at delivery, but not during pregnancy, were negatively associated with birth weight. A prediction model was created using IL-10 and sTNF-RII cut-off points. For primigravidae the model had a sensitivity of 88.9% (95%CI 45.7–98.7%) and specificity of 83.3% (95% CI 57.1–94.9%) for diagnosing malaria during pregnancy. For secundi- and multigravidae the sensitivity (81.8% and 56.5% respectively) was lower, while specificity (100.0% and 94.3% respectively) was relatively high. Sub-microscopic infections were detected in 2 out of 3 secundi- and 5 out of 12 multigravidae.

Conclusions

The combination of biomarkers IL-10 and sTNF-RII have the potential to support malaria diagnosis in pregnancy. Additional markers may be needed to increase sensitivity and specificity, this is of particular importance in populations with sub-microscopic infections or in whom other inflammatory diseases are prevalent.

Electronic supplementary material

The online version of this article (10.1186/s40364-017-0114-7) contains supplementary material, which is available to authorized users.

In vitro evaluation of traditionally used Surinamese medicinal plants for their potential anti-leishmanial efficacy

ETHNOPHARMACOLOGICAL RELEVANCE

Plant-based preparations are extensively used in Surinamese folk medicine for treating leishmaniasis, but often without a scientific rationale.

AIM OF THE STUDY

To evaluate 25 Surinamese medicinal plants for their potential efficacy against leishmaniasis.

MATERIALS AND METHODS

Concentrated plant extracts were evaluated for their effect on the viability of L. (V.) guyanensis AMC, L. (L.) major NADIM5, and L. (L.) donovani GEDII promastigotes, as well as intracellular amastigotes of L. (L.) donovani BHU814 in infected THP-1 cells. Selectivity was assessed by cytotoxicity against THP-1 cells.

RESULTS

The only plant extract that showed potentially meaningful anti-leishmanial activity was that from Solanum lycocarpum that displayed mean IC50 values of about 51, 61, and <16 µg/mL against L. (V) guyanensis, L. (L) major, and L. (L) donovani promastigotes, respectively; about 374 µg/mL against L. (L) donovani amastigotes; and >500 µg/mL against THP-1 cells. The Bryophyllum pinnatum, Inga alba, and Quassia amara extracts displayed moderate to high IC50 values against promastigotes (about 51 to >500 µg/mL) and/or amastigotes (about 224 to >500 µg/mL) but were relatively toxic to THP-1 cells (IC50 values <16 to about 42 µg/mL). The remaining plant extracts exhibited in many cases IC50 values close to, around, or above 500µg/mL against promastigotes, amastigotes, and THP-1 cells.

CONCLUSIONS

The S. lycocarpum preparation may be useful against leishmaniasis and may have a good safety index, warranting further investigations into its active constituents and mechanism(s) of action.

Leishmania donovani infection drives the priming of human monocyte-derived dendritic cells during Plasmodium falciparum co-infections

Functional impairment of dendritic cells (DCs) is part of a survival strategy evolved by Leishmania and Plasmodium parasites to evade host immune responses. Here, the effects of co-exposing human monocyte-derived DCs to Leishmania donovani promastigotes and Plasmodium falciparum-infected erythrocytes were investigated. Co-stimulation resulted in a dual, dose-dependent effect on DC differentiation which ranged from semi-mature cells, secreting low interleukin(-12p70 levels to a complete lack of phenotypic maturation in the presence of high parasite amounts. The effect was mainly triggered by the Leishmania parasites, as illustrated by their ability to induce semi-mature, interleukin-10-producing DCs, that poorly responded to lipopolysaccharide stimulation. Conversely, P. falciparum blood-stage forms failed to activate DCs and only slightly interfered with lipopolysaccharide effects. Stimulation with high L. donovani concentrations triggered phosphatidylserine translocation, whose onset presented after initiating the maturation impairment process. When added in combination, the two parasites could co-localize in the same DCs, confirming that the leading effects of Leishmania over Plasmodium may not be due to mutual exclusion. Altogether, these results suggest that in the presence of visceral leishmaniasis-malaria co-infections, Leishmania-driven effects may overrule the more silent response elicited by P. falciparum, shaping host immunity towards a regulatory pattern and possibly delaying disease resolution.

Ability of immunodiagnostic tests to differentiate between dogs naturally infected with Leishmania infantum and Leishmune(®)-vaccinated dogs

Visceral leishmaniasis (VL) is a serious chronic disease with a lethality rate of up to 10% in humans. In urban areas of Brazil, dogs are the main reservoirs of the etiological agent (Leishmania infantum) of VL, and the Brazilian Ministry of Health recommends the euthanasia of animals that are seropositive in both the immunochromatographic dual path platform rapid test (DPP(®); Bio-Manguinhos) and the enzyme-linked immunosorbent assay (ELISA) with an L. major-like antigen (Bio-Manguinhos). Vaccination is an additional tool in the control of canine VL, but the use of Leishmune(®) (Zoetis Indústria de Produtos Veterinários, São Paulo, SP, Brazil), which contains the fucose mannose ligand (FML) isolated from L. donovani, is not currently recommended by the Brazilian Ministry of Health because vaccinated animals may exhibit positive serology and there are reservations regarding the efficacy of the vaccine. The aims of the present study were: (i) to verify the abilities of the fast agglutination screening test (FAST), the direct agglutination test (DAT), the indirect fluorescent-antibody test (IFAT), the DPP rapid test, and ELISA tests with L. major-like and FML antigens to differentiate between L. infantum-infected and Leishmune(®)-vaccinated dogs, and (ii) to analyze the sensitivities and specificities of the different methods. The reactivities to these tests of Leishmune(®)-vaccinated dogs (n = 71), asymptomatic (n = 20) and symptomatic (n = 20) naturally infected dogs, and unvaccinated healthy control dogs (n = 5) were compared. None of the Leishmune(®)-vaccinated dogs tested seropositive in FAST and DAT, although one dog was reactive to DPP and four dogs to ELISA/L. major-like and IFAT tests. While 69 (97%) of vaccinated dogs reacted to ELISA/FML, only one was seropositive in both ELISA/L. major-like and IFAT tests. Individually, all immunodiagnostic tests presented high specificities and positive likelihood ratios (LR+), and high specificity values were obtained when the tests were considered in pairs. However, sensitivity and LR- values were low for ELISA/L. major-like and IFAT tests individually, and for all pair combinations of tests except for FAST with DPP.

Serological evidence of Leishmania donovani infection in apparently healthy dogs using direct agglutination test (DAT) and rk39 dipstick tests in Kafta Humera, north-west Ethiopia

Leishmania (Kinetoplastida: Trypanosomatidae) are protozoan parasites of significant medical and veterinary importance. Over the last decade, visceral leishmaniasis (VL) has emerged as a major opportunistic infection associated with HIV/AIDS in North Western Ethiopia. This paper reports on serological evidence of possible Leishmania donovani (L. donovani) infection in dogs using two serological tests: direct agglutination test (DAT) and Kalazar detect rapid test (KDRT). Two hundred and seventeen asymptomatic local breed dogs were examined for L. donovani antibodies. Performance of the DAT and KDRT was assessed in 162 matching samples of blood collected on filter paper and serum, respectively. Using DAT and KDRT testing in parallel, the overall seroprevalence of L. donovani infection was 27.7% and 14.8%, respectively. The degree of agreement was found to be fair (68.8%, k = 0.234). Univariable logistic regression analysis of some risk factors for L. donovani infection in dogs using DAT indicates that place of residence, sex, age, dog keeping purpose and dog housing condition were not significantly associated with seropositivity. The high proportion of positive dogs suggests the exposure of these animals to L. donovani infection and needs further investigation. Isolation and typing of the parasite aiming at confirming the role of these animals in maintenance and transmission of kala-azar is advocated.

Plasmodium falciparum malaria in pregnancy: prevalence of peripheral parasitaemia, anaemia and malaria care-seeking behaviour among pregnant women attending two antenatal clinics in Edo State, Nigeria

SUMMARY

This study evaluated malaria care-seeking behaviour, as well as the prevalence of parasitaemia and anaemia among pregnant women attending antenatal clinics of two tertiary healthcare facilities in Edo State, Nigeria. Malaria was highly prevalent in the study group (20% by microscopy and estimated 25% by PCR), but parasitaemia and incidence decreased with increasing number of pregnancies. Although the level of education of the study participants was relatively high, antimalarial control measures during pregnancy were found to be poorly utilised by the women and malaria care-seeking was often delayed. A minority of the interviewed pregnant women said they had received sulphadoxine/pyrimethamine-based intermittent preventive therapy (IPT) during current pregnancy. Moreover, the use of inferior antimalaria treatment (e.g. chloroquine) was frequent. The majority of the pregnant women, mainly primigravidae, were anaemic. Efforts to improve antimalaria healthcare must be intensified, targeting pregnant women, particularly the primigravidae and secundigravidae and the healthcare providers.

Treatment assessment by monitoring parasite load in skin biopsies from patients with cutaneous leishmaniasis, using quantitative nucleic acid sequence-based amplification

BACKGROUND

Current diagnostic methods for cutaneous leishmaniasis (CL) have low sensitivity or are not useful for treatment follow-up. We previously described the quantitative nucleic acid sequence-based amplification (QT-NASBA) method as a sensitive and specific assay for detection and quantification of Leishmania parasites in skin biopsies. This assay could be a valuable instrument for monitoring response to treatment of CL and identifying treatment failures at an early stage.

AIM

QT-NASBA results of skin biopsies at the end and 6 weeks after treatment from patients with proven CL on various treatment regimens were compared with clinical outcome.

METHODS

The QT-NASBA assay measured the parasite load in skin biopsies before, at the end and 6 weeks after treatment. The results were compared with treatment outcome (clinical cure, delayed healing response or treatment failure) up to 6 months after treatment.

RESULTS

In total, 137 skin biopsies were obtained from 53 patients. A positive QT-NASBA result 6 weeks after treatment was significantly associated with treatment failure/delayed healing up to 6 months (P < 0.001). The positive predictive value (PPV) was 100% and the negative predictive value (NPV) was 92% (95% CI 82-100%). QT-NASBA results at the end of treatment and clinical outcome showed a less significant association (P < 0.05), with a PPV of 46% (95% CI 16-75% and an NPV of 89% (95% CI 79-99%).

CONCLUSIONS

The QT-NASBA assay is a useful instrument to monitor parasite load in skin biopsies of patients with CL 6 weeks after treatment and can help to predict clinical outcome.

Diagnosis of canine leishmaniasis in the endemic area of Belo Horizonte, Minas Gerais, Brazil by parasite, antibody and DNA detection assays

Canine leishmaniasis caused by Leishmania chagasi (L. infantum) is found throughout the South American continent, including Brazil, and dogs are considered to be the main reservoir host for this parasite. To support the implementation of a diagnostic protocol for surveillance of the disease in the region of Belo Horizonte (Minas Gerais, Brazil) we have compared the sensitivity and specificity of two serological tests, indirect immunofluorescent antibody test (IFAT) and direct agglutination test (DAT), with the combination of direct microscopy-culture-PCR as the gold standard, using samples obtained from 103 dogs in the city of Belo Horizonte, Minas Gerais. The currently used standard serodiagnostic test, IFAT, had a sensitivity of 100% and its specificity was 74% compared to the gold standard of the study. The sensitivity and specificity of the DAT were 100% and 91%, respectively. On the basis of this study it is recommended to change from the IFAT to DAT for the serodiagnosis of canine leishmaniasis because of the superior specificity of the test combined with its user-friendliness.

Quantification of the response to miltefosine treatment for visceral leishmaniasis by QT-NASBA

A male patient with psoriatic arthritis and visceral Leishmania infantum infection was treated with oral miltefosine 50 mg three times a day for 4 weeks at the Academic Medical Center, Amsterdam, The Netherlands. Miltefosine plasma concentrations were measured with liquid chromatography/mass spectrometry. The parasite load was followed by quantitative nucleic acid sequence-based amplification (QT-NASBA) assay in blood. Miltefosine elicited a prompt therapeutic effect. After an initial worsening of symptoms and an increase of QT-NASBA values during the first week, recovery was rapidly achieved. QT-NASBA values declined exponentially and were negative after 6 weeks. Miltefosine plasma concentrations continued to accumulate during the 4 weeks of treatment. The terminal elimination half-life was 14.8 days.

Field evaluation of a fast anti-Leishmania antibody detection assay in Ethiopia

A fast agglutination screening test (FAST) for the detection of Leishmania antibodies in human serum samples was evaluated under harsh field conditions in northern Ethiopia. Test performance was compared with a standard serological test, namely the direct agglutination test (DAT), and with parasitology. In total, 103 suspected cases were recruited for the study. Based on parasitological examination, 49 patients were confirmed of having visceral leishmaniasis (VL) and the other 54 suspected cases were parasitologically negative. Field evaluation of FAST was possible in blood samples of 89 patients. FAST had 4 false negative results and 13 false positive results. DAT had 2 false negative results and 20 false positive results. A good degree of agreement (86.9%) was observed between FAST and DAT (kappa value 0.73). In this field-based evalauation, the sensitivity and specificity of FAST were found to be 91.1% (95% CI 77.9-97.1) and 70.5% (95% CI 54.6-82.8), respectively, compared with 95.3% (95% CI 82.9-99.2) and 62.3% (95% CI 47.9-74.9) for DAT. FAST had a high predictive value of a negative test, demonstrating that FAST could be utilised to exclude rapidly non-VL patients from a large population of suspects with fever and splenomegaly in endemic areas.

Plasmodium falciparum: evaluation of a quantitative nucleic acid sequence-based amplification assay to predict the outcome of sulfadoxine-pyrimethamine treatment of uncomplicated malaria

A quantitative nucleic acid sequence-based amplification (QT-NASBA) assay was employed to predict retrospectively the outcome of sulfadoxine-pyrimethamine (SP) treatment of uncomplicated malaria in children aged <6 years in an endemic region. Blood samples were collected at initial diagnosis and during follow-up. Mutation-specific nested PCR methods to analyse DHFR (Arg-59) and DHPS (Glu-540) mutations that are associated with SP drug resistance were applied. Parasite genotyping was performed to distinguish between re-infection and recrudescence. Eighty-six patients were recruited of which 66 were available for follow-up. Nine children were classified as early treatment failure, 13 cases were classified as late clinical failure, 32 as late parasitological failure, and only 12 children had an adequate clinical and parasitological response. DHFR and DHPS mutations conferring SP resistance were abundant in the Plasmodium population. Blood samples obtained 7 days after treatment were used to predict retrospectively the outcome of SP treatment. QT-NASBA was able to give a correct prediction of treatment outcome in 85.7% of the cases. Positive predictive value (PPV) of QT-NASBA case was 95% (95% confidence interval = 88.3-100) and negative predictive value (NPV) was 63% (95% CI = 39.5-86.5). In contrast, microscopy correctly predicted outcome in only 37.5% of the cases. PPV of microscopy was 100% (95% CI = 73.9-100) and the NPV was 25.5% (95% CI = 13.0-38.0). The analysis of a day 7 blood sample with QT-NASBA allows for the prediction of late clinical or parasitological treatment failure in the majority of the cases analysed in the present study.

Application of riboprinting for the identification of isolates of cutaneous Leishmania spp

Riboprinting is one of several molecular methods that can generate comparative data independently of the complexity of the organism's morphology. Restriction fragment length polymorphism (RFLP) profiles derived from digestion of polymerase chain reaction (PCR) products of the ribosomal 18S from Leishmania spp. yields a typical 'riboprint' profile that can vary intraspecifically. A selection of 76 stocks of L. major and L. tropica, isolated from patients with cutaneous leishmaniasis, was analysed by riboprinting to assess divergence within and between species. L. major and L. tropica could be easily differentiated from each other. Analysis of PCR-RFLP profiles indicated that stocks of Leishmania spp. could be broadly partitioned into 2 species corresponding to L. major and L. tropica. To test if ribosomal 18S sequences were homogeneous within each species, several isolates of each of the Leishmania spp. were digested. Interpretation of the riboprint profiles of the 18S independently amplified by PCR, there would appear to be one restriction pattern present within cach Leishmania spp. Homogeneity within copies of the ribosomal 18S within a single genome has, therefore, been demonstrated. The species designation established by riboprinting results were in agreement with the zymodeme analysis of the same isolates. The restriction patterns produced were simple, reproducible and easy to interpret.

Usefulness of quantitative nucleic Acid sequence-based amplification for diagnosis of malaria in an academic hospital setting

The aim of the present study was to evaluate the usefulness of quantitative nucleic acid sequence-based amplification (QT-NASBA) to detect Plasmodium spp. in diagnostic specimens of patients suspected of having malaria in a clinical setting in a non-endemic country. During the 4-month recruitment period, 113 patients were enrolled in the study, of which 93 were diagnosed as non-malaria and 20 as malaria cases on the basis of clinical and microscopic criteria. All microscopically positive cases had QT-NASBA counts of >0.1 parasites/ micro l and there was a significant positive correlation between the parasite counts obtained with both diagnostic methods. Of the 93 microscopically negative cases, six had a positive QT-NASBA result. Three of these cases had a recent history of malaria for which specific treatment was taken. In the other three cases there was no history of malaria and QT-NASBA results in these cases were near the cut-off level (>0.1 parasites/ micro l) of the test. The results demonstrate that QT-NASBA is a useful technology for the diagnosis of malaria in a reference laboratory, and it is very helpful in cases of low parasitemia.

Development of a fast agglutination screening test (FAST) for the detection of anti-Leishmania antibodies in dogs

A fast agglutination screening test (FAST) for the detection of anti-Leishmania antibodies in serum samples from dogs with visceral leishmaniosis was developed. The test is based on the direct agglutination test (DAT), but combines a higher parasite concentration with a smaller test volume. In contrast to the DAT, the FAST makes use of only one serum dilution and the results can be read within 3 h as opposed to 18-20 h for the DAT. The FAST was evaluated using serum samples of confirmed cases of the disease and healthy controls collected in the most important endemic regions of canine visceral leishmaniosis, import cases of canine leishmaniosis in a non-endemic country, from non-endemic healthy controls and from dogs with other diseases. The performance of the FAST was compared with standard DAT. In the present study, the FAST had a sensitivity of 93.6% and a specificity of 89.0%. The DAT had a sensitivity of 88.6% and a specificity of 96.7%. Furthermore, using a large panel of serum samples of previously examined DAT positive or negative dogs it was shown that degree of agreement between the two tests was high (95.7%; kappa value = 0.91). The FAST offers the advantages of the DAT based on freeze-dried antigen with respect to stability of the antigen, sensitivity and specificity. Moreover, the FAST allows the rapid screening of a large number of samples, which makes the test very useful for epidemiological screening of large populations of dogs.

Sero-epidemiological assessment and diagnosis of visceral leishmaniasis in an endemic locality using Fast Agglutination Screening Test (FAST)

The Fast Agglutination Screening Test (FAST) was employed on sera obtained from an endemic area of visceral leishmaniasis in southwestern Ethiopia, in February 2000. The study involved (i) active case detection among 1575 residents of two villages; and (ii) passive case detection in an outpatient clinic. Sera of 1587 individuals, including 143 sera of previously treated VL patients, were tested. Based on the size of agglutination mat, the FAST results were read qualitatively as non-reactive (-), weakly reactive (1+), moderately reactive (2+) and highly reactive (3+). All FAST reactive sera were re-tested with the Direct Agglutination Test (DAT). After clinical screening of 1625 individuals, 61 individuals with signs and symptoms of early or late VL were found; 26 sera were FAST positive. Twenty-two of these suspected VL cases were subjected to parasitological examination using lymph node aspirates. Eighteen (81.8%) were confirmed either by demonstration of amastigotes in smears or promastigotes in NNN cultures. FAST reactive anti-leishmanial antibodies were detected in 4.5% of untreated and 70.6% of previously treated patients. Forty-five sera of 1390 previously untreated asymptomatic individuals (3.2%) were found to be FAST positive. This report demonstrates that FAST is a rapid and cost-effective screening test for the diagnosis and sero-epidemiological surveillance of visceral leishmaniasis.