Risk factors affecting the feeding site predilection of ticks on cattle in Ghana

Ticks are important disease vectors affecting animal health and causing substantial economic loss, especially in the tropics and subtropics. To examine the tick burden of cattle and associated risk factors for tick infestation, ticks were collected from 388 cattle within five regions in Ghana. Most of the cattle were males (50.3%) and generally older than 3 years (65%). Of the animals sampled, 2187 ticks were collected with a mean tick burden of 5.6 ticks per cattle, and the average tick burden on the udder/scrotum being significantly higher than in the anal region (Generalized Linear Mix Model [GLMM], p = 0.01197). The tick species identified were predominantly Amblyomma variegatum (42.6%) and Hyalomma rufipes (26.2%). High proportions of cattle examined were found to have A. variegatum infesting the udder/scrotum. Furthermore, H. rufipes infested mostly the anal region compared to other examined body parts (OR 14.8, 95% CI 8.6-25.4, p < 0.001). Using the GLMM, tick abundance was found to be significantly higher in cattle older than 3 years. The tick burden in the udder/scrotum was higher than that from the chest and leg/thigh of the cattle (GLMM, p < 0.05). The tick burden at the anal region was also significantly higher than the leg/thigh and chest. This study indicates that the preferred attachment sites of ticks on cattle are species-dependent and effective treatment with acaricides should take into consideration the udder/scrotum and anal regions as well as prioritizing older cattle.

Whole genome sequencing of outbreak strains from 2017 to 2018 reveals an endemic clade of dengue 1 virus in Cameroon

Dengue fever is expanding as a global public health threat including countries within Africa. For the past few decades, Cameroon has experienced sporadic cases of arboviral infections including dengue fever. Here, we conducted genomic analyses to investigate the origin and phylogenetic profile of Cameroon DENV-1 outbreak strains and predict the impact of emerging therapeutics on these strains. Bayesian and maximum-likelihood phylogenetic inference approaches were employed in virus evolutionary analyses. An in silico analysis was performed to assess the divergence in immunotherapeutic and vaccine targets in the new genomes. Six complete DENV-1 genomes were generated from 50 samples that met a clinical definition for DENV infection. Phylogenetic analyses revealed that the strains from the current study belong to a sub-lineage of DENV-1 genotype V and form a monophyletic taxon with a 2012 strain from Gabon. The most recent common ancestor (TMRCA) of the Cameroon and Gabon strains was estimated to have existed around 2008. Comparing our sequences to the vaccine strains, 19 and 15 amino acid (aa) substitutions were observed in the immuno-protective prM-E protein segments of the Dengvaxia® and TetraVax-DV-TV003 vaccines, respectively. Epitope mapping revealed mismatches in aa residues at positions E155 and E161 located in the epitope of the human anti-DENV-1 monoclonal antibody HMAb 1F4. The new DENV strains constitute a conserved genomic pool of viruses endemic to the Central African region that needs prospective monitoring to track local viral evolution. Further work is needed to ascertain the performance of emerging therapeutics in DENV strains from the African region.

A Preliminary Study to Compare Recombinase Polymerase Amplification-Lateral Flow and Quantitative PCR in the Detection of Cutaneous Leishmania in Communities from the Volta Region of Ghana

Background: Leishmaniasis is a parasitic disease that mostly affects populations in tropical and subtropical countries. In Ghana, cutaneous leishmaniasis (CL) is the most common form of the disease affecting communities of the Volta Region. Conventional parasitological method (microscopy) is the commonly used test for CL diagnosis in many endemic countries, but has low sensitivity in chronic cases. Therefore, there is a clear need for a sensitive and easy-to-use point-of-care diagnostic method like an isothermal recombinase polymerase amplification-lateral flow (RPA-LF) test, suitable for use in austere and low-resource settings for the identification of CL cases. This study compared the efficacy of RPA-LF test with quantitative PCR (qPCR) in detecting Leishmania in suspected CL cases from the Volta Region. Methods: Twenty-five participants between 5 and 14 years were enrolled in the study from whom a total of 26 samples were obtained. Lesion samples were collected using FTA^® filter papers applied to ulcerated lesions for molecular diagnosis. DNA isolated from filter papers was used for both the RPA-LF test and qPCR. Results: Twenty-two participants (88%) presented with one or two ulcerated active lesions per individual, while the rest of them had plaques or dried lesions. Among the 26 samples, 19/26 (73%) had concordant results when comparing the two diagnostic methods. Conclusion: Data from this study suggest that the RPA-LF test can be used in addition to a conventional parasitological diagnostic test (microscopy) to detect CL cases in communities of the Volta Region.

DESCRIPTION, BIOLOGY, AND MEDICAL SIGNIFICANCE OF LEISHMANIA (MUNDINIA) CHANCEI N. SP. (KINETOPLASTEA: TRYPANOSOMATIDAE) FROM GHANA AND LEISHMANIA (MUNDINIA) PROCAVIENSIS N. SP. (KINETOPLASTEA: TRYPANOSOMATIDAE) FROM NAMIBIA

Genetic and phylogenetic analysis was performed on 2 isolates of Leishmania using DNA sequence data from the RNA polymerase II large subunit gene and the ribosomal protein L23a intergenic sequence. This showed the isolates to represent 2 new species within the subgenus Leishmania (Mundinia). The addition of Leishmania (Mundinia) chancei and Leishmania (Mundinia) procaviensis creates a total of 6 named species to date within this recently described subgenus of parasitic protozoa, containing both human pathogens and nonpathogens. Their widespread geographical distribution, basal phylogenetic position within the genus Leishmania, and probable non-sand fly vectors make these L. (Mundinia) species of significant medical and biological interest.

Chikungunya viruses containing the A226V mutation detected retrospectively in Cameroon form a new geographical subclade

BACKGROUND

Chikungunya virus (CHIKV) is a re-emerging arbovirus associated with sporadic outbreaks in Cameroon since 2006. Viral whole genomes were generated to analyze the origins of evolutionary lineages, the potential of emergence/re-emergence, and to infer transmission dynamics of recent Cameroon CHIKV outbreak strains.

METHODS

Samples collected between 2016 and 2019 during CHIKV outbreaks in Cameroon were screened for CHIKV using reverse transcription PCR (RT-PCR), followed by whole genome sequencing of positive samples.

RESULTS

Three coding-complete CHIKV genomes were obtained from samples, which belong to an emerging sub-lineage of the East/Central/South African genotype and formed a monophyletic taxon with previous Central African strains. This clade, which we have named the new Central African clade, appears to be evolving at 3.0 × 10^-4 nucleotide substitutions per site per year (95% highest posterior density (HPD) interval of 1.94 × 10^-4 to 4.1 × 10^-4). Notably, mutations in the envelope proteins (E1-A226V, E2-L210Q, and E2-I211T), which are known to enhance CHIKV adaptability and infectious potential in Aedes albopictus, were present in all strains and mapped to established high-density Ae. albopictus populations.

CONCLUSIONS

These new CHIKV strains constitute a conserved genomic pool of an emerging sub-lineage, reflecting a putative vector host adaptation to Ae. albopictus, which has practically displaced Aedes aegypti from select regions of Cameroon.

Prevalence of Leishmania infection in three communities of Oti Region, Ghana

BACKGROUND

Leishmaniasis is a neglected tropical disease caused by parasites of the genus Leishmania and is transmitted by various species of female phlebotomine sand flies. The first report of cutaneous leishmaniasis (CL) in Ghana refer to a cluster of cases in 1999-2003 in the Ho municipality of the Volta Region. We conducted an epidemiological assessment in the Oti Region, encouraged by recent reports of potential cases of CL.

METHODOLOGY/PRINCIPAL FINDINGS

Using a cross-sectional study design, the exposure to Leishmania was investigated in three communities of the Oti Region based on the leishmanin skin test (LST). LST results for 3,071 participants comprising 1091, 848, and 1132 persons from the communities of Ashiabre, Keri, and Sibi Hilltop, indicated an overall prevalence of exposure to Leishmania infection of 41.8% and individual community prevalence of 39.4%, 55.1%, and 34.2% respectively. Being male [AOR = 1.27; CI: 1.09, 1.49], and living in Keri [AOR = 1.83; CI: 1.43, 2.34] were associated with an increase in the odds of exposure to Leishmania. Being 5-10 years old [AOR = 1.48; CI: 1.06, 2.05], 11-17 years old [AOR = 2.03; CI: 1.45, 2.85], 18-40 years old [AORR = 2.83; CI: 1.81, 4.43] and 41-65 years old [AOR = 5.08; CI: 2.98, 8.68] were also significantly associated with increased odds of being exposed to Leishmania.

CONCLUSIONS/SIGNIFICANCE

This study demonstrated exposure to Leishmania in the study communities and also identified associated factors. Future efforts aimed at reducing exposure to Leishmania infection in the study area should take the associated factors into consideration.

Detection of cutaneous leishmaniasis in three communities of Oti Region, Ghana

Background

Cutaneous leishmaniasis (CL) is the most common type of leishmaniasis, a neglected tropical disease caused by parasites of the genus Leishmania. In Ghana, some studies in the Volta region have detected Leishmania parasites among persons with skin ulcers.

Methodology/Principal findings

Using a cross-sectional study design, the prevalence of CL in three communities of the Oti Region of Ghana was investigated. Demographic and epidemiological data were obtained by a structured interviewer administered questionnaire. A total of 426 (12.4%) out of 3,440 participants screened had at least one skin ulcer. Of 595 skin ulcers sampled and tested by PCR for Leishmania infection, 150 (25.2%) ulcers from 136 individuals tested positive, accounting for an overall CL prevalence of 31.9% among persons with skin ulcers. Individual community CL prevalence of 23.2%, 29.8%, and 36.8% was observed in Ashiabre, Keri, and Sibi Hilltop respectively among persons with skin ulcers.

Conclusions/Significance

Confirmation of CL in the study area suggests an active cycle of transmission of Leishmania infection. The observation of skin ulcers which tested negative to Leishmania infection suggests a need to test for additional causes of skin ulcers such as Treponema pallidum pertenue and Mycobacterium ulcerans in the study area.

Cutaneous leishmaniasis (CL) is a neglected tropical disease caused by parasites of the genus Leishmania and is transmitted by various species of female sandflies. CL usually begins as painless nodules and is usually characterized by skin ulcers which may be single or multiple. Although ulcers due to CL are often self-healing, they may become painful and result in scarring after healing. Typically, CL occurs on exposed parts of the body such as the neck, limbs, and face, which may be easily accessible to sandflies. Although cases of CL had previously been reported in some parts of the Volta region of Ghana, no previous case of CL had been reported in the Oti region. This study was initiated following reports of skin ulcers which were suggestive of CL in some communities of the Oti region. This study confirmed Leishmania infection in 150(25.5%) out of 595 skin ulcer samples obtained from 426 study participants. Given that 445(74,8%) of the skin ulcers tested negative for Leishmania parasite suggests a need for investigation of additional causes of skin ulcers such as yaws and Buruli ulcer in the study area.

In vitro activity of Erythrophleum ivorense extract against the promastigote stage of cutaneous Leishmania parasite, a member of Leishmania (Mundinia) enriettii complex isolates from Ghana

BACKGROUND

Cutaneous leishmaniasis causes physical disfigurement and impairment on affected individuals, however, little attention has been paid to it eradication. The situation of this neglected disease is complicated with the expansion of the non-human pathogenic Leishmania enriettii complex causing infection in humans. We have previously shown that the extract from Erythrophleum ivorense has leishmanicidal activity against promastigote stages of the L. enriettii complex isolate from Ghana and L eishmania donovani. The extract of E. ivorense has shown to have anti-inflammatory, wound-healing ability, antiallergic, antimalarial and antischistosomal activity. However, the concentration threshold of E. ivorense extract required for leishmanicidal activity against the emerging human pathogenic L. enriettii complex isolates is not clear.

AIM

To test for the concentration threshold of E. ivorense extract required to obtain ideal leishmanicidal activity against the promastigote stage of human pathogenic L. enriettii complex isolates from Ghana.

METHOD

The ethanolic leaf extract of E. ivorense was serially diluted and tested against the promastigote stage of the L. enriettii complex. Parasite inhibition was measured at 590 nm using a spectrophotometer after staining parasites with trypan blue. To select the threshold concentration for maximum inhibition of the promastigote stage of the L. enriettii complex, the concentration cut-off statistic was used.

RESULTS

The MIC of E. ivorense extract for L. enriettii promastigote inhibition was 62.3 μg ml-1. The highest promastigote inhibition was observed at 72 h.

CONCLUSION

We show that a MIC of 62.3 μg ml-1 of E. ivorense leaf extract exhibits an ideal leishmanicidal activity against the promastigote stage of L. enriettii complex isolates.

In vitro anti-Leishmania activity of tetracyclic iridoids from Morinda lucida, benth

Leishmaniasis is an infectious disease transmitted by the sand fly. It is caused by over 20 different species of Leishmania and has affected over 14 million people worldwide. One of the main forms of control of leishmaniasis is chemotherapy, but this is limited by the high cost and/or toxicity of available drugs. We previously found three novel compounds with an iridoid tetracyclic skeleton to have activity against trypanosome parasites. In this study, we determined the activity of the three anti-trypanosome compounds against Leishmania using field strain, 010, and the lab strain Leishmania hertigi. The minimum inhibitory concentration (MIC) of the compounds against 010 was determined by microscopy while the IC50 of compounds against L. hertigi was determined by fluorescence-activated cell sorting with Guava viacount analysis. We found two of the three compounds, molucidin and ML-F52, to have anti-Leishmania activity against both strains. The fluor-microscope observation with DAPI stain revealed that both Molucidin and ML-F52 induced abnormal parasites with two sets of nucleus and kinetoplast in a cell, suggesting that compounds might inhibit cytokinesis in Leishmania parasites. Molucidin and ML-F52 might be good lead compounds for the development of new anti-Leishmania chemotherapy.