COVID-19 Response: The case for Phytomedicines in Africa with particular focus on Cameroon

Despite enormous efforts deployed and considerable positive results obtained in the global fight against the Coronavirus disease 2019 (COVID-19) the scourge remains a major international public health hazard. The main control measures at the onset consisted in the application of barrier and hygiene measures to stop the spread of the virus and case identification and clinical management of symptoms in the absence of widely available anti-COVOD-19 drugs. Vaccination as a major control measure became widely available in the advanced countries of the global north, but not in Africa where less than 5-10% 0f the population are vaccinated against COVID-19. However, African countries, possibly excluding South Africa, have been less impacted by COVID-19 pandemic as they registered fewer cases, hospitalizations and deaths. Herein it is postulated that the wide use of African traditional Phytomedicines (herbal medicines) has contributed, at least in part, to the better control of the COVID-19 pandemic in Africa. Abundant evidence in the literature suggests the availability of anti-viral, anti-oxidant and immune-stimulatory agents in the proposed COVID-19 herbal remedies., these activities being similar to those the standard drugs used in the standard treatment/ management of COVID-19. The review also examines a number of COVID-19 herbal medicines including COVID Organics CVO (Madagascar) ADSAR, ELISIR COVID, COROCUR (Cameroon) IHP Detox Tea (Nigeria) and COVIDEX (Uganda) and notes that though approved by the competent authorities in the respective African countries, these phytomedicines have not been approved by the WHO. It is proposed that additional studies be carried out to validate the Africa herbal remedies for possible use as stand-alone or complementary treatment of COVID-19 in addition to vaccination and barrier and hygiene control measures

Priority Research themes in the fight Against the COVID-19 with particular reference to Cameroon

The ongoing SARS CoV-2 pandemic also known as COVID-19 is a highly infectious and deadly disease that has disrupted socio- economic activities  and killed over 500 000 people worldwide during the past six months since it first erupted in Wuhan China in December 2019.While intensive efforts  are under way in the developed countries to find a vaccine and cure for the disease, Cameroon and other African countries should not fold their hands and wait , but join the search for new remedies including from cures from traditional herbs while rigorously applying barrier and social  distancing measures that have proven effective in in curbing the spread of the disease. Herein we enumerate a short list of research priorities that are feasible in our milieu and that could improve on diagnostics, treatment and prevention of the disease in the short and medium terms. Key Words: SARS CoV-2, COVID-19, research, diagnostics, medicinal plants, traditional medicine, pandemic, Cameroon

Malaria vectors and transmission dynamics in coastal south-western Cameroon

BACKGROUND: Malaria is a major public health problem in Cameroon. Unlike in the southern forested areas where the epidemiology of malaria has been better studied prior to the implementation of control activities, little is known about the distribution and role of anophelines in malaria transmission in the coastal areas. METHODS: A 12-month longitudinal entomological survey was conducted in Tiko, Limbe and Idenau from August 2001 to July 2002. Mosquitoes captured indoors on human volunteers were identified morphologically. Species of the Anopheles gambiae complex were identified using the polymerase chain reaction (PCR). Mosquito infectivity was detected by the enzyme-linked immunosorbent assay and PCR. Malariometric indices (plasmodic index, gametocytic index, parasite species prevalence) were determined in three age groups (<5 yrs, 5–15 yrs, >15 yrs) and followed-up once every three months. RESULTS: In all, 2,773 malaria vectors comprising Anopheles gambiae (78.2%), Anopheles funestus (17.4%) and Anopheles nili (7.4%) were captured. Anopheles melas was not anthropophagic. Anopheles gambiae had the highest infection rates. There were 287, 160 and 149 infective bites/person/year in Tiko, Limbe and Idenau, respectively. Anopheles gambiae accounted for 72.7%, An. funestus for 23% and An. nili for 4.3% of the transmission. The prevalence of malaria parasitaemia was 41.5% in children <5 years of age, 31.5% in those 5–15 years and 10.5% in those >15 years, and Plasmodium falciparum was the predominant parasite species. CONCLUSION: Malaria transmission is perennial, rainfall dependent and An. melas does not contribute to transmission. These findings are important in the planning and implementation of malaria control activities in coastal Cameroon and West Africa

Genetic diversity and drug resistance surveillance of Plasmodium falciparum for malaria elimination: is there an ideal tool for resource-limited sub-Saharan Africa?

The intensification of malaria control interventions has resulted in its global decline, but it remains a significant public health burden especially in sub-Saharan Africa (sSA). Knowledge on the parasite diversity, its transmission dynamics, mechanisms of adaptation to environmental and interventional pressures could help refine or develop new control and elimination strategies. Critical to this is the accurate assessment of the parasite's genetic diversity and monitoring of genetic markers of anti-malarial resistance across all susceptible populations. Such wide molecular surveillance will require selected tools and approaches from a variety of ever evolving advancements in technology and the changing epidemiology of malaria. The choice of an effective approach for specific endemic settings remains challenging, particularly for countries in sSA with limited access to advanced technologies. This article examines the current strategies and tools for Plasmodium falciparum genetic diversity typing and resistance monitoring and proposes how the different tools could be employed in resource-poor settings. Advanced approaches enabling targeted deep sequencing is valued as a sensitive method for assessing drug resistance and parasite diversity but remains out of the reach of most laboratories in sSA due to the high cost of development and maintenance. It is, however, feasible to equip a limited number of laboratories as Centres of Excellence in Africa (CEA), which will receive and process samples from a network of peripheral laboratories in the continent. Cheaper, sensitive and portable real-time PCR methods can be used in peripheral laboratories to pre-screen and select samples for targeted deep sequence or genome wide analyses at these CEAs

Molecular typing reveals substantial Plasmodium vivax infection in asymptomatic adults in a rural area of Cameroon

BACKGROUND: Malaria in Cameroon is due to infections by Plasmodium falciparum and, to a lesser extent, Plasmodium malariae and Plasmodium ovale, but rarely Plasmodium vivax. A recent report suggested “Plasmodium vivax–like” infections around the study area that remained unconfirmed. Therefore, molecular and antigenic typing was used to investigate the prevalence of P. vivax and Duffy in asymptomatic adults resident in Bolifamba. METHODS: A cross-sectional study was conducted from July 2008 to October 2009. The status of all parasite species was determined by nested PCR in 269 blood samples collected. The P. falciparum and P. vivax anti-MSP/CSP antibody status of each subject was also determined qualitatively by a rapid card assay. Parasite DNA was extracted from a sample infected with three parasite species, purified and sequenced. The Duffy antigen status of 12 subjects infected with P. vivax was also determined by sequencing. In silico web-based tools were used to analyse sequence data for similarities and matches to reference sequences in public DNA databases. RESULTS: The overall malaria parasite prevalence in 269 individuals was 32.3% (87) as determined by PCR. Remarkably, 14.9% (13/87) of infections were caused either exclusively or concomitantly by P. vivax, established both by PCR and microscopic examination of blood smears, in individuals both positive (50%, 6/12) and negative (50%, 6/12) for the Duffy receptor. A triple infection by P. falciparum, P. vivax and P. malariae, was detected in one infected individual. Anti-MSP/CSP antibodies were detected in 72.1% (194/269) of samples, indicating high and continuous exposure to infection through mosquito bites. DISCUSSION: These data provide the first molecular evidence of P. vivax in Duffy positive and negative Cameroonians and suggest that there may be a significant prevalence of P. vivax infection than expected in the study area. Whether the P. vivax cases were imported or due to expansion of a founder effect was not investigated. Notwithstanding, the presence of P. vivax may complicate control efforts if these parasites become hypnozoitic or latent as the liver stage. CONCLUSIONS: These data strongly suggest that P. vivax is endemic to the south-west region of Cameroon and should be taken into account when designing malaria control strategies

Intermittent preventive treatment with Sulphadoxine-Pyrimethamine (IPTp-SP) is associated with protection against sub-microscopic P. falciparum infection in pregnant women during the low transmission dry season in southwestern Cameroon: A Semi - longitudinal study.

The current guidelines for malaria prevention and control during pregnancy in Africa is predicated on the prevention of infection and/or disease through intermittent preventive treatment in pregnancy (IPTp), insecticide-treated nets (ITNs) and effective malaria case diagnosis and management. Concerns that increasing SP resistance in some areas of SSA may have compromised IPTp-SP efficacy prompted this contemporaneous study, designed to assess the prevalence and risk factors of sub-microscopic infection in parturient women during the low transmission season in Mutengene, a rapidly growing semi-urban area in Southwest Region, Cameroon. Pregnant women originally reporting for the establishment of antenatal clinic care during the dry season were followed-up to term and their pregnancy outcomes recorded. About 2 ml of venous blood was collected for malaria diagnosis using PfHRP2/pLDH malaria rapid diagnostic kit and light microscopy. DNA was extracted from dried blood spots by the Chelex-100 method and the Plasmodium falciparum status detected by nested PCR amplification of the 18SrRNA gene using specific predesigned primers. Of the 300 women enrolled, the proportion of malaria parasite infected as determined by microscopy, RDT and PCR was 12.9%, 16.4% and 29.4% respectively, with 39.9% overall infected with P. falciparum by microscopy and/or RDT and/or PCR and a very low-density infection, averaging 271 parasites per microliter of blood. About 25.0% (68/272) of women who were negative by microscopy were positive by PCR (submicroscopic P. falciparum infection), with primigravidae and IPTp-SP non usage identified as independent risk factors for submicroscopic P. falciparum parasitaemia while fever history (aOR = 4.83, 95% CI = 1.28-18.22, p = 0.020) was associated with risk of malaria parasite infection overall. IPTp-SP use (p = 0.007) and dosage (p = 0.005) significantly influenced whether or not the participant will be malaria parasite negative or carry submicroscopic or microscopic infection. Although Infant birthweight and APGAR score were independent of the mother's P. falciparum infection and submicroscopic status, infant's birthweight varied with the gravidity status (p = 0.001) of the mother, with significantly lower birthweight neonates born to primigravidae compared to secundigravidae (p = 0.001) and multigravidae (p = 0.003). Even in holo-endemic dry season, there exists a large proportion of pregnant women with very low density parasitaemia. IPTp-SP seems to be relevant in controlling submicroscopic P. falciparum infections, which remains common in pregnant women, and are hard to diagnose, with potentially deleterious consequences for maternal and fetal health. Future studies should be carried out in hyperendemic malaria foci where the parasitemia levels are substantially higher in order to confirm the efficacy of IPTp-SP

EditorialThe role of universities in research for sustainable development

No Abstract. Journal of the Cameroon Academy of Sciences Vol. 5(1) 2005: iii-

Antibacterial effects of some Cameroonian medicinal plants against common pathogenic bacteria

We screened forty crude extracts of twenty Cameroonian medicinal plants commonly used to treat bacterial infections for broad spectrum antibacterial activity, as a more affordable alternative against resistant organisms. The extracts were screened on common pathogenic gram negative and gram positive bacteria initially by the disc diffusion method followed by the tube dilution method. Using discs containing 30µg of extract, Escherichia coli showed sensitivity to 23 extracts with diameter of zone of inhibition ranging from 7 – 19mm, fifteen of which were up to or > 10mm. Pseudomonas aeruginosa was sensitive to 11 extracts, whereas Salmonella typhimurium and Staphylococcus aureus were not sensitive to any of the extracts. Based on the zones of inhibition the activity of the extracts were equivalent to 30 to 138 % efficacy of the standard antibiotic discs. The lowest Minimum Inhibitory Concentration (MIC) recorded was 2 mg/ml for Euphorbia hirta against S. aureus and P. aeruginosa and the lowest Minimum Bactericidal Concentration (MBC) was 6 mg/ml for six extracts from Ageratum conyzoides, Aframomum citratum, Euphorbia hirta, Momordica charantia, Mangifera indica and Khaya senegalensis against three bacterial species. Three extracts had broad spectrum bacteriostatic activity (MICs &#8804; 4 mg/ml) while in terms of MBCs none of the extracts showed broad spectrum bactericidal activity. We conclude that most of the tested plants used as traditional antibacterials have a bacteriostatic effect on gram-negative pathogenic bacteria. Keywords: plant extracts, broad spectrum, bacteriostatic, bactericidal African Journal of Traditional, Complementary and Alternative Medicines Vol. 3(2) 2006: 84-9

<it>Hypericum lanceolatum </it>(Hypericaceae) as a potential source of new anti-malarial agents: a bioassay-guided fractionation of the stem bark

Abstract Background Malaria is a major public health threat in Africa, and traditional medicine continues to play a key role in its control especially in rural areas. A bioassay-guided fractionation was carried out in order to evaluate the anti-malarial potential and the safety of the methanol extract of the Hypericum lanceolatum stem bark. Methods The anti-plasmodial activity was assayed by the lactate dehydrogenase method (pLDH) against the multidrug-resistant W2mef laboratory strain, and a field isolate (SHF4) of Plasmodium falciparum. Cytotoxicity tests were carried out using the LLC-MK2 monkey kidney epithelial cells. Results Five compounds were isolated from the most active and least cytotoxic ethylacetate sub-extract: betulinic acid (HLT1), 2,2',5,6'-tetrahydroxybenzophenone (HLT2), 5-hydroxy-3-methoxyxanthone (HLT3), 3-hydroxy-5-methoxyxanthone (HLT4) and HLT0 (yet to be identified). Three of the tested compounds presented significant anti-plasmodial activities (with 50% inhibitory concentration, IC50 50 of 25 μg/mL. Conclusions These findings justify the use of H. lanceolatum stem bark as anti-malarial by traditional healers of Western Cameroon, and could constitute a good basis for further studies towards development of new drug candidates or phytomedicines for malaria.</p