Detection of Plasmodium falciparum DNA in saliva samples stored at room temperature: potential for a non-invasive saliva-based diagnostic test for malaria.

BACKGROUND: Current malaria diagnostic methods require blood collection, that may be associated with pain and the risk of transmitting blood-borne pathogens, and often create poor compliance when repeated sampling is needed. On the other hand, the collection of saliva is minimally invasive; but saliva has not been widely used for the diagnosis of malaria. The aim of this study was to evaluate the diagnostic performance of saliva collected and stored at room temperature using the OMNIgene®â€¢ORAL kit for diagnosing Plasmodium falciparum malaria. METHODS: Paired blood and saliva samples were collected from 222 febrile patients in Cameroon. Saliva samples were collected using the OMNIgene®â€¢ORAL (OM-501) kit and stored at room temperature for up to 13 months. Thick blood film microscopy (TFM) was used to detect P. falciparum blood-stage parasites in blood. Detection of P. falciparum DNA in blood and saliva was based on amplification of the multi-copy 18 s rRNA gene using the nested-polymerase chain reaction (nPCR). RESULTS: Prevalence of malaria detected by TFM, nPCR-saliva and nPCR-blood was 22, 29, and 35%, respectively. Using TFM as the gold standard, the sensitivity of nPCR-saliva and nPCR-blood in detecting P. falciparum was 95 and 100%, respectively; with corresponding specificities of 93 and 87%. When nPCR-blood was used as gold standard, the sensitivity of nPCR-saliva and microscopy was 82 and 68%, respectively; whereas, the specificity was 99 and 100%, respectively. Nested PCR-saliva had a very good agreement with both TFM (kappa value 0.8) and blood PCR (kappa value 0.8). At parasitaemia > 10,000 parasites/µl of blood, the sensitivity of nPCR-saliva was 100%. Nested PCR-saliva detected 16 sub-microscopic malaria infections. One year after sample collection, P. falciparum DNA was detected in 80% of saliva samples stored at room temperature. CONCLUSIONS: Saliva can potentially be used as an alternative non-invasive sample for the diagnosis of malaria and the OMNIgene®â€¢ORAL kit is effective at transporting and preserving malaria parasite DNA in saliva at room temperature. The technology described in this study for diagnosis of malaria in resource-limited countries adds on to the armamentarium needed for elimination of malaria.

COVID-19 Preventive Behaviours in Cameroon: A Six-Month Online National Survey.

Since March 2020, the Cameroonian government implemented nationwide measures to stall COVID-19 transmission. However, little is known about how well these unprecedented measures are being observed as the pandemic evolves. We conducted a six-month online survey to assess the preventive behaviour of Cameroonian adults during the COVID-19 outbreak. A five-point adherence score was constructed based on self-reported observance of the following preventive measures: physical distancing, face mask use, hand hygiene, not touching one's face, and covering the mouth when coughing or sneezing. Predictors of adherence were investigated using ordinal logistic regression models. Of the 7381 responses received from all ten regions, 73.3% were from male respondents and overall mean age was 32.8 ± 10.8 years. Overall mean adherence score was 3.96 ± 1.11 on a scale of 0-5. Mean weekly adherence scores were initially high, but gradually decreased over time accompanied by increasing incidence of COVID-19 during the last study weeks. Predictors for higher adherence included higher age, receiving COVID-19 information from health personnel, and agreeing with the necessity of lockdown measures. Meanwhile, experiencing flu-like symptoms was associated with poor adherence. Continuous observance of preventive measures should be encouraged among Cameroonians in the medium- to long-term to avoid a resurgence in COVID-19 infections.

Pyrethroid resistance in Anopheles gambiae from the rubber cultivated area of Niete, South Region of Cameroon.

Anti-vector intervention remains the most effective way of controlling malaria. Although in Cameroon and elsewhere focus is on the use of long-lasting insecticidal nets and indoor residual spraying, the efficacy of both methods greatly depends on the continuing susceptibility of the vectors to the insecticides used. The emergence and spread of insecticide resistance in the major malaria vectors constitute a huge challenge to control programmes. Consequently, routine monitoring and evaluation of vector resistance status to insecticides are mandatory for early detection of resistance should it arise, and effectively planning future anti-vector interventions especially in areas reputed for routine application in agriculture. The WHO bioassay kit was used to determine the susceptibility status of Anopheles gambiae s.l. populations to seven insecticides belonging to four classes (organochlorine, organophosphate, carbamate and pyrethroids) in Niete, an area of intense rubber cultivation in southern forested Cameroon. Species and molecular forms of An. gambiae s.l. as well as the presence of knock down resistance (kdr) mutations were determined using polymerase chain reaction (PCR) techniques. All Anopheles tested was identified as An. gambiae s.s. and of the M molecular form. Based on WHO classification, while the mosquitoes were fully (100%) susceptible to malathion and bendiocarb, resistance was confirmed to DDT and the pyrethroids, permethrin and lambda-cyhalothrin. The other pyrethroids (deltamethrin and cyfluthrin) showed signs of developing resistance. Resistance to DDT and pyrethroids is indicative of existing cross resistance mechanisms between these insecticides. The increase in knockdown times was greater than twofold that of the reference susceptible strain, suggesting the possible involvement of kdr mutations, also confirmed in this study. The findings highlight the need for constant evaluation, re-evaluation and monitoring of the insecticides for malaria vector control in Cameroon. However, bendiocarb and malathion can be used and may require alternation or combination with insecticides of other classes to better manage the occurrence and spread of resistance in Niete.