A Multidisciplinary Investigation of the First Chikungunya Virus Outbreak in Matadi in the Democratic Republic of the Congo.

Early March 2019, health authorities of Matadi in the Democratic Republic of the Congo alerted a sudden increase in acute fever/arthralgia cases, prompting an outbreak investigation. We collected surveillance data, clinical data, and laboratory specimens from clinical suspects (for CHIKV-PCR/ELISA, malaria RDT), semi-structured interviews with patients/caregivers about perceptions and health seeking behavior, and mosquito sampling (adult/larvae) for CHIKV-PCR and estimation of infestation levels. The investigations confirmed a large CHIKV outbreak that lasted February-June 2019. The total caseload remained unknown due to a lack of systematic surveillance, but one of the two health zones of Matadi notified 2686 suspects. Of the clinical suspects we investigated (n = 220), 83.2% were CHIKV-PCR or IgM positive (acute infection). One patient had an isolated IgG-positive result (while PCR/IgM negative), suggestive of past infection. In total, 15% had acute CHIKV and malaria. Most adult mosquitoes and larvae (>95%) were Aedes albopictus. High infestation levels were noted. CHIKV was detected in 6/11 adult mosquito pools, and in 2/15 of the larvae pools. This latter and the fact that 2/6 of the CHIKV-positive adult pools contained only males suggests transovarial transmission. Interviews revealed that healthcare seeking shifted quickly toward the informal sector and self-medication. Caregivers reported difficulties to differentiate CHIKV, malaria, and other infectious diseases resulting in polypharmacy and high out-of-pocket expenditure. We confirmed a first major CHIKV outbreak in Matadi, with main vector Aedes albopictus. The health sector was ill-prepared for the information, surveillance, and treatment needs for such an explosive outbreak in a CHIKV-naïve population. Better surveillance systems (national level/sentinel sites) and point-of-care diagnostics for arboviruses are needed.

Molecular characterization of chikungunya virus during the 2019 outbreak in the Democratic Republic of the Congo.

Early 2019, a chikungunya virus (CHIKV) outbreak hit the Democratic Republic of the Congo (DRC). Though seldomly deadly, this mosquito-borne disease presents as an acute febrile (poly)arthralgia often followed by long-term sequelae. Although Aedes aegypti is the primary vector, an amino acid substitution in the viral envelope gene E1 (A226V) is causing concern as it results in increased transmission by Aedes albopictus, a mosquito with a much wider geographical distribution. Between January and March 2019, we collected human and mosquito samples in Kinshasa and Kongo Central province (Kasangulu and Matadi). Of the patients that were tested within 7 days of symptom onset, 49.7% (87/175) were RT-qPCR positive, while in the mosquito samples CHIKV was found in 1/2 pools in Kinshasa, 5/6 pools in Kasangulu, and 8/26 pools in Matadi. Phylogenetic analysis on whole-genome sequences showed that the circulating strain formed a monophyletic group within the ECSA2 lineage and harboured the A226V mutation. Our sequences did not cluster with sequences from previously reported outbreaks in the DRC nor with other known A226V-containing ECSA2 strains. This indicates a scenario of convergent evolution where A226V was acquired independently in response to a similar selection pressure for transmission by Ae. albopictus. This is in line with our entomological data where we detected Ae. albopictus more frequently than Ae. aegypti in two out of three affected areas. In conclusion, our findings suggest that CHIKV is adapting to the increased presence of Aedes albopictus in DRC.

Role of Wildlife in Emergence of Ebola Virus in Kaigbono (Likati), Democratic Republic of the Congo, 2017.

After the 2017 Ebola virus (EBOV) outbreak in Likati, a district in northern Democratic Republic of the Congo, we sampled small mammals from the location where the primary case-patient presumably acquired the infection. None tested positive for EBOV RNA or antibodies against EBOV, highlighting the ongoing challenge in detecting animal reservoirs for EBOV.

Detection of Zika Virus Replication in Human Semen by Reverse-Transcription Polymerase Chain Reaction Targeting of Antisense Ribonucleic Acid.

BACKGROUND: Persistence of Zika virus (ZIKV) ribonucleic acid (RNA) in semen is common after infection. METHODS: We designed a reverse-transcription polymerase chain reaction assay that targets antisense ZIKV RNA (asRNA) to assess ZIKV replication competence in ZIKV RNA-positive semen samples. RESULTS: We detected ZIKV asRNA in semen of 9 of 19 men (47.4%) diagnosed with ZIKV infection. All asRNA-positive samples had high ZIKV loads (cycle threshold values <26) and were obtained within 21 days of symptom onset. CONCLUSIONS: The sensitivity of the asRNA assay for detection of ZIKV replication was higher than that of conventional virus isolation methods (47.4% vs 21.1%, P = .032).

Dengue and chikungunya among outpatients with acute undifferentiated fever in Kinshasa, Democratic Republic of Congo: A cross-sectional study.

BACKGROUND: Pathogens causing acute fever, with the exception of malaria, remain largely unidentified in sub-Saharan Africa, given the local unavailability of diagnostic tests and the broad differential diagnosis. METHODOLOGY: We conducted a cross-sectional study including outpatient acute undifferentiated fever in both children and adults, between November 2015 and June 2016 in Kinshasa, Democratic Republic of Congo. Serological and molecular diagnostic tests for selected arboviral infections were performed on blood, including PCR, NS1-RDT, ELISA and IFA for acute, and ELISA and IFA for past infections. RESULTS: Investigation among 342 patients, aged 2 to 68 years (mean age of 21 years), with acute undifferentiated fever (having no clear focus of infection) revealed 19 (8.1%) acute dengue-caused by DENV-1 and/or DENV-2 -and 2 (0.9%) acute chikungunya infections. Furthermore, 30.2% and 26.4% of participants had been infected in the past with dengue and chikungunya, respectively. We found no evidence of acute Zika nor yellow fever virus infections. 45.3% of patients tested positive on malaria Rapid Diagnostic Test, 87.7% received antimalarial treatment and 64.3% received antibacterial treatment. DISCUSSION: Chikungunya outbreaks have been reported in the study area in the past, so the high seroprevalence is not surprising. However, scarce evidence exists on dengue transmission in Kinshasa and based on our data, circulation is more important than previously reported. Furthermore, our study shows that the prescription of antibiotics, both antibacterial and antimalarial drugs, is rampant. Studies like this one, elucidating the causes of acute fever, may lead to a more considerate and rigorous use of antibiotics. This will not only stem the ever-increasing problem of antimicrobial resistance, but will-ultimately and hopefully-improve the clinical care of outpatients in low-resource settings. TRIAL REGISTRATION: ClinicalTrials.gov NCT02656862.

Slow growth of Burkholderia pseudomallei compared to other pathogens in an adapted blood culture system in Phnom Penh, Cambodia.

PURPOSE: Burkholderia pseudomallei is a key pathogen causing bloodstream infections at Sihanouk Hospital Center of Hope, Phnom Penh, Cambodia. Here, visual instead of automated detection of growth of commercial blood culture bottles is done. The present study assessed the performance of this system. METHODOLOGY: Blood culture sets, consisting of paired adult aerobic and anaerobic bottles (bioMérieux, FA FAN 259791 and FN FAN 252793) were incubated in a standard incubator for 7 days after reception. Each day, the bottle growth indicator was visually inspected for colour change indicating growth. Blind subculture was performed from the aerobic bottle at day 3. RESULTS: From 2010 to 2015, 11  671 sets representing 10  389 suspected bloodstream infection episodes were documented. In 1058 (10.2  %) episodes, pathogens grew; they comprised Escherichia coli (31.7 %), Salmonella Paratyphi A (13.9 %), B. pseudomallei (8.5 %), Staphylococcus aureus (7.8 %) and Klebsiella pneumoniae (7.0 %). Blind subculture yielded 72 (4.1  %) pathogens, mostly (55/72, 76.4 %) B. pseudomallei. Cumulative proportions of growth at day 2 were as follows: E. coli: 85.0 %, Salmonella Paratyphi A: 85.0 %, K. pneumoniae: 76.3  % and S. aureus: 52.2  %; for B. pseudomallei, this was only 4.0  %, which increased to 70.1  % (70/99) at day 4 mainly by detection on blind subculture (55/99). Compared to the anaerobic bottles, aerobic bottles had a higher yield and a shorter time-to-detection, particularly for B. pseudomallei. CONCLUSIONS: Visual inspection for growth of commercial blood culture bottles in a low-resource setting provided satisfactory yield and time-to-detection. However, B. pseudomallei grew slowly and was mainly detected by blind subculture. The aerobic bottle outperformed the anaerobic bottle.

Zika virus in semen: a prospective cohort study of symptomatic travellers returning to Belgium.

OBJECTIVE: To prospectively monitor Zika viral loads in semen from Belgian travellers with confirmed Zika virus infection, who returned from the Americas during the 2016 Zika virus epidemic. METHODS: We recruited symptomatic travellers consulting our clinic and we confirmed infection with either reverse-transcriptase (RT) polymerase chain reaction (PCR) assay or virus neutralization test. The participants produced semen samples weekly, either at the clinic or at home. For the initial sample, the laboratory staff did a microscopy analysis if they received the sample within an hour of production. Using RT-PCR, we monitored Zika virus ribonucleic acid (RNA) loads in semen until we obtained two negative results. FINDINGS: We detected Zika virus RNA in nine of 15 participants' semen, one of whom was vasectomized. The median time to loss of RNA detection in semen was 83 days after symptom onset (95% confidence interval, CI: 57-108). The longest duration of viral shedding in semen before obtaining the first negative RT-PCR result was 144 days after symptom onset. All of the 11 participants, for whom we microscopically analysed their semen, had presence of leukocytes, 10 showed haematospermia and six showed oligospermia. These abnormalities occurred irrespective of Zika virus detection in semen. CONCLUSION: The majority of men in our study had detectable Zika virus RNA in their semen. We recommend that semen from Zika virus-infected men should be analysed with RT-PCR and that health professionals should advise infected men, even if they are vasectomized, about current recommendations for prevention of sexual transmission of the virus.

Comparative Genomics of Burkholderia singularis sp. nov., a Low G+C Content, Free-Living Bacterium That Defies Taxonomic Dissection of the Genus Burkholderia.

Four Burkholderia pseudomallei-like isolates of human clinical origin were examined by a polyphasic taxonomic approach that included comparative whole genome analyses. The results demonstrated that these isolates represent a rare and unusual, novel Burkholderia species for which we propose the name B. singularis. The type strain is LMG 28154T (=CCUG 65685T). Its genome sequence has an average mol% G+C content of 64.34%, which is considerably lower than that of other Burkholderia species. The reduced G+C content of strain LMG 28154T was characterized by a genome wide AT bias that was not due to reduced GC-biased gene conversion or reductive genome evolution, but might have been caused by an altered DNA base excision repair pathway. B. singularis can be differentiated from other Burkholderia species by multilocus sequence analysis, MALDI-TOF mass spectrometry and a distinctive biochemical profile that includes the absence of nitrate reduction, a mucoid appearance on Columbia sheep blood agar, and a slowly positive oxidase reaction. Comparisons with publicly available whole genome sequences demonstrated that strain TSV85, an Australian water isolate, also represents the same species and therefore, to date, B. singularis has been recovered from human or environmental samples on three continents.

Global and regional dissemination and evolution of Burkholderia pseudomallei.

The environmental bacterium Burkholderia pseudomallei causes an estimated 165,000 cases of human melioidosis per year worldwide and is also classified as a biothreat agent. We used whole genome sequences of 469 B. pseudomallei isolates from 30 countries collected over 79 years to explore its geographic transmission. Our data point to Australia as an early reservoir, with transmission to Southeast Asia followed by onward transmission to South Asia and East Asia. Repeated reintroductions were observed within the Malay Peninsula and between countries bordered by the Mekong River. Our data support an African origin of the Central and South American isolates with introduction of B. pseudomallei into the Americas between 1650 and 1850, providing a temporal link with the slave trade. We also identified geographically distinct genes/variants in Australasian or Southeast Asian isolates alone, with virulence-associated genes being among those over-represented. This provides a potential explanation for clinical manifestations of melioidosis that are geographically restricted.

Development, Evaluation, and Integration of a Quantitative Reverse-Transcription Polymerase Chain Reaction Diagnostic Test for Ebola Virus on a Molecular Diagnostics Platform.

BACKGROUND: The 2013-2016 Ebola epidemic in West Africa resulted in accelerated development of rapid diagnostic tests for emergency outbreak preparedness. We describe the development and evaluation of the Idylla™ prototype Ebola virus test, a fully automated sample-to-result molecular diagnostic test for rapid detection of Zaire ebolavirus (EBOV) and Sudan ebolavirus (SUDV). METHODS: The Idylla™ prototype Ebola virus test can simultaneously detect EBOV and SUDV in 200 µL of whole blood. The sample is directly added to a disposable cartridge containing all reagents for sample preparation, RNA extraction, and amplification by reverse-transcription polymerase chain reaction analysis. The performance was evaluated with a variety of sample types, including synthetic constructs and whole blood samples from healthy volunteers spiked with viral RNA, inactivated virus, and infectious virus. RESULTS: The 95% limits of detection for EBOV and SUDV were 465 plaque-forming units (PFU)/mL (1010 copies/mL) and 324 PFU/mL (8204 copies/mL), respectively. In silico and in vitro analyses demonstrated 100% correct reactivity for EBOV and SUDV and no cross-reactivity with relevant pathogens. The diagnostic sensitivity was 97.4% (for EBOV) and 91.7% (for SUDV), the specificity was 100%, and the diagnostic accuracy was 95.9%. CONCLUSIONS: The Idylla™ prototype Ebola virus test is a fast, safe, easy-to-use, and near-patient test that meets the performance criteria to detect EBOV in patients with suspected Ebola.

Phylogenomic Analysis Reveals an Asian Origin for African Burkholderia pseudomallei and Further Supports Melioidosis Endemicity in Africa.

Burkholderia pseudomallei, an environmental bacterium that causes the deadly disease melioidosis, is endemic in northern Australia and Southeast Asia. An increasing number of melioidosis cases are being reported in other tropical regions, including Africa and the Indian Ocean islands. B. pseudomallei first emerged in Australia, with subsequent rare dissemination event(s) to Southeast Asia; however, its dispersal to other regions is not yet well understood. We used large-scale comparative genomics to investigate the origins of three B. pseudomallei isolates from Madagascar and two from Burkina Faso. Phylogenomic reconstruction demonstrates that these African B. pseudomallei isolates group into a single novel clade that resides within the more ancestral Asian clade. Intriguingly, South American strains reside within the African clade, suggesting more recent dissemination from West Africa to the Americas. Anthropogenic factors likely assisted in B. pseudomallei dissemination to Africa, possibly during migration of the Austronesian peoples from Indonesian Borneo to Madagascar ~2,000 years ago, with subsequent genetic diversity driven by mutation and recombination. Our study provides new insights into global patterns of B. pseudomallei dissemination and adds to the growing body of evidence of melioidosis endemicity in Africa. Our findings have important implications for melioidosis diagnosis and management in Africa. IMPORTANCE Sporadic melioidosis cases have been reported in the African mainland and Indian Ocean islands, but until recently, these regions were not considered areas where B. pseudomallei is endemic. Given the high mortality rate of melioidosis, it is crucial that this disease be recognized and suspected in all regions of endemicity. Previous work has shown that B. pseudomallei originated in Australia, with subsequent introduction into Asia; however, the precise origin of B. pseudomallei in other tropical regions remains poorly understood. Using whole-genome sequencing, we characterized B. pseudomallei isolates from Madagascar and Burkina Faso. Next, we compared these strains to a global collection of B. pseudomallei isolates to identify their evolutionary origins. We found that African B. pseudomallei strains likely originated from Asia and were closely related to South American strains, reflecting a relatively recent shared evolutionary history. We also identified substantial genetic diversity among African strains, suggesting long-term B. pseudomallei endemicity in this region.

Confirmed Zika virus infection in a Belgian traveler returning from Guatemala, and the diagnostic challenges of imported cases into Europe.

We report the first laboratory-confirmed Zika virus (ZIKV) infection in a Belgian traveler after a three week holiday in Guatemala, December 2015. This case along with other imported cases into Europe emphases once again the need for accurate diagnostic tools for this rapidly emerging virus. The challenge is to diagnose patients in the acute phase, which appears short, as serological testing is complicated by cross-reactivity, vaccination status and scarce availability of specific ZIKV tests.

Burkholderia stagnalis sp. nov. and Burkholderia territorii sp. nov., two novel Burkholderia cepacia complex species from environmental and human sources.

Nine Burkholderia cepacia complex (Bcc) bacteria were isolated during environmental surveys for the ecological niche of Burkholderia pseudomallei, the aetiological agent of melioidosis, in the Northern Territory of Australia. They represented two multi-locus sequence analysis-based clusters, referred to as Bcc B and Bcc L. Three additional environmental and clinical Bcc B isolates were identified upon deposition of the sequences in the PubMLST database. Analysis of the concatenated nucleotide sequence divergence levels within both groups (1.4 and 1.9%, respectively) and towards established Bcc species (4.0 and 3.9%, respectively) demonstrated that the two taxa represented novel Bcc species. All 12 isolates were further characterized using 16S rRNA and recA gene sequence analysis, RAPD analysis, DNA base content determination, fatty acid methyl ester analysis and biochemical profiling. Analysis of recA gene sequences revealed a remarkable diversity within each of these taxa, but, together, the results supported the affiliation of the two taxa to the Bcc. Bcc B strains can be differentiated from most other Bcc members by the assimilation of maltose. Bcc L strains can be differentiated from other Bcc members by the absence of assimilation of N-acetylglucosamine. The names Burkholderia stagnalis sp. nov. with type strain LMG 28156(T) ( = CCUG 65686(T)) and Burkholderia territorii sp. nov. with type strain LMG 28158(T) ( = CCUG 65687(T)) are proposed for Bcc B and Bcc L bacteria, respectively.

Whole-genome sequencing confirms that Burkholderia pseudomallei multilocus sequence types common to both Cambodia and Australia are due to homoplasy.

Burkholderia pseudomallei isolates with shared multilocus sequence types (STs) have not been isolated from different continents. We identified two STs shared between Australia and Cambodia. Whole-genome analysis revealed substantial diversity within STs, correctly identified the Asian or Australian origin, and confirmed that these shared STs were due to homoplasy.

Bloodstream infection among adults in Phnom Penh, Cambodia: key pathogens and resistance patterns.

BACKGROUND: Bloodstream infections (BSI) cause important morbidity and mortality worldwide. In Cambodia, no surveillance data on BSI are available so far. METHODS: From all adults presenting with SIRS at Sihanouk Hospital Centre of HOPE (July 2007-December 2010), 20 ml blood was cultured. Isolates were identified using standard microbiological techniques; antibiotic susceptibilities were assessed using disk diffusion and MicroScan®, with additional E-test, D-test and double disk test where applicable, according to CLSI guidelines. RESULTS: A total of 5714 samples from 4833 adult patients yielded 501 clinically significant organisms (8.8%) of which 445 available for further analysis. The patients' median age was 45 years (range 15-99 y), 52.7% were women. HIV-infection and diabetes were present in 15.6% and 8.8% of patients respectively. The overall mortality was 22.5%. Key pathogens included Escherichia coli (n = 132; 29.7%), Salmonella spp. (n = 64; 14.4%), Burkholderia pseudomallei (n = 56; 12.6%) and Staphylococcus aureus (n = 53; 11.9%). Methicillin resistance was seen in 10/46 (21.7%) S. aureus; 4 of them were co-resistant to erythromycin, clindamycin, moxifloxacin and sulphamethoxazole-trimethoprim (SMX-TMP). We noted combined resistance to amoxicillin, SMX-TMP and ciprofloxacin in 81 E. coli isolates (62.3%); 62 isolates (47.7%) were confirmed as producers of extended spectrum beta-lactamase. Salmonella isolates displayed high rates of multidrug resistance (71.2%) with high rates of decreased ciprofloxacin susceptibility (90.0%) in Salmonella Typhi while carbapenem resistance was observed in 5.0% of 20 Acinetobacter sp. isolates. CONCLUSIONS: BSI in Cambodian adults is mainly caused by difficult-to-treat pathogens. These data urge for microbiological capacity building, nationwide surveillance and solid interventions to contain antibiotic resistance.

Does HIV status affect the aetiology, bacterial resistance patterns and recommended empiric antibiotic treatment in adult patients with bloodstream infection in Cambodia?

OBJECTIVE: The microbiologic causes of bloodstream infections (BSI) may differ between HIV-positive and HIV-negative patients and direct initial empiric antibiotic treatment (i.e. treatment before culture results are available). We retrospectively assessed community-acquired BSI episodes in adults in Cambodia according to HIV status for spectrum of bacterial pathogens, antibiotic resistance patterns and appropriateness of empiric antibiotics. METHODS: Blood cultures were systematically performed in patients suspected of BSI in a referral hospital in Phnom Penh, Cambodia. Data were collected between 1 January 2009 and 31 December 2011. RESULTS: A total of 452 culture-confirmed episodes of BSI were recorded in 435 patients, of whom 17.9% and 82.1% were HIV-positive and HIV-negative, respectively. Escherichia coli accounted for one-third (n = 155, 32.9%) of 471 organisms, with similar rates in both patient groups. Staphylococcus aureus and Salmonella cholereasuis were more frequent in HIV-positive vs. HIV-negative patients (17/88 vs. 38/383 (P = 0.02) and 10/88 vs. 5/383 (P < 0.001)). Burkholderia pseudomallei was more common in HIV-negative than in HIV-positive patients (39/383 vs. 2/88, P < 0.001). High resistance rates among commonly used antibiotics were observed, including 46.6% ceftriaxone resistance among E. coli isolates. Empiric antibiotic treatments were similarly appropriate in both patient groups but did not cover antibiotic-resistant E. coli (both patient groups), S. aureus (both groups) and B. pseudomallei (HIV-negative patients). CONCLUSION: The present data do not warrant different empiric antibiotic regimens for HIV-positive vs. HIV-negative patients in Cambodia. The overall resistance rates compromise the appropriateness of the current treatment guidelines.

Azithromycin and ciprofloxacin resistance in Salmonella bloodstream infections in Cambodian adults.

BACKGROUND: Salmonella enterica is a frequent cause of bloodstream infection (BSI) in Asia but few data are available from Cambodia. We describe Salmonella BSI isolates recovered from patients presenting at Sihanouk Hospital Centre of Hope, Phnom Penh, Cambodia (July 2007-December 2010). METHODOLOGY: Blood was cultured as part of a microbiological prospective surveillance study. Identification of Salmonella isolates was performed by conventional methods and serotyping. Antibiotic susceptibilities were assessed using disk diffusion, MicroScan and E-test macromethod. Clonal relationships were assessed by Pulsed Field Gel Electrophoresis; PCR and sequencing for detection of mutations in Gyrase and Topoisomerase IV and presence of qnr genes. PRINCIPAL FINDINGS: Seventy-two Salmonella isolates grew from 58 patients (mean age 34.2 years, range 8-71). Twenty isolates were identified as Salmonella Typhi, 2 as Salmonella Paratyphi A, 37 as Salmonella Choleraesuis and 13 as other non-typhoid Salmonella spp. Infection with human immunodeficiency virus (HIV) was present in 21 of 24 (87.5%) patients with S. Choleraesuis BSI. Five patients (8.7%) had at least one recurrent infection, all with S. Choleraesuis; five patients died. Overall, multi drug resistance (i.e., co-resistance to ampicillin, sulphamethoxazole-trimethoprim and chloramphenicol) was high (42/59 isolates, 71.2%). S. Typhi displayed high rates of decreased ciprofloxacin susceptibility (18/20 isolates, 90.0%), while azithromycin resistance was very common in S. Choleraesuis (17/24 isolates, 70.8%). Two S. Choleraesuis isolates were extended spectrum beta-lactamase producer. CONCLUSIONS AND SIGNIFICANCE: Resistance rates in Salmonella spp. in Cambodia are alarming, in particular for azithromycin and ciprofloxacin. This warrants nationwide surveillance and revision of treatment guidelines.

Melioidosis, phnom penh, Cambodia.

We describe 58 adult patients with melioidosis in Cambodia (2007-2010). Diabetes was the main risk factor (59%); 67% of infections occurred during the rainy season. Bloodstream infection was present in 67% of patients, which represents 12% of all bloodstream infections. The case-fatality rate was 52% and associated with inappropriate empiric treatment.