Filarial Antigenemia and Loa loa Night Blood Microfilaremia in an Area Without Bancroftian Filariasis in the Democratic Republic of Congo

Bakajika, Didier; Nigo, Maurice M; Lotsima, Jean Pierre; Masikini, Germain A.; Fischer, Kerstin; Lloyd, Melanie M.; Weil, Gary J.; Fischer, Peter U.

doi:10.4269/ajtmh.14-0358

Cited by 53 publications

(55 citation statements)

References 21 publications

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“…Higher prevalences using ICT compared to Og4C3 ELISA was also observed in Togo during a school-based TAS conducted 3 years after stopping MDA [14], although the reasons for this are unclear. Loa loa microfilaraemia has been shown to be associated with ICT-positivity at both the community and individual levels [15, 16]; however, the same studies showed no association between ICT-positivity and the prevalence of M. perstans , the only other filarial parasite endemic in the study area [17]. …”

Section: Discussionmentioning

confidence: 99%

Dynamics of antigenemia and transmission intensity of Wuchereria bancrofti following cessation of mass drug administration in a formerly highly endemic region of Mali

Coulibaly

Dolo

et al. 2016

Parasites Vectors

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BackgroundAfter seven annual rounds of mass drug administration (MDA) in six Malian villages highly endemic for Wuchereria bancrofti (overall prevalence rate of 42.7%), treatment was discontinued in 2008. Surveillance was performed over the ensuing 5 years to detect recrudescence.MethodsCirculating filarial antigen (CFA) was measured using immunochromatographic card tests (ICT) and Og4C3 ELISA in 6–7 year-olds. Antibody to the W. bancrofti infective larval stage (L3) antigen, Wb123, was tested in the same population in 2012. Microfilaraemia was assessed in ICT-positive subjects. Anopheles gambiae complex specimens were collected monthly using human landing catch (HLC) and pyrethrum spray catch (PSC). Anopheles gambiae complex infection with W. bancrofti was determined by dissection and reverse transcriptase polymerase chain reaction (RT-PCR) of mosquito pools.ResultsAnnual CFA prevalence rates using ICT in children increased over time from 0% (0/289) in 2009 to 2.7% (8/301) in 2011, 3.9% (11/285) in 2012 and 4.5% (14/309) in 2013 (trend χ 2 = 11.85, df =3, P = 0.0006). Wb123 antibody positivity rates in 2013 were similar to the CFA prevalence by ELISA (5/285). Although two W. bancrofti-infected Anopheles were observed by dissection among 12,951 mosquitoes collected by HLC, none had L3 larvae when tested by L3-specific RT-PCR. No positive pools were detected among the mosquitoes collected by pyrethrum spray catch. Whereas ICT in 6–7 year-olds was the major surveillance tool, ICT positivity was also assessed in older children and adults (8–65 years old). CFA prevalence decreased in this group from 4.9% (39/800) to 3.5% (28/795) and 2.8% (50/1,812) in 2009, 2011 and 2012, respectively (trend χ 2 = 7.361, df =2, P = 0.0067). Some ICT-positive individuals were microfilaraemic in 2009 [2.6% (1/39)] and 2011 [8.3% (3/36)], but none were positive in 2012 or 2013.ConclusionAlthough ICT rates in children increased over the 5-year surveillance period, the decrease in ICT prevalence in the older group suggests a reduction in transmission intensity. This was consistent with the failure to detect infective mosquitoes or microfilaraemia. The threshold of ICT positivity in children may need to be re-assessed and other adjunct surveillance tools considered.

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Section: Discussionmentioning

confidence: 99%

Dynamics of antigenemia and transmission intensity of Wuchereria bancrofti following cessation of mass drug administration in a formerly highly endemic region of Mali

Coulibaly

Dolo

et al. 2016

Parasites Vectors

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“…Furthermore, the presence of CFA is not always corroborated by W. bancrofti microfilaremia 3. Moreover, there have been several instances in which CFA positivity has been associated with Loa loa microfilaremia 4–6. In a study conducted in Orientale Province in eastern Democratic Republic of Congo, an association between L. loa microfilarial density assessed at night (between 9:00 pm and 1:00 am ) and ICT positivity was observed,4 although there was no attempt to demonstrate a quantitative relationship between L. loa microfilaremia (during the day) and ICT positivity.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, there have been several instances in which CFA positivity has been associated with Loa loa microfilaremia 4–6. In a study conducted in Orientale Province in eastern Democratic Republic of Congo, an association between L. loa microfilarial density assessed at night (between 9:00 pm and 1:00 am ) and ICT positivity was observed,4 although there was no attempt to demonstrate a quantitative relationship between L. loa microfilaremia (during the day) and ICT positivity. In addition, quantitative polymerase chain reaction (qPCR) on dried night blood retrieved from stained smears or ICT card application pads confirmed the presence of L. loa and the absence of W. bancrofti DNA 4…”

Section: Introductionmentioning

confidence: 99%

Positivity of Antigen Tests Used for Diagnosis of Lymphatic Filariasis in Individuals Without Wuchereria bancrofti Infection But with High Loa loa Microfilaremia

Pion

Montavon

Chesnais

et al. 2016

The American Journal of Tropical Medicine and Hygiene

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Since the mid-2000s, the immunochromatographic card test (ICT), a point-of-care test for detecting Wuchereria bancrofti circulating filarial antigens (CFAs), has been the backbone for mapping and monitoring lymphatic filariasis (LF) worldwide. Recently, there have been instances in which CFA positivity has been associated with Loa loa microfilaremia. Here, we examined the association, at both the community and individual levels, between L. loa and CFA using additional diagnostic tools (quantitative polymerase chain reaction [qPCR], Og4C3 enzyme-linked immunosorbent assay, and IgG4 antibodies to Wb123 assays) to demonstrate the relationship between L. loa microfilaremia and ICT positivity. In May 2013, peripheral blood was collected during the day from 1,812 individuals living in southern Cameroon. ICT tests were done on the spot, and positive individuals were resampled at night. Results of qPCR and Wb123 assays concurred proving the absence of W. bancrofti infection. Og4C3 assays indicate a quantitative relationship between the level of L. loa microfilaremia and that of CFA. This was confirmed by epidemiological analyses, which reveal a strong association between L. loa microfilaremia and ICT positivity, with 50% of ICT reacting to L. loa when its microfilarial density exceeds 30,000 microfilariae/mL. At the community level, the proportion of positive ICT would exceed 2% when the prevalence of L. loa microfilaremia in the total population is above 20%. This has significant implications in terms of mapping and control of LF caused by W. bancrofti in Loa-endemic areas. Cross-reactivity of ICT with L. loa has to be considered in the context of both individual and community diagnostics.

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“…Their ability to measure ongoing exposure to the infective stages of filariae and to detect infection at an earlier time point, particularly with low infection intensities prior to patency (5, 7) as may be seen in children, makes an antibody-based assay highly useful for post-MDA surveillance and monitoring of a population for years following cessation of MDA. In addition, recent findings have determined that the ICT is cross-reactive in loiasis patients with high microfilarial burdens, which is problematic in regions where Loa loa is coendemic (13). In contrast, measurements of Wb123 antibodies using the prototype biplex cassettes and eluted blood spots from 44 patients with false-positive ICTs and with Loa loa microfilarial levels of Ͼ30,000/ml were uniformly negative (data not shown).…”

Section: Resultsmentioning

confidence: 95%

Rapid Point-of-Contact Tool for Mapping and Integrated Surveillance of Wuchereria bancrofti and Onchocerca volvulus Infection

Steel

Golden

Stevens

et al. 2015

Clin Vaccine Immunol

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Elimination programs for Wuchereria bancrofti and Onchocerca volvulus are in critical need of sensitive, specific, and point-ofcontact (POC) tools that can be used for surveillance years beyond cessation of mass drug administration when infection intensities are low. Previously, Wb123 and Ov16 were identified individually as potential filarial antigens for an antibody-based POC test. The present study compares single-antigen Wb123-and Ov16-based POC tests with an integrated configuration to detect antibodies to Wb123 and Ov16 simultaneously. Wb123 and Ov16 isolates were striped onto lateral flow strips containing antiIgG4. Sera from W. bancrofti-, O. volvulus-, and other helminth-infected or -uninfected individuals were added to the strips with buffer. Strips were read for the appearance of a positive or negative test line for both antigens at 20 min and following drying. Sensitivity, specificity, and predictive values were calculated for the single-antigen and biplex strips. Single and biplex lateral flow strips showed nearly identical results, with >90% sensitivity for Ov16 and >92% sensitivity for Wb123. Overall specificities for the single and biplex tests were 98% and 96% for Ov16 and Wb123, respectively. Biplex tests performed as well as the singleantigen tests regardless of the intensity of patient IgG4 response. The high sensitivity and specificity make these new biplex tests extremely useful for POC long-term surveillance following mass drug administration in Africa that should reduce time and cost in areas where bancroftian filariasis and onchocerciasis are coendemic.

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Filarial Antigenemia and Loa loa Night Blood Microfilaremia in an Area Without Bancroftian Filariasis in the Democratic Republic of Congo

Cited by 53 publications

References 21 publications

Dynamics of antigenemia and transmission intensity of Wuchereria bancrofti following cessation of mass drug administration in a formerly highly endemic region of Mali

Dynamics of antigenemia and transmission intensity of Wuchereria bancrofti following cessation of mass drug administration in a formerly highly endemic region of Mali

Positivity of Antigen Tests Used for Diagnosis of Lymphatic Filariasis in Individuals Without Wuchereria bancrofti Infection But with High Loa loa Microfilaremia

Rapid Point-of-Contact Tool for Mapping and Integrated Surveillance of Wuchereria bancrofti and Onchocerca volvulus Infection

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