The Galabat-Metema cross-border onchocerciasis focus: The first coordinated interruption of onchocerciasis transmission in Africa

Katabarwa, Moses; Zarroug, Isam M. A.; Negussu, Nebiyu; Aziz, Nabil; Tadesse, Zerihun; ElMubark, Wigdan A.; Shumo, Zainab; Meribo, Kadu; Hashim, Kamal; Mohammed, Aderajew; Bitew, Yewondwossen; Seid, Tewodros; Bekele, Firdaweke; Yilak, Abebual; Endeshaw, Tekola; Hassen, Mohammed; Tillahun, Abate; Samuel, Fikresilasie; Birhanu, Henok; Asmare, Tadesse; Boakye, Daniel; Feleke, Sindew Mekasha; Unnasch, Thomas R.; Post, R.J.; Higazi, Tarig B.; Griswold, Emily; Mackenzie, Charles D.; Richards, Frank O.

doi:10.1371/journal.pntd.0007830

Cited by 20 publications

(21 citation statements)

References 21 publications

(27 reference statements)

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“…14 The buffer zone was defined as at least a 20-km limit where Simulium damnosum –infected flies cannot cross from one transmission zone to another. 15 Because the only vector in these foci was S. neavei which exhibits a flight range less than 6 kms, 16 a buffer zone of at least 8 kms between the Wambabya–Rwamarongo focus was sufficient to prevent infected vectors from crossing Budongo. Moreover, when there is no shade, the flight distance for S. neavei is drastically reduced, as the flies avoid sunny or hot open areas.…”

Section: Methodsmentioning

confidence: 99%

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Elimination of Simulium neavei–Transmitted Onchocerciasis in Wambabya–Rwamarongo Focus of Western Uganda

Katabarwa

Habomugisha²,

Khainza³

et al. 2020

The American Journal of Tropical Medicine and Hygiene

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. Wambabya–Rwamarongo onchocerciasis focus is one of the eight foci Uganda verified using the WHO verification guidelines. The approach for elimination was twice yearly treatment with ivermectin for every round, treating at least 90% of all the eligible population. This was in combination with vector elimination using Abate ® (BASF SE, Limburgerhof, Germany) since elimination nationwide policy was launched. From 2008 to 2013, the program distributed ivermectin with a mean treatment coverage of the ultimate treatment goal (UTG) or eligible population of 91.2%, with a range of 85–96%. In 2009, vector elimination based on ground larviciding had a dramatic impact on the Simulium vectors, as the last fly was observed in October 2009. No more Simulium vectors were observed during a period of at least 7 years, including the 3-year posttreatment surveillance (PTS) until the focus was reclassified as eliminated in August 2017. During the PTS period, none of the 10,578 trapped crabs were found infested with the aquatic stages of the vector. The last infested crab was observed in March 2010, and for at least 7 years, no infested crabs were observed. Serological surveys showed that of 2,978 young children examined in 2013, only one was OV16 positive (0.0%; 95% CI: 0–0.21). In 2017, after the PTS period, all 3,079 young children examined were negative for OV16 (95% CI: 0–0.16). Therefore, entomological and serological results provided evidence that resulted in the reclassification of Wambabya–Rwamarongo focus from “transmission interrupted” to “transmission eliminated” with no possibility of recrudescence.

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Section: Methodsmentioning

confidence: 99%

“…Pool Screen ® software (Version 2.0; University of 238 Alabama, Birmingham, AL) was used to estimate the proportion of flies carrying infective stages of O. volvulus as well as the associated 95% CIs. 15 …”

Section: Methodsmentioning

confidence: 99%

Elimination of Simulium neavei–Transmitted Onchocerciasis in Wambabya–Rwamarongo Focus of Western Uganda

Katabarwa

Habomugisha²,

Khainza³

et al. 2020

The American Journal of Tropical Medicine and Hygiene

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“…The O-150 PCR has been widely applied to collect entomological data verifying elimination of transmission in a number of foci, for example, Mexico, Guatemala, one focus in Sudan 78,80 and a Sudan-Ethiopia cross-border focus. 81 The cost to process a single pool of 100 flies is US$ 6.90 per pool. 82 This technique has been successful apart from challenges associated with collecting sufficient vectors and choosing a suitable geographical assessment unit.…”

Section: Detection Of Parasites In Black Flies By Pool-screeningmentioning

confidence: 99%

<p>Onchocerciasis Elimination: Progress and Challenges</p>

Lakwo¹,

Oguttu²,

Ukety

et al. 2020

RRTM

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Onchocerciasis is a parasitic infection caused by the filarial nematode Onchocerca volvulus and transmitted through the bites of black flies of the genus Similium that breed in rivers and streams. The impact of mass treatment with ivermectin and supplemented by vector control in some countries has changed the global scene of onchocerciasis. There has been reported progress made in elimination of onchocerciasis in central and southern American countries and in some localities in Africa. The target for elimination in the Americas has been set at 2022 while for 12 countries in Africa this is expected in 2030. This review was conducted to examine the current status of onchocerciasis elimination at the global level and report on progress made. Literature searches were made through PubMed, articles in English or English abstracts, reports and any other relevant articles related to the subject. The global burden of onchocerciasis is progressively reducing and is no longer a public health problem in some regions. However, programs are challenged with a range of issues: cross-border transmission, diagnostic tools, Loa loa co-endemicity, limited workforce in entomology and maintaining enthusiasm among community drug distributors. More concerted effort using appropriate tools is required to overcome the challenges.

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“…8,9 Local control of vector blackflies (S. neavei) has been used in conjunction with twice per year ivermectin MDA to rapidly achieve suppression and interruption of transmission in several foci in Uganda. [10][11][12][13][14][15][16] This has been achieved using insecticides delivered through a regimented, vertical program. However, to be successful and sustainable the long term, control efforts will have to be affordable and less reliant on structured government programs.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Slash and Clear Community-Directed Control of Simulium damnosum Sensu Stricto in Northern Uganda

Jacob

Loum²,

Munu³

et al. 2021

The American Journal of Tropical Medicine and Hygiene

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Onchocerciasis, caused by infection with Onchocerca volvulus, has been targeted for elimination by 2030. Currently, onchocerciasis elimination programs rely primarily on mass distribution of ivermectin. However, ivermectin alone may not be sufficient to achieve elimination in some circumstances, and additional tools may be needed. Vector control has been used as a tool to control onchocerciasis, but vector control using insecticides is expensive and ecologically detrimental. Community-directed removal of the trailing vegetation black fly larval attachment sites (slash and clear) has been shown to dramatically reduce vector biting densities. Here, we report studies to optimize the slash and clear process. Conducting slash and clear interventions at Simulium damnosum sensu stricto breeding sites located within 2 km of afflicted communities resulted in a 95% reduction in vector biting. Extending slash and clear further than 2 km resulted in no further decrease. A single intervention conducted at the first half of the rainy season resulted in a 97% reduction in biting rate, whereas an intervention conducted at the end of the rainy season resulted in a 94% reduction. Vector numbers in any of the intervention villages did not fully recover by the start of the following rainy season. These results suggest that slash and clear may offer an inexpensive and effective way to augment ivermectin distribution in the effort to eliminate onchocerciasis in Africa.

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The Galabat-Metema cross-border onchocerciasis focus: The first coordinated interruption of onchocerciasis transmission in Africa

Cited by 20 publications

References 21 publications

Elimination of Simulium neavei–Transmitted Onchocerciasis in Wambabya–Rwamarongo Focus of Western Uganda

Elimination of Simulium neavei–Transmitted Onchocerciasis in Wambabya–Rwamarongo Focus of Western Uganda

<p>Onchocerciasis Elimination: Progress and Challenges</p>

Optimization of Slash and Clear Community-Directed Control of Simulium damnosum Sensu Stricto in Northern Uganda

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