Om Prakash Singh1,2, Puja Tiwary1,3, Anurag Kumar Kushwaha1, Shakti Kumar Singh4,5, Dhiraj Kumar Singh4,6, Phillip Lawyer7, Edgar Rowton8, Rahul Chaubey4, Abhishek Kumar Singh1, Tulika Kumari Rai1, Michael P Fay9, Jaya Chakravarty1, David Sacks7, Shyam Sundar1. 1. Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India. 2. Department of Biochemistry, Institute of Science, Banaras Hindu University, Varanasi, Uttar Pradesh, India. 3. Department of Molecular Biology, Laboratory for Molecular Infection Medicine Sweden, Umea University, Umea, Sweden. 4. Kala-Azar Medical Research Center, Muzaffarpur, Bihar, India. 5. Ministry of Environment, Forest and Climate Change, New Delhi, India. 6. Department of Zoology, Rameshwar College, Babasaheb Bhimrao Ambedkar Bihar University, Muzaffarpur, Bihar, India. 7. Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA. 8. Division of Entomology, Walter Reed Army Institute of Research, Silver Spring, MD, USA. 9. Biostatistics Research Branch, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA.
Abstract
BACKGROUND: Visceral leishmaniasis, also known on the Indian subcontinent as kala-azar, is a fatal form of leishmaniasis caused by the protozoan parasite Leishmania donovani and transmitted by the bites of the vector sandfly Phlebotomus argentipes. To achieve and sustain elimination of visceral leishmaniasis, the transmission potential of individuals exposed to L donovani from across the infection spectrum needs to be elucidated. The aim of this study was to evaluate the relative infectiousness to the sandfly vector of patients with visceral leishmaniasis or post-kala-azar dermal leishmaniasis, before and after treatment, and individuals with asymptomatic infection. METHODS: In this prospective xenodiagnosis study done in Muzaffarpur district of Bihar, India, we included patients with clinically confirmed active visceral leishmaniasis or post-kala-azar dermal leishmaniasis who presented to the Kala-Azar Medical Research Center. These participants received treatment for L donovani infection. We also included asymptomatic individuals identified through a serosurvey of 17 254 people living in 26 high-transmission clusters. Eligible participants were aged 12-64 years, were HIV negative, and had clinically or serologically confirmed L donovani infection. During xenodiagnosis, the forearms or lower legs of participants were exposed to 30-35 female P argentipes sandflies for 30 min. Blood-engorged flies were held in an environmental cabinet at 28°C and 85% humidity for 60-72 h, after which flies were dissected and evaluated for L donovani infection by microscopy and quantitative PCR (qPCR). The primary endpoint was the proportion of participants with visceral leishmaniasis or post-kala-azar dermal leishmaniasis, before and after treatment, as well as asymptomatic individuals, who were infectious to sandflies, with a participant considered infectious if promastigotes were observed in one or more individual flies by microscopy, or if one or more of the pools of flies tested positive by qPCR. FINDINGS: Between July 12, 2016, and March 19, 2019, we recruited 287 individuals, including 77 with active visceral leishmaniasis, 26 with post-kala-azar dermal leishmaniasis, and 184 with asymptomatic infection. Of the patients with active visceral leishmaniasis, 42 (55%) were deemed infectious to sandflies by microscopy and 60 (78%) by qPCR before treatment. No patient with visceral leishmaniasis was found to be infectious by microscopy at 30 days after treatment, although six (8%) were still positive by qPCR. Before treatment, 11 (42%) of 26 patients with post-kala-azar dermal leishmaniasis were deemed infectious to sandflies by microscopy and 23 (88%) by qPCR. Of 23 patients who were available for xenodiagnosis after treatment, one remained infectious to flies by qPCR on the pooled flies, but none remained positive by microscopy. None of the 184 asymptomatic participants were infectious to sandflies. INTERPRETATION: These findings confirm that patients with active visceral leishmaniasis and patients with post-kala-azar dermal leishmaniasis can transmit L donovani to the sandfly vector and suggest that early diagnosis and treatment could effectively remove these individuals as infection reservoirs. An important role for asymptomatic individuals in the maintenance of the transmission cycle is not supported by these data. FUNDING: Bill & Melinda Gates Foundation.
BACKGROUND: Visceral leishmaniasis, also known on the Indian subcontinent as kala-azar, is a fatal form of leishmaniasis caused by the protozoan parasite Leishmania donovani and transmitted by the bites of the vector sandfly Phlebotomus argentipes. To achieve and sustain elimination of visceral leishmaniasis, the transmission potential of individuals exposed to L donovani from across the infection spectrum needs to be elucidated. The aim of this study was to evaluate the relative infectiousness to the sandfly vector of patients with visceral leishmaniasis or post-kala-azar dermal leishmaniasis, before and after treatment, and individuals with asymptomatic infection. METHODS: In this prospective xenodiagnosis study done in Muzaffarpur district of Bihar, India, we included patients with clinically confirmed active visceral leishmaniasis or post-kala-azar dermal leishmaniasis who presented to the Kala-Azar Medical Research Center. These participants received treatment for L donovani infection. We also included asymptomatic individuals identified through a serosurvey of 17 254 people living in 26 high-transmission clusters. Eligible participants were aged 12-64 years, were HIV negative, and had clinically or serologically confirmed L donovani infection. During xenodiagnosis, the forearms or lower legs of participants were exposed to 30-35 female P argentipes sandflies for 30 min. Blood-engorged flies were held in an environmental cabinet at 28°C and 85% humidity for 60-72 h, after which flies were dissected and evaluated for L donovani infection by microscopy and quantitative PCR (qPCR). The primary endpoint was the proportion of participants with visceral leishmaniasis or post-kala-azar dermal leishmaniasis, before and after treatment, as well as asymptomatic individuals, who were infectious to sandflies, with a participant considered infectious if promastigotes were observed in one or more individual flies by microscopy, or if one or more of the pools of flies tested positive by qPCR. FINDINGS: Between July 12, 2016, and March 19, 2019, we recruited 287 individuals, including 77 with active visceral leishmaniasis, 26 with post-kala-azar dermal leishmaniasis, and 184 with asymptomatic infection. Of the patients with active visceral leishmaniasis, 42 (55%) were deemed infectious to sandflies by microscopy and 60 (78%) by qPCR before treatment. No patient with visceral leishmaniasis was found to be infectious by microscopy at 30 days after treatment, although six (8%) were still positive by qPCR. Before treatment, 11 (42%) of 26 patients with post-kala-azar dermal leishmaniasis were deemed infectious to sandflies by microscopy and 23 (88%) by qPCR. Of 23 patients who were available for xenodiagnosis after treatment, one remained infectious to flies by qPCR on the pooled flies, but none remained positive by microscopy. None of the 184 asymptomatic participants were infectious to sandflies. INTERPRETATION: These findings confirm that patients with active visceral leishmaniasis and patients with post-kala-azar dermal leishmaniasis can transmit L donovani to the sandfly vector and suggest that early diagnosis and treatment could effectively remove these individuals as infection reservoirs. An important role for asymptomatic individuals in the maintenance of the transmission cycle is not supported by these data. FUNDING: Bill & Melinda Gates Foundation.
Authors: Gabriel Reis Ferreira; José Carlos Castelo Branco Ribeiro; Antônio Meneses Filho; Teresinha de Jesus Cardoso Farias Pereira; Daniela Moura Parente; Humberto Feitosa Pereira; Jailthon Carlos da Silva; Danielle Alves Zacarias; Letiano Vieira da Silva; Symonara Karina Medeiros Faustino; Walfrido Salmito Almeida Neto; Dorcas Lamounier Costa; Ivete Lopes de Mendonça; Carlos Henrique Nery Costa Journal: Am J Trop Med Hyg Date: 2018-01 Impact factor: 2.345
Authors: Mary M Cameron; Alvaro Acosta-Serrano; Caryn Bern; Marleen Boelaert; Margriet den Boer; Sakib Burza; Lloyd A C Chapman; Alexandra Chaskopoulou; Michael Coleman; Orin Courtenay; Simon Croft; Pradeep Das; Erin Dilger; Geraldine Foster; Rajesh Garlapati; Lee Haines; Angela Harris; Janet Hemingway; T Déirdre Hollingsworth; Sarah Jervis; Graham Medley; Michael Miles; Mark Paine; Albert Picado; Richard Poché; Paul Ready; Matthew Rogers; Mark Rowland; Shyam Sundar; Sake J de Vlas; David Weetman Journal: Parasit Vectors Date: 2016-01-27 Impact factor: 3.876
Authors: Jaspreet Toor; Jonathan I D Hamley; Claudio Fronterre; María Soledad Castaño; Lloyd A C Chapman; Luc E Coffeng; Federica Giardina; Thomas M Lietman; Edwin Michael; Amy Pinsent; Epke A Le Rutte; T Déirdre Hollingsworth Journal: PLoS Negl Trop Dis Date: 2021-05-13
Authors: Johannes S P Doehl; Helen Ashwin; Najmeeyah Brown; Audrey Romano; Samuel Carmichael; Jon W Pitchford; Paul M Kaye Journal: Front Immunol Date: 2021-12-16 Impact factor: 7.561