LASSA FEVER - WEST AFRICA (20): NIGERIA

Posted on 07TH JUN 2017
tagged Lassa Fever, West Africa; Nigeria

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International Society for Infectious Diseases
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Date: Fri 2 Jun 2017
Source: Nigeria Centre for Disease Control [NCDC] Weekly Epidemiological Report 7(20) [edited]
http://www.ncdc.gov.ng/reports/weekly

Lassa fever
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Please note that the data reflects the routine reports, that is, all suspected cases, including the laboratory positive and negative cases
1. 4 suspected cases of Lassa fever with one laboratory confirmed and 2 deaths (CFR [case fatality rate], 50.0 percent) were reported from 4 LGAs [local government areas] (3 states) in week 20, 2017 [week ending 19 May 2017], compared with zero during the same period in 2016.

2. Lassa fever (Plateau - 1), 3 negatives (Cross River - 1, Nasarawa - 1 and Plateau - 1).

3. Between weeks 1-20 (2017) [1 Jan-19 May 2017], 262 suspected Lassa fever cases with 59 laboratory confirmed cases and 48 deaths (CFR, 18.32 percent) from 54 LGAs (20 states) were reported compared with 658 suspected cases with 63 laboratory confirmed cases and 75 deaths (CFR, 11.40 percent) from 122 LGAs (27 states) during the same period in 2016 (Figure 1 [all figures are available at the source URL above]).

4. Between weeks 1-52 2016, 921 suspected Lassa fever cases with 109 laboratory confirmed cases and 119 deaths (CFR, 12.92 percent) from 144 LGAs (28 states and FCT [Federal Capital Territory]) were reported compared with 430 suspected cases with 25 laboratory confirmed cases and 40 deaths (CFR, 9.30 percent) from 37 LGAs (14 states and FCT) during the same period in 2015 (Figure 2).

5. Investigation and active case search ongoing in affected States with coordination of response activities by the NCDC, with support from partners.
5.1 National Lassa Fever Working Group meeting and weekly National Surveillance and Outbreak Response meeting on-going at NCDC to keep abreast of the current Lassa fever situation in the country.
5.2 Response materials for VHFs [viral haemorrhagic fevers] prepositioned across the country by NCDC at the beginning of the dry season;
5.3 New VHF guidelines have been developed by the NCDC (Interim National Viral Haemorrhagic Fevers Preparedness guidelines and Standard Operating Procedures for Lassa fever management).
5.4 Ongoing reclassification of reported Lassa fever cases.
5.5 Ongoing review of the variables for case-based surveillance for VHF [viral hemorrhagic fever].
5.6 VHF case-based forms completed by affected states are being entered into the new VHF management system. This system allows for the creation of a VHF database for the country.
5.7 Confirmed cases are being treated at identified treatment/isolation centres across the states with ribavirin and necessary supportive management also instituted.
5.8 Onsite support was earlier provided to Ogun, Nasarawa, Taraba, Ondo, and Borno states by the NCDC and partners.
5.9 Offsite support provided by NCDC/partners in all affected states.
5.10 States are enjoined to intensify surveillance

Figure 1: Map of Nigeria showing area affected by Lassa fever, week 1-20, 2016 and 2017

Figure 2: Map of Nigeria showing areas affected by Lassa fever, week 1-53, 2015 and week 1-52, 2016

Table of cases by state, cumulative data weeks 1-20 [1 Jan-19 May 2017]:
State: Cases / Lab Confirmed / Deaths
Adamawa: 6 / 0 / 2
Bauchi: 9 / 3 / 3
Cross River: 6 / 0 / 0
Ebonyi: 4 / 1 / 1
Edo: 91 / 20 / 9
Enugu: 1 / 1 / 1
FCT: 2 / 0 / 0
Gombe: 15 / 0 / 1
Jigawa: 1 / 0 / 0
Kadun: 1 / 0 / 0
Kano: 23 / 2 / 10
Kebbi: 1 / 0 / 1
Kogi: 2 / 1 / 1
Nasarawa: 28 / 6 / 2
Ogun: 8 / 1 / 0
Ondo: 13 / 6 / 2
Plateau: 7 / 5 / 5
Rivers: 6 / 1 / 0
Taraba: 37 / 12 / 9
Yobe: 1 / 0 / 1
262 59 48
Total: 262 / 59 / 48

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Communicated by:
Olutayo Olajide Babalobi
Lecturer and Consultant Epizootiologist
(One Health, Participatory Epizootiology and Veterinary ICT Research Group)
Department of Veterinary Public Health and Preventive Medicine
Faculty of Veterinary Medicine
University of Ibadan
Ibadan, Nigeria

[Dr. Babalobi is thanked for sending in this report.

Numbers of cases of Lassa fever are continuing to slowly increase in Nigeria. As noted in earlier comments, Lassa fever remains a problem in Nigeria because the virus is endemic there. Virus transmission to humans occurs when people are in contact with the reservoir rodent host, the multimammate mouse (in the genus _Mastomys_) or their excreta. Transmission also occurs in health facilities when personal protective equipment is not employed and barrier nursing practices are not adequate to protect staff from blood and secretions of infected patients.

Also, as noted in earlier posts, prevention and control of Lassa fever in nature depends on control of the rodent reservoir, which occurs across Nigeria and beyond. Reduction of populations of this rodent will require active participation at the village level. That will necessitate mounting a public education program with support of rodent control technicians. Preventing entry of rodents into the home and keeping food materials tightly covered are helpful measures to prevent infection. Elimination of these rodents completely is probably not possible.

Images of _Mastomys_ mice can be seen at http://www.ispot.org.za/node/255877.

Maps of Nigeria can be accessed at http://www.un.org/Depts/Cartographic/map/profile/nigeria.pdf and http://healthmap.org/promed/p/62. - Mod.TY]

See Also
Lassa fever - West Africa (19): Nigeria 20170604.5082193
Lassa fever - West Africa (18): Nigeria 20170530.5070103
Lassa fever - West Africa (17): Nigeria 20170513.5033800
Lassa fever - West Africa (16): Nigeria (BA) 20170412.4967018
Lassa fever - West Africa (15): Nigeria (KO) 20170404.4947996
Lassa fever - West Africa (14): Nigeria 20170402.4943005
Lassa fever - West Africa (13): update 20170328.4931422
Lassa fever - West Africa (12): Nigeria 20170327.4929174
Lassa fever - West Africa (11): Nigeria 20170319.4911462
Lassa fever - West Africa (10): Benin, Togo, Burkina Faso 20170312.4896305
Lassa fever - West Africa (09): Nigeria (BO) 20170302.4875164
Lassa fever - West Africa (08): Benin 20170301.4872702
Lassa fever - West Africa (07): Nigeria (BA) 20170225.4864837
Lassa fever - West Africa (06): Nigeria 20170225.4862689
Lassa fever - West Africa (05): Nigeria (NA) 20170215.4842179
Lassa fever - West Africa (04): Liberia 20170209.4827934
Lassa fever - West Africa (03): Nigeria (RI) 20170122.4782917
Lassa fever - West Africa (02): Nigeria (NA) 20170118.4773375
Lassa fever - West Africa (01): Nigeria (OG) 20170101.4735363
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