LASSA FEVER - WEST AFRICA (21): NIGERIA

Posted on 06TH APR 2018
tagged Lassa Fever, West Africa; Nigeria

A ProMED-mail post
http://www.promedmail.org
ProMED-mail is a program of the
International Society for Infectious Diseases
http://www.isid.org

In this update:
[1] National update
[2] Predictors of outcome

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[1] National update
Date: Sun 1 Apr 2018
Source: Nigeria Centre for Disease Control Situation Report [edited]
http://www.ncdc.gov.ng/diseases/sitreps/?cat=5&name=An%20update%20of%20L...

Highlights
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- In the reporting week 13 (26 Mar-1 Apr 2018) 6 new confirmed cases were recorded from 5 states -- Edo (2 cases), Ondo (1), Bauchi (1), Plateau (1), and Abia (1) with 2 new deaths in confirmed cases from FCT [Federal Capital Territory] (1), and Abia (1).
- From 1 Jan-1 Apr 2018, a total of 1706 suspected cases have been reported. Of these, 400 were confirmed positive, 9 are probable, 1273 are negative (not a case), and 24 are awaiting laboratory results (pending)
- Since the onset of the 2018 outbreak, there have been 142 deaths: 97 in positive-confirmed cases, 9 in probable cases, and 36 in negative cases. Case fatality rate in confirmed cases is 24.3 percent -- Table 1.
- 20 states have recorded at least one confirmed case across 57 local government areas [LGA] (Edo, Ondo, Bauchi, Nasarawa, Ebonyi, Anambra, Benue, Kogi, Imo, Plateau, Lagos, Taraba, Delta, Osun, Rivers, FCT, Gombe, Ekiti, Kaduna, and Abia); 8 states have exited the active phase of the outbreak while 12 states remain active -- Table 1/Figure 1.
- In the reporting week 14 [2-8 Apr 2018], 2 new healthcare workers were affected with one death. Since the onset of the outbreak, 25 health care workers have been affected in 8 states: Ebonyi (15), Nasarawa (1), Kogi (2), Benue (1), Ondo (2), Edo (3), and Abia (1), with 5 deaths in Ebonyi (3) Kogi (1), and Abia (1).
- 81 percent of all confirmed cases are from Edo (42 percent), Ondo (23 percent), and Ebonyi (16 percent) states.
- 30 cases are currently under treatment in treatment centres across nine states -- Edo (9), Ebonyi (6), Bauchi (7), Ondo (5), Plateau (1), Osun (1), and Kogi (1).
- A total of 4274 contacts have been identified from 20 states. Of these 662 (15 percent) are currently being followed up, 3605 (84.8 percent) have completed 21 days follow up while 7 (0.2 percent) were lost follow up. 27 (40 percent) of the 67 contacts have tested positive from 5 states (Edo-12, Ondo-7, Ebonyi-3, Kogi-3, and Bauchi-1).
- WHO and NCDC has scaled up response at National and State levels.
- National RRT [rapid response team] team (NCDC [Nigeria Centre for Disease Control] staff and NFELTP Nigeria Field Epidemiology and Laboratory Training Program] residents) batch C continues response support in Ebonyi, Ondo, Edo, Bauchi and Taraba State
- National Lassa fever multi-partner multi-agency Emergency Operations Centre (EOC) continues to coordinate the response activities at all levels.

Figure 1 [map]. Distribution of confirmed Lassa fever cases in Nigeria as at 1 Apr 2018
Figure 2 [map]. Distribution of suspected and confirmed Lassa fever cases in Nigeria by LGA
Figure 3 [graph]. Confirmed (400) and probable (9) cases of Lassa fever by epidemiological week in Nigeria week 1-13, 2018
Figure 4 [graph]. Confirmed Lassa fever cases in Nigeria with state specific case fatality rates (CFR) as at 1 Apr 2018
Figure 5 [graph]: Epicurve of confirmed cases Lassa fever in Edo state week 1-13, 2018
Figure 6 [graph]: Distribution of Lassa fever confirmed cases in Edo state by LGA as at 1 Apr 2018
Figure 7 [graph]: Epicurve of Lassa fever confirmed cases in Ondo state week 1-13, 2018
Figure 8 [graph]: Epicurve of Lassa fever confirmed cases in Ebonyi state week 1-13, 2018

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Communicated by:
ProMED-mail

[The graphs of the epidemic curves continue to indicate that the peak number of cases nationally has passed. However, the Lassa fever period can be expected to continue for another 2-3 months, into June 2018. New cases have occurred over the past few days in several states. Providing adequate surveillance and timely treatment over such a large geographic area is challenging. Fortunately, there is international help participating in treatment and surveillance. Unfortunately, a female physician in Abia state became ill and was diagnosed with the disease after attending to an 11-month old baby who later died. The baby was, however, not confirmed to have been infected with Lassa fever before his death (https://www.thecable.ng/lassa-fever-kills-doctor-abia-month-starting-work).

The maps and graphs in the report above are interesting and provide a good picture of how the outbreak has progressed over time. They can be accessed at the source URL above.

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

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[2] Predictors of outcome
Date: Tue 6 Mar 2018
Source: The Lancet journal [edited]
http://www.thelancet.com/journals/laninf/article/PIIS1473-3099%2818%2930...

[Ref: Okokhere P, Colubri A, Azubike C, et al. Clinical and laboratory predictors of Lassa fever outcome in a dedicated treatment facility in Nigeria: a retrospective, observational cohort study.
Lancet Infect Dis. 2018. pii: S1473-3099(18)30121-X. doi: 10.1016/S1473-3099(18)30121-X]
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Summary
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Background
Lassa fever is a viral haemorrhagic disease endemic to west Africa. No large-scale studies exist from Nigeria, where the Lassa virus (LASV) is most diverse. LASV diversity, coupled with host genetic and environmental factors, might cause differences in disease pathophysiology. Small-scale studies in Nigeria suggest that acute kidney injury is an important clinical feature and might be a determinant of survival. We aimed to establish the demographic, clinical, and laboratory factors associated with mortality in Nigerian patients with Lassa fever, and hypothesised that LASV was the direct cause of intrinsic renal damage for a subset of the patients with Lassa fever.

Methods
We did a retrospective, observational cohort study of consecutive patients in Nigeria with Lassa fever, who tested positive for LASV with RT-PCR, and were treated in Irrua Specialist Teaching Hospital. We did univariate and multivariate statistical analyses, including logistic regression, of all demographic, clinical, and laboratory variables available at presentation to identify the factors associated with patient mortality.

Findings
Of 291 patients treated in Irrua Specialist Teaching Hospital between 3 Jan 2011, and 11 Dec 2015, 284 (98 percent) had known outcomes (died or survived) and 7 (2 percent) were discharged against medical advice. Overall case-fatality rate was 24 percent (68 of 284 patients), with a 1.4 times increase in mortality risk for each 10 years of age (p=0·00017), reaching 39 percent (22 of 57) for patients older than 50 years. Of 284 patients, 81 (28 percent) had acute kidney injury and 104 (37 percent) had CNS manifestations and thus both were considered important complications of acute Lassa fever in Nigeria. Acute kidney injury was strongly associated with poor outcome (case-fatality rate of 60 percent [49 of 81 patients]; ratio [OR] 15, p less than 0.00001). Compared with patients without acute kidney injury, those with acute kidney injury had higher incidence of proteinuria (32 [82 percent] of 39 patients) and haematuria (29 [76 percent] of 38) and higher mean serum potassium (4.63 [SD 1.04] mmol/L) and lower blood urea nitrogen to creatinine ratio (8.6 for patients without clinical history of fluid loss), suggesting intrinsic renal damage. Normalisation of creatinine concentration was associated with recovery. Elevated serum creatinine (OR 1.3; p=0·046), aspartate aminotransferase (OR 1.5; p=0.075), and potassium (OR 3.6; p=0.0024) were independent predictors of death.

Interpretation
Our study presents detailed clinical and laboratory data for Nigerian patients with Lassa fever and provides strong evidence for intrinsic renal dysfunction in acute Lassa fever. Early recognition and treatment of acute kidney injury might significantly reduce mortality.

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Communicated by:
ProMED-mail Rapporteur Mary Marshall

[This study indicates that Lassa fever likely induces acute renal dysfunction in a significant portion of patients and is an indicator of progression to mortality. This study provides useful insight into the pathophysiology of Lassa fever virus infections. - Mod.TY]

See Also
Lassa fever - West Africa (20): Nigeria 20180327.5714291
Lassa fever - West Africa (19): Nigeria 20180315.5687321
Lassa fever - West Africa (18): Nigeria (BA) 20180313.5683816
Lassa fever - West Africa (16): Nigeria 20180306.5670231
Lassa fever - West Africa (14): Nigeria 20180228.5655382
Lassa fever - West Africa (13): Nigeria 20180222.5645501
Lassa fever - West Africa (12): Nigeria 20180221.5641157
Lassa fever - West Africa (11): Nigeria, WHO 20180215.5629350
Lassa fever - West Africa (10): Nigeria 20180212.5622070
Lassa fever - West Africa (07): Nigeria 20180206.5608967
Lassa fever - West Africa (06): Nigeria (DE, ON) 20180201.5600192
Lassa fever - West Africa (05): Nigeria 20180131.5597457
Lassa fever - West Africa (04): Nigeria 20180125.5585380
Lassa fever - West Africa (03): Benin (AK) ex Nigeria, WHO 20180124.5581805
Lassa fever - West Africa (02): Nigeria, Benin (AK) ex Nigeria 20180124.5576379
Lassa fever - West Africa: Nigeria 20180115.5561615
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