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Lassa fever epidemiology and demographics

Introduction

Overview

Overview

Lassa fever is endemic in West Africa and is rare in developed countries. Lassa virus infects 100,000-300,000 individuals annually with a case fatality rate typically reaching 1-5% but may be as high as 65% during outbreaks.[1] There is no predilection to specific age groups, gender, or race. However, young age and pregnancy are associated with increased risk of Lassa fever-associated complications.

Epidemiology and Demographics

Epidemiology and Demographics

Incidence

  • Lassa virus infects 100,000-300,000 individuals annually. However, these figures are inaccurate given that disease surveillance for cases is not routinely performed.
  • In areas of high endemicity, up to 10%-15% of hospitalized patients are diagnosed with Lassa fever.

Case Fatality Rates

  • Generally, the overall case-fatality rate is 5-15%.
  • The case fatality rate increases among patients hospitalized for severe infection, and during outbreaks, Lassa fever may be associated with case-fatality rates that reach up to 35-65%.[2]

Age

  • There is no age preponderance for Lassa virus infection.
  • However, fetuses are at high-risk of death following infection with Lassa fever.

Gender

  • There is no gender preponderance for Lassa virus infection.
  • Women in the third trimester of pregnancy are considered high-risk for development of Lassa fever-associated complications and death.

Seasonal Variation

  • The highest incidence of Lassa fever occurs during the dry months from November to April.[3]

Race

  • There is no races preponderance for Lassa virus infection.

Developed Countries

  • The following table lists the individuals infected with Lassa fever and were imported and hospitalized in the United States:[4]
Year of import Clinical features From To
1969 Fever, malaise, headache, nausea, sore throat, epigastric/right upper quadrant tenderness, pleural effusion, facial/cervical edema, dysphagia, elevated transaminases, cough, dyspnea, pulmonary infiltrates, epiglottal edema, lethargy, nystagmus, lightheadedness, dizziness without vertigo, ataxia, alopecia Nigeria New York
1975 Abdominal pain, diarrhea, fever, headache, myalgia, arthralgia, conjunctival injection, lymphadenopathy, weight loss, pleuritic chest pain, pleural effusion, unilateral deafness Sierra Leone Washington, DC
1976 Abdominal cramps, nausea, vomiting, diarrhea, fatigue, headache, retroorbital pain, neck/back pain, paresthesias, right ear pain, fever, vertigo, syncope, dysmorphopsias, alopecia, weight loss, ecchymoses, insomnia, depression, hypotension, left-sided facial weakness, right-sided Babinski reflex, Weber test lateralized to the left Sierra Leone Washington, DC
1989 Shaking chills, fever, sore throat, myalgia, headache, dysphagia, bloody diarrhea, elevated transaminases, hypotension, adult respiratory distress syndrome, death Nigeria Chicago, IL
2004 Chills, fever, sore throat, diarrhea, back pain, adult respiratory distress syndrome, death Sierra Leone and Liberia Trenton, New Jersy
2015 Fever, sore throat, tiredness, death Liberia New Jersy

Data from the Center of Disease Control and Prevention, as of May 2015

  • The following table lists the individuals infected with Lassa fever who were imported and hospitalized in other non-endemic countries except the United States:[4]
Year of import Occupation From To Clinical outcome
1971 Nurse Sierra Leone United Kingdom Survived
1971 Physician Sierra Leone United Kingdom Survived
1972 Nurse Sierra Leone United Kingdom Survived
1974 Physician Nigeria Germany Survived
1975 Physician Nigeria United Kingdom Died
1976 Engineer Nigeria United Kingdom Survived
1980 Aid worker Upen Volta Netherlands Survived
1981 Teacher Nigeria United Kingdom Survived
1982 Diplomat Nigeria United Kingdom Survived
1984 Geologist Sierra Leone United Kingdom Survived
1985 Nurse Sierra Leone United Kingdom Survived
1987 Engineer Sierra Leone/Liberia Israel Survived
1987 Engineer Sierra Leone Japan Survived
1989 Agricultural specialist Nigeria Canada Survived
2000 Student Cotê d’Ivoire/Burkina Faso/Ghana Germany Died
2000 Peace Keeper CSierra Leone United Kingdom Died
2000 Unknown Nigeria Germany Died
2000 Physician Sierra Leone Netherlands Died
2003 Peace Keeper Sierra Leone United Kingdom Survived
2006 – Sierra Leone Germany Survived

Data from the Center of Disease Control and Prevention, as of May 2015

Developing Countries

Lassa virus is most prevalent in countries of West and Central Africa:[5][6][7],[8][9][10][11]

  • Sierra Leone
  • Guinea
  • Nigeria
  • Ivory Coast
  • Mali
  • Benin
  • Central African Republic
  • Liberia
  • Burkina Faso
  • Senegal
  • Ghana
  • Gambia

The maps below demonstrate the outbreak distribution of Lassa fever:[12][13][14]

Outbreak Distribution Map Lassa Fever[1]
Geographic distribution of patients presenting to Sierra Leone with LASV antigenemia and anti-LASV IgM serpositivity, 2008–12.[15]
Map of Nigeria showing States where cases of acute abdomen from Lassa fever were reported.[15]
References

References

  1. ↑ 1.0 1.1 “The Centers for Disease Control and Prevention facts sheets” (PDF).
  2. ↑ Monath TP, Mertens PE, Patton R, Moser CR, Baum JJ, Pinneo L; et al. (1973). “A hospital epidemic of Lassa fever in Zorzor, Liberia, March-April 1972”. Am J Trop Med Hyg. 22 (6): 773–9. PMID 4745236.
  3. ↑ McCormick JB, Webb PA, Krebs JW, Johnson KM, Smith ES (1987). “A prospective study of the epidemiology and ecology of Lassa fever”. J Infect Dis. 155 (3): 437–44. PMID 3805771.
  4. ↑ 4.0 4.1 “Historical Lassa Fever Reports and 30-year Clinical Update-The Centers for Disease Control and Prevention articles” (PDF). Invalid parameter “lassa” in <ref> tag. The supported parameters are: dir, follow, group, name.
  5. ↑ Carey DE, Kemp GE, White HA, Pinneo L, Addy RF, Fom AL; et al. (1972). “Lassa fever. Epidemiological aspects of the 1970 epidemic, Jos, Nigeria”. Trans R Soc Trop Med Hyg. 66 (3): 402–8. PMID 5046380 : 5046380 Check |pmid= value (help).
  6. ↑ Bowen GS, Tomori O, Wulff H, Casals J, Noonan A, Downs WG (1975). “Lassa fever in Onitsha, East Central State, Nigeria in 1974”. Bull World Health Organ. 52 (4–6): 599–604. PMC 2366632. PMID 1085214.
  7. ↑ Frame JD, Jahrling PB, Yalley-Ogunro JE, Monson MH (1984). “Endemic Lassa fever in Liberia. II. Serological and virological findings in hospital patients”. Trans R Soc Trop Med Hyg. 78 (5): 656–60. PMID 6390808.
  8. ↑ Fisher-Hoch SP, Tomori O, Nasidi A, Perez-Oronoz GI, Fakile Y, Hutwagner L; et al. (1995). “Review of cases of nosocomial Lassa fever in Nigeria: the high price of poor medical practice”. BMJ. 311 (7009): 857–9. PMC 2550858. PMID 7580496.
  9. ↑ Bajani MD, Tomori O, Rollin PE, Harry TO, Bukbuk ND, Wilson L; et al. (1997). “A survey for antibodies to Lassa virus among health workers in Nigeria”. Trans R Soc Trop Med Hyg. 91 (4): 379–81. PMID 9373625.
  10. ↑ Fisher-Hoch SP, McCormick JB (2004). “Lassa fever vaccine”. Expert Rev Vaccines. 3 (2): 189–97. doi:10.1586/14760584.3.4.S189. PMID 15056044.
  11. ↑ Omilabu SA, Badaru SO, Okokhere P, Asogun D, Drosten C, Emmerich P; et al. (2005). “Lassa fever, Nigeria, 2003 and 2004”. Emerg Infect Dis. 11 (10): 1642–4. doi:10.3201/eid1110.041343. PMC 3366737. PMID 16355508.
  12. ↑ Gonzalez JP, Emonet S, de Lamballerie X, Charrel R (2007). “Arenaviruses”. Curr Top Microbiol Immunol. 315: 253–88. PMID 17848068.
  13. ↑ Safronetz D, Lopez JE, Sogoba N, Traore’ SF, Raffel SJ, Fischer ER; et al. (2010). “Detection of Lassa virus, Mali”. Emerg Infect Dis. 16 (7): 1123–6. doi:10.3201/eid1607.100146. PMC 3321918. PMID 20587185.
  14. ↑ Günther S, Emmerich P, Laue T, Kühle O, Asper M, Jung A; et al. (2000). “Imported lassa fever in Germany: molecular characterization of a new lassa virus strain”. Emerg Infect Dis. 6 (5): 466–76. doi:10.3201/eid0605.000504. PMC 2627947. PMID 10998376.
  15. ↑ 15.0 15.1 “Lassa Fever in Post-Conflict Sierra Leone”.

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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ammu Susheela, M.D. [2]