Lice Outbreaks: Transmission and Avenues for Treatment Quyen Vu

2. Lice Outbreaks: Transmission and Avenues for Treatment Quyen Vu

3. Goals • Understand the main differences between the three types of lice affecting humans • Morphology and vector biology • Disease risk • Most effective treatments • Prevention strategies • Learn about the disease risks associated with body lice, especially in situations of humanitarian crisis • Burundi case study • Appropriate control strategies

4. Vector Biology Three types of lice: • Head lice: Pediculushumanuscapitis (2-3 mm long) • Body lice: Pediculushumanushumanus (2.3-3.6 mm long) • Pubic lice (crabs): Phthirus pubis (1.1-1.8 mm long)

5. Vector Biology • All three types of lice: • Are ectoparasites: lice live on the surface of the host • Move by crawling, as opposed to flying • Have humans as their only host • Have similar life cycles Head Lice Body Lice Pubic Lice

6. Lice Life Cycle • Lice stages: • Egg/nit • Nymph (3 molts) • Adult • Both nymphs and adults take blood meals from the human host.

7. History of Lice & Humans • DNA evidence suggests that human lice split off from gorilla lice approximately 3-4 million years ago

8. History of Lice & Humans • Pediculushumanuscapitis(head lice) and Pediculushumanuscorporis(body lice) diverged when humans started using clothing • Used DNA sequencing to estimate how long ago common ancestors lived • Body lice usually found in clothing • Diverged ~72,000 years ago

9. Lice in the News • Outbreaks do show up in national news! • Not severe: most of the stories related to school and campus outbreaks • “Head Lice Epidemic Closes Anderson Schools” 1973 • “Lice Outbreak Cancels Classes” 1980

10. Symptoms Head Lice • Itching • Difficulty sleeping • Sores and secondary bacterial infections from scratching

11. Symptoms (Continued) • Body lice: Intense itching • Skin discoloration/thickening • Secondary bacterial infection also possible from prolonged scratching • Red rash • Pubic lice “crabs”: Itching

12. Disease • Head lice: does not spread disease • Body lice spreads bacterial disease! • Pubic lice: does not spread disease

13. Body Lice Diseases • Louse-Borne Relapsing Fever (Borreliarecurrentis) • 1 Million cases observed in North Africa (WWII) • Case fatality rate 10% • Related to tick-borne relapsing fever (B. duttonii) • Trench Fever (Bartonellaquintana) • Less serious, rarely fatal • Characteristic five-day fever • Epidemic typhus (Rickettsia prowazekii)

14. Diagnosis by Direct Visualization • Observation of live nymphs or adult lice. • Finding nits is suggestive of infection but not definitive. • Use fine-tooth comb and magnifying glass. NITS

15. Epidemiology & Risk Factors Head lice: “head-to-head” transmission • 6-12 million cases/yr in the United States in children age 3-11 • Found worldwide • Girls at higher risk than boys • African Americans lower risk than other racial groups

16. Epidemiology & Risk Factors (Continued) Pubic Lice (“Crabs”): • Current worldwide prevalence estimated 2% • Spread through sexual contact and is considered an STD • Can be spread through fomites: contact with clothing, linens, and towels belonging to an infected person. • Pubic lice found on children can be an indicator of sexual abuse.

17. Epidemiology & Risk Factors (Continued) Body lice: humanitarian crises & disenfranchised groups • Associated with poor hygiene and crowded living conditions • In the United States: prisons, homeless transient populations

18. Epidemic Typhus (Rickettsia prowazekii) • Pathogen type: gram negative bacteria • In North America, animal reservoir is the flying squirrel • Was first observed and described in Italy in year 1083 • Typhus epidemics associated with extremely high mortality throughout history • Civil War • WWI: 3 million deaths in Russia • WWII • Featured in literature • Jane Eyre, Lolita, Doctor Zhivago, among others!

19. Epidemic Typhus (Rickettsia prowazekii) • Also known as: “jail fever”, “camp fever”, “famine fever” • Body lice • Transmission: 1. Louse feeds on human infected w/ R. prowazekii 2. R. prowazekii grows in louse’s gut 3. R. prowazekii excreted in louse feces 4. Human scratches louse bite, rubs feces into wound • Symptoms: • Severe headache, sustained high fever, rash, muscle pain • Can be treated with antibiotics

20. Humanitarian Crisis in Burundi • Civil war ongoing 1993-2005 • Ethnic divisions: Hutus, Tutsis • Hutu president was assassinated by Tutsi extremists • Further aggravated by regional violence between Hutus and Tutsis (Rwandan Genocide) • Many refugees and internally-displaced persons • Total estimated death toll: 300,000

21. Jail Fever Outbreak in Burundi • Nurse observed clinical symptoms in prisoners (1997) • Abrupt fever of up to 40 degrees C. • Serologic testing: R. prowazekii confirmed. • Body lice in jail • Conditions noted: “cold weather, poor hygiene, poverty” • “Confirmation of a typhus outbreak in Burundi is of concern, given the relative political instability…”

22. Large Epidemic Typhus Outbreak (Burundi) • Jail outbreak in 1995-1996 predates large outbreak in Burundi 1997 • World Health Organization identified 24,000 cases in Bujumbura Province (Burundi). • Cases were later identified in six provinces • Largest outbreak in 50 years • Risk identified: Burundi, Zaire, Rwanda

23. Lice Treatment OTC Medications • Pyrethins: kill live lice but not the nits • Permethrin lotion 1%: similar to Pyrethin, kills the adult lice but not the nits.

24. Lice Treatment (Continued) Prescription Medications • Malathion lotion 0.5%: kills live lice and partially ovicidal (kills some eggs.) Can be irritating to skin/scalp. • Benzyl alcohol lotion 5%: does not kill live eggs • Lindane shampoo 1%: not recommended as first-line therapy because can cause neurological damage

25. Which treatments should be used? • Most parents use the “Nix” shampoo: Permethrin 1%. • Usually cited as the standard treatment. • If Permethrin is unsuccessful, move to prescription treatments • Lindane is currently not recommended by the American Academy of Pediatrics (AAP): should only be used if all the other treatments are ineffective.

26. Additional Lice Treatments • Several studies have looked at oral ivermectin administration as an alternative to topical medications • Oral ivermectin was found to be more effective than topical malathion lotion • Important given issues of resistance to existing topical treatments • Recent news! The FDA has approved a topical ivermectin-based lotion (brand-name Sklice)

27. Additional Lice Treatments (Continued) Fumigation and dusting with chemical insecticides: DDT, 1% malathion, or 1% permethrin. • First used in WWII: U.S. military dusted DDT powder on troops and refugees. • 10% DDT louse powder on patient, clothing, bedding and members of household • Highly effective (lice mortality of 99% from 1% DDT; lice mortality 96% in 0.1% DDT)

28. Prevention • Avoid methods of transmission (head-to-head contact, sexual contact) • Improved hygiene/sanitation for body lice • Regular change of clothes • Regular bathing • Laundry and soaking in hot water • Pets do not play a role in lice outbreaks

29. Prevention in Schools: No-Nit Policy Controversy • No-Nit Policy: Education, screening, and treatment of children with lice in order to prevent transmission and maintain “nit-free” environments • Emphasize accurate diagnosis • Education about prevention techniques • Temporary dismissal of children with lice • American Academy of Pediatricians oppose the strict no-nit policy • Causes lost classroom time for children • (Head) lice aren’t a severe medical problem • Recommend: common sense

30. Summary • Body lice are more serious than pubic or head lice because they can transmit disease. • Diseases associated with body lice are severe! • Epidemic typhus (R. prowazekii) • Refugees and those affected by humanitarian crises are particularly at risk. • Insecticide spraying is an important control measure

31. References Blanton, F. S. (1952). The Control of Epidemic Typhus. Journal of the New York Entomological Society, 60(3), 153-156. Burundi Civil War. GlobalSecurity.org. http://www.globalsecurity.org/military/world/war/burundi.htm. Chosidow, O., Giraudeau, B., Cottrell, J., Izri, A., Hofmann, R., Ph, D., Mann, S. G., et al. (2010). Oral Ivermectin versus Malathion Lotion for Difficult-to-Treat Head Lice. NEJM, 362, 896-905. Hand, L. 2012. FDA Approves New Lotion for Head Lice Treatment. Medscape Today. http:// www.medscape.com/viewarticle/758344 Head lice. PubMed Health, 2012. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001843/ Lepes, T. J. (1960). Susceptibility of Body-lice to DDT in a Heavily Treated Area of Yugoslavia. World Health Organization Bulletin, 22, 515-518. Lice. Mayo Clinic, 2012. http://www.mayoclinic.com/health/lice/DS00368/DSECTION=symptoms Parasites – Lice. CDC, 2012. http://www.cdc.gov/parasites/lice/index.html.

32. References (Cont.) Raoult, D. et al. Jail Fever (epidemic typhus) outbreak in Burundi. Emerging Infectious Diseases, 1997. 3(3) 357-360. Reed, D. L., Light, J. E., Allen, J. M., & Kirchman, J. J. (2007). Pair of lice lost or parasites regained : the evolutionary history of anthropoid primate lice. BMC Biology, 11, 1-11. doi:10.1186/1741-7007-5-7 Travis, J. (2003). The Naked Truth? Lice Hint at a Recent Origin of Clothing. Science News, 164, 118. Weindling, P. (2000). Epidemics and Genocide in Eastern Europe, 1890-1945. Oxford University Press.