Benchmarks for lice management

Public Health Significance of Urban Pests 297 to transmit disease. The widespread distribution of homeless people with positive sero- logy for trench fever indicates that this disease is probably transmitted regularly when lousy individuals come in contact with and are exposed to infected louse faeces Jackson Spach, 1996. This also indicates that infestation with body lice may be widespread and that, as there is no mechanism for monitoring the infestation due to the withdrawal of appropriate environmental health services, the level of lousiness in society may be consi- derably higher than previously thought. It is unlikely that epidemic typhus or LBRF could enter Europe or North America under current conditions, although individual cases, resulting from travel to endemic areas, could arise; in those circumstances, howe- ver, onward transmission would be highly unlikely. Unforeseen social disruptions in the future, however, could alter this position.

9.9. Conclusions

The majority of environmental health and public health workers currently consider body lice a low priority. The exception to this is a small group of investigators who have iden- tified residual body louse populations as potentially active vectors of disease causing orga- nisms, mainly rickettsiae – some of which are zoonotic. The survival of both body lice and the diseases they have carried for the past half century, despite intensive efforts to eradicate them in the middle of the 20th century, indicates that they are not in decline. Indeed, the limited and often anecdotal information about body louse infestation in populations in high- and middle-income countries suggests that levels of infestation are increasing slowly, despite various efforts to reduce poverty and deprivation. Irrespective of the possibility of body louse prevalence increasing, the risk of disease trans- mission to a larger segment of the populace remains, because rickettsial organisms are spread primarily by dried faecal matter that can drift on air currents from the clothing of infested individuals to others in the vicinity that are not infested. Any services directed towards the homeless also require some matched services for the remainder of society, because body lice carry a greater stigma than other infestations and because the public facilities established long ago for dealing with this infestation have now disappeared from most countries. To reduce the risk of disease from body louse infestations, some policy options should be consi- dered by environmental and public health services as a first stage of the process: • make voluntary organizations that offer assistance to homeless and vagrant people more aware of body lice and their disease vector capacity; • monitor lousiness through medical services directed towards the homeless community, especially when an infestation is associated with febrile illness; • advise the homeless about louse-borne disease, with the aim to encourage them to seek help; • increase the availability of treatment options for lousiness – such as disinfestation or replacement of clothing, the use of impregnated materials, and possibly group iver- mectin therapy Foucault et al., 2006 – to reduce the prevalence of lice; and Human body lice 296 control, although the actual resistance of body lice throughout most of the world is cur- rently completely unknown. Following the use of pyrethrin and DDT in controlling outbreaks of louse-borne typhus in North Africa and central Italy during the Second World War, neurotoxic insecticides – first DDT, then lindane, followed by malathion and permethrin – became the treat- ments of choice until resistance rendered most of them ineffective in mass treatment pro- grammes Hurlburt, Altman Nibley, 1952; Kitaoka, 1952; Nicoli Sautet, 1955; Miller et al., 1972; Cole et al., 1973; Sholdt et al., 1977; Gratz, 1985.

9.7.3.1. Impregnated fabric

Fabrics impregnated with insecticides are one way to prevent or restrict body louse infes- tations. Where deemed a viable option, treating the garments of people likely to be affec- ted is the approach of choice. For example, among other functions, impregnation of mili- tary uniforms with permethrin may help to prevent their infestation should exposures arise – say, through contact with refugees or prisoners of war who have acquired a body louse infestation. Impregnation of clothing of so-called at-risk groups, such as vagrants in high- and middle-income communities or people living in areas where body louse infestation is endemic, is often impractical, as it is usually easier to provide alternative means of control – for example, by offering replacement clothing or by treating garments with heat. Under some circumstances, it may be possible to use impregnation as a control measure – for example, under conditions of social disruption. Products applied to skin are inappropriate for control of body lice, as the insects colonize clothing rather than the skin.

9.8. Benchmarks for lice management

All efforts to treat louse infestations are expected to achieve 100 success. Survival of a single insect constitutes failure. However, the validation of a cure is not clear and has spawned ideas that may result in inappropriate actions, such as insistence on the remo- val of every louse eggshell after head louse treatment before children can return to school. When such an approach has been applied rigorously, despite other potential measures of effectiveness being available, it has had considerable social and economic impact in such countries as the United States Williams et al., 2001. The threat of louse infestation is perceived differently in different societies and cultures. In the high- and middle-income countries, it often results in stigmatization. The public perception of lice as an important health topic greatly outweighs their impor- tance in real terms. From a practical clinical viewpoint, lice do not constitute a major threat to public health, unless normal sanitation measures break down and the risk of disease transmission increases, as in a natural disaster. Recent studies indicate that lice have been underestimated or overlooked as vectors able Public Health Significance of Urban Pests 299 References 1 British Department of Health and Social Security DHSS 1987. Department of Health and Social Security 1986 statistics. In: School health surveillance by nurses. London, DHSS Statistics Division: section 8mi. Burgess IF 2004. H uman lice and their control. Annual Review of Entomology, 49:457–481. Burgess IF, Brown CM 1999. Management of insecticide resistance in head lice Pediculus capitis Anoplura: Pediculidae. In: Robinson WH , Rettich F, Rambo GW, eds. Proceedings of the 3rd International Conference on Urban Pests, 19–22 July 1999, Prague, Czech Republic . Hronov, Czech Republic, Grafické Závody:249–253. Busvine JR 1978. Evidence from double infestations for the specific status of human head and body lice Anoplura. Systematic Entomology, 3:1–8. Buxton PA 1947. The louse, 2nd edn. London, Edward Arnold Company. Cole MM et al. 1973. Resistance to malathion in a strain of body lice from Burundi. Journal of Economic Entomology , 66:118–119. Downs AMR, Harvey I, Kennedy CTC 1999. The epidemiology of head lice and sca- bies in the UK. Epidemiology and Infection, 122:471–477. Drancourt M et al. 1995. Bartonella Rochalimaea quintana endocarditis in three home- less men. The New England Journal of Medicine, 332:419–423. Evans FC, Smith FE 1952. The intrinsic rate of natural increase for the human louse Pediculus humanus . The American Naturalist, 86:299–310. Fisher RI, Morton RS 1970. Phthirus pubis infestation. The British Journal of Venereal Diseases , 46:326–329. Foucault C et al. 2006. Oral ivermectin in the treatment of body lice. T he Journal of Infectious Diseases , 193:474–476. Fournier PE et al. 2002. Human pathogens in body and head lice. Emerging Infectious Diseases , 8:1515–1518. Gratz NG 1985. Epidemiology of louse infestations. In: Orkin M, Maibach HI, eds. Cutaneous infestations and insect bites. New York, Marcel Dekker:187–198. Human body lice 298 • evaluate treatment options by recording the number of cases for each district. It is unlikely that any policy is going to eliminate body lice or any other human lice, but reducing the risk of possible disease transmission should have a recognized priority, espe- cially as incidents of infection in the general population make diagnosis, in the absence of infestation, a relatively prolonged and costly process. Even where infections due to Bartonella bacilli and other rickettsial microorganisms are derived from flea, cat scratch or other zoonotic sources, it is possible that further transmission could occur via body lice in infested homeless Jackson Spach, 1996; Jacomo et al., 2002. 1 The literature review conducted for this chapter is not intended to be a comprehensive review of the scientific literature. The refe- rences cited are as extensive as possible for a general overview of the subject. Whenever available, data presented in peer-reviewed articles were considered. In some cases, however, it was necessary to refer to other sources of nonetheless trustworthy origin. Public Health Significance of Urban Pests 301 Nuttall GHF 1917. The biology of Pediculus humanus. Parasitology, 10:80–185. Nuttall GHF 1918. Combating lousiness among soldiers and civilians. Parasitology, 10:411–586. Peacock AD 1916. The louse problem at the Western Front. Journal of the Royal Army Medical Corps , 27:31–60. 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Jackson LA, Spach DH 1996. Emergence of Bartonella quintana infection among home- less persons. Emerging Infectious Diseases, 2:141–144. Kitaoka M 1952. DDT-resistant louse in Tokyo. Japanese Journal of Medical Science Biology , 5:75–88. Kondaj R 2002. Management of refugee crisis in Albania during the 1999 Kosovo conflict. Croatian Medical Journal, 43:190–194. Kristensen M et al. 2005. Survey of permethrin and malathion resistance in human head lice populations from Denmark. Journal of Medical Entomology, 43:533–538. Lang JD 1975. Biology and control of the head louse, Pediculus humanus capitis Anoplura: Pedciculidae in a semi-arid urban area [PhD thesis]. Tucson, University of Arizona. Leeson HS 1941. The effect of temperature upon the hatching of the eggs of Pediculus humanus corporis De Geer Anoplura. Parasitology, 33:243–249. Lindsay SW 1993. 200 Years of lice in Glasgow: an index of social deprivation. Parasitology Today , 9:412–417. Lloyd L 1919. Lice and their menace to man. London, Henry Frowde, Oxford University Press. MacLeod J, Craufurd-Benson HJ 1941. Casual beds as a source of louse infestation. Parasitology , 33:211–213. Meinking TL 1999. Infestations. Current Problems in Dermatology, 11:73–120. Mellanby K 1941. The incidence of head lice in England. Medical Officer, 65:39–42. Mellanby K 1943. The incidence of head lice in England after four years of war. Medical Officer , 70:205–207. Miller RN et al. 1972. First report of resistance of human body lice to malathion. Transactions of the Royal Society of Tropical Medicine and Hygiene , 66:372–375. Nicoli JL, Sautet J 1955. Rapport sur la fréquence et la sensibilité aux insecticides de Pediculus humanus humanus L . dans le sud-est de la France . Paris, Institut National d’Hygiene Monographie de l’Institut National d’Hygiene Paris, No. 8. Public Health Significance of Urban Pests 303

10. Ticks

Howard S. Ginsberg and Michael K. Faulde Summary The most common vector-borne diseases in both Europe and North America are trans- mitted by ticks. Lyme borreliosis LB, a tick-borne bacterial zoonosis, is the most highly prevalent. Other important tick-borne diseases include TBE tick-borne encephalitis and Crimean-Congo haemorrhagic fever in Europe, Rocky Mountain spotted fever RMSF in North America, and numerous less common tick-borne bacterial, viral, and protozoan diseases on both continents. The major etiological agent of LB is Borrelia burg- dorferi in North America, while in Europe several related species of Borrelia can also cause human illness. These Borrelia genospecies differ in clinical manifestations, ecology for example, some have primarily avian and others primarily mammalian reservoirs, and transmission cycles, so the epizootiology of LB is more complex in Europe than in North America. Ticks dwell predominantly in woodlands and meadows, and in association with animal hosts, with only limited colonization of human dwellings by a few species. Therefore, suburbanization has contributed substantially to the increase in tick-borne disease trans- mission in North America by fostering increased exposure of humans to tick habitat. The current trend toward suburbanization in Europe could potentially result in similar increases in transmission of tick-borne diseases. Incidence of tick-borne diseases can be lowered by active public education campaigns, targeted at the times and places of grea- test potential for encounter between humans and infected ticks. Similarly, vaccines e.g., against TBE are most effective when made available to people at greatest risk, and for high-prevalence diseases such as LB. Consultation with vector-borne disease experts during the planning stages of new human developments can minimize the potential for residents to encounter infected ticks e.g., by appropriate dwelling and landscape design. Furthermore, research on tick vectors, pathogens, transmission ecology, and on geogra- phic distribution, spread, and management of tick-borne diseases can lead to innovative and improved methods to lower the incidence of these diseases. Surveillance programs to monitor the distribution and spread of ticks, associated pathogens, and their reservoirs, can allow better-targeted management efforts, and provide data to assess effectiveness and to improve management programs.