Lice Infection Research Articles

Does ozone have any effect on daily hospital admissions for circulatory diseases?

Treatment of head louse infection is primarily through topical insecticides. However, there is growing evidence of resistance. A representative population sample was tested using biochemical and molecular methods; it was...

The physiological effects of salmon lice (Lepeophtheirus salmonis) infections on returning post-smolt sea trout (Salmo truttaL.) in western Ireland, 1996

The physiological impact and pathological effect of salmon lice Lepeophtheirus salmonis (Kroyer, 1837), on wild sea trout Salmo trutta L., was investigated in 10 rivers in Western Ireland. No skin damage was apparent on fish with mobile pre-adult and adult lice, but severe fin erosion was recorded in many of the fish that were infected with chalimus stages. The attached copepodid and chalimus stages of the parasite did not reduce the physiological performance of the sea trout although there was a significant reduction in total protein, serum albumin and cholesterol in fish with mobile stages compared with fish with attached stages only and fish with no lice. This may reflect the feeding history of the fish, as most of the fish with mobile lice were from the same area, or the physiological effects of lice infections may be stage-specific.

Effects of salmon lice Lepeophtheirus salmonis on sea trout Salmo trutta at different times after seawater transfer.

The physiological and behavioural effects and skin damage caused by salmon lice Lepeophtheirus salmonis (Krøyer) infections on sea trout Salmo trutta L. smolts were greater in fish infected with lice 2 wk after seawater transfer than in fish infected 6 wk after seawater transfer. The initial prevalence of infection was 100% for both groups and the intensity of infection decreased significantly with time over 5 wk. Significantly fewer of the fish infected 2 wk after seawater transfer had resumed feeding by the end of the experiment, leading to a loss of body condition. Furthermore, these fish suffered more severe damage to the skin and detrimental changes in physiological integrity than fish infected 6 wk after seawater transfer as a direct consequence of feeding preadult lice, leading to osmoregulatory failure and death. Although this study was carried out in laboratory conditions, results indicate that lice infections may potentially have a detrimental impact on the survival of wild smolts after seawater transfer.

Comparison of the susceptibility of sea trout (Salmo trutta L.) and Atlantic salmon (Salmo salar L.) to sea lice (Lepeophtheirus salmonis (Krøyer, 1837)) infections

The relative susceptibility of sea trout (Salmo trutta L.) and Atlantic salmon (Salmo salar L.) to sea lice infections was investigated under experimental conditions. Skin damage was described for both sea trout and Atlantic salmon, associated with the accumulation of feeding copepodids and chalimus on the dorsal fin and the settlement patterns of the pre-adult and adult lice, on the head and operculum, dorsal ridge, and behind the anal fin. Attachment and survival of chalimus stages were significantly lower on Atlantic salmon than on sea trout because of non-selective settlement of the copepodids, followed by differential mortality. The survival of pre-adult and adult sea lice declined more rapidly on sea trout than on Atlantic salmon, but ultimately, Atlantic salmon had a lower abundance of lice than sea trout. Two possibilities were considered to explain the differences in skin damage—parasite numbers and distribution of lice between sea trout and Atlantic salmon. A greater antibody response by Atlantic salmon to sea lice infection may indicate an immunological strategy rather than the possible behavioural adaptation of a freshwater return by infected sea trout. Alternatively, differences may reflect the parasite's adaptation to the host's migratory patterns in order to enhance survival of the sea lice population.

The physiological effects of salmon lice infection on post-smolt of Atlantic salmon

The physiological effects of salmon lice infection on post-smolt of Atlantic salmon

Superinfection and the evolution of parasite virulence

Earlier ideas that parasites evolve toward becoming harmless to their hosts have, in recent years, given way to more analytic studies, focused on the 'basic reproductive rate', R0, of individual parasites. In general, the biology of the parasite life cycle will lead to constraining relations between virulence (parasite-associated host death or reduction in fertility) and transmissibility: the maximum R0 may then be attained by virulence being high, or low, or at some intermediate level, depending on the details of the constraining relations. Such studies have not generally included superinfection (where an already-infected host is infected by another parasite). Here we propose a general, but simple, model of superinfection, which is amenable to analytical treatment. In such models selection does not simply act to maximize R0; superinfection leads to selection for higher levels of virulence, highly polymorphic parasite populations and very complicated dynamics. We calculate the equilibrium distribution of parasite strains and the maximum level of virulence that can be maintained by superinfection. We also note the equivalence between our 'superinfection model' and recent approaches to the study of the meta-population dynamics of multi-species interactions.

A Comparison of Two Insecticidal Shampoos in the Treatment of Head Louse Infection

The efficacy and tolerability of a phenothrin liquid shampoo was compared with a carbaryl shampoo in 50 children with head lice infection. Twenty-five children were treated with a phenothrin liquid shampoo and 25 with a carbaryl shampoo. Each treatment was applied on three occasions at three-day intervals. Reinspection two weeks after initiation of treatment revealed two apparent treatment failures in the carbaryl group and one in the phenothrin group. No side effects were reported for either treatment. It is concluded that phenothrin liquid shampoo is a safe and effective treatment for head louse infection and is therefore a useful addition to those insecticides currently employed.

Comparison of Phenothrin Shampoo and Malathion Lotion in the Treatment of Head Louse Infection

Eighty patients (age range 4-10 years) with head lice infection were recruited to the study. Forty patients were treated with a single application of 0.2% w/v phenothrin liquid shampoo and 40 with 0.2% w/v malathion lotion. Inspection of the patients one week later revealed that no live lice remained in either group, but that two patients had viable eggs in the malathion lotion group. Re-inspection four weeks after application revealed that five patients of the phenothrin shampoo group and seven of the malathion lotion group had viable eggs. Live lice were not seen to be present in either treatment group. The results indicate that both products are effective in the treatment of head lice infection and that the phenothrin shampoo would be a useful addition to the insecticides currently employed.

Pediculosis

One of the most annoying but least serious diseases affecting man is infestation with lice. Three types of louse infections are known, but only the body louse carries disease. The others are a concern more for reasons of personal cleanliness than for the seriousness of the diseases they produce.

Trimethoprim-sulfamethoxazole in the treatment of malaria, toxoplasmosis, and pediculosis.

The status of trimethoprim-sulfamethoxazole (TMP-SMZ) as a chemotherapeutic agent for malaria, toxoplasmosis, and pediculosis is reviewed. The use of TMP-SMZ may be advocated for the treatment of malaria when concurrent bacterial infections are present or when conventional antimalarial agents are not available. Present evidence suggests that TMP-SMZ is effective in the treatment of toxoplasmosis; however, its role in treatment of this disease requires study. Although TMP-SMZ can eliminate head louse infections, topical insecticidal preparations are the preferred treatment.