The Black Death and Other Pandemics
Scott M. Jackson in Skin Disease and the History of Dermatology, 2023
Epidemic typhus is an infection with a bacterium called Rickettsia prowazekii that is transmitted from person to person by the human body louse; the bacterium resides in the feces of the louse. This louse is slightly different from the lice that infest the hair of schoolchildren. Instead, it infests the body and garments of persons of poor health and hygiene living in unclean conditions. Scratching the louse bites causes the person to rub the louse feces into the wound, thus inoculating the body with the bacterium. The signs and symptoms of typhus include fever, chills, headache, rapid breathing, body aches, cough, nausea, vomiting, confusion, and a rash. The red, petechial rash starts on the torso and spreads outward to the arms and legs. The mortality rate of untreated epidemic typhus is anywhere from 10 to 60 percent; with antibiotics, the condition is uniformly survivable. Epidemic typhus should be distinguished from endemic (murine) typhus, which occurs worldwide and is spread by the rat flea, and typhoid, a febrile condition with red spots on the skin caused by S. typhi, made famous in the twentieth century by the life and career of “Typhoid Mary.”
Scabies and pediculosis
Robert A. Norman in Geriatric Dermatology, 2020
Lice are arthropods belonging to the order Phthiraptera (wingless insects). They include the suborder Anoplura (sucking lice) and the families Pediculidae and Phthiriidae. Two species of lice infest humans, Pediculus humanus and Pthirus pubis (pubic louse). Pediculus humanus is divided into 2 subspecies, Pediculus humanus capitis (head louse) and Pediculus humanus corporis (body louse). These subspecies have identical morphology, although the body louse tends to be larger, and the subspecies are interfertile. Interestingly, their differences may represent a response to environment: head lice grown on the body acquire the characteristics of body lice and vice versa21. Pediculosis refers to infestation with any of these parasites. There are no free-living forms of these insects, and they cannot survive on other animals. Lice are host-specific, and dog lice cannot infest humans, nor will human lice survive on pets.
Principles of Clinical Diagnosis
Susan Bayliss Mallory, Alanna Bree, Peggy Chern in Illustrated Manual of Pediatric Dermatology, 2005
Major pointsBody louse infestations present with excoriated papules and pustules on trunk and perineumPediculosis capitis usually presents with pruritic papules at nape of neck (Figure 10.5)Nits and lice can be detected in scalp or clothing, especially seams of clothingNits are white ovoid bodies, tightly adherent to hair shaftsHead lice are infrequent in Black patientsPubic lice (‘crabs’) occasionally with blue-black crusted macules (maculae ceruleae)Pubic lice can also be seen in eyelashes or the scalp of young children
Larvicidal activity of Zinc oxide and titanium dioxide nanoparticles Synthesis using Cuscuta reflexa extract against malaria vector (Anopheles stephensi)
Published in Egyptian Journal of Basic and Applied Sciences, 2020
The larvae of An. stephensi were found highly susceptible to the TiO2 NPs. The first and fourth instar larvae have shown the 100% mortality after 48 h of exposure. Whereas, the second instar (LC50 10 ppm) and third instar (LC50 50 ppm) larvae were observed with their probit equations and 95% confidential limit, R2, chi-square, and p value after 48 h (Table 1). No mortality was observed in the control group. The larvicidal activity of titanium dioxide nanoparticles (TiO2 NPS) synthesized from the root aqueous extract of M. citrifolia against the larvae of An. stephensi, Ae. aegypti and Cx. quinquefasciatus has been assessed [17]. The biosynthesized TiO2 NPS showed maximum activity against the larvae of An. stephensi, Ae. aegypti and Cx. quinquefasciatus when compared to the aqueous extract of M. citrifolia. Similarly, the anti-parasitic activity of TiO2 NPs against the larvae of R. microplus, H. anatolicum anatolicum and H. bispinosa, fourth instar larvae of An. subpictus, and Cx. quinquefasciatus has been assessed by [16]. The maximum efficacy was observed in synthesized TiO2 NPs against the larvae of R. microplus, H. anatolicum anatolicum, H. bispinosa, An. subpictus, and Cx. quinquefasciatus with LC value of 28.56, 33.17, 23.81, 5.84, and 4.34 mg/L, respectively. Recently, the larvicidal and the pediculicidal activity of synthesized titanium dioxide nanoparticles (TiO2 NPs) using the leaf aqueous extract of V. negundo against the fourth instar larvae of the malaria vector, An. subpictus Grassi and filariasis vector, Cx. quinquefasciatus Say and the head louse, P. humanus capitis De Geer have been carried out by [18]. The maximum activity has been observed in the synthesized TiO2 NPs against An. subpictus, Cx. quinquefasciatus and lice, (LC50 = 7.52, 7.23, and 24.32 mg/L; χ2 = 0.161, 2.678, and 4.495; r2 = 0.663, 0.742, and 0.924), respectively.
Related Knowledge Centers
- Molecular Clock
- Obligate Parasite
- Parasitism
- Typhus
- Clade
- Host
- Disease Vector
- Head Louse
- Body Louse
- Pediculus Humanus