References

Abbas K, el Toum IA, Hassan AM (1992). Oral leishmaniasis associated with kala-azar. A case report. Oral Surg Oral Med Oral Pathol 73 583-4. Addy M, Nandy A (1992). Ten years of kala-azar in west Bengal, Part I. Did post-kala-azar dermal leishmaniasis initiate the outbreak in 24-Parganas Bull World Health Org 70 341-6. Akuffo H, Darce M, Maasho K, Berhan TY (1995). In vivo evaluation of immune responses in leishmaniasis the use of cross-species leishmanin preparations for skin testing. Am J...

Info

From Anderson and May (1991), with permission. From Anderson and May (1991), with permission. most bacterial and viral infections. It implies that no infection can maintain itself unless R0 is greater than unity. In practice, we observe that the values of R0 for some common infections are in the range 318 (Table 2.1). This implies that a primary case of measles, say, can infect 11-17 other people during the course of the primary infection, and that the 11-17 secondary cases can each do the...

Clinical Features

Primary Amebic Meningoencephalitis due to Naegleria fowleri PAM is an acute, rapidly progressing illness. It is characterized by bifrontal or bitemporal headaches, fever, nausea, vomiting and stiff neck. The symptoms progress rapidly, leading to lethargy, confusion, coma and, in most cases, to death in a few hours. Seizures, and sometimes abnormalities in taste or smell and ataxia, may be seen. Nuchal rigidity with positive Kernig's and Brudzinski's signs may be present. Photophobia may be...

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Table 19c.1 Summary of non-human migrating helminths Table 19c.1 Summary of non-human migrating helminths Cutaneous larva migrans Eosinophilic enteritis 10 thiabendazole paste with occlusive 10 thiabendazole paste with occlusive dressing inflammatory lesions Visceral disease pulmonary, myelitis-encephalitis, ocular Clinical features, biopsy, antibody capture EIA CSF eosinophilic antibody capture EIA Clinical features, CT scan, excision Chest X-ray, eosinophilia and antibody capture EIA History...

Immunology

Great strides have been made toward understanding the immunology of leishmanial infections during the past two decades (Locksley and Louis, 1992 Reiner and Locksley, 1993 Scharton-Kersten and Scott, 1995). The life cycle has been reproduced entirely in vitro, genetically susceptible and resistant inbred strains of mice have been used to explore the immunogenetics of murine infection, and the immunology of human disease has been studied in a number of endemic areas. The findings indicate that...

Therapy

Drugs with Anti-leishmanial Activity The optimal treatment of leishmaniasis depends on the infecting Leishmania sp. and the clinical syndrome (Pearson and Sousa, 1996 Berman, 1997). Pentavalent antimony (Sbv)-containing drugs, sodium stibogluconate (Pentostam) and meglumine antimonate (Glucantime) have been the mainstay of therapy for decades, but untoward effects are common and therapeutic failures have been increasingly recognized (Grogl et al, 1992 Herwaldt and Berman, 1992). Amphotericin B...

Pathogenesis And Clinical Significance

Almost all of the organs of the human body can be infected by one or more of the spectrum of 14 microsporidian species described in the previous section. Many tissues and cell types are involved (Table 8.1). According to site of infection, clinical manifestations may be diarrhoea, weight loss, cholecystitis, cholangitis, bronchitis, bronchiolitis, pneumonitis, sinusitis, rhinitis, hepatitis, peritonitis, nephritis, ureteritis, cystitis, urethritis, prostatitis, keratoconjunctivitis, corneal...

Estimating The Burden Of Parasitic Disease

Parasitic infections are amongst the most ubiquitous of infections of humans. The first estimates of the global extent of infection suggested that more than a quarter of the world's population was infected with one or more important pathogen at any one time (Stoll, 1947) and the latest estimates suggest the same conclusion (Chan et al, 1994a Michael et al., 1996 Bundy, 1998 WHO, 1997). In Table 2.2 we show the most current estimates of some of the major parasitic infections of humans. But...

Clinical Management

The treatment of B. hominis infections remains controversial, particularly in light of its uncertain pathogenicity. Strong opinions have been expressed regarding the use of potentially dangerous chemotherapeutic agents to treat B. hominis, particularly without a thorough investigation of other possible causes of symptoms (Markell and Udkow, 1990 Markell, 1995). Additionally, there is some evidence that infection may be self-limiting in some cases, and intervention may not be required (Sun et...

Development Of Helminthology

The first description of this helminthic infection has been attributed to Moses in the Book of Numbers (Foster, 1965) the Israelites were at that time living in the Gulf of Akaba. The Papyrus Ebers (Nunn, 1996) also describes probable dracontiasis there were also several convincing reports during the Middle Ages. However, the first scientific descriptions were by British Army medical officers serving in India during the early years of the nineteenth century (Foster, 1965), suggesting that the...

The Future Vaccination

With CE, some authorities consider that vaccination of livestock, particularly sheep, may be a useful approach where reinfection of livestock is likely to occur from outside the control area (Heath and Lightowlers, 1997). The recent development of an effective recombinant vaccine against ovine echinococcosis (Lightowlers et al., 1996) may thus provide a useful adjunct in control programmes. The vaccine is currently being trialled in a number of geographical areas where CE is endemic, in order...

Treatment

With newer definitions of clinical syndromes in lymphatic filariasis and new tools to assess clinical status (e.g. ultrasound, lymphoscintigraphy, circulating filarial antigen assays), approaches to treatment based on infection status and pathogenesis have been proposed (Addiss and Dreyer, 1999). These changing perspectives of lymphatic filariasis have important implications for treatment. In areas where lymphatic filariasis is endemic, most infected persons are clinically asymptomatic despite...

Nonspecific Immunity and Innate Resistance

Individuals vary in their susceptibility to consequences of malaria infection. A proportion of individuals in an endemic area die from disease, but the majority develop clinical immunity that protects them throughout life in the presence of continued exposure. Children may survive several episodes of clinical or asymptomatic infection before succumbing to P. falciparum malaria. In model systems, 'non-specific' immunity can be induced with immune stimulants such as Corynebacterium parvum or BCG,...

Pathogenesis

The majority of lesions of onchocerciasis are caused by the host's inflammatory response to dead and dying microfilariae. These dying microfilariae cause local inflammation, leading to damage to surrounding tissues, which accumulates and produces the pathological features of the disease. Early skin changes include perivascular inflammatory infiltrates of eosinophils, plasma cells, histiocytes and lymphocytes hyperkeratosis acanthosis, with increased melanin in the upper dermis and dilated...

Vn

An area of necrosis with perivascular inflammatory infiltrate and clusters of intracellular tachyzoites (arrow). Extracellular tachyzoites are more difficult to distinguish from fragments of necrotic cells. Haematoxylin and eosin stain. Bar 50 m Frenkel, 1973, 1988). In mice fed bradyzoites, the first step appears to be local invasion of the small intestinal epithelium. The bradyzoite and tachy-zoite are both capable of active invasion of many cell types, and...

Epidemiology

The majority of cases of echinostomiasis in humans occur in Asia, including Indonesia, Thailand, The Philippines, Taiwan, Japan, Korea, China, Malaysia and Singapore (Table 24.1). In addition, there have been reports of infection from Africa, Brazil, Romania, Russia, Italy and Egypt. Ingestion of molluscs, fish, clams or amphibians is the major risk factor. While most areas surveyed have low infection Fig. 24.3 Intestinal trematode eggs. (A) Fasciolopsis buski, average size 130-140x80-85 m. (B)...

Clinical Manifestations

Leishmaniasis is a spectral disease (Pearson and Sousa, 1996). The clinical manifestations depend on complex interactions between the virulence characteristics of the infecting Leishmania spp. and the genetically determined cell-mediated immune responses of its human host. There are three major clinical syndromes cutaneous, mucosal or visceral leishmaniasis. Variations occur in each of these, and many Leishmania spp. can cause more than one syndrome. In simple cutaneous leishmaniasis, lesions...

Description Of The Organism

Morphological description of Strongyloides stercoralis is based on the work of Little (1966) and Speare (1986). These works have been thoroughly reviewed by Speare (1989), Schad (1989) and Grove (1996). Clinical parasitologists may never encounter a parasitic female (Figure 18c.l) of S. stercoralis throughout their careers, since this stage is very seldom seen in the stool and was to be removed from the intestine using special techniques. They may, however, be found in patients with very severe...

Clinical Disease

Schistosomes are well adapted to the human host and generally establish a balanced host-parasite relationship. As a result, the majority of infected people are asymptomatic or have only mild nonspecific symptoms. Severe symptoms and major clinical sequelae occur in approximately 10-15 of the infected populations without treatment. The life expectancy of patients with mild schistosomiasis is probably not substantially shorter than that of uninfected individuals living in the same geographic...

References Parasitology

Anthelmintic effects of levamisole, ivermectin, albendazole and fenbendazole on larval Toxocara canis infection in mice. Res Vet Sei 36 8791. Abo-Shehada MN, Sharif L, El-Sukhon SN, Abuharfeil N, Atmeh RF (1992). Seroprevalence of Toxocara canis antibodies in humans in Northern Jordan. J Helminthol 66 75-8. Akao N, Desowitz RS, Kondo K (1990). Decrease in litter size of female mice with Toxocara canis. Trans R Soc Trop Med Hyg 84 724. Arpino C, Curatolo P...

Therapy And Management Of Toxoplasmosis

Drugs for Treatment of Toxoplasmosis The major drugs used for the therapy of toxoplasmosis are targeted at the folate pathway of the parasite. The best-established regimen is a combination of pryrimethamine and sulfadiazine. Both of these agents inhibit parasite folate metabolism. Pyrimethamine in adults should be started with a loading dose of 100-200 mg over 1 day in divided doses, followed by a daily dose of 25-100 mg day for 3-4 weeks. The drug is available only in 25 mg tablets, is well...

Development Of Protozoology

Protozoology Babes

The development of this discipline was totally dependent on the introduction of satisfactory microscopes Cole, 1926 . Although Gesner was probably the first to visualise a protozoan parasite in 1565, it was a century later that Robert Hooke 1635-1703 produced a diagram in his Micrographia. The birth of protozoology as a science was, however, due to van Leeuwenhoek Dobell, 1932 Figure 1.4 who, in 1674, visualised free-living ciliates in fresh water he later described cysts of Eimeria stediae in...

Clinical Management And Prevention

In immunocompetent people microsporidial infections are likely to be self-limiting and require no treatment but chemotherapy can be given if necessary. In immunocompromised people, E. bieneusi causes chronic disorders diarrhoea, cholecystitis, etc. and, in the absence of any really effective drug, only palliative measures, such as non-specific antidiarrhoeal medication are useful. Microsporidioses due to the Encephalitozoon spp. are progressive, with potentially fatal outcome if untreated. The...

Intestinal Nematodes and Cognitive Function

Intestinal nematodes have been identified as a major source of chronic ill-health, compromising the growth potential and intellectual achievements of children throughout the world. This association was first suggested by a study early in the twentieth century that demonstrated a correlation between helminth infection and the educational achievements of school children Stiles, 1902 . Children with hookworm infection and, to a lesser extent, Ascaris, developed more slowly at school and had a...

Pathogenesis And Immunology

Clinical illness with Giardia results from the interaction of an individual Giardia isolate with the human host and the host's subsequent response to the parasite. The precise pathogenic mechanisms are not known but appear to be multifactorial. Contribution of the Parasite to Disease Following oral ingestion of as few as 10-25 Giardia cysts Rendtorff, 1954 , there is ex-cystation, multiplication of trophozoites and colonization of the small bowel. In murine models of Giardia muris infection,...

Historical Background

Strongyloides stercoralis might be described as 'the military worm'. It was first described by a military physician in soldiers returning from war and in recent times much work on diagnosis, immunology and epidemiology has been conducted on veterans of World War II and Vietnam. Louis Normand 1876 first described Strongyloides stercoralis in French soldiers returning from Cochin China now Vietnam , who were suffering intractable diarrhoea. This was an important breakthrough, since at last a...

History Of Parasitology

Dracunculus Medinensis Life Cycle

The first description of the microfilariae of Onchocerca volvulus was probably made by O'Neill 1875 from samples taken from the skin of six West African natives with papular skin rashes. He described the microfilaria as . . . easily detectable by its violent contortions. Thread-like in form, at one time undulating, and now twisted as if into an inexplicable knot, then, having rapidly untwined itself, it curls and coils into many loops. This evocative description is readily recognised by those...

Blastocystis Hominis Ninos Cuba

Use of Hemo-De to eliminate toxic agents used for concentration and trichrome staining of intestinal parasites. J Clin Microbiol 30 1893-5. Albrecht H, Stellbrink HJ, Koperski K, Greten H 1995 . Blastocystis hominis infection in human immunodeficiency virus-related diarrhea. Scand J Gastroenterol 30 909-14. Al-Tawil YS, Gilger MA, Gopalakrishna GS, Langston C, Bommer KE 1994 . Invasive Blastocystis hominis infection in a child. Arch Pediatr Adolesc Med 148 882-5....