Strongyloidiasis

Strongyloidiasis is a

Strongyloidiasis is a type of soil-transmitted helminthiasis. Low estimates postulate it to affect 30–100 million people worldwide,^[1] mainly in tropical and subtropical countries, while higher estimates conservatively extrapolate that infection is upwards to or above 370 million people.^[2] It belongs to the group of neglected tropical diseases, and worldwide efforts are aimed at eradicating the infection.^[3]

Signs and symptoms

Strongyloides infection occurs in five forms. As the infection continues and the larvae matures, there may be respiratory symptoms (Löffler's syndrome). The infection may then become chronic with mainly digestive symptoms. On reinfection (when larvae migrate through the body) from the skin to the lungs and finally to the small intestine, there may be respiratory, skin and digestive symptoms. Finally, the hyperinfection syndrome causes symptoms in many organ systems, including the central nervous system.^[4][5]

Uncomplicated disease

Frequently

It is important to note that there is not necessarily any eosinophilia in the disseminated disease. Absence of eosinophilia in an infection limited to the gastrointestinal tract may indicate poor prognosis.[13] Eosinophilia is often absent in disseminated infection. Steroids will also suppress eosinophilia, while leading to dissemination and potential hyperinfection.^{[citation needed]}

Escalated disseminated infections caused by immunosuppression can result in a wide variety and variable degree of disparate symptoms depending on the condition and other biological aspects of the individual, that may emulate other diseases or diagnoses. In addition to the many palpable gastrointestinal and varied other symptoms drastic cachexia amidst lassitude is often present, although severe disseminated infections can occur in individuals without weight loss regardless of body mass index.^{[citation needed]}

Diagnosis

The stool can be examined in wet mounts:^{[citation needed]}

• directly
• after concentration (formalin-ethyl acetate)
• after recovery of the larvae by the Baermann funnel technique
• after culture by the Harada-Mori filter paper technique
• after culture in agar plates

Culture techniques are the most sensitive, but are not routinely available in the West. In the UK, culture is available at either of the Schools of Tropical Medicine in Liverpool or London. Direct examination must be done on stool that is freshly collected and not allowed to cool down, because hookworm eggs hatch on cooling and the larvae are very difficult to distinguish from Strongyloides.^{[citation needed]}

Finding Strongyloides in the stool is negative in up to 70% of tests. It is important to undergo frequent stool sampling as well as duodenal biopsy if a bad infection is suspected. The duodenal fluid can be examined using techniques such as the Enterotest string or duodenal aspiration.^[15] Larvae may be detected in sputum from patients with disseminated strongyloidiasis.^{[citation needed]}

Given the poor ability of stool examination to diagnose Strongyloides, detecting

It would be greatly useful to have significant advances in the sensitivity of the means of diagnosis, as it would also solve the challenging problem of proof of cure. If definitive diagnosis is solved then it stands to reason that proof of cure becomes easily realizable.[19]

Treatment

The consensus drug of choice for the treatment of uncomplicated strongyloidiasis is

Treatment of strongyloidiasis can be difficult and if ceasing treatment before being entirely cleared Strongyloides via the autoinfective cycle has been known to live in individuals for decades;[22] even after initial or inadequate sustained treatment. Continued treatment, blood and stool monitoring thus may be necessary even if symptoms temporarily resolve. As cited earlier, due to the fact that some infections are insidiously asymptomatic, and relatively expensive bloodwork is often inconclusive via false-positives or false-negatives,^[23] just as stool samples can be unreliable in diagnoses,^[24] there is yet unfortunately no real gold standard for proof of cure, mirroring the lack of an efficient and reliable methodology of diagnosis.^[4][19][25] An objective eradication standard for strongyloidiasis is elusive given the high degree of suspicion needed to even begin treatment, the sometimes difficulty of the only definitive diagnostic criteria of detecting and isolating larvae or adult Strongyloides, the importance of early diagnosis, particularly before steroid treatments,^[26] and the very wide variability and exclusion/inclusion of differing collections of diffuse symptoms. Disregarding mis-ascribing bonafide delusional parasitosis disorders,^[27][28][29] strongyloidiasis should be more well known among medical professionals and have serious consideration for broad educational campaigns in effected geographic locales both within the semi-tropical developed world and otherwise, as well as in the tropical developing world where, among many other neglected tropical diseases, it is endemic.^[30][31]

Government programs are needed to help decontaminate endemic areas and to help effected populations from infection.^[32] Furthermore, progress is required in establishing financial support to facilitate and cover affordable medications for individuals in effected at-risk regions and communities to help continuing treatments.^[33]

There are conflicting reports on effective drug treatments. Ivermectin ineffectiveness and rising

Low estimates postulate it to affect 30–100 million people worldwide,[1] mainly in tropical and subtropical countries, while higher estimates conservatively extrapolate that infection is upwards to or above 370 million people.^[2] It belongs to the group of neglected tropical diseases, and worldwide efforts are aimed at eradicating the infection.^[3]

History

The disease was first recognized in 1876 by the French physician Louis Alexis Normand, working in the naval hospital in Toulon; he identified the adult worms, and sent them to Arthur Réné Jean Baptiste Bavay, chief inspector for health, who observed that these were the adult forms of the larvae found in the stool. In 1883 the German parasitologist Rudolf Leuckart made initial observations on the life cycle of the parasite, and Belgian physician Paul Van Durme (building on observations by the German parasitologist Arthur Looss) described the mode of infection through the skin. The German parasitologist Friedrich Fülleborn described autoinfection and the way by which strongyloidiasis involves the intestine. Interest in the condition increased in the 1940s when it was discovered that those who had acquired the infection abroad and then received immunosuppression developed hyperinfestation syndrome.^[46]

References