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Infections Acquired Percutaneously


Soil

There are estimated to be billions of microorganisms in a handful of soil, so it might be considered surprising that it does not serve as a source for more pathogens. Indeed, given that soil cannot be decontaminated globally, and thus soil-acquired infections like tetanus can never be eradicated, this is fortunate. ‘Soil-transmitted helminths’ (STHs) is the collective term (interchangeable with ‘geohelminths’) applied principally to three intestinal nematode infections for which egg-contaminated soil plays an important lifecycle role: roundworm ( Ascaris lumbricoides ), whipworm ( Trichuris trichiura ) and hookworms ( Ancylostoma duodenale and Necator americanus ). However, the term can be confusing, as the former two are acquired through ingestion of food or water contaminated by helminth eggs from the soil (and therefore described in Chapter 3 ), whereas hookworm larvae enter the human body through the skin by direct contact. Though Strongyloides stercoralis is acquired in a similar fashion to hookworm and is thus strictly speaking an STH, it is rarely considered as part of this group because of lower prevalence and lower associated morbidity. It is also not included in mass drug administration programmes for STH control.

Bacterial

Fig. 2.01, Neonatal tetanus.

Fig. 2.02, Progress towards elimination of maternal and neonatal tetanus.

Fig. 2.03, Opisthotonos in tetanus.

Fig. 2.04, Risus sardonicus in adult tetanus.

Fig. 2.05, Burkholderia pseudomallei , the cause of melioidosis.

Fig. 2.06, Pneumonia due to melioidosis.

Fig. 2.07, Suppurating parotid abscess due to Burkholderia pseudomallei.

Helminthic

Fig. 2.08, Estimated global burden of hookworm.

Fig. 2.09, Adult Ancylostoma attached to intestinal mucosa (left) with ingested red blood cells visible in the intestine of the worm in cross-sectional view (right).

Fig. 2.10–2.14, Life cycle of Necator americanus and Ancylostoma duodenale.

Fig. 2.15, Ecology of geohelminth infection.

Fig. 2.16, Hookworm anaemia.

Fig. 2.17, Cutaneous larva migrans (‘creeping eruption’) due to larvae of animal Ancylostoma hookworms.

Fig. 2.18, Adult Ancylostoma caninum in human ileum.

Fig. 2.19, Distribution of strongyloidiasis.

Fig. 2.20, Life cycle of Strongyloides stercoralis.

Fig. 2.21, Rhabditiform larva of Strongyloides stercoralis in faeces.

Fig. 2.22, Sections of parasitic female and eggs embedded in jejunal mucosa.

Fig. 2.23, Migrating larvae of Strongyloides stercoralis in skin—larva currens.

Fig. 2.24, Haemorrhagic pneumonia in disseminated Strongyloides stercoralis infection.

Fig. 2.25, Section of lung from a patient with disseminated Strongyloides stercoralis.

Fig. 2.26, Eggs of Strongyloides fülleborni in faeces.

Fig. 2.27, Head capsule of adult Ternidens deminutus.

Fig. 2.28, Eggs of Ternidens deminutus and hookworm compared.

Fig. 2.29, Adult male Trichostrongylus .

Fig. 2.30, Eggs of Trichostrongylus and Strongyloides stercoralis in faeces.

Fig. 2.31, Oesophagostomum bifurcum in the human colon.

Fig. 2.32, ’Dapaong tumour’ in a Togolese boy.

Fig. 2.33, Oesophagostomum in a human appendix.

Water

Humans have a daily need for water for multiple purposes. In addition to the danger posed by ingestion of unsafe water ( Chapter 3 ), cutaneous and mucocutaneous contact with contaminated water can also expose individuals to a significant number of infectious pathogens.

Table 2.1
HIV-associated opportunistic infections and neoplastic disorders
Category Agent Clinical syndrome Distribution Atlas reference
Viral infections CMV Retinitis, colitis, oesophagitis Global 2.103 , 2.104
HSV Mucocutaneous ulceration of increased severity Global 2.72
VZV Increased risk of varicella zoster reactivation (‘shingles’) and dissemination Global 4.16 , 4.17
JC virus Progressive multifocal leucoencephalopathy Global 3.12
Molluscum contagiosum virus Molluscum contagiosum (more extensive and persistent in HIV) Global 2.105
EBV Oral hairy leukoplakia, lymphoma Global 2.102
Bacterial infections Mycobacterium tuberculosis Pulmonary and extrapulmonary TB Global 4.34 - 4.70
Mycobacterium avium intracellulare Fever, reticulo-endothelial system involvement Global -
Streptococcus pneumoniae Pneumonia and sepsis Global 4.18 - 4.20
Non-typhoidal salmonellae Sepsis syndrome Global 1.137
Mycobacterium leprae Modified disease manifestations Leprosy-endemic regions 4.71 - 4.93
Bartonella henselae Bacillary angiomatosis Global 2.135
Fungal infections Cryptococcus sp. Meningitis, sepsis Global 4.111 - 4.113
Pneumocystis jirovecii Pneumonia Global 4.94 , 4.95
Candida sp. Oral and oesophageal candidiasis Global 2.160 , 2.161
Talaromyces (formerly Penicillium ) marneffei Sepsis syndrome, rash South-east Asia 4.97 - 4.99
Histoplasma capsulatum Rash, pneumonia, bone-marrow involvement Global 4.100 - 4.102
Paracoccidioidomycosis Cutaneous, mucosal, pulmonary, reticulo-endothelial system involvement Central and South America 2.175 , 4.103 - 4.107
Protozoal infections Plasmodium sp. Malaria Malaria endemic regions 1.102 - 1.166
Toxoplasma gondii Cerebral abscess Global 3.53 , 3.57
Trypanosoma cruzi Meningoencephalitis, myocarditis Central and South America 1.197 - 1.220
Leishmania sp. Visceral leishmaniasis 1 Leishmania endemic regions 1.221 - 1.282
Cryptosporidium sp. Diarrhoea Global 3.38 , 3.52
Isospora sp. Diarrhoea Global 3.38 , 3.51
Microsporidia ( Encephalitozoon hellem, Enterocytozoon bineusi ) Diarrhoea Global 3.59
Malignancies Kaposi sarcoma Cutaneous, pulmonary and gastrointestinal involvement Global – aetiological agent is KSHV (HHV-8) 8.5
Non-Hodgkins lymphoma Visceral and lymph node lymphoma Global – associated with EBV infection -
Primary cerebral lymphoma Cerebral space-occupying lesion Global – associated with EBV infection -
Cervical carcinoma Cervix mass lesion Global – associated with HPV infection 2.76
Anal squamous cell carcinoma Anal mass lesion Global – associated with HPV infection -
Multicentric Castleman’s disease Lymph node enlargement Global – associated with HHV-8 infection -
CMV, cytomegalovirus; EBV, ebola virus; HHV, human herpes virus; HPV, human papilloma virus; HSV, herpes simplex virus; JC virus, John Cunningham virus; KSHV, Kaposi sarcoma-associated herpes virus; TB, tuberculosis; VZV, varicella zoster virus.

1 Lack of evidence of increased risk of cutaneous leishmaniasis in HIV.

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