EndemicTreponematoses¶

Chapter 188 | Part 5: Infectious Diseases · Part 5 – Infectious Diseases: Bacterial · Chapter 188

Key Clinical Points¶

Endemic treponematoses (yaws, bejel, pinta) are caused by Treponema pallidum subspecies (pertenue, endemicum, carateum) and differ from venereal syphilis in transmission mode and clinical features.
Yaws is common in moist tropical areas; bejel in arid climates (West Africa/Middle East); pinta is rare and found in the Americas.
Leptospirosis is a zoonotic disease (Leptospira species) with rodents as primary reservoirs, often presenting with conjunctival suffusion and potentially progressing to Weil's syndrome.
Weil's syndrome is characterized by the triad of jaundice, renal dysfunction, and hemorrhagic diathesis; pulmonary hemorrhage is a critical complication.
Treponematoses diagnosis relies on clinical morphology and serology (RPR/TPPA); NAAT identifies specific subspecies.
Leptospirosis diagnosis involves a biphasic approach: blood/CSF in acute phase; urine/serology in convalescent phase.
Yaws treatment: Azithromycin (30 mg/kg) or Benzathine Penicillin G (2.4 million units IM).
Leptospirosis treatment: Doxycycline (200 mg BID for 7 days), Penicillin G, or Azithromycin; severe cases require IV therapy and organ support.
Conjunctival suffusion (redness without exudate) is a hallmark of leptospirosis.
Distinctive clinical markers: 'Crab yaws' (painful papillomatous lesions on soles), bejel mucosal papules, and pinta dyschromic macules.

1. DEFINITION & OVERVIEW¶

• Treponematoses: Chronic, non-venereal infections caused by Treponema pallidum subspecies (pertenue, endemicum, carateum) that differ from syphilis in transmission mode and clinical features. • Leptospirosis: A zoonotic disease caused by pathogenic Leptospira species (over 260 serovars across 26 serogroups) with rodents as primary reservoirs.

1.1 Classification of Treponematoses¶

• Syphilis: T. pallidum subsp. pallidum (Venereal; transmission via sexual/transplacental routes). • Yaws: T. pallidum subsp. pertenue (Moist tropical regions; skin-to-skin contact). • Bejel: T. pallidum subsp. endemicum (Arid climates of West Africa/Middle East; mouth-to-mouth or shared utensils). • Pinta: T. carateum (Temperate Americas; skin-to-skin contact).

2. EPIDEMIOLOGY¶

• Yaws: ◦ High prevalence in moist tropical regions. ◦ WHO eradication programs (1952–1969) reduced prevalence from >20% to 10% in parts of Ghana/Senegal, but resurgence occurs in Africa and Pacific Islands. • Bejel & Pinta: ◦ Both are now rare. Bejel is found in arid climates (West Africa/Middle East); Pinta is found in Central/South America. • Leptospirosis: ◦ Global distribution; highest incidence in tropics/subtropics. ◦ Transmission via urine-contaminated water/soil, especially during floods. ◦ Risk factors: Agricultural workers, sewage handlers, fishermen, and urban areas with rodent infestations.

• Treponemal Pathogenesis: ◦ Genetic similarity: Subspecies differ by only ~0.2%. ◦ Immune Response: Requires both humoral (antibodies) and cellular (interferon γ) immunity for healing. ◦ Persistence: Antigenic variation of TprK protein allows immune evasion and persistence. • Leptospiral Pathogenesis: ◦ Entry: Skin or mucosa → Hematogenously disseminate to organs (liver, kidney, brain). ◦ Mechanism: Endothelial activation, thrombocytopenia, and consumptive coagulopathy. ◦ Histopathology: Tubular necrosis, hepatocyte apoptosis, and hemorrhagic infiltration.

4. CLINICAL FEATURES¶

• Yaws: ◦ Primary: Painful papillomatous or ulcerative skin lesions on extremities. ◦ Secondary: Cutaneous/mucosal rash, condylomata lata, osteoperiostitis. ◦ Late: Destructive gummas of skin, bone, and cartilage. • Bejel: ◦ Primary: Mucosal papules (oral/genital). ◦ Secondary: Mucous patches, split papules, condylomata lata. ◦ Late: Destructive gummas of skin and bone. • Pinta: ◦ Primary: Non-ulcerating papule with satellites on extremities/face. ◦ Secondary: Pintides (pigmented macules). ◦ Note: No destructive complications. • Leptospirosis: ◦ Incubation: 5–14 days. ◦ Initial Phase: Fever, headache, myalgia (especially calf), conjunctival suffusion. ◦ Severe Phase (Weil's Syndrome): Jaundice, renal failure, hemorrhage, and pulmonary hemorrhage.

5. DIFFERENTIAL DIAGNOSIS¶

• Treponematoses: ◦ Syphilis (distinguished by sexual transmission). ◦ Leprosy (hypopigmented macules). ◦ Cutaneous leishmaniasis (ulcerative lesions). • Leptospirosis: ◦ Viral hepatitis. ◦ Dengue fever. ◦ Rickettsial infections. ◦ Other hemorrhagic fevers.

6. INVESTIGATIONS & DIAGNOSIS¶

Treponematoses Identification: • Clinical evaluation of lesions and epidemiology → Differentiation from syphilis. • Serology: RPR and TPPA (same as syphilis). • Specificity: NAAT to identify specific subspecies (pertenue, endemicum, carateum).
Leptospirosis Identification: • Acute Phase (Leptospiremic): • Blood and CSF → Culture or PCR (preferred for early detection). • Serology: Samples 1 & 2 are acute-phase serum samples. • Convalescent Phase: • Urine → Culture (detects shedding). • Serology: Sample 3 is a convalescent-phase sample (detects delayed immune response). • Follow-up: Samples 4 & 5 provide epidemiologic information, such as the presumptive infecting serogroup.

7. MANAGEMENT & TREATMENT¶

Treponematoses Treatment: • First-line: Azithromycin (30 mg/kg single dose) OR Benzathine Penicillin G (2.4 million units IM). • Note: Macrolide resistance is emerging in some regions.
Leptospirosis Treatment: • Mild cases: Doxycycline (200 mg BID for 7 days) OR Azithromycin (500 mg daily). • Severe cases: • IV Penicillin G (18–24 million units/day in divided doses) OR Ceftriaxone. • Support: Management of renal failure, liver failure, and DIC.

8. PROGNOSIS & COMPLICATIONS¶

• Treponematoses: ◦ Early treatment → Prevents late complications (gummas, CNS/cardiac involvement). • Leptospirosis: ◦ Mortality: ~10% in severe cases. ◦ Critical Complications: Pulmonary hemorrhage and renal failure are primary causes of death. ◦ Long-term: Survivors may have persistent renal or hepatic dysfunction.

9. SPECIAL CONSIDERATIONS¶

• Geographic Risk Zones: ◦ Yaws: Sub-Saharan Africa, Pacific Islands. ◦ Bejel: Middle East, West Africa. ◦ Pinta: Central/South America. ◦ Leptospirosis: Global (high in tropics/subtropics). • Occupational Risks: ◦ Farmers, fishermen, sewage workers, and veterinarians.

10. KEY PEARLS & CLINICAL TRAPS¶

• Leptospirosis Hallmark: Conjunctival suffusion (redness without exudate). • Yaws Hallmark: 'Crab yaws' (painful papillomatous lesions on soles). • Pinta Hallmark: Dyschromic macules without destruction. • Bejel Hallmark: Mucosal papules and osteoperiostis. • Diagnostic Timing: Culture/PCR are most effective in blood/CSF during the acute phase; serology is best for convalescent diagnosis.

Reference Tables¶

TABLE 188-1 Classic Comparison of the Agents of the Human Treponematoses and Their Associated Diseases FEATURE Organism…¶

Harrison's 22e, p.1437

FEATURE	SYPHILIS	YAWS	BEJEL (ENDEMIC SYPHILIS)	PINTA
Organism	T. pallidum subsp. pallidum	T. pallidum subsp. pertenue	T. pallidum subsp. endemicum	T. carateum
	Sexual, transplacental, skin-to-skin	Skin-to-skin	Mouth-to-mouth or via shared drinking/eating utensils, skin to skin, sexuala
Usual age of acquisition	Sexual maturity or in utero	Childhood	Early childhood, adulthooda	Late childhood
	Mucocutaneous ulcer (chancre)	Papilloma, often ulcerative	Mucosal papule, rarely seen
Common location	Genital, oral, anal	Extremities	Oral, occasionally sexuala	Extremities, face
	Cutaneous rash and mucosal lesions; condylomata lata, ocular and otic syphilis	Cutaneous papillomatous or ulcerative lesions; condylomata lata, osteoperiostitis	Mucocutaneous lesions (mucous patch, split papule, condylomata lata); osteoperiostitis
Infectious relapses	~25%	Common	Unknown	Unknown
	Gummas, cardiovascular and central nervous system involvement	Destructive gummas of skin, bone, cartilageb	Destructive gummas of skin, bone, cartilageb