Risk factors for the transmission of kala-azar in Fangak, South Sudan

Author(s): John Lagu Nyunguraa (a), Venny C.S Nyambatib (b), Mugo Muitac (c) and Eric Muchirid (d)

(a) MSc. Applied Epidemiology Ministry of Health, Government of Southern Sudan [email protected]
(b) PhD. Department of Biochemistry, Jomo Kenyatta University of Agriculture and Technology, Nairobi, Kenya
(c) MD MPH. Resident Advisor, Field Epidemiology and Laboratory Training Program, Southern Sudan 
(d) PhD. Field Epidemiology and Laboratory Training Program Nairobi, Kenya


This article reports a case controlled study of kala-azar done in Fangak County in 2007. Fifty-six percent of the cases were under 5 years old. Most patients came for treatment two months or more after the onset of symptoms.

Outdoor night-time activities and the use of “Smoking” (non-insecticide treated) bed nets were associated with kala-azar infection whereas the use of bed nets during the rainy season decreased the risk of infection.

It is recommended that there should be a greater distribution of treated bed nets and more kala-azar treatment centres in the county.


Leishmaniases are caused by 20 species of Leishmania (L) and transmitted by 30 species of sandfly (3). The sandfly bites humans at night, primarily at twilight. Ninety percent of kala-azar/Visceral leishmaniasis cases occur in Bangladesh, India, Nepal, Sudan and Brazil (4). Kala-azar is caused by L. donovani complex, which includes L. donovani, L. infantum and L. chagasi. It is characterised by

  • prolonged irregular fever
  • lymphadenopathy
  • hepato-splenomegaly and
  • progressive anaemia (5).

The disease kills almost all untreated patients (6).

The endemic belt in the Sudan stretches from the Atbara River in the north-east to the Southern Sudan, Nuba Mountains and Darfur (7).         Phlebotomus orientalis is the vector transmitting kala-azar in Sudan and is associated with black cotton soils and vegetations of Acacia seyal and Balanites aegyptiaca (8). However, in Kapoeta P. martini may be the vector (9). 

Materials and methods

An unmatched case control study was carried out in Fangak County from October to December 2007. Questionnaires drafted in English were translated orally into the Nuer language. Exposure histories were taken retrospectively for the past year. This study was managed at the Coordinating Committee of the Organization for Voluntary Service (COSV) at a primary health care centre (PHCC).

The target population was kala-azar patients aged above two months old who had been living in Fangak County for at least two months and who presented for medical care. The sample size was calculated using statcalc in Epi Info 3.3.2 software. The following was employed: ratio of controls to cases, 2:1; power of 80%; confidence interval level of 95%.  A sample size of 144 was obtained.

Two health facility controls that tested negative by dipstick were randomly selected for each case identified. Relatives of kala-azar patients were excluded as controls. Data were entered into the computer using Epi Info version 3.3.2 and kept confidential. Univariate, bivariate and unconditional logistic regression analyses were performed. 


There were 144 study recruits, 48 (33%) were cases and 96 (67%) were controls. Among the cases, 21 (44%) were males and 27 were females. Twenty-seven (56%) of all cases were under five years old (see Table 1) and 24 (89%) of these were under three years old.

Table 1. Distribution of cases and controls by age


n (%)


n (%)




Age in years



0- 5

27 (56)

60 (63)


10 (21)

8 (8)


  2 (4)

4 (4)


  3 (6)

4 (4)


  3 (6)

4 (4)


  3 (6)

16 (17)

Age range

9 mo-45 yrs

5 mo-62 yrs


Thirty-seven (77%) kala-azar patients presented for treatment at two months or more after the onset of symptoms (see Figure 1). Often traditional treatment is tried first. Figure 2 shows a child who has been treated with facial tattoos.  Figure 3 is a child with kala-azar seen during the 2010 outbreak. 

All cases of kala-azar had fever and enlarged lymph nodes (lymphadenopathy), 46% had an enlarged spleen (splenomegaly) and 42% an enlarged liver (hepatomegaly). Table 2 shows the number of cases and controls sleeping under different types of bed nets. Only 4 cases and 2 controls did not use a bed net. 69% of both cases and controls used bed nets purchased by the family.

Figure 2. Distribution of patients by duration of illness before starting treatment

Table 2. Bed net use by cases and controls

Bed net use


n (%)


n (%)

Uses no bed net

4 (8)

2 (2)

Family purchased bed net

33 (69)

66 (69)

Type of bed nets used:

“Polyethylene” insecticide treated bed nets

0 (0)

24 (25)

“Dhamoria” non insecticide treated bed net

24 (50)

46 (48)

“Smoking” non insecticide treated bed nets

20 (42)

24 (25)

Total using any type of bed net

44 (92)

94 (98)

Note: The “Dhamoria” and the “Smoking” are types of non-insecticide treated bed nets. “Smoking” bed nets are made of green silky fibre in Khartoum. “Smoking” clothes are a favourite garment for Sudanese women who cover themselves with smoking from head to toes. People in Fangak prefer this type of bed net because it gives privacy outside during the hot season (see Figure 4)


Table 3. Multiple logistic regression analysis for bed net use and the occurrence of kala-azar infection



(95% C.I.)

P- value

Always uses bed net in rainy season




Uses “Smoking” type of bed nets





Table 3 shows that the use of the “Smoking” type of bed nets was statistically significantly associated with kala-azar infection, while consistent use of a bed net during the rainy season (May to October 2007) was protective against kala-azar.


Figure 2. Attempt to treat Kala-azar using traditional treatment (facial tattoos)


Table 4. Bivariate analysis for environmental factors





Keep sleeping on damp/wet floor




Cracks inside or outside  sleeping house




Sleeping house less than 100m from the river/stagnant water source





House near an anthill




House near Acacia seyal (Seb or Luor) 




House near Balanites aegyptiaca (Thaou)




House near Azadiracta indica (Neem)




Occasionally play in the dark in the forest or around houses





Of the environmental factors analysed in Table 4, outdoor night activities were associated with kala-azar infection (p = 0.02). There was a “tendency towards significance”/borderline association when anthills (p = 0.07) and B. aegytiaca were near homes. When these factors were subjected to multiple logistic regression analysis, only outdoor night activities retained statistical significance (p = 0.01) (see Table 5).

Figure 3. Patient with Lala-azar seen during the 2010 outbreak at Fangar. He is visibly wasted and has an enlarged abdomen (splenomegaly)


Table 5. Multiple logistic regression analysis

Environmental variables


(95% C.I.)

P- value

B. aegyptiaca in the compound




Ant hills near home




Often spends time in night time activities (traditional dances and children games)





More than half of the participants affected by kala-azar were children aged less than five years. The greater susceptibility of the young children in the Fangak study could be due to malnutrition and an immature immune system. Lack of knowledge on kala-azar treatment by the family may have contributed to patients coming late for treatment.

This study indicated the following statistically significant associations:

  • Engaging in night-time activities (e.g. dancing and games) increases the risk of kala-azar infection.
  • A person is two and half times more likely to be at risk of getting kala-azar using a “Smoking” bed net than a treated bed net. The reason for this is not clear.  However the “Smoking” type of bed nets are made of light silk fibre so are easily blown away by the wind while the person is sleeping.
  • The regular use of a bed net during the rainy seasons provides a degree of protection from kala-azar - a finding similar to that in a study from Bangladesh (10).

Although it was reported that almost everyone slept under a bed net, most used non-insecticide treated bed nets. It was reported that among the kala-azar cases nobody was sleeping under an insecticide-treated bed net; 42% of cases were using “Smoking” bed nets compared with 25% of the controls.

Further analyses are needed to clarify the associations between kala-azar and other types of non-treated bed nets, and whether people using “Smoking” bed nets are more likely than others to be involved with night-time activities. It is hoped to publish these results later.

The authors recommend increased distribution of treated bed nets and the expansion of kala-azar treatment centres in the county.

Figure 4. Types of bed nets is use (smoking on left and Dhamoria on right)

Treatment of kala-azar

The official guideline adopted by the Ministry of Health is:

1.     Sodium stibogluconate (20mg/kg)/day and paromomycin (15 mg/kg)/day for 17 days
2.     Sodium stibogluconate 20mg/kg/day for 30 days
3.     Liposomal amphotericin 3-5mg/kg/day infusion for over 6-10 days up to a total of 30mg/kg
4.     Amphotericin B deoxycholate 0.75-1 mg/kg/day by infusion daily or on alternate days for 15-20 doses
5.     Miltefosine orally at 2.5 mg/kg/day for 28 days

NB: The first three are the medicines currently in use in South Sudan.



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Further reading