Report on Ngoma health post’s scabies outbreak (2021-2022)
Tom Bombarde
2022-06-28
Summary
Scabies is a worldwide health problem with a particular weight on developing countries (Brooks and Grace, 2022). Despite increased access to Water and Sanitation/Hygiene (WASH) facilities, Ngoma’s health post catchment area (HPC) in Zambia’s Northern province has experienced a rise and persistence of scabies since mid-2021. This report investigated the main drivers of scabies in the region that feed into policy recommendations. Field surveys were conducted at two villages under Kasama district (N=91). Data on the outbreak was taken from Ngoma and Mwamba health clinics. There were three takeaways. (1) Low awareness of scabies may be strongest predictor of scabies in the catchment area. Treatment and preventative measures may not be high enough for water and sanitation/hygiene to play on a role. (2) The list of medicines targeted for scabies would benefit from including Ivermectin. (3) There are structural supply chain issues which worsen chronic stock depletion. Supply chain reforms require greater investment in storage space and distribution fleet. Each problem leads to a set of policy recommendations emphasising the need to raise awareness among community members and clinic staff, invest in supply chains to meet government ambitions, and reevaluate current treatment standards.
I Introduction and background
1.1 Scabies as a health risk
As of 2017, the World Health Organisation (WHO) recognises scabies as
a neglected tropical disease and major public health issue (Hay,
Engelman and Walton, 2022; B&G, 2022). In ordinary cases, 10 to 20
mites that burrow eggs into the host’s skin cause lesions across the
body. In rarer cases, crusted scabies is characterized by higher
contagion and up to 1 million mites per host (Sissons, 2022). Confirming
diagnosis requires identifying mites from their burrow by observing a
skin scraping under microscope, or from the tip of needle. Asymptomatic
individuals carrying 10 to 15 mites are at high risk of false negatives
(Centers for Disease Control and Prevention, 2010).
Though not directly lethal, scabies raises severe health risks. The
parasites both facilitates bacterial superinfection and malnutrition,
while itchiness may lead to social stigma and sleep deprivation
(B&G, 2022). In developing countries with underfunded care services,
costs of treatment present an additional weight on households. The
groups most affected tend to be the most at risk of complications:
children and the elderly in over-crowded, isolated, or poor areas of
hot, tropical climates. Crusted scabies present higher rates among those
with pre-existing conditions such as HIV, dementia, or lymphoma (HEG,
2022; van der Linden, et al, 2019). Scabies is both a physical and
social burden on the world’s large parts of the world, with a particular
toll on the most vulnerable.
1.2 Ngoma Health Post
map of Ngoma HP catchment area, photographed in Ngoma health clinic
Ngoma HP’s catchment area is a group of 14 village in Kasama district, counting 3028 inhabitants as of 2021. Family visits make travel between villages a common occurrence. Villages concerned are Ngoma, Lufila, Kakululu, Africa, Misombo, Mubati, Ntutuka, Muba, Masela, Katampa, Malata and Petro Kabwe villages. Petro Kabwe and Ntutuka were dropped from this discussion due to a lack of available data. Taking all patients registered at the clinic, the sample size was 1817. Demographics served by the health post are presented in Table 1. Gender ratios appear equal across villages. 502 pupils attend Nkole Mwanakulya primary school within Ngoma. Rates of scabies within each grade below was collected by the head of Ngoma HP through 2021.
| Village | Number of males | Number of females | Female:Male ratio | Number of households | Average number of household members | Proportions of households using latrines | Coverage of adequate latrine in village | Borehole Coverage |
|---|---|---|---|---|---|---|---|---|
| Ngoma | 156 | 159 | 1.02 | 64 | 4.9 | 0.16 | 0.70 | 0.003 |
| Lufila | 278 | 297 | 1.07 | 96 | 6.0 | 0.12 | 0.23 | 0.003 |
| Kakululu | 72 | 80 | 1.11 | 54 | 2.8 | 0.15 | 0.13 | 0.013 |
| Africa | 35 | 36 | 1.03 | 15 | 4.6 | 0.17 | 0.67 | 0.029 |
| Misombo | 37 | 37 | 1.00 | 17 | 5.1 | 0.15 | 0.29 | 0.000 |
| Mubati | 60 | 59 | 0.98 | 26 | 4.6 | 0.18 | 0.46 | 0.017 |
| Muba | 122 | 118 | 0.97 | 47 | 5.1 | 0.14 | 0.00 | 0.000 |
| Masela | 56 | 63 | 1.12 | 34 | 3.5 | 0.19 | 0.97 | 0.000 |
| Katampa | 26 | 32 | 1.23 | 42 | 1.4 | 0.55 | 0.36 | 0.052 |
| Malata | 41 | 43 | 1.05 | 21 | 4.0 | 0.38 | 0.14 | 0.000 |
1.3 Previous studies
Predictors of scabies
Previous epidemiological surveys have found higher rates of scabies
among children, adolescents, and the elderly, (Curie and Walton, 2019;
Engelman and Steer, 2018). Three independents studies look at scabies
outbreaks in schools in Ethiopia, Cameroon, and Iran (Eijigu et al ,
2019; Koutou et al , 2016; Sanei-Dehkordi et al ,2021). All find
predictors of scabies to be – in decreasing order of significance – male
sex, low education or knowledge of scabies, and correlates of poor
hygiene. Female patients often report being subject to more stigma and
restrictions than males (van der Linden et al , 2019), which could
contribute to less female-to-female transmissions or risk taking
behavior. Poor socio-economic status, levels of education and knowledge
of scabies could decrease possible precautions against skin-to-skin
contact and facilitate contagion. Finally, the role of personal hygiene
is contentious. Rinaldi and Poulter (2021) refer to successful decreases
in scabies rates after sensitizing local populations to environmental
clean-up. However, Cinetti, et al (2015) show that alcohol-based
hand-rub washing has no effect on the number of mites infesting the
host. In light of these previous studies, gender, awarness, and schools
were investigated as predictors of infection rates in Ngoma HP. Current
debates on the role of hygiene motivated enquiry into the role of WASH
facilities.
Treatment
Topical scabicides are the most common form of treatment. Lindane
(1%) was most used in Western countries until withdrawn and replaced by
Permethrin (5%) due to a risk of neurotoxicity. Both treatments’ high
costs makes Benzyl Benzoate (25%) a more viable option for developing
countries. Ivermectin is increasingly prescribed as an oral treatment in
effective mass drug administration campaigns (Rinaldi and Poulter, 2019;
Walton and Currie, 2018), although avoided for pregnant women and
infants. New alternative treatments such as tea tree give promising
results, motivating further research. Cyclical outbreaks have supported
research into the role of herd immunity, however, persistent infection
in tropical regions and their correlation with other parasites such as
lice suggests that patterns may instead emerge from social dynamics
(Walton and Currie, 2018). This report will consider Lindane (1%),
Permethrin (5%), Benzyl Benzoate (25%) and Ivermectin as potential
treatments for scabies in Kasama district.
1.5 Motivation for this report
2022’s annual feedback revealed scabies as a primary issue for
inhabitants of Mwamba Area Program. Cases have risen despite greater
water accessibility, sanitation, and hygiene. The dissonance between
increased sanitation and infection rates has raised frustration within
communities and concern from World Vision staff. This report sought to
develop a clearer vision of the outbreak in 2021 to feed into strategies
for the prevention, treatment, and control of scabies henceforth. A
literature review fed into possible predictors. Two qualititative
surveys and interviews with Ngoma, Mwamba and District Health Office
clinicians assessed general awarness of scabies. An illustrative
cost/effectiveness analysis questions the optimality of current
treatment standards. Qualitative surveys in Ngoma HP’s villages
identifies risky behaviours in transmission and treatment. Finally, the
district health office and naitonal standards were consulted to address
supply chain issues. Policy recommendations follow from these three
approaches.
II Methods
2.1 Data
There had been no previous outbreaks in community members or health
staff’s memory. Health clinics diagnosed scabies by symptomatic lesions
across the body. Scabies symptoms can be confused with other skin
conditions, however, none of which are contagious (Santhakumar and Bard,
2021). Data collected from Ngoma health post, providing rates of scabies
infection across village, gender, and school years was complimented by
two qualitative surveys from mothers present for Growth Monitoring
Program (GMP) sessions. The first was conducted on the 2nd/June/2022,
from 26 mothers in Lufila village. The second was collected at the Ngoma
health post from 62 females and 3 males from various villages on the
24th/June/2022. The full questionnaire is presented in the appendix.
Boreholes per village were identified with mWater. T-tests on the
influence of boreholes or latrines in scabies prevalence held limited
statistical power, so emphasis was put on data visualisation without
generalisation. However, Ngoma’s GMO survey and the data collected from
Ngoma HP met the requirement for at least 80% statistical power.
2.2 Effectiveness of treatment
Successful treatment rates were taken from Bush and Dubin (2003).
This report assumes the following:
(1) a single application of topical Permethrin 5% to be 98.7% effective
in eliminating scabies
(2) a single dose of oral Ivermectin 200 \(\mu\)g/kg to be 95% as effective as a
single application Permethrin.
(3) a single application of Lindane 1% solution to be equivalent to a
single dose of Ivermectin 200 \(\mu\)g/kg
(4) two applications of Benzyl Benzoate 10% solution to be equivalent to
a single dose of Ivermectin 100 \(\mu\)g/kg. In lack of further information,
this report assumes that Benzyl Benzoate 25% (BB) is equivalent to a 200
\(\mu\)g/kg dose of Ivermectin
(I).
For simplicity, costs and benefits are limited to treating isolated
patients, omitting environment and interaction. The treatment success
(cure) rate is assumed to be constant with respect to iteration of
treatment. As such, proportion of patients cured at time n with
treatment k is the sum of those cured at time \((n-1)\) and those successfully cured by
treatment \(k_{n-1}\) . Hence, the cure
rate of the n-th treatment of a treatment k is:
\[k_n=k_{n-1}(1-r) + k_{n-1}\]
Assumption (4) is then that:
\[r_{I} = BB_{1}(1-r_{BB}) + BB_{1}\] Or:
\[r_{I} = rr_{BB}(1-r_{BB}) + r_{BB}\]
Where \(r_{I}\) is the effectivness
of a single dose of Ivermectin 200 \(\mu\)g/kg. Solving for the cure rate for
Benzyl Benzoate 25% gives:
\[r_{BB} = 1- \sqrt{ 1-r_{I} } \]
2.3 Cost of treatment
In a first instance, costs were pooled from available internet
sources to reflect US prices. Drugs.com (2022) reported the price of
Ivermectin as 4.66$ per 3mg tablet, Lindane 1% as
125.83$ per 60ml, and Permethrin 5% as 62.81$
per 60g. The lowest possible price for Benzyl Benzoate at Walmart was
283.7 $ per 500ml. Next, US prices fed into price per
treatment, using: - the necessary dose of Ivermectin for a 60kg adult. -
30g of Permethrin 5% for treating scabies on an average adult, as
suggested by Drugs.com (2020). - 30ml for treatment of Lindane 1%. Thus,
estimates gave 13.98$ for a dose of Ivermectin,
31.405$ for an application of Permethrin 5%,
62.915$ for Lindane 1% and 17.02$ for Benzyl
Benzoate (25%). The cost of each treatment over ten periods were
computed by iterating treatment to all those not cured in the previous
period, assuming the same success rate for initial and incremental
treatments.
Second, prices were collected where available from 3 Kasama pharmacies.
2 only had stocks of Benzyl Benzoate (25%). The set prices for 100ml of
Benzyl Benzoate were 30ZMW (1.84$) and 20ZMW
(1.22$). Taking the mean as reference price, the cost of a
single treatment of Benzyl Benzoate (25%) is 8.33 ZMW
(0.51$). Only 1 pharmacy could provide tablets of
Ivermectin (12mg), priced at 1000 ZMW (61.27$) for a box of
100 tablets. For a 60kg adult, the price of one dose would be \(\frac{0.2*60}{12}\) \(\frac{1000}{10}\) = 10 ZMW
(0.61$).
No pharmacies were able to provide prices of Lindane, Permethrin or
Malathion.
Cost/benefit was computed as the expected cost of successful treatment
over the probability of the patient being cured after 2 periods. This
method neglects environmental factors and interaction, however, allows
an illustrative estimate of cost/benefit.
III Results
3.1 Outbreak description
| Village | Infection rate | Number of infected individuals | Total Population |
|---|---|---|---|
| Ngoma | 0.06 | 20 | 315 |
| Lufila | 0.46 | 266 | 575 |
| Kakululu | 0.48 | 73 | 152 |
| Africa | 0.10 | 7 | 69 |
| Misombo | 1.00 | 86 | 86 |
| Mubati | 1.00 | 119 | 119 |
| Muba | 0.09 | 21 | 240 |
| Masela | 0.18 | 21 | 119 |
| Katampa | 1.00 | 58 | 58 |
| Malata | 0.21 | 18 | 84 |
Ngoma and Mwamba clinicians date the start of the outbreak to mid 2021, and its peak during the rainy season. All villages and 38% of all Ngoma HP’s patients reported scabies throughout the year. The mean village infection percentage was 45%, with median 21%. Infected households recall all members being infected around the same time, with no group of individuals affected earlier than others. Village population was not a significant predictor of infection rate (p-value = 0.1987, T statistic CI : [-0.8199591; 0.2016258]). In Katampa and Misombo, all community members reported being affected in the past year. Ngoma (6%) and Muba (9%) reported the lowest number of cases. Lufila represents both 32% of Ngoma HP’s population and 39% of its cases. Misombo and Mubati are particularly affected, as reflected by their inflation from respectively 5% and 7% to 12% to 17% of all values (Figure 3a and 3b). A survey of 60 mothers and children and 5 men during a Growth Monitoring program (GMP) in Ngoma counted 56 out 65 community members with scabies. If this were a random sample from Ngoma’s population, the full proportion of infected patients could be estimated at 86% (CI: [0.69, 1]) from Ngoma villages’ survey, using finite-population bootstrap. However, the population that attends Growth Monitoring Programs may be more sentized or mobile than the rest of Ngoma’s catchemnt area, skewing the survey’s result.
Total population and reported scabies cases per village served by Ngoma health post in 2021
Population and infection proportions for villages served by Ngoma health Post in 2021
3.2 Transmission
Community members appeared largely unaware of the nature of scabies
Community members and health staff shared confusion on the nature of
scabies. Of the 65 community members surveyed during Ngoma’s GMP, 56 had
had scabies in the past year. When asked what causes scabies, community
members in Lufila and Ngoma cited “contaminated water”, “air”,
“weather”, “bad soap”, “food” and “sexual intercourse”. A nurse in
Mwamba described scabies as a virus transmitted through ‘bodily fluids’.
An Ngoma clinician described scabies as a ‘bacterial infection’. Both
associated scabies cases to dirty bathing a transmission through water,
which is highely unlikely.
None reported having received treatment. Instead, mothers – that
reported themselves as the main points of contact for the health post –
said to have washed more regularly despite a lack of clean water, soap,
or soap of higher quality. Those asked said the lack of spare clothes
made it unfeasible to isolate all cloth items for 3 days, as often
recommended in the treatment of scabies. Health staff also showed
confusion. In Ngoma village, 18/65 of those present prefered a topical
application rather than oral treatment such as Ivermectin.
Gender, school grade, and hygiene does not predict scabies cases
No households claimed to have reduce contacts with other friends and
relatives within or outside their own village. Gender for all age groups
did not show any influence on scabies infection rates (p-value: 0.91,
mean infection rate for males: 0.43, mean infection rate for females:
0.44).
A visit by Ngoma HP’s head clinician in June 2022 diagnosed 31% of
puplis at Nkole Mwanakulya with scabies. Most infected pupils were
allowed to continue to attend. All grades experienced rates of scabies
without a significant pattern, although infection rates were higher for
pupils in higher grades (Figure 4).
No pattern appears in plotting WASH criteria to infection rates (Figure
5). Neither coverage of latrines or boreholes nor latrine use was
significant enough to be sole predictor of infection rates. This was
established by t-tests to the mean infection rates of villages with
latrine-use above and below median latrine use (p-value:0.34, first
mean: 0.14, second mean: 0.08), adequate latrines (p-value:0.15, first
mean: 0.30, second mean: 0.09), and boreholes to population
(p-value=0.26, first mean: 0.31, second mean: 0.61). The means for
borehole and latrine coverage presented wide confidence intervals, and
the ratio of the two groups’ infection rates between the two mean groups
were high infection rates (Figure 4).
Rates of scabies per grade in Nkole Mwanakulya school in 2021
Infection rate per latrine use and coverage of villages served by Ngoma health post
3.3 Treatment: Benzyl Benzoate is not unilaterally the most cost-effecient
| Treatment | Cure rate | Cured after X periods | Cost per treatment (US) | Total cost of treatment over X periods (US) | Cost/benefit ratio (US) | Cost per treatment (Kasama) | Total cost of treatment over X periods (Kasama) | Cost/benefit (Kasama) |
|---|---|---|---|---|---|---|---|---|
| Permethrin 5% | 0.978 | 1.000 | 31.405 | 94.199 | 94.200 | NA | NA | NA |
| Benzyl Benzoate 25% | 0.734 | 0.981 | 17.018 | 49.526 | 50.479 | 0.523 | 1.521 | 1.550 |
| Lindane 1% | 0.929 | 1.000 | 62.915 | 188.406 | 188.473 | NA | NA | NA |
| Ivermectin (200micrograms/kg) | 0.929 | 1.000 | 13.980 | 41.865 | 41.880 | 0.613 | 1.834 | 1.835 |
The health clinic ran out of its only treatment for scabies (Benzyl
Benzoate 25%) in May 2022. Nurses in Mwamba clinic reported more
frequent periods of stockouts - which could last up to 4 months -
through the rainy season. Because of Mwamba clinic’s relative ease of
access, its stockouts are a consequence of depletion at the Health
District Office itself, on which the clinic still relies on for
treatments of scabies despite recent reform. In Ngoma, the District
Health Office was unable to supply stocks through the rainy season due
to unclear roots and only one light track vehicle for
distribution.
Cost/effectivness of treatment reveals Ivermectin as a competitive option.
US
Permethrin 5% and Ivermectin 200 μg/kg display the highest cure rates. In this simplified treatment model, a single dose of Ivermectin 200 μg/kg is both the cheapest and most cost/effective, followed by Benzyl Benzoate 25%, Permethrin 5% and Lindane 1%.
Zambia
Prices obtained at Kasama pharmacies make Benzyl Benzoate the most cost efficient. In addition, qualitative surveys reveal a prefernce for topical applications. 18/65 (~28%) mothers interviewed in Ngoma HP reported preference for a 24 hour long topical application over a dose of oral treatment. Assuming the survey to be a random sample from Ngoma HP’s population, an empirical bootstrap estimate for all Ngoma HP is 27% with 95% confidence interval [6%, 49%].
IV Discussion
4.1 Scabies prelevance
Transmission sites
Awareness in the Ngoma Health Post’s catchment area is minimal. This
increases the likelihood of three transmission channels. Firstly,
interviewees in Ngoma reported frequent trips to relatives in
neighbouring villages. None suggested that they limited travel because
of scabies. Inter-village visits thus present a reasonable hypothesis
for transmission across the health post’s area. Secondly, community
members interviewed at Ngoma confirmed buying clothes from the village
monthly market. The monthly market passes through all villages of the
Kasama district, reselling clothes from across villages. Because mites
can live up to three days without a host, second-hand clothes within
ambulant markets may have acted as vehicles for scabies (Bush and Dubin,
2003). Finally, continued school attendance may have allowed mites to
propagate from children with scabies. Children wearing the same uniform
everyday may have additionally increased risks treatment failure.
The role of latrines and boreholes in scabies control
The lack of significant correlation between WASH facilities may be a
consequence of poor awareness.
Mean infection rate for those above and below median borehole or latrine
coverage present a two-fold difference and wide confidence intervals,
and this report lacked the statistical power to dismiss WASH facilities
as a co-predictors of scabies rates. WASH facilities may in fact be
particularly relevant to Ngoma HP. Community members without spare
clothes dismissed being able to isolate items for three days. This makes
thorough washing of bedding and clothes the only viable recommended
option for environmental treatment.
However, no community members interviewed in either surveyed said to
have treated clothes or bedding. Awareness may hence have been too low
to make a WASH a decisive factor for Ngoma HP, as reflected in
patternless Figure 5. Moreover, despite clinics’ fears, the water-borne
transmission of scabies is “highly unlikely” (CDC, 2020). Walton and
Currie (2007) point to high scabies rates among populations with strict
hygiene. The erroneous association of scabies to hygiene problem is
associated to confounding scabies with a bacterial or viral infection,
rather than parasitic mites (Middleton et al, 2018). As such, this
report joins previous studies in failing to substantiate a link between
hygiene, sanitation, and scabies proliferation.
4.2 Medecine
Treatment choice
Ivermectin appears to be a neglected cost/effecient treatment of
scabies. Opting out of Ivermectin may be justified by its unsuitability
to pregnant women or infants, or community members’ preference for
topical treatments expressed in Lufila and Ngoma. The standard treatment
guidelines of the Ministry of Health for Zambia (2020) omit Ivermectin
as a treatment for scabies, prescribing instead solely Benzyl Benzoate
25%, Permethrin 5% or Malathion 0.5% - a scabicide more expensive than
Benzyl Benzoate 25% and less effective than Lindane 1% (Goldust and
Rezaee, 2013). Ngoma health clinic has stocked on Benzyl Benzoate (25%)
under a budget constraint. Such a choice holds for Kasama pharmacies,
however, drops for US data, which reverses the price order and
cost-effectiveness of Benzyl Benzoate (25%) versus Ivermectin.
Meanwhile, Ivermection has been shown to be more efficient than
Permetherin 5% against cases of crusted scabies and in mass drug
administration campaings (Shenfield, 2004; Rinaldi and Poulter, 2019).
The cost efficiency of Ivermectin calls for further consideration.
Chronic shortages have exacerbated the outbreak. Shortages slow
treatment and run additional health risks. Members of the health clinic
reported prescribing penicillin and anti-biotics once depleted of Benzyl
Benzoate (25%), breaching rational drug use guidelines (Ministry of
Health, 2020). Such a practice may confuse yearly quantification of drug
usage in Kasama, as well as add to an overprescription of anti-biotics
that accelerates the development of antimicrobial resistance, a worlwide
health risk (Ferri et al, 2017). Though beneficial for potential
infection of scratches, these prescriptions cannot cure scabies on their
own, and thus appear ultimately inefficient as well as high risk (Buffet
and Dupin, 2003).
Stockouts as a consequence of supply chain issues
Ngoma health post reported depleting its stock of Benzyl Benzoate (25%) in May 2022. Visiting Kasama District Health Office (DHO) bore insight into systemic issues. Namely, health facilities such as Ngoma HP fail to meet the minimum storage requirements set out by the National guidelines on operating health shops (MoH, 2017). Kasama DHO ’s distribution fleet consists of a light track vehicle for 45 health clinics. Deliveries to all clinics may take up to a week of commutes. The light track vehicle cannot reach Ngoma HP during the rainy season. These inadequacies reflect poorly on high investment ambitions set by the 2019-2021 national Health Sector Supply Chain Strategy and Implementation Plan (HSSCIP, MoH, 2019). In addition, the HSSCSIP aims to transfer all health clinics from a three-tier to a more efficient two-tier drug provision system (Ladder et al, 2019, which Ngoma HP has yet to complete. In sum, chronic shortages of scabies treatments in Ngoma HP succeeds substandard storage space, distribution fleet at the central district health office, and a drug provisionment model Zambia is currently abandonning.
V Policy recommendations
Facilitate the sensitization of community members and local authorities to the nature, treatment and transmission of scabies . World Vision has built strong relationships and communication with local communities. Medical case studies emphasise awareness of scabies as the first predictor of scabies. To tackle the outbreak in Ngoma, community members need to know to (1) reduce contact with other households if affected by scabies, (2) apply treatments to all household members simultaneously, (3) wash clothes or let these out to dry for a period of minimum 3 days. Local authorities should be notified of the skin-to-skin transmission of scabies mites so as to limit spread by monthly markets, schools, and events with high rates of bodily contact. The association of scabies to bathing in contaminated water could discourage community members without access to cleaner sources from sanitation, increasing the likelihood of superinfection. It should be stressed that water-borne transmission of mites is highely unlikely.
Add government standards on storage and drug provision to Citizen Voice and Action documents, namely: the Health Sector Supply Chain STrategy and Implementation Plan (MoH, 2019) and GUIDELINES ON OPERATING A HEALTH SHOPS (MoH, 2017). Kasama HDO has highlighted a number of sub-standard delivery problems in the district. World Vision Zambia has successfully implemented Citizen Voice and Action programs that establish dialogue between government providers and community members (World Vision, 2021). By providing communities with government standards and monitoring their implementation, citizens are emboldened to resolve problems alongside government officials. However, the documents provided to CVA groups as of yet fail to include drug provisionment and health faciltity storage standards. Doing so may highlight and address shortcomings in health facilities such as Ngoma HP. In addition to collecting monitored provision of drug orders and prescriptions, CVAs are thus likely to hold high potential if the Health Sector Supply Chain STrategy and Implementation Plan (MoH, 2019) and Guidelines on operating a Health Shop (MoH, 2017) are included in the handout on standards provided.
Request Iveremectin and Benzyl Benzoate as Emergency and Supplementary Gifts in Kind from donors. Supply chain issues are a challenge being addressed by national reforms in Zambia being implemented since 2019. In the meantime, however, Ngoma HP remains underserved as Kasama District Health Office (HDO) itself has depleted its stock of Benzyl Benzoate. In the US, Ivermectin is cheaper per scabies treatment than Benzyl Benzoate (25%). As of yet, Ivermectin is the most effective drug in mass administration campaigns tackling institutional scabies, such as those experienced by Ngoma’s catchment area’s schools. Regrettably, Ivermectin is not listed on the Zambian Ministry of Health’s Standard Treatment Guidelines for scabies, which are still undergoing review. As such, Kasama DHO is unable to procure the drug, but can redistribute it if received as a donation. Donations of Ivermectin are thus desirable to help alleviate chronic drug shortages, provide a more cost-effective treatment, and fill a gap in the DHO’s own strategy. For these reasons, World Vision has high potential impact in liasing between donors for which Ivermectin is the most cost-effective and Health clinics unable to restock on both adequate and optimal treatment.
V Limits of this report:
This report was constrained by a lack of available data. Firstly, data on scabies and WASH facilities in other areas of Northern Zambia could lead to more conclusive their relationship. This study has shown that it is unlikely that a single WASH facility is a sole predictor of scabies. Increasing its sample size would allow for inference on the combined effect of WASH facilities, or the difference between those in the most and least access to WASH. Secondly, clinicians reported an increase in HIV cases over the past year. Immnodeficiency increases the risk of crusted scabies, which increases contagion. Data on the evolution of crusted scabies might reveal any links to rises in HIV. Finally, this report’s cost-effeciency analysis has relied on the simplifying treatment success rates to be constant with iteration. Additionally, it was inferred that two applications of Benzyl Benzoate (25%) are equivalent to one dose of Ivermectin (0.2mg/kg). Amending both assumptions requires further data on the efficacy of treatments. This would be necessary for conclusive cost-effectiveness model of scabies, such as proposed by van der Linden et al (2019), that considers probabilities of successful diagnosis, developing crusted scabies, correctly applying treatments, and reinfection.
VI Conclusion
The scabies outbreak in Ngoma Health Post has affected equally across gender and age. The persistence of scabies cases is facilitated by high transmission rates and struggling treatment. Low awareness have made continued visits to relatives, markets, and schools easy spreading sites. Treatment has struggled in provision and compliance. A limited distribution fleet and substandard storage space in Ngoma clinic have increased the likelihood of chronic stockouts. Available treatments are unlikely to be followed by necessary clothes and bedding washes. Finally, the prescription of Benzyl Benzoate is not necessarily the most-efficient. Ivermectin may be potentially cheaper per treatment more effectiveness in mass drug administrations. It’s omission from national standard treatment guidelines calls for reconsideration. Ultimately, the scabies outbreak in Ngoma stress needs to better sensitize communities to the nature and treatment of new epidemics, investment in supply chains infrastructure in line with government standards, and updates to national standard treatment guidelines.
Appendix
Questionnaire delivered during Lufila(22/June/2022, n=26) and Ngoma(24/June/2022, n=65) growth monitoring program sessions:
- Do you send your children to school with scabies?
- Who is most likely to go the health clinic for scabies affecting the
entire household?
- Have you taken up any practices to treat and control scabies?
- Have you visited the clinic for scabies?
- Have you mixed with other households knowing that either members has
scabies?
- What do you believe causes scabies?
- When and how do you wash?
- Do you remember which member of the household first started display
scabies symptoms?
- Has anyone received treatment?
- Do you remember when the outbreak started?
Statistical power for estimating boreholes and latrines use as predictors for village infection rates
I challenge the assumption that boreholes or access to latrines is
the sole predictor of scabies. The minimum infection rate was 0.01, the
maximum 1. I thus assume a great difference between mean infection rates
for a village with scabies, and the other without : (0.95 - 0.05) =
0.9.
I then make a conservative estimate of standard deviation for a village
infection rate. The number of infected community members follows a
binomial distribution with n being the number of villagers and p being
the probability of being infected. I take the minimum village headcount,
Katampa’s 58 members, and the probability of infection yielding the
highest variance, p = 0.5. Then Katampa’s maximum variance of infection
rate is 14.5/(58)=0.25 with standard deviation 0.5.
So
mean1-mean2=0.9
sd=0.5
Cohen’s d = 0.9/0.5 = 1.8
pwr.t.test(d=1.8, power=.8)
Output: Two-sample t test power calculation
n = 5.976665
d = 1.8
sig.level = 0.05
power = 0.8
alternative = two.sidedNOTE: n is number in each group
Then at maximum, the sample size of each sample of village(number of villages) require to have 80% statistical power is smaller or equal to 6. Because I dichotomies villages above and below median boreholes or latrines coverage, these conditions satisfy 80% statistical power. However, this limits the study to assessing whether boreholes per village, latrine coverage, or latrine use are the sole predictors of scabies in an Ngoma villages. A greater number of villages would allow for a less stringent assumptions.
```
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